Project import generated by Copybara.

GitOrigin-RevId: da3cb82c964457b1c719c915a48e545b980af64b

.bazelrc

@@ -12,9 +12,9 @@ build --copt='-Wno-comment'
 build --copt='-Wno-return-type'
 build --copt='-Wno-unused-local-typedefs'
 build --copt='-Wno-ignored-attributes'
-# Temporarily set the incompatibility flag for Bazel 0.27.0 and above
-build --incompatible_disable_deprecated_attr_params=false
-build --incompatible_depset_is_not_iterable=false
+
+# Tensorflow needs remote repo
+build --experimental_repo_remote_exec
 
 # Sets the default Apple platform to macOS.
 build --apple_platform_type=macos
@@ -23,6 +23,10 @@ build --apple_platform_type=macos
 build --apple_generate_dsym
 
 # Android configs.
+# Note: the documentation tells us to use @androidndk//:default_crosstool, but
+# the automatic configuration transition uses //external:android/crosstool.
+# Using it here works and spares us from having two different config_settings
+# for Android.
 build:android --crosstool_top=//external:android/crosstool
 build:android --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
 build:android --linkopt=-landroid

Dockerfile

@@ -48,7 +48,7 @@ RUN pip install future
 RUN pip3 install six
 
 # Install bazel
-ARG BAZEL_VERSION=1.1.0
+ARG BAZEL_VERSION=2.0.0
 RUN mkdir /bazel && \
     wget --no-check-certificate -O /bazel/installer.sh "https://github.com/bazelbuild/bazel/releases/download/${BAZEL_VERSION}/b\
 azel-${BAZEL_VERSION}-installer-linux-x86_64.sh" && \

WORKSPACE

@@ -2,16 +2,15 @@ workspace(name = "mediapipe")
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
-skylib_version = "0.8.0"
+skylib_version = "0.9.0"
 http_archive(
     name = "bazel_skylib",
     type = "tar.gz",
-    url = "https://github.com/bazelbuild/bazel-skylib/releases/download/{}/bazel-skylib.{}.tar.gz".format (skylib_version, skylib_version),
-    sha256 = "2ef429f5d7ce7111263289644d233707dba35e39696377ebab8b0bc701f7818e",
+    url = "https://github.com/bazelbuild/bazel-skylib/releases/download/{}/bazel_skylib-{}.tar.gz".format (skylib_version, skylib_version),
+    sha256 = "1dde365491125a3db70731e25658dfdd3bc5dbdfd11b840b3e987ecf043c7ca0",
 )
 load("@bazel_skylib//lib:versions.bzl", "versions")
-versions.check(minimum_bazel_version = "1.0.0",
-               maximum_bazel_version = "1.2.1")
+versions.check(minimum_bazel_version = "2.0.0")
 
 
 # ABSL cpp library lts_2020_02_25
@@ -93,11 +92,13 @@ http_archive(
     build_file = "@//third_party:libyuv.BUILD",
 )
 
+# Note: protobuf-javalite is no longer released as a separate download, it's included in the main Java download.
+# ...but the Java download is currently broken, so we use the "source" download.
 http_archive(
     name = "com_google_protobuf_javalite",
-    sha256 = "79d102c61e2a479a0b7e5fc167bcfaa4832a0c6aad4a75fa7da0480564931bcc",
-    strip_prefix = "protobuf-384989534b2246d413dbcd750744faab2607b516",
-    urls = ["https://github.com/google/protobuf/archive/384989534b2246d413dbcd750744faab2607b516.zip"],
+    sha256 = "a79d19dcdf9139fa4b81206e318e33d245c4c9da1ffed21c87288ed4380426f9",
+    strip_prefix = "protobuf-3.11.4",
+    urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.11.4.tar.gz"],
 )
 
 http_archive(
@@ -117,19 +118,18 @@ http_archive(
     ],
 )
 
-# 2020-02-12
-# The last commit before TensorFlow switched to Bazel 2.0
-_TENSORFLOW_GIT_COMMIT = "77e9ffb9b2bfb1a4f7056e62d84039626923e328"
-_TENSORFLOW_SHA256= "176ccd82f7dd17c5e117b50d353603b129c7a6ccbfebd522ca47cc2a40f33f13"
+# 2020-04-01
+_TENSORFLOW_GIT_COMMIT = "805e47cea96c7e8c6fccf494d40a2392dc99fdd8"
+_TENSORFLOW_SHA256= "9ee3ae604c2e1345ac60345becee6d659364721513f9cb8652eb2e7138320ca5"
 http_archive(
     name = "org_tensorflow",
     urls = [
       "https://mirror.bazel.build/github.com/tensorflow/tensorflow/archive/%s.tar.gz" % _TENSORFLOW_GIT_COMMIT,
       "https://github.com/tensorflow/tensorflow/archive/%s.tar.gz" % _TENSORFLOW_GIT_COMMIT,
     ],
-    # A compatibility patch
     patches = [
-        "@//third_party:org_tensorflow_528e22eae8bf3206189a066032c66e9e5c9b4a61.diff"
+        "@//third_party:org_tensorflow_compatibility_fixes.diff",
+        "@//third_party:org_tensorflow_protobuf_updates.diff",
     ],
     patch_args = [
         "-p1",
@@ -154,10 +154,6 @@ http_archive(
     sha256 = "5ba6d0db4e784621fda44a50c58bb23b0892684692f0c623e2063f9c19f192f1"
 )
 
-# Please run
-# $ sudo apt-get install libopencv-core-dev libopencv-highgui-dev \
-#                        libopencv-calib3d-dev libopencv-features2d-dev \
-#                        libopencv-imgproc-dev libopencv-video-dev
 new_local_repository(
     name = "linux_opencv",
     build_file = "@//third_party:opencv_linux.BUILD",
@@ -170,7 +166,6 @@ new_local_repository(
     path = "/usr"
 )
 
-# Please run $ brew install opencv@3
 new_local_repository(
     name = "macos_opencv",
     build_file = "@//third_party:opencv_macos.BUILD",
@@ -203,79 +198,6 @@ http_archive(
     url = "https://github.com/opencv/opencv/releases/download/3.2.0/opencv-3.2.0-ios-framework.zip",
 )
 
-RULES_JVM_EXTERNAL_TAG = "2.2"
-RULES_JVM_EXTERNAL_SHA = "f1203ce04e232ab6fdd81897cf0ff76f2c04c0741424d192f28e65ae752ce2d6"
-
-http_archive(
-    name = "rules_jvm_external",
-    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
-    sha256 = RULES_JVM_EXTERNAL_SHA,
-    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
-)
-
-load("@rules_jvm_external//:defs.bzl", "maven_install")
-
-maven_install(
-    artifacts = [
-        "androidx.annotation:annotation:aar:1.1.0",
-        "androidx.appcompat:appcompat:aar:1.1.0-rc01",
-        "androidx.camera:camera-core:aar:1.0.0-alpha06",
-        "androidx.camera:camera-camera2:aar:1.0.0-alpha06",
-        "androidx.constraintlayout:constraintlayout:aar:1.1.3",
-        "androidx.core:core:aar:1.1.0-rc03",
-        "androidx.legacy:legacy-support-v4:aar:1.0.0",
-        "androidx.recyclerview:recyclerview:aar:1.1.0-beta02",
-        "com.google.android.material:material:aar:1.0.0-rc01",
-    ],
-    repositories = [
-        "https://dl.google.com/dl/android/maven2",
-        "https://repo1.maven.org/maven2",
-    ],
-)
-
-maven_server(
-    name = "google_server",
-    url = "https://dl.google.com/dl/android/maven2",
-)
-
-maven_jar(
-    name = "androidx_lifecycle",
-    artifact = "androidx.lifecycle:lifecycle-common:2.0.0",
-    sha1 = "e070ffae07452331bc5684734fce6831d531785c",
-    server = "google_server",
-)
-
-maven_jar(
-    name = "androidx_concurrent_futures",
-    artifact = "androidx.concurrent:concurrent-futures:1.0.0-alpha03",
-    sha1 = "b528df95c7e2fefa2210c0c742bf3e491c1818ae",
-    server = "google_server",
-)
-
-maven_jar(
-    name = "com_google_guava_android",
-    artifact = "com.google.guava:guava:27.0.1-android",
-    sha1 = "b7e1c37f66ef193796ccd7ea6e80c2b05426182d",
-)
-
-maven_jar(
-    name = "com_google_common_flogger",
-    artifact = "com.google.flogger:flogger:0.3.1",
-    sha1 = "585030fe1ec709760cbef997a459729fb965df0e",
-)
-
-maven_jar(
-    name = "com_google_common_flogger_system_backend",
-    artifact = "com.google.flogger:flogger-system-backend:0.3.1",
-    sha1 = "287b569d76abcd82f9de87fe41829fbc7ebd8ac9",
-)
-
-maven_jar(
-    name = "com_google_code_findbugs",
-    artifact = "com.google.code.findbugs:jsr305:3.0.2",
-    sha1 = "25ea2e8b0c338a877313bd4672d3fe056ea78f0d",
-)
-
 # You may run setup_android.sh to install Android SDK and NDK.
 android_ndk_repository(
     name = "androidndk",
@@ -289,9 +211,15 @@ android_sdk_repository(
 
 http_archive(
     name = "build_bazel_rules_apple",
-    sha256 = "bdc8e66e70b8a75da23b79f1f8c6207356df07d041d96d2189add7ee0780cf4e",
-    strip_prefix = "rules_apple-b869b0d3868d78a1d4ffd866ccb304fb68aa12c3",
-    url = "https://github.com/bazelbuild/rules_apple/archive/b869b0d3868d78a1d4ffd866ccb304fb68aa12c3.tar.gz",
+    sha256 = "7a7afdd4869bb201c9352eed2daf37294d42b093579b70423490c1b4d4f6ce42",
+    url = "https://github.com/bazelbuild/rules_apple/releases/download/0.19.0/rules_apple.0.19.0.tar.gz",
+    patches = [
+        # Bypass checking ios unit test runner when building MP ios applications.
+        "@//third_party:build_bazel_rules_apple_bypass_test_runner_check.diff"
+    ],
+    patch_args = [
+        "-p1",
+    ],
 )
 
 load(
@@ -325,3 +253,49 @@ http_archive(
     build_file = "@//third_party:google_toolbox_for_mac.BUILD",
 )
 
+# Maven dependencies.
+
+RULES_JVM_EXTERNAL_TAG = "3.2"
+RULES_JVM_EXTERNAL_SHA = "82262ff4223c5fda6fb7ff8bd63db8131b51b413d26eb49e3131037e79e324af"
+
+http_archive(
+    name = "rules_jvm_external",
+    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
+    sha256 = RULES_JVM_EXTERNAL_SHA,
+    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+# Important: there can only be one maven_install rule. Add new maven deps here.
+maven_install(
+    name = "maven",
+    artifacts = [
+        "junit:junit:4.12",
+        "androidx.test.espresso:espresso-core:3.1.1",
+        "org.hamcrest:hamcrest-library:1.3",
+        "androidx.concurrent:concurrent-futures:1.0.0-alpha03",
+        "androidx.lifecycle:lifecycle-common:2.2.0",
+        "androidx.annotation:annotation:aar:1.1.0",
+        "androidx.appcompat:appcompat:aar:1.1.0-rc01",
+        "androidx.camera:camera-core:aar:1.0.0-alpha06",
+        "androidx.camera:camera-camera2:aar:1.0.0-alpha06",
+        "androidx.constraintlayout:constraintlayout:aar:1.1.3",
+        "androidx.core:core:aar:1.1.0-rc03",
+        "androidx.legacy:legacy-support-v4:aar:1.0.0",
+        "androidx.recyclerview:recyclerview:aar:1.1.0-beta02",
+        "com.google.android.material:material:aar:1.0.0-rc01",
+        "com.google.code.findbugs:jsr305:3.0.2",
+        "com.google.flogger:flogger-system-backend:0.3.1",
+        "com.google.flogger:flogger:0.3.1",
+        "com.google.guava:guava:27.0.1-android",
+    ],
+    repositories = [
+        "https://jcenter.bintray.com",
+        "https://maven.google.com",
+        "https://dl.google.com/dl/android/maven2",
+        "https://repo1.maven.org/maven2",
+    ],
+    fetch_sources = True,
+    version_conflict_policy = "pinned",
+)

mediapipe/BUILD

@@ -14,6 +14,9 @@
 
 licenses(["notice"])  # Apache 2.0
 
+# Note: yes, these need to use "//external:android/crosstool", not
+# @androidndk//:default_crosstool.
+
 config_setting(
     name = "android",
     values = {"crosstool_top": "//external:android/crosstool"},

mediapipe/calculators/core/BUILD

@@ -228,7 +228,9 @@ cc_library(
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework:collection_item_id",
         "//mediapipe/framework:packet",
+        "//mediapipe/framework/formats:detection_cc_proto",
         "//mediapipe/framework/formats:landmark_cc_proto",
+        "//mediapipe/framework/formats:matrix",
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/framework/port:integral_types",
         "//mediapipe/framework/port:ret_check",
@@ -249,12 +251,14 @@ cc_library(
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework:collection_item_id",
         "//mediapipe/framework:packet",
+        "//mediapipe/framework/formats:classification_cc_proto",
         "//mediapipe/framework/formats:landmark_cc_proto",
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/framework/port:integral_types",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/framework/port:status",
         "//mediapipe/util:render_data_cc_proto",
+        "@org_tensorflow//tensorflow/lite:framework",
     ],
     alwayslink = 1,
 )
@@ -265,10 +269,11 @@ cc_test(
     deps = [
         ":begin_loop_calculator",
         ":end_loop_calculator",
-        "//mediapipe/calculators/core:packet_cloner_calculator",
+        ":gate_calculator",
         "//mediapipe/framework:calculator_context",
         "//mediapipe/framework:calculator_contract",
         "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework:packet",
         "//mediapipe/framework/port:gtest_main",
         "//mediapipe/framework/port:integral_types",
         "//mediapipe/framework/port:parse_text_proto",
@@ -334,6 +339,7 @@ cc_library(
     deps = [
         ":clip_vector_size_calculator_cc_proto",
         "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/formats:detection_cc_proto",
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/framework/port:status",
@@ -693,15 +699,17 @@ cc_test(
     name = "previous_loopback_calculator_test",
     srcs = ["previous_loopback_calculator_test.cc"],
     deps = [
+        ":gate_calculator",
+        ":make_pair_calculator",
+        ":pass_through_calculator",
         ":previous_loopback_calculator",
-        "//mediapipe/calculators/core:make_pair_calculator",
-        "//mediapipe/calculators/core:pass_through_calculator",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework:calculator_runner",
         "//mediapipe/framework:timestamp",
         "//mediapipe/framework/port:gtest_main",
         "//mediapipe/framework/port:integral_types",
         "//mediapipe/framework/port:parse_text_proto",
+        "//mediapipe/framework/port:status",
         "//mediapipe/framework/stream_handler:immediate_input_stream_handler",
         "//mediapipe/framework/tool:sink",
         "@com_google_absl//absl/time",
@@ -769,9 +777,11 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         ":split_vector_calculator_cc_proto",
+        "//mediapipe/framework/formats:detection_cc_proto",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework/formats:landmark_cc_proto",
         "//mediapipe/framework/formats:rect_cc_proto",
+        "//mediapipe/framework/formats:matrix",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/framework/port:status",
         "//mediapipe/util:resource_util",

mediapipe/calculators/core/begin_end_loop_calculator_graph_test.cc

@@ -20,6 +20,8 @@
 #include "mediapipe/calculators/core/end_loop_calculator.h"
 #include "mediapipe/framework/calculator_contract.h"
 #include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/packet.h"
+#include "mediapipe/framework/port/gmock.h"
 #include "mediapipe/framework/port/gtest.h"
 #include "mediapipe/framework/port/integral_types.h"
 #include "mediapipe/framework/port/parse_text_proto.h"
@@ -28,6 +30,13 @@
 namespace mediapipe {
 namespace {
 
+MATCHER_P2(PacketOfIntsEq, timestamp, value, "") {
+  Timestamp actual_timestamp = arg.Timestamp();
+  const auto& actual_value = arg.template Get<std::vector<int>>();
+  return testing::Value(actual_timestamp, testing::Eq(timestamp)) &&
+         testing::Value(actual_value, testing::ElementsAreArray(value));
+}
+
 typedef BeginLoopCalculator<std::vector<int>> BeginLoopIntegerCalculator;
 REGISTER_CALCULATOR(BeginLoopIntegerCalculator);
 
@@ -59,8 +68,8 @@ REGISTER_CALCULATOR(EndLoopIntegersCalculator);
 
 class BeginEndLoopCalculatorGraphTest : public ::testing::Test {
  protected:
-  BeginEndLoopCalculatorGraphTest() {
-    graph_config_ = ParseTextProtoOrDie<CalculatorGraphConfig>(
+  void SetUp() override {
+    auto graph_config = ParseTextProtoOrDie<CalculatorGraphConfig>(
         R"(
           num_threads: 4
           input_stream: "ints"
@@ -82,94 +91,222 @@ class BeginEndLoopCalculatorGraphTest : public ::testing::Test {
             output_stream: "ITERABLE:ints_plus_one"
           }
         )");
-    tool::AddVectorSink("ints_plus_one", &graph_config_, &output_packets_);
+    tool::AddVectorSink("ints_plus_one", &graph_config, &output_packets_);
+    MP_ASSERT_OK(graph_.Initialize(graph_config));
+    MP_ASSERT_OK(graph_.StartRun({}));
   }
 
-  CalculatorGraphConfig graph_config_;
+  void SendPacketOfInts(Timestamp timestamp, std::vector<int> ints) {
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "ints", MakePacket<std::vector<int>>(std::move(ints)).At(timestamp)));
+  }
+
+  CalculatorGraph graph_;
   std::vector<Packet> output_packets_;
 };
 
+TEST_F(BeginEndLoopCalculatorGraphTest, InputStreamForIterableIsEmpty) {
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  // EndLoopCalc will forward the timestamp bound because there are no packets
+  // to process.
+  ASSERT_EQ(0, output_packets_.size());
+
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
+}
+
 TEST_F(BeginEndLoopCalculatorGraphTest, SingleEmptyVector) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-  auto input_vector = absl::make_unique<std::vector<int>>();
-  Timestamp input_timestamp = Timestamp(0);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector.release()).At(input_timestamp)));
-  MP_ASSERT_OK(graph.WaitUntilIdle());
+  SendPacketOfInts(Timestamp(0), {});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
 
   // EndLoopCalc will forward the timestamp bound because there are no elements
   // in collection to output.
-  ASSERT_EQ(0, output_packets_.size());
+  EXPECT_TRUE(output_packets_.empty());
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 }
 
 TEST_F(BeginEndLoopCalculatorGraphTest, SingleNonEmptyVector) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-  auto input_vector = absl::make_unique<std::vector<int>>();
-  input_vector->emplace_back(0);
-  input_vector->emplace_back(1);
-  input_vector->emplace_back(2);
   Timestamp input_timestamp = Timestamp(0);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector.release()).At(input_timestamp)));
-  MP_ASSERT_OK(graph.WaitUntilIdle());
+  SendPacketOfInts(input_timestamp, {0, 1, 2});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
 
-  ASSERT_EQ(1, output_packets_.size());
-  EXPECT_EQ(input_timestamp, output_packets_[0].Timestamp());
-  std::vector<int> expected_output_vector = {1, 2, 3};
-  EXPECT_EQ(expected_output_vector, output_packets_[0].Get<std::vector<int>>());
+  EXPECT_THAT(output_packets_,
+              testing::ElementsAre(
+                  PacketOfIntsEq(input_timestamp, std::vector<int>{1, 2, 3})));
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 }
 
 TEST_F(BeginEndLoopCalculatorGraphTest, MultipleVectors) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-
-  auto input_vector0 = absl::make_unique<std::vector<int>>();
-  input_vector0->emplace_back(0);
-  input_vector0->emplace_back(1);
   Timestamp input_timestamp0 = Timestamp(0);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector0.release()).At(input_timestamp0)));
+  SendPacketOfInts(input_timestamp0, {0, 1});
 
-  auto input_vector1 = absl::make_unique<std::vector<int>>();
   Timestamp input_timestamp1 = Timestamp(1);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector1.release()).At(input_timestamp1)));
+  SendPacketOfInts(input_timestamp1, {});
 
-  auto input_vector2 = absl::make_unique<std::vector<int>>();
-  input_vector2->emplace_back(2);
-  input_vector2->emplace_back(3);
   Timestamp input_timestamp2 = Timestamp(2);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector2.release()).At(input_timestamp2)));
+  SendPacketOfInts(input_timestamp2, {2, 3});
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
-
-  ASSERT_EQ(2, output_packets_.size());
-
-  EXPECT_EQ(input_timestamp0, output_packets_[0].Timestamp());
-  std::vector<int> expected_output_vector0 = {1, 2};
-  EXPECT_EQ(expected_output_vector0,
-            output_packets_[0].Get<std::vector<int>>());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 
   // At input_timestamp1, EndLoopCalc will forward timestamp bound as there are
   // no elements in vector to process.
+  EXPECT_THAT(output_packets_,
+              testing::ElementsAre(
+                  PacketOfIntsEq(input_timestamp0, std::vector<int>{1, 2}),
+                  PacketOfIntsEq(input_timestamp2, std::vector<int>{3, 4})));
+}
 
-  EXPECT_EQ(input_timestamp2, output_packets_[1].Timestamp());
-  std::vector<int> expected_output_vector2 = {3, 4};
-  EXPECT_EQ(expected_output_vector2,
-            output_packets_[1].Get<std::vector<int>>());
+// Passes non empty vector through or outputs empty vector in case of timestamp
+// bound update.
+class PassThroughOrEmptyVectorCalculator : public CalculatorBase {
+ public:
+  static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    cc->SetProcessTimestampBounds(true);
+    cc->Inputs().Index(0).Set<std::vector<int>>();
+    cc->Outputs().Index(0).Set<std::vector<int>>();
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Open(CalculatorContext* cc) override {
+    cc->SetOffset(TimestampDiff(0));
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Process(CalculatorContext* cc) override {
+    if (!cc->Inputs().Index(0).IsEmpty()) {
+      cc->Outputs().Index(0).AddPacket(cc->Inputs().Index(0).Value());
+    } else {
+      cc->Outputs().Index(0).AddPacket(
+          MakePacket<std::vector<int>>(std::vector<int>())
+              .At(cc->InputTimestamp()));
+    }
+    return ::mediapipe::OkStatus();
+  }
+};
+
+REGISTER_CALCULATOR(PassThroughOrEmptyVectorCalculator);
+
+class BeginEndLoopCalculatorGraphProcessingEmptyPacketsTest
+    : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    auto graph_config = ParseTextProtoOrDie<CalculatorGraphConfig>(
+        R"(
+          num_threads: 4
+          input_stream: "ints"
+          input_stream: "force_ints_to_be_timestamp_bound_update"
+          node {
+            calculator: "GateCalculator"
+            input_stream: "ints"
+            input_stream: "DISALLOW:force_ints_to_be_timestamp_bound_update"
+            output_stream: "ints_passed_through"
+          }
+          node {
+            calculator: "BeginLoopIntegerCalculator"
+            input_stream: "ITERABLE:ints_passed_through"
+            output_stream: "ITEM:int"
+            output_stream: "BATCH_END:timestamp"
+          }
+          node {
+            calculator: "IncrementCalculator"
+            input_stream: "int"
+            output_stream: "int_plus_one"
+          }
+          node {
+            calculator: "EndLoopIntegersCalculator"
+            input_stream: "ITEM:int_plus_one"
+            input_stream: "BATCH_END:timestamp"
+            output_stream: "ITERABLE:ints_plus_one"
+          }
+          node {
+            calculator: "PassThroughOrEmptyVectorCalculator"
+            input_stream: "ints_plus_one"
+            output_stream: "ints_plus_one_passed_through"
+          }
+        )");
+    tool::AddVectorSink("ints_plus_one_passed_through", &graph_config,
+                        &output_packets_);
+    MP_ASSERT_OK(graph_.Initialize(graph_config));
+    MP_ASSERT_OK(graph_.StartRun({}));
+  }
+
+  void SendPacketOfIntsOrBound(Timestamp timestamp, std::vector<int> ints) {
+    // All "ints" packets which are empty are forced to be just timestamp
+    // bound updates for begin loop calculator.
+    bool force_ints_to_be_timestamp_bound_update = ints.empty();
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "force_ints_to_be_timestamp_bound_update",
+        MakePacket<bool>(force_ints_to_be_timestamp_bound_update)
+            .At(timestamp)));
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "ints", MakePacket<std::vector<int>>(std::move(ints)).At(timestamp)));
+  }
+
+  CalculatorGraph graph_;
+  std::vector<Packet> output_packets_;
+};
+
+TEST_F(BeginEndLoopCalculatorGraphProcessingEmptyPacketsTest,
+       SingleEmptyVector) {
+  SendPacketOfIntsOrBound(Timestamp(0), {});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  EXPECT_THAT(output_packets_, testing::ElementsAre(PacketOfIntsEq(
+                                   Timestamp(0), std::vector<int>{})));
+
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(BeginEndLoopCalculatorGraphProcessingEmptyPacketsTest,
+       SingleNonEmptyVector) {
+  SendPacketOfIntsOrBound(Timestamp(0), {0, 1, 2});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  EXPECT_THAT(output_packets_, testing::ElementsAre(PacketOfIntsEq(
+                                   Timestamp(0), std::vector<int>{1, 2, 3})));
+
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(BeginEndLoopCalculatorGraphProcessingEmptyPacketsTest, MultipleVectors) {
+  SendPacketOfIntsOrBound(Timestamp(0), {});
+  // Waiting until idle to guarantee all timestamp bound updates are processed
+  // individually. (Timestamp bounds updates occur in the provide config only
+  // if input is an empty vector.)
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  SendPacketOfIntsOrBound(Timestamp(1), {0, 1});
+  SendPacketOfIntsOrBound(Timestamp(2), {});
+  // Waiting until idle to guarantee all timestamp bound updates are processed
+  // individually. (Timestamp bounds updates occur in the provide config only
+  // if input is an empty vector.)
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  SendPacketOfIntsOrBound(Timestamp(3), {2, 3});
+  SendPacketOfIntsOrBound(Timestamp(4), {});
+  // Waiting until idle to guarantee all timestamp bound updates are processed
+  // individually. (Timestamp bounds updates occur in the provide config only
+  // if input is an empty vector.)
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
+
+  EXPECT_THAT(
+      output_packets_,
+      testing::ElementsAre(PacketOfIntsEq(Timestamp(0), std::vector<int>{}),
+                           PacketOfIntsEq(Timestamp(1), std::vector<int>{1, 2}),
+                           PacketOfIntsEq(Timestamp(2), std::vector<int>{}),
+                           PacketOfIntsEq(Timestamp(3), std::vector<int>{3, 4}),
+                           PacketOfIntsEq(Timestamp(4), std::vector<int>{})));
 }
 
 class MultiplierCalculator : public CalculatorBase {
@@ -199,8 +336,8 @@ REGISTER_CALCULATOR(MultiplierCalculator);
 
 class BeginEndLoopCalculatorGraphWithClonedInputsTest : public ::testing::Test {
  protected:
-  BeginEndLoopCalculatorGraphWithClonedInputsTest() {
-    graph_config_ = ParseTextProtoOrDie<CalculatorGraphConfig>(
+  void SetUp() override {
+    auto graph_config = ParseTextProtoOrDie<CalculatorGraphConfig>(
         R"(
           num_threads: 4
           input_stream: "ints"
@@ -226,109 +363,85 @@ class BeginEndLoopCalculatorGraphWithClonedInputsTest : public ::testing::Test {
             output_stream: "ITERABLE:multiplied_ints"
           }
         )");
-    tool::AddVectorSink("multiplied_ints", &graph_config_, &output_packets_);
+    tool::AddVectorSink("multiplied_ints", &graph_config, &output_packets_);
+    MP_ASSERT_OK(graph_.Initialize(graph_config));
+    MP_ASSERT_OK(graph_.StartRun({}));
   }
 
-  CalculatorGraphConfig graph_config_;
+  void SendPackets(Timestamp timestamp, int multiplier, std::vector<int> ints) {
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "ints", MakePacket<std::vector<int>>(std::move(ints)).At(timestamp)));
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "multiplier", MakePacket<int>(multiplier).At(timestamp)));
+  }
+
+  void SendMultiplier(Timestamp timestamp, int multiplier) {
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "multiplier", MakePacket<int>(multiplier).At(timestamp)));
+  }
+
+  CalculatorGraph graph_;
   std::vector<Packet> output_packets_;
 };
 
-TEST_F(BeginEndLoopCalculatorGraphWithClonedInputsTest, SingleEmptyVector) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-  auto input_vector = absl::make_unique<std::vector<int>>();
+TEST_F(BeginEndLoopCalculatorGraphWithClonedInputsTest,
+       InputStreamForIterableIsEmpty) {
   Timestamp input_timestamp = Timestamp(42);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector.release()).At(input_timestamp)));
-  auto multiplier = absl::make_unique<int>(2);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "multiplier", Adopt(multiplier.release()).At(input_timestamp)));
-  MP_ASSERT_OK(graph.WaitUntilIdle());
+  SendMultiplier(input_timestamp, /*multiplier=*/2);
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
+
+  // EndLoopCalc will forward the timestamp bound because there are no packets
+  // to process.
+  ASSERT_EQ(0, output_packets_.size());
+
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(BeginEndLoopCalculatorGraphWithClonedInputsTest, SingleEmptyVector) {
+  SendPackets(Timestamp(0), /*multiplier=*/2, /*ints=*/{});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
 
   // EndLoopCalc will forward the timestamp bound because there are no elements
   // in collection to output.
-  ASSERT_EQ(0, output_packets_.size());
+  EXPECT_TRUE(output_packets_.empty());
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 }
 
 TEST_F(BeginEndLoopCalculatorGraphWithClonedInputsTest, SingleNonEmptyVector) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-  auto input_vector = absl::make_unique<std::vector<int>>();
-  input_vector->emplace_back(0);
-  input_vector->emplace_back(1);
-  input_vector->emplace_back(2);
   Timestamp input_timestamp = Timestamp(42);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector.release()).At(input_timestamp)));
-  auto multiplier = absl::make_unique<int>(2);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "multiplier", Adopt(multiplier.release()).At(input_timestamp)));
-  MP_ASSERT_OK(graph.WaitUntilIdle());
+  SendPackets(input_timestamp, /*multiplier=*/2, /*ints=*/{0, 1, 2});
+  MP_ASSERT_OK(graph_.WaitUntilIdle());
 
-  ASSERT_EQ(1, output_packets_.size());
-  EXPECT_EQ(input_timestamp, output_packets_[0].Timestamp());
-  std::vector<int> expected_output_vector = {0, 2, 4};
-  EXPECT_EQ(expected_output_vector, output_packets_[0].Get<std::vector<int>>());
+  EXPECT_THAT(output_packets_,
+              testing::ElementsAre(
+                  PacketOfIntsEq(input_timestamp, std::vector<int>{0, 2, 4})));
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 }
 
 TEST_F(BeginEndLoopCalculatorGraphWithClonedInputsTest, MultipleVectors) {
-  CalculatorGraph graph;
-  MP_EXPECT_OK(graph.Initialize(graph_config_));
-  MP_EXPECT_OK(graph.StartRun({}));
-
-  auto input_vector0 = absl::make_unique<std::vector<int>>();
-  input_vector0->emplace_back(0);
-  input_vector0->emplace_back(1);
   Timestamp input_timestamp0 = Timestamp(42);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector0.release()).At(input_timestamp0)));
-  auto multiplier0 = absl::make_unique<int>(2);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "multiplier", Adopt(multiplier0.release()).At(input_timestamp0)));
+  SendPackets(input_timestamp0, /*multiplier=*/2, /*ints=*/{0, 1});
 
-  auto input_vector1 = absl::make_unique<std::vector<int>>();
   Timestamp input_timestamp1 = Timestamp(43);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector1.release()).At(input_timestamp1)));
-  auto multiplier1 = absl::make_unique<int>(2);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "multiplier", Adopt(multiplier1.release()).At(input_timestamp1)));
+  SendPackets(input_timestamp1, /*multiplier=*/2, /*ints=*/{});
 
-  auto input_vector2 = absl::make_unique<std::vector<int>>();
-  input_vector2->emplace_back(2);
-  input_vector2->emplace_back(3);
   Timestamp input_timestamp2 = Timestamp(44);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "ints", Adopt(input_vector2.release()).At(input_timestamp2)));
-  auto multiplier2 = absl::make_unique<int>(3);
-  MP_ASSERT_OK(graph.AddPacketToInputStream(
-      "multiplier", Adopt(multiplier2.release()).At(input_timestamp2)));
+  SendPackets(input_timestamp2, /*multiplier=*/3, /*ints=*/{2, 3});
 
-  MP_ASSERT_OK(graph.CloseAllPacketSources());
-  MP_ASSERT_OK(graph.WaitUntilDone());
-
-  ASSERT_EQ(2, output_packets_.size());
-
-  EXPECT_EQ(input_timestamp0, output_packets_[0].Timestamp());
-  std::vector<int> expected_output_vector0 = {0, 2};
-  EXPECT_EQ(expected_output_vector0,
-            output_packets_[0].Get<std::vector<int>>());
+  MP_ASSERT_OK(graph_.CloseAllPacketSources());
+  MP_ASSERT_OK(graph_.WaitUntilDone());
 
   // At input_timestamp1, EndLoopCalc will forward timestamp bound as there are
   // no elements in vector to process.
-
-  EXPECT_EQ(input_timestamp2, output_packets_[1].Timestamp());
-  std::vector<int> expected_output_vector2 = {6, 9};
-  EXPECT_EQ(expected_output_vector2,
-            output_packets_[1].Get<std::vector<int>>());
+  EXPECT_THAT(output_packets_,
+              testing::ElementsAre(
+                  PacketOfIntsEq(input_timestamp0, std::vector<int>{0, 2}),
+                  PacketOfIntsEq(input_timestamp2, std::vector<int>{6, 9})));
 }
 
 }  // namespace

mediapipe/calculators/core/begin_loop_calculator.cc

@@ -16,7 +16,9 @@
 
 #include <vector>
 
+#include "mediapipe/framework/formats/detection.pb.h"
 #include "mediapipe/framework/formats/landmark.pb.h"
+#include "mediapipe/framework/formats/matrix.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 
 namespace mediapipe {
@@ -31,4 +33,13 @@ typedef BeginLoopCalculator<std::vector<::mediapipe::NormalizedRect>>
     BeginLoopNormalizedRectCalculator;
 REGISTER_CALCULATOR(BeginLoopNormalizedRectCalculator);
 
+// A calculator to process std::vector<Detection>.
+typedef BeginLoopCalculator<std::vector<::mediapipe::Detection>>
+    BeginLoopDetectionCalculator;
+REGISTER_CALCULATOR(BeginLoopDetectionCalculator);
+
+// A calculator to process std::vector<Matrix>.
+typedef BeginLoopCalculator<std::vector<Matrix>> BeginLoopMatrixCalculator;
+REGISTER_CALCULATOR(BeginLoopMatrixCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/core/begin_loop_calculator.h

@@ -52,20 +52,28 @@ namespace mediapipe {
 //   output_stream: "OUTPUT:aggregated_result"     # IterableU @ext_ts
 // }
 //
-// BeginLoopCalculator accepts an optional input stream tagged with "TICK"
-// which if non-empty, wakes up the calculator and calls
-// BeginLoopCalculator::Process(). Input streams tagged with "CLONE" are cloned
-// to the corresponding output streams at loop timestamps. This ensures that a
-// MediaPipe graph or sub-graph can run multiple times, once per element in the
-// "ITERABLE" for each pakcet clone of the packets in the "CLONE" input streams.
+// Input streams tagged with "CLONE" are cloned to the corresponding output
+// streams at loop timestamps. This ensures that a MediaPipe graph or sub-graph
+// can run multiple times, once per element in the "ITERABLE" for each pakcet
+// clone of the packets in the "CLONE" input streams.
 template <typename IterableT>
 class BeginLoopCalculator : public CalculatorBase {
   using ItemT = typename IterableT::value_type;
 
  public:
   static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    // The below enables processing of timestamp bound updates, and that enables
+    // correct timestamp propagation by the companion EndLoopCalculator.
+    //
+    // For instance, Process() function will be still invoked even if upstream
+    // calculator has updated timestamp bound for ITERABLE input instead of
+    // providing actual value.
+    cc->SetProcessTimestampBounds(true);
+
     // A non-empty packet in the optional "TICK" input stream wakes up the
     // calculator.
+    // DEPRECATED as timestamp bound updates are processed by default in this
+    // calculator.
     if (cc->Inputs().HasTag("TICK")) {
       cc->Inputs().Tag("TICK").SetAny();
     }

mediapipe/calculators/core/clip_vector_size_calculator.cc

@@ -17,6 +17,7 @@
 #include <vector>
 
 #include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/formats/detection.pb.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 
 namespace mediapipe {
@@ -25,4 +26,8 @@ typedef ClipVectorSizeCalculator<::mediapipe::NormalizedRect>
     ClipNormalizedRectVectorSizeCalculator;
 REGISTER_CALCULATOR(ClipNormalizedRectVectorSizeCalculator);
 
+typedef ClipVectorSizeCalculator<::mediapipe::Detection>
+    ClipDetectionVectorSizeCalculator;
+REGISTER_CALCULATOR(ClipDetectionVectorSizeCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/core/end_loop_calculator.cc

@@ -16,9 +16,11 @@
 
 #include <vector>
 
+#include "mediapipe/framework/formats/classification.pb.h"
 #include "mediapipe/framework/formats/landmark.pb.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 #include "mediapipe/util/render_data.pb.h"
+#include "tensorflow/lite/interpreter.h"
 
 namespace mediapipe {
 
@@ -37,4 +39,11 @@ typedef EndLoopCalculator<std::vector<::mediapipe::RenderData>>
     EndLoopRenderDataCalculator;
 REGISTER_CALCULATOR(EndLoopRenderDataCalculator);
 
+typedef EndLoopCalculator<std::vector<::mediapipe::ClassificationList>>
+    EndLoopClassificationListCalculator;
+REGISTER_CALCULATOR(EndLoopClassificationListCalculator);
+
+typedef EndLoopCalculator<std::vector<TfLiteTensor>> EndLoopTensorCalculator;
+REGISTER_CALCULATOR(EndLoopTensorCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/core/previous_loopback_calculator.cc

@@ -25,13 +25,17 @@ namespace mediapipe {
 // together with some previous output.
 //
 // For the first packet that arrives on the MAIN input, the timestamp bound is
-// advanced on the output. Downstream calculators will see this as an empty
+// advanced on the PREV_LOOP. Downstream calculators will see this as an empty
 // packet. This way they are not kept waiting for the previous output, which
 // for the first iteration does not exist.
 //
-// Thereafter, each packet received on MAIN is matched with a packet received
-// on LOOP; the LOOP packet's timestamp is changed to that of the MAIN packet,
-// and it is output on PREV_LOOP.
+// Thereafter,
+// - Each non-empty MAIN packet results in:
+//   a) a PREV_LOOP packet with contents of the LOOP packet received at the
+//      timestamp of the previous non-empty MAIN packet
+//   b) or in a PREV_LOOP timestamp bound update if the LOOP packet was empty.
+// - Each empty MAIN packet indicating timestamp bound update results in a
+//   PREV_LOOP timestamp bound update.
 //
 // Example config:
 // node {
@@ -56,83 +60,115 @@ class PreviousLoopbackCalculator : public CalculatorBase {
     // TODO: an optional PREV_TIMESTAMP output could be added to
     // carry the original timestamp of the packet on PREV_LOOP.
     cc->SetInputStreamHandler("ImmediateInputStreamHandler");
+    // Process() function is invoked in response to MAIN/LOOP stream timestamp
+    // bound updates.
+    cc->SetProcessTimestampBounds(true);
     return ::mediapipe::OkStatus();
   }
 
   ::mediapipe::Status Open(CalculatorContext* cc) final {
     main_id_ = cc->Inputs().GetId("MAIN", 0);
     loop_id_ = cc->Inputs().GetId("LOOP", 0);
-    loop_out_id_ = cc->Outputs().GetId("PREV_LOOP", 0);
+    prev_loop_id_ = cc->Outputs().GetId("PREV_LOOP", 0);
     cc->Outputs()
-        .Get(loop_out_id_)
+        .Get(prev_loop_id_)
         .SetHeader(cc->Inputs().Get(loop_id_).Header());
-
-    // Use an empty packet for the first round, since there is no previous
-    // output.
-    loopback_packets_.push_back({});
-
     return ::mediapipe::OkStatus();
   }
 
   ::mediapipe::Status Process(CalculatorContext* cc) final {
-    Packet& main_packet = cc->Inputs().Get(main_id_).Value();
-    if (!main_packet.IsEmpty()) {
-      main_ts_.push_back(main_packet.Timestamp());
-    }
-    Packet& loopback_packet = cc->Inputs().Get(loop_id_).Value();
-    if (!loopback_packet.IsEmpty()) {
-      loopback_packets_.push_back(loopback_packet);
-      while (!main_ts_.empty() &&
-             main_ts_.front() <= loopback_packets_.front().Timestamp()) {
-        main_ts_.pop_front();
-      }
-    }
-    auto& loop_out = cc->Outputs().Get(loop_out_id_);
+    // Non-empty packets and empty packets indicating timestamp bound updates
+    // are guaranteed to have timestamps greater than timestamps of previous
+    // packets within the same stream. Calculator tracks and operates on such
+    // packets.
 
-    while (!main_ts_.empty() && !loopback_packets_.empty()) {
-      Timestamp main_timestamp = main_ts_.front();
-      main_ts_.pop_front();
-      Packet previous_loopback = loopback_packets_.front().At(main_timestamp);
-      loopback_packets_.pop_front();
-
-      if (previous_loopback.IsEmpty()) {
-        // TODO: SetCompleteTimestampBound would be more useful.
-        loop_out.SetNextTimestampBound(main_timestamp + 1);
+    const Packet& main_packet = cc->Inputs().Get(main_id_).Value();
+    if (prev_main_ts_ < main_packet.Timestamp()) {
+      Timestamp loop_timestamp;
+      if (!main_packet.IsEmpty()) {
+        loop_timestamp = prev_non_empty_main_ts_;
+        prev_non_empty_main_ts_ = main_packet.Timestamp();
       } else {
-        loop_out.AddPacket(std::move(previous_loopback));
+        // Calculator advances PREV_LOOP timestamp bound in response to empty
+        // MAIN packet, hence not caring about corresponding loop packet.
+        loop_timestamp = Timestamp::Unset();
+      }
+      main_packet_specs_.push_back({.timestamp = main_packet.Timestamp(),
+                                    .loop_timestamp = loop_timestamp});
+      prev_main_ts_ = main_packet.Timestamp();
+    }
+
+    const Packet& loop_packet = cc->Inputs().Get(loop_id_).Value();
+    if (prev_loop_ts_ < loop_packet.Timestamp()) {
+      loop_packets_.push_back(loop_packet);
+      prev_loop_ts_ = loop_packet.Timestamp();
+    }
+
+    auto& prev_loop = cc->Outputs().Get(prev_loop_id_);
+    while (!main_packet_specs_.empty() && !loop_packets_.empty()) {
+      // The earliest MAIN packet.
+      const MainPacketSpec& main_spec = main_packet_specs_.front();
+      // The earliest LOOP packet.
+      const Packet& loop_candidate = loop_packets_.front();
+      // Match LOOP and MAIN packets.
+      if (main_spec.loop_timestamp < loop_candidate.Timestamp()) {
+        // No LOOP packet can match the MAIN packet under review.
+        prev_loop.SetNextTimestampBound(main_spec.timestamp + 1);
+        main_packet_specs_.pop_front();
+      } else if (main_spec.loop_timestamp > loop_candidate.Timestamp()) {
+        // No MAIN packet can match the LOOP packet under review.
+        loop_packets_.pop_front();
+      } else {
+        // Exact match found.
+        if (loop_candidate.IsEmpty()) {
+          // However, LOOP packet is empty.
+          prev_loop.SetNextTimestampBound(main_spec.timestamp + 1);
+        } else {
+          prev_loop.AddPacket(loop_candidate.At(main_spec.timestamp));
+        }
+        loop_packets_.pop_front();
+        main_packet_specs_.pop_front();
       }
     }
 
-    // In case of an empty loopback input, the next timestamp bound for
-    // loopback input is the loopback timestamp + 1.  The next timestamp bound
-    // for output is set and the main_ts_ vector is truncated accordingly.
-    if (loopback_packet.IsEmpty() &&
-        loopback_packet.Timestamp() != Timestamp::Unstarted()) {
-      Timestamp loopback_bound =
-          loopback_packet.Timestamp().NextAllowedInStream();
-      while (!main_ts_.empty() && main_ts_.front() <= loopback_bound) {
-        main_ts_.pop_front();
-      }
-      if (main_ts_.empty()) {
-        loop_out.SetNextTimestampBound(loopback_bound.NextAllowedInStream());
-      }
-    }
-    if (!main_ts_.empty()) {
-      loop_out.SetNextTimestampBound(main_ts_.front());
-    }
-    if (cc->Inputs().Get(main_id_).IsDone() && main_ts_.empty()) {
-      loop_out.Close();
+    if (main_packet_specs_.empty() && cc->Inputs().Get(main_id_).IsDone()) {
+      prev_loop.Close();
     }
     return ::mediapipe::OkStatus();
   }
 
  private:
+  struct MainPacketSpec {
+    Timestamp timestamp;
+    // Expected timestamp of the packet from LOOP stream that corresponds to the
+    // packet from MAIN stream descirbed by this spec.
+    Timestamp loop_timestamp;
+  };
+
   CollectionItemId main_id_;
   CollectionItemId loop_id_;
-  CollectionItemId loop_out_id_;
+  CollectionItemId prev_loop_id_;
 
-  std::deque<Timestamp> main_ts_;
-  std::deque<Packet> loopback_packets_;
+  // Contains specs for MAIN packets which only can be:
+  // - non-empty packets
+  // - empty packets indicating timestamp bound updates
+  //
+  // Sorted according to packet timestamps.
+  std::deque<MainPacketSpec> main_packet_specs_;
+  Timestamp prev_main_ts_ = Timestamp::Unstarted();
+  Timestamp prev_non_empty_main_ts_ = Timestamp::Unstarted();
+
+  // Contains LOOP packets which only can be:
+  // - the very first empty packet
+  // - non empty packets
+  // - empty packets indicating timestamp bound updates
+  //
+  // Sorted according to packet timestamps.
+  std::deque<Packet> loop_packets_;
+  // Using "Timestamp::Unset" instead of "Timestamp::Unstarted" in order to
+  // allow addition of the very first empty packet (which doesn't indicate
+  // timestamp bound change necessarily).
+  Timestamp prev_loop_ts_ = Timestamp::Unset();
 };
 REGISTER_CALCULATOR(PreviousLoopbackCalculator);
 

mediapipe/calculators/core/previous_loopback_calculator_test.cc

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <algorithm>
+#include <functional>
 #include <memory>
 #include <string>
 #include <vector>
@@ -25,12 +26,17 @@
 #include "mediapipe/framework/port/gtest.h"
 #include "mediapipe/framework/port/integral_types.h"
 #include "mediapipe/framework/port/parse_text_proto.h"
+#include "mediapipe/framework/port/status.h"
 #include "mediapipe/framework/port/status_matchers.h"
 #include "mediapipe/framework/timestamp.h"
 #include "mediapipe/framework/tool/sink.h"
 
 namespace mediapipe {
 
+using ::testing::ElementsAre;
+using ::testing::Eq;
+using ::testing::Pair;
+using ::testing::Value;
 namespace {
 
 // Returns the timestamp values for a vector of Packets.
@@ -43,6 +49,23 @@ std::vector<int64> TimestampValues(const std::vector<Packet>& packets) {
   return result;
 }
 
+MATCHER(EmptyPacket, negation ? "isn't empty" : "is empty") {
+  if (arg.IsEmpty()) {
+    return true;
+  }
+  return false;
+}
+
+MATCHER_P(IntPacket, value, "") {
+  return Value(arg.template Get<int>(), Eq(value));
+}
+
+MATCHER_P2(PairPacket, timestamp, pair, "") {
+  Timestamp actual_timestamp = arg.Timestamp();
+  const auto& actual_pair = arg.template Get<std::pair<Packet, Packet>>();
+  return Value(actual_timestamp, Eq(timestamp)) && Value(actual_pair, pair);
+}
+
 TEST(PreviousLoopbackCalculator, CorrectTimestamps) {
   std::vector<Packet> in_prev;
   CalculatorGraphConfig graph_config_ =
@@ -81,32 +104,30 @@ TEST(PreviousLoopbackCalculator, CorrectTimestamps) {
     MP_EXPECT_OK(graph_.AddPacketToInputStream(
         input_name, MakePacket<int>(n).At(Timestamp(n))));
   };
-  auto pair_values = [](const Packet& packet) {
-    auto pair = packet.Get<std::pair<Packet, Packet>>();
-    int first = pair.first.IsEmpty() ? -1 : pair.first.Get<int>();
-    int second = pair.second.IsEmpty() ? -1 : pair.second.Get<int>();
-    return std::make_pair(first, second);
-  };
 
   send_packet("in", 1);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(in_prev), (std::vector<int64>{1}));
-  EXPECT_EQ(pair_values(in_prev.back()), std::make_pair(1, -1));
+  EXPECT_THAT(TimestampValues(in_prev), ElementsAre(1));
+  EXPECT_THAT(in_prev.back(),
+              PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())));
 
   send_packet("in", 2);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(in_prev), (std::vector<int64>{1, 2}));
-  EXPECT_EQ(pair_values(in_prev.back()), std::make_pair(2, 1));
+  EXPECT_THAT(TimestampValues(in_prev), ElementsAre(1, 2));
+  EXPECT_THAT(in_prev.back(),
+              PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))));
 
   send_packet("in", 5);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(in_prev), (std::vector<int64>{1, 2, 5}));
-  EXPECT_EQ(pair_values(in_prev.back()), std::make_pair(5, 2));
+  EXPECT_THAT(TimestampValues(in_prev), ElementsAre(1, 2, 5));
+  EXPECT_THAT(in_prev.back(),
+              PairPacket(Timestamp(5), Pair(IntPacket(5), IntPacket(2))));
 
   send_packet("in", 15);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(in_prev), (std::vector<int64>{1, 2, 5, 15}));
-  EXPECT_EQ(pair_values(in_prev.back()), std::make_pair(15, 5));
+  EXPECT_THAT(TimestampValues(in_prev), ElementsAre(1, 2, 5, 15));
+  EXPECT_THAT(in_prev.back(),
+              PairPacket(Timestamp(15), Pair(IntPacket(15), IntPacket(5))));
 
   MP_EXPECT_OK(graph_.CloseAllInputStreams());
   MP_EXPECT_OK(graph_.WaitUntilDone());
@@ -185,24 +206,24 @@ TEST(PreviousLoopbackCalculator, ClosesCorrectly) {
 
   send_packet("in", 1);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs), (std::vector<int64>{1}));
+  EXPECT_THAT(TimestampValues(outputs), ElementsAre(1));
 
   send_packet("in", 2);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs), (std::vector<int64>{1, 2}));
+  EXPECT_THAT(TimestampValues(outputs), ElementsAre(1, 2));
 
   send_packet("in", 5);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs), (std::vector<int64>{1, 2, 5}));
+  EXPECT_THAT(TimestampValues(outputs), ElementsAre(1, 2, 5));
 
   send_packet("in", 15);
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs), (std::vector<int64>{1, 2, 5, 15}));
+  EXPECT_THAT(TimestampValues(outputs), ElementsAre(1, 2, 5, 15));
 
   MP_EXPECT_OK(graph_.CloseAllInputStreams());
   MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs),
-            (std::vector<int64>{1, 2, 5, 15, Timestamp::Max().Value()}));
+  EXPECT_THAT(TimestampValues(outputs),
+              ElementsAre(1, 2, 5, 15, Timestamp::Max().Value()));
 
   MP_EXPECT_OK(graph_.WaitUntilDone());
 }
@@ -247,16 +268,12 @@ TEST(PreviousLoopbackCalculator, EmptyLoopForever) {
         input_name, MakePacket<int>(n).At(Timestamp(n))));
   };
 
-  send_packet("in", 0);
-  MP_EXPECT_OK(graph_.WaitUntilIdle());
-  EXPECT_EQ(TimestampValues(outputs), (std::vector<int64>{0}));
-
-  for (int main_ts = 1; main_ts < 50; ++main_ts) {
+  for (int main_ts = 0; main_ts < 50; ++main_ts) {
     send_packet("in", main_ts);
     MP_EXPECT_OK(graph_.WaitUntilIdle());
     std::vector<int64> ts_values = TimestampValues(outputs);
     EXPECT_EQ(ts_values.size(), main_ts + 1);
-    for (int j = 0; j < main_ts; ++j) {
+    for (int j = 0; j < main_ts + 1; ++j) {
       EXPECT_EQ(ts_values[j], j);
     }
   }
@@ -266,5 +283,487 @@ TEST(PreviousLoopbackCalculator, EmptyLoopForever) {
   MP_EXPECT_OK(graph_.WaitUntilDone());
 }
 
+class PreviousLoopbackCalculatorProcessingTimestampsTest
+    : public testing::Test {
+ protected:
+  void SetUp() override {
+    CalculatorGraphConfig graph_config =
+        ParseTextProtoOrDie<CalculatorGraphConfig>(R"(
+          input_stream: 'input'
+          input_stream: 'force_main_empty'
+          input_stream: 'force_loop_empty'
+          # Used to indicate "main" timestamp bound updates.
+          node {
+            calculator: 'GateCalculator'
+            input_stream: 'input'
+            input_stream: 'DISALLOW:force_main_empty'
+            output_stream: 'main'
+          }
+          node {
+            calculator: 'PreviousLoopbackCalculator'
+            input_stream: 'MAIN:main'
+            input_stream: 'LOOP:loop'
+            input_stream_info: { tag_index: 'LOOP' back_edge: true }
+            output_stream: 'PREV_LOOP:prev_loop'
+          }
+          node {
+            calculator: 'PassThroughCalculator'
+            input_stream: 'input'
+            input_stream: 'prev_loop'
+            output_stream: 'passed_through_input'
+            output_stream: 'passed_through_prev_loop'
+          }
+          # Used to indicate "loop" timestamp bound updates.
+          node {
+            calculator: 'GateCalculator'
+            input_stream: 'input'
+            input_stream: 'DISALLOW:force_loop_empty'
+            output_stream: 'loop'
+          }
+          node {
+            calculator: 'MakePairCalculator'
+            input_stream: 'passed_through_input'
+            input_stream: 'passed_through_prev_loop'
+            output_stream: 'passed_through_input_and_prev_loop'
+          }
+        )");
+    tool::AddVectorSink("passed_through_input_and_prev_loop", &graph_config,
+                        &output_packets_);
+    MP_ASSERT_OK(graph_.Initialize(graph_config, {}));
+    MP_ASSERT_OK(graph_.StartRun({}));
+  }
+
+  void SendPackets(int timestamp, int input, bool force_main_empty,
+                   bool force_loop_empty) {
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "input", MakePacket<int>(input).At(Timestamp(timestamp))));
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "force_main_empty",
+        MakePacket<bool>(force_main_empty).At(Timestamp(timestamp))));
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "force_loop_empty",
+        MakePacket<bool>(force_loop_empty).At(Timestamp(timestamp))));
+  }
+
+  CalculatorGraph graph_;
+  std::vector<Packet> output_packets_;
+};
+
+TEST_F(PreviousLoopbackCalculatorProcessingTimestampsTest,
+       MultiplePacketsEmptyMainNonEmptyLoop) {
+  SendPackets(/*timestamp=*/1, /*input=*/1, /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2, /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3, /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5, /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15,
+              /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket())),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), EmptyPacket()))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(PreviousLoopbackCalculatorProcessingTimestampsTest,
+       MultiplePacketsNonEmptyMainEmptyLoop) {
+  SendPackets(/*timestamp=*/1, /*input=*/1,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket())),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), EmptyPacket()))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(PreviousLoopbackCalculatorProcessingTimestampsTest,
+       MultiplePacketsAlteringMainNonEmptyLoop) {
+  SendPackets(/*timestamp=*/1, /*input=*/1,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2, /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), IntPacket(1)))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), IntPacket(1))),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), IntPacket(3)))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15,
+              /*force_main_empty=*/true,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), IntPacket(1))),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), IntPacket(3))),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), EmptyPacket()))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(PreviousLoopbackCalculatorProcessingTimestampsTest,
+       MultiplePacketsNonEmptyMainAlteringLoop) {
+  SendPackets(/*timestamp=*/1, /*input=*/1,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1)))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), IntPacket(3)))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15,
+              /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), IntPacket(3))),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), EmptyPacket()))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(PreviousLoopbackCalculatorProcessingTimestampsTest,
+       MultiplePacketsCheckIfLastCorrectAlteringMainAlteringLoop) {
+  int num_packets = 1000;
+  for (int i = 0; i < num_packets; ++i) {
+    bool force_main_empty = i % 3 == 0 ? true : false;
+    bool force_loop_empty = i % 2 == 0 ? true : false;
+    SendPackets(/*timestamp=*/i + 1, /*input=*/i + 1, force_main_empty,
+                force_loop_empty);
+  }
+  SendPackets(/*timestamp=*/num_packets + 1,
+              /*input=*/num_packets + 1, /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+  SendPackets(/*timestamp=*/num_packets + 2,
+              /*input=*/num_packets + 2, /*force_main_empty=*/false,
+              /*force_loop_empty=*/false);
+
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  ASSERT_FALSE(output_packets_.empty());
+  EXPECT_THAT(
+      output_packets_.back(),
+      PairPacket(Timestamp(num_packets + 2),
+                 Pair(IntPacket(num_packets + 2), IntPacket(num_packets + 1))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+// Similar to GateCalculator, but it doesn't propagate timestamp bound updates.
+class DroppingGateCalculator : public CalculatorBase {
+ public:
+  static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    cc->Inputs().Index(0).SetAny();
+    cc->Inputs().Tag("DISALLOW").Set<bool>();
+    cc->Outputs().Index(0).SetSameAs(&cc->Inputs().Index(0));
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Process(CalculatorContext* cc) final {
+    if (!cc->Inputs().Index(0).IsEmpty() &&
+        !cc->Inputs().Tag("DISALLOW").Get<bool>()) {
+      cc->Outputs().Index(0).AddPacket(cc->Inputs().Index(0).Value());
+    }
+    return ::mediapipe::OkStatus();
+  }
+};
+REGISTER_CALCULATOR(DroppingGateCalculator);
+
+// Tests PreviousLoopbackCalculator in cases when there are no "LOOP" timestamp
+// bound updates and non-empty packets for a while and the aforementioned start
+// to arrive at some point. So, "PREV_LOOP" is delayed for a couple of inputs.
+class PreviousLoopbackCalculatorDelayBehaviorTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    CalculatorGraphConfig graph_config =
+        ParseTextProtoOrDie<CalculatorGraphConfig>(R"(
+          input_stream: 'input'
+          # Drops "loop" when set to "true", delaying output of prev_loop, hence
+          # delaying output of the graph.
+          input_stream: 'delay_next_output'
+          node {
+            calculator: 'PreviousLoopbackCalculator'
+            input_stream: 'MAIN:input'
+            input_stream: 'LOOP:loop'
+            input_stream_info: { tag_index: 'LOOP' back_edge: true }
+            output_stream: 'PREV_LOOP:prev_loop'
+          }
+          node {
+            calculator: 'PassThroughCalculator'
+            input_stream: 'input'
+            input_stream: 'prev_loop'
+            output_stream: 'passed_through_input'
+            output_stream: 'passed_through_prev_loop'
+          }
+          node {
+            calculator: 'DroppingGateCalculator'
+            input_stream: 'input'
+            input_stream: 'DISALLOW:delay_next_output'
+            output_stream: 'loop'
+          }
+          node {
+            calculator: 'MakePairCalculator'
+            input_stream: 'passed_through_input'
+            input_stream: 'passed_through_prev_loop'
+            output_stream: 'passed_through_input_and_prev_loop'
+          }
+        )");
+    tool::AddVectorSink("passed_through_input_and_prev_loop", &graph_config,
+                        &output_packets_);
+    MP_ASSERT_OK(graph_.Initialize(graph_config, {}));
+    MP_ASSERT_OK(graph_.StartRun({}));
+  }
+
+  void SendPackets(int timestamp, int input, bool delay_next_output) {
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "input", MakePacket<int>(input).At(Timestamp(timestamp))));
+    MP_ASSERT_OK(graph_.AddPacketToInputStream(
+        "delay_next_output",
+        MakePacket<bool>(delay_next_output).At(Timestamp(timestamp))));
+  }
+
+  CalculatorGraph graph_;
+  std::vector<Packet> output_packets_;
+};
+
+TEST_F(PreviousLoopbackCalculatorDelayBehaviorTest, MultipleDelayedOutputs) {
+  SendPackets(/*timestamp=*/1, /*input=*/1, /*delay_next_output=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2, /*delay_next_output=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3, /*delay_next_output=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5, /*delay_next_output=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15, /*delay_next_output=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), EmptyPacket())),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket())),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), IntPacket(5)))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
+TEST_F(PreviousLoopbackCalculatorDelayBehaviorTest,
+       NonDelayedOutputFollowedByMultipleDelayedOutputs) {
+  SendPackets(/*timestamp=*/1, /*input=*/1, /*delay_next_output=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/2, /*input=*/2, /*delay_next_output=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1)))));
+
+  SendPackets(/*timestamp=*/3, /*input=*/3, /*delay_next_output=*/true);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1)))));
+
+  SendPackets(/*timestamp=*/5, /*input=*/5, /*delay_next_output=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+                  PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))),
+                  PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+                  PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket()))));
+
+  SendPackets(/*timestamp=*/15, /*input=*/15, /*delay_next_output=*/false);
+  MP_EXPECT_OK(graph_.WaitUntilIdle());
+  EXPECT_THAT(
+      output_packets_,
+      ElementsAre(
+          PairPacket(Timestamp(1), Pair(IntPacket(1), EmptyPacket())),
+          PairPacket(Timestamp(2), Pair(IntPacket(2), IntPacket(1))),
+          PairPacket(Timestamp(3), Pair(IntPacket(3), EmptyPacket())),
+          PairPacket(Timestamp(5), Pair(IntPacket(5), EmptyPacket())),
+          PairPacket(Timestamp(15), Pair(IntPacket(15), IntPacket(5)))));
+
+  MP_EXPECT_OK(graph_.CloseAllInputStreams());
+  MP_EXPECT_OK(graph_.WaitUntilDone());
+}
+
 }  // anonymous namespace
 }  // namespace mediapipe

mediapipe/calculators/core/split_vector_calculator.cc

@@ -16,7 +16,9 @@
 
 #include <vector>
 
+#include "mediapipe/framework/formats/detection.pb.h"
 #include "mediapipe/framework/formats/landmark.pb.h"
+#include "mediapipe/framework/formats/matrix.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 #include "tensorflow/lite/interpreter.h"
 
@@ -48,13 +50,25 @@ typedef SplitVectorCalculator<::mediapipe::NormalizedLandmark, false>
     SplitLandmarkVectorCalculator;
 REGISTER_CALCULATOR(SplitLandmarkVectorCalculator);
 
+typedef SplitVectorCalculator<::mediapipe::NormalizedLandmarkList, false>
+    SplitNormalizedLandmarkListVectorCalculator;
+REGISTER_CALCULATOR(SplitNormalizedLandmarkListVectorCalculator);
+
 typedef SplitVectorCalculator<::mediapipe::NormalizedRect, false>
     SplitNormalizedRectVectorCalculator;
 REGISTER_CALCULATOR(SplitNormalizedRectVectorCalculator);
 
+typedef SplitVectorCalculator<Matrix, false> SplitMatrixVectorCalculator;
+REGISTER_CALCULATOR(SplitMatrixVectorCalculator);
+
 #if !defined(MEDIAPIPE_DISABLE_GL_COMPUTE)
 typedef SplitVectorCalculator<::tflite::gpu::gl::GlBuffer, true>
     MovableSplitGlBufferVectorCalculator;
 REGISTER_CALCULATOR(MovableSplitGlBufferVectorCalculator);
 #endif
+
+typedef SplitVectorCalculator<::mediapipe::Detection, false>
+    SplitDetectionVectorCalculator;
+REGISTER_CALCULATOR(SplitDetectionVectorCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/image/BUILD

@@ -86,6 +86,14 @@ mediapipe_cc_proto_library(
     deps = [":opencv_image_encoder_calculator_proto"],
 )
 
+mediapipe_cc_proto_library(
+    name = "opencv_encoded_image_to_image_frame_calculator_cc_proto",
+    srcs = ["opencv_encoded_image_to_image_frame_calculator.proto"],
+    cc_deps = ["//mediapipe/framework:calculator_cc_proto"],
+    visibility = ["//visibility:public"],
+    deps = [":opencv_encoded_image_to_image_frame_calculator_proto"],
+)
+
 mediapipe_cc_proto_library(
     name = "mask_overlay_calculator_cc_proto",
     srcs = ["mask_overlay_calculator.proto"],
@@ -172,6 +180,7 @@ cc_library(
     srcs = ["opencv_encoded_image_to_image_frame_calculator.cc"],
     visibility = ["//visibility:public"],
     deps = [
+        ":opencv_encoded_image_to_image_frame_calculator_cc_proto",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework/formats:image_frame_opencv",
         "//mediapipe/framework/port:opencv_imgcodecs",
@@ -422,9 +431,12 @@ cc_library(
         ":recolor_calculator_cc_proto",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework/formats:image_frame",
+        "//mediapipe/framework/formats:image_frame_opencv",
         "//mediapipe/framework/port:status",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/util:color_cc_proto",
+        "//mediapipe/framework/port:opencv_core",
+        "//mediapipe/framework/port:opencv_imgproc",
     ] + select({
         "//mediapipe/gpu:disable_gpu": [],
         "//conditions:default": [
@@ -554,6 +566,27 @@ proto_library(
     deps = ["//mediapipe/framework:calculator_proto"],
 )
 
+proto_library(
+    name = "opencv_encoded_image_to_image_frame_calculator_proto",
+    srcs = ["opencv_encoded_image_to_image_frame_calculator.proto"],
+    visibility = ["//visibility:public"],
+    deps = ["//mediapipe/framework:calculator_proto"],
+)
+
+proto_library(
+    name = "feature_detector_calculator_proto",
+    srcs = ["feature_detector_calculator.proto"],
+    deps = ["//mediapipe/framework:calculator_proto"],
+)
+
+mediapipe_cc_proto_library(
+    name = "feature_detector_calculator_cc_proto",
+    srcs = ["feature_detector_calculator.proto"],
+    cc_deps = ["//mediapipe/framework:calculator_cc_proto"],
+    visibility = ["//visibility:public"],
+    deps = [":feature_detector_calculator_proto"],
+)
+
 cc_library(
     name = "mask_overlay_calculator",
     srcs = ["mask_overlay_calculator.cc"],
@@ -569,3 +602,30 @@ cc_library(
     ],
     alwayslink = 1,
 )
+
+cc_library(
+    name = "feature_detector_calculator",
+    srcs = ["feature_detector_calculator.cc"],
+    visibility = ["//mediapipe:__subpackages__"],
+    deps = [
+        ":feature_detector_calculator_cc_proto",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/formats:image_frame",
+        "//mediapipe/framework/formats:image_frame_opencv",
+        "//mediapipe/framework/formats:landmark_cc_proto",
+        "//mediapipe/framework/formats:video_stream_header",
+        "//mediapipe/framework/port:integral_types",
+        "//mediapipe/framework/port:logging",
+        "//mediapipe/framework/port:opencv_core",
+        "//mediapipe/framework/port:opencv_features2d",
+        "//mediapipe/framework/port:opencv_imgproc",
+        "//mediapipe/framework/port:ret_check",
+        "//mediapipe/framework/port:status",
+        "//mediapipe/framework/port:threadpool",
+        "//mediapipe/framework/tool:options_util",
+        "@com_google_absl//absl/memory",
+        "@com_google_absl//absl/synchronization",
+        "@org_tensorflow//tensorflow/lite:framework",
+    ],
+    alwayslink = 1,
+)

mediapipe/calculators/image/feature_detector_calculator.cc

@@ -0,0 +1,210 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <memory>
+#include <vector>
+
+#include "absl/memory/memory.h"
+#include "absl/synchronization/blocking_counter.h"
+#include "mediapipe/calculators/image/feature_detector_calculator.pb.h"
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/formats/image_frame.h"
+#include "mediapipe/framework/formats/image_frame_opencv.h"
+#include "mediapipe/framework/formats/landmark.pb.h"
+#include "mediapipe/framework/formats/video_stream_header.h"
+#include "mediapipe/framework/port/integral_types.h"
+#include "mediapipe/framework/port/logging.h"
+#include "mediapipe/framework/port/opencv_core_inc.h"
+#include "mediapipe/framework/port/opencv_features2d_inc.h"
+#include "mediapipe/framework/port/opencv_imgproc_inc.h"
+#include "mediapipe/framework/port/ret_check.h"
+#include "mediapipe/framework/port/status.h"
+#include "mediapipe/framework/port/threadpool.h"
+#include "mediapipe/framework/tool/options_util.h"
+#include "tensorflow/lite/interpreter.h"
+
+namespace mediapipe {
+
+const char kOptionsTag[] = "OPTIONS";
+const int kPatchSize = 32;
+const int kNumThreads = 16;
+
+// A calculator to apply local feature detection.
+// Input stream:
+//   IMAGE: Input image frame of type ImageFrame from video stream.
+// Output streams:
+//   FEATURES: The detected keypoints from input image as vector<cv::KeyPoint>.
+//   PATCHES:  Optional output the extracted patches as vector<cv::Mat>
+class FeatureDetectorCalculator : public CalculatorBase {
+ public:
+  ~FeatureDetectorCalculator() override = default;
+
+  static ::mediapipe::Status GetContract(CalculatorContract* cc);
+
+  ::mediapipe::Status Open(CalculatorContext* cc) override;
+  ::mediapipe::Status Process(CalculatorContext* cc) override;
+
+ private:
+  FeatureDetectorCalculatorOptions options_;
+  cv::Ptr<cv::Feature2D> feature_detector_;
+  std::unique_ptr<::mediapipe::ThreadPool> pool_;
+
+  // Create image pyramid based on input image.
+  void ComputeImagePyramid(const cv::Mat& input_image,
+                           std::vector<cv::Mat>* image_pyramid);
+
+  // Extract the patch for single feature with image pyramid.
+  cv::Mat ExtractPatch(const cv::KeyPoint& feature,
+                       const std::vector<cv::Mat>& image_pyramid);
+};
+
+REGISTER_CALCULATOR(FeatureDetectorCalculator);
+
+::mediapipe::Status FeatureDetectorCalculator::GetContract(
+    CalculatorContract* cc) {
+  if (cc->Inputs().HasTag("IMAGE")) {
+    cc->Inputs().Tag("IMAGE").Set<ImageFrame>();
+  }
+  if (cc->Outputs().HasTag("FEATURES")) {
+    cc->Outputs().Tag("FEATURES").Set<std::vector<cv::KeyPoint>>();
+  }
+  if (cc->Outputs().HasTag("LANDMARKS")) {
+    cc->Outputs().Tag("LANDMARKS").Set<NormalizedLandmarkList>();
+  }
+  if (cc->Outputs().HasTag("PATCHES")) {
+    cc->Outputs().Tag("PATCHES").Set<std::vector<TfLiteTensor>>();
+  }
+  return ::mediapipe::OkStatus();
+}
+
+::mediapipe::Status FeatureDetectorCalculator::Open(CalculatorContext* cc) {
+  options_ =
+      tool::RetrieveOptions(cc->Options(), cc->InputSidePackets(), kOptionsTag)
+          .GetExtension(FeatureDetectorCalculatorOptions::ext);
+  feature_detector_ = cv::ORB::create(
+      options_.max_features(), options_.scale_factor(),
+      options_.pyramid_level(), kPatchSize - 1, 0, 2, cv::ORB::FAST_SCORE);
+  pool_ = absl::make_unique<::mediapipe::ThreadPool>("ThreadPool", kNumThreads);
+  pool_->StartWorkers();
+  return ::mediapipe::OkStatus();
+}
+
+::mediapipe::Status FeatureDetectorCalculator::Process(CalculatorContext* cc) {
+  const Timestamp& timestamp = cc->InputTimestamp();
+  if (timestamp == Timestamp::PreStream()) {
+    // Indicator packet.
+    return ::mediapipe::OkStatus();
+  }
+  InputStream* input_frame = &(cc->Inputs().Tag("IMAGE"));
+  cv::Mat input_view = formats::MatView(&input_frame->Get<ImageFrame>());
+  cv::Mat grayscale_view;
+  cv::cvtColor(input_view, grayscale_view, cv::COLOR_RGB2GRAY);
+
+  std::vector<cv::KeyPoint> keypoints;
+  feature_detector_->detect(grayscale_view, keypoints);
+  if (keypoints.size() > options_.max_features()) {
+    keypoints.resize(options_.max_features());
+  }
+
+  if (cc->Outputs().HasTag("FEATURES")) {
+    auto features_ptr = absl::make_unique<std::vector<cv::KeyPoint>>(keypoints);
+    cc->Outputs().Tag("FEATURES").Add(features_ptr.release(), timestamp);
+  }
+
+  if (cc->Outputs().HasTag("LANDMARKS")) {
+    auto landmarks_ptr = absl::make_unique<NormalizedLandmarkList>();
+    for (int j = 0; j < keypoints.size(); ++j) {
+      auto feature_landmark = landmarks_ptr->add_landmark();
+      feature_landmark->set_x(keypoints[j].pt.x / grayscale_view.cols);
+      feature_landmark->set_y(keypoints[j].pt.y / grayscale_view.rows);
+    }
+    cc->Outputs().Tag("LANDMARKS").Add(landmarks_ptr.release(), timestamp);
+  }
+
+  if (cc->Outputs().HasTag("PATCHES")) {
+    std::vector<cv::Mat> image_pyramid;
+    ComputeImagePyramid(grayscale_view, &image_pyramid);
+    std::vector<cv::Mat> patch_mat;
+    patch_mat.resize(keypoints.size());
+    absl::BlockingCounter counter(keypoints.size());
+    for (int i = 0; i < keypoints.size(); i++) {
+      pool_->Schedule(
+          [this, &image_pyramid, &keypoints, &patch_mat, i, &counter] {
+            patch_mat[i] = ExtractPatch(keypoints[i], image_pyramid);
+            counter.DecrementCount();
+          });
+    }
+    counter.Wait();
+    const int batch_size = options_.max_features();
+    auto patches = absl::make_unique<std::vector<TfLiteTensor>>();
+    TfLiteTensor tensor;
+    tensor.type = kTfLiteFloat32;
+    tensor.dims = TfLiteIntArrayCreate(4);
+    tensor.dims->data[0] = batch_size;
+    tensor.dims->data[1] = kPatchSize;
+    tensor.dims->data[2] = kPatchSize;
+    tensor.dims->data[3] = 1;
+    int num_bytes = batch_size * kPatchSize * kPatchSize * sizeof(float);
+    tensor.data.data = malloc(num_bytes);
+    tensor.bytes = num_bytes;
+    tensor.allocation_type = kTfLiteArenaRw;
+    float* tensor_buffer = tensor.data.f;
+    for (int i = 0; i < keypoints.size(); i++) {
+      for (int j = 0; j < patch_mat[i].rows; ++j) {
+        for (int k = 0; k < patch_mat[i].cols; ++k) {
+          *tensor_buffer++ = patch_mat[i].at<uchar>(j, k) / 128.0f - 1.0f;
+        }
+      }
+    }
+    for (int i = keypoints.size() * kPatchSize * kPatchSize; i < num_bytes / 4;
+         i++) {
+      *tensor_buffer++ = 0;
+    }
+
+    patches->emplace_back(tensor);
+    cc->Outputs().Tag("PATCHES").Add(patches.release(), timestamp);
+  }
+
+  return ::mediapipe::OkStatus();
+}
+
+void FeatureDetectorCalculator::ComputeImagePyramid(
+    const cv::Mat& input_image, std::vector<cv::Mat>* image_pyramid) {
+  cv::Mat tmp_image = input_image;
+  cv::Mat src_image = input_image;
+  for (int i = 0; i < options_.pyramid_level(); ++i) {
+    image_pyramid->push_back(src_image);
+    cv::resize(src_image, tmp_image, cv::Size(), 1.0f / options_.scale_factor(),
+               1.0f / options_.scale_factor());
+    src_image = tmp_image;
+  }
+}
+
+cv::Mat FeatureDetectorCalculator::ExtractPatch(
+    const cv::KeyPoint& feature, const std::vector<cv::Mat>& image_pyramid) {
+  cv::Mat img = image_pyramid[feature.octave];
+  float scale_factor = 1 / pow(options_.scale_factor(), feature.octave);
+  cv::Point2f center =
+      cv::Point2f(feature.pt.x * scale_factor, feature.pt.y * scale_factor);
+  cv::Mat rot = cv::getRotationMatrix2D(center, feature.angle, 1.0);
+  rot.at<double>(0, 2) += kPatchSize / 2 - center.x;
+  rot.at<double>(1, 2) += kPatchSize / 2 - center.y;
+  cv::Mat cropped_img;
+  // perform the affine transformation
+  cv::warpAffine(img, cropped_img, rot, cv::Size(kPatchSize, kPatchSize),
+                 cv::INTER_LINEAR);
+  return cropped_img;
+}
+
+}  // namespace mediapipe

mediapipe/calculators/image/feature_detector_calculator.proto

@@ -0,0 +1,24 @@
+// Options for FeatureDetectorCalculator
+syntax = "proto2";
+
+package mediapipe;
+
+import "mediapipe/framework/calculator.proto";
+
+message FeatureDetectorCalculatorOptions {
+  extend CalculatorOptions {
+    optional FeatureDetectorCalculatorOptions ext = 278741680;
+  }
+
+  // Set to true if output patches, otherwise only output cv::KeyPoint
+  optional bool output_patch = 1;
+
+  // The max number of detected features.
+  optional int32 max_features = 2 [default = 200];
+
+  // The number of pyramid levels.
+  optional int32 pyramid_level = 3 [default = 4];
+
+  // Pyramid decimation ratio.
+  optional float scale_factor = 4 [default = 1.2];
+}

mediapipe/calculators/image/image_cropping_calculator.cc

@@ -219,8 +219,10 @@ REGISTER_CALCULATOR(ImageCroppingCalculator);
   const auto& input_img = cc->Inputs().Tag(kImageTag).Get<ImageFrame>();
   cv::Mat input_mat = formats::MatView(&input_img);
 
-  auto [target_width, target_height, rect_center_x, rect_center_y, rotation] =
-      GetCropSpecs(cc, input_img.Width(), input_img.Height());
+  RectSpec specs = GetCropSpecs(cc, input_img.Width(), input_img.Height());
+  int target_width = specs.width, target_height = specs.height,
+      rect_center_x = specs.center_x, rect_center_y = specs.center_y;
+  float rotation = specs.rotation;
 
   // Get border mode and value for OpenCV.
   int border_mode;
@@ -403,8 +405,10 @@ void ImageCroppingCalculator::GetOutputDimensions(CalculatorContext* cc,
                                                   int src_width, int src_height,
                                                   int* dst_width,
                                                   int* dst_height) {
-  auto [crop_width, crop_height, x_center, y_center, rotation] =
-      GetCropSpecs(cc, src_width, src_height);
+  RectSpec specs = GetCropSpecs(cc, src_width, src_height);
+  int crop_width = specs.width, crop_height = specs.height,
+      x_center = specs.center_x, y_center = specs.center_y;
+  float rotation = specs.rotation;
 
   const float half_width = crop_width / 2.0f;
   const float half_height = crop_height / 2.0f;

mediapipe/calculators/image/opencv_encoded_image_to_image_frame_calculator.cc

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include "mediapipe/calculators/image/opencv_encoded_image_to_image_frame_calculator.pb.h"
 #include "mediapipe/framework/calculator_framework.h"
 #include "mediapipe/framework/formats/image_frame_opencv.h"
 #include "mediapipe/framework/port/opencv_imgcodecs_inc.h"
@@ -34,7 +35,11 @@ namespace mediapipe {
 class OpenCvEncodedImageToImageFrameCalculator : public CalculatorBase {
  public:
   static ::mediapipe::Status GetContract(CalculatorContract* cc);
+  ::mediapipe::Status Open(CalculatorContext* cc) override;
   ::mediapipe::Status Process(CalculatorContext* cc) override;
+
+ private:
+  mediapipe::OpenCvEncodedImageToImageFrameCalculatorOptions options_;
 };
 
 ::mediapipe::Status OpenCvEncodedImageToImageFrameCalculator::GetContract(
@@ -44,13 +49,29 @@ class OpenCvEncodedImageToImageFrameCalculator : public CalculatorBase {
   return ::mediapipe::OkStatus();
 }
 
+::mediapipe::Status OpenCvEncodedImageToImageFrameCalculator::Open(
+    CalculatorContext* cc) {
+  options_ =
+      cc->Options<mediapipe::OpenCvEncodedImageToImageFrameCalculatorOptions>();
+  return ::mediapipe::OkStatus();
+}
+
 ::mediapipe::Status OpenCvEncodedImageToImageFrameCalculator::Process(
     CalculatorContext* cc) {
   const std::string& contents = cc->Inputs().Index(0).Get<std::string>();
   const std::vector<char> contents_vector(contents.begin(), contents.end());
-  cv::Mat decoded_mat =
-      cv::imdecode(contents_vector, -1 /* return the loaded image as-is */);
-
+  cv::Mat decoded_mat;
+  if (options_.apply_orientation_from_exif_data()) {
+    // We want to respect the orientation from the EXIF data, which
+    // IMREAD_UNCHANGED ignores, but otherwise we want to be as permissive as
+    // possible with our reading flags. Therefore, we use IMREAD_ANYCOLOR and
+    // IMREAD_ANYDEPTH.
+    decoded_mat = cv::imdecode(contents_vector,
+                               cv::IMREAD_ANYCOLOR | cv::IMREAD_ANYDEPTH);
+  } else {
+    // Return the loaded image as-is
+    decoded_mat = cv::imdecode(contents_vector, cv::IMREAD_UNCHANGED);
+  }
   ImageFormat::Format image_format = ImageFormat::UNKNOWN;
   cv::Mat output_mat;
   switch (decoded_mat.channels()) {
@@ -70,7 +91,8 @@ class OpenCvEncodedImageToImageFrameCalculator : public CalculatorBase {
              << "Unsupported number of channels: " << decoded_mat.channels();
   }
   std::unique_ptr<ImageFrame> output_frame = absl::make_unique<ImageFrame>(
-      image_format, decoded_mat.size().width, decoded_mat.size().height);
+      image_format, decoded_mat.size().width, decoded_mat.size().height,
+      ImageFrame::kGlDefaultAlignmentBoundary);
   output_mat.copyTo(formats::MatView(output_frame.get()));
   cc->Outputs().Index(0).Add(output_frame.release(), cc->InputTimestamp());
   return ::mediapipe::OkStatus();

mediapipe/calculators/image/opencv_encoded_image_to_image_frame_calculator.proto

@@ -0,0 +1,30 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto2";
+
+package mediapipe;
+
+import "mediapipe/framework/calculator.proto";
+
+message OpenCvEncodedImageToImageFrameCalculatorOptions {
+  extend CalculatorOptions {
+    optional OpenCvEncodedImageToImageFrameCalculatorOptions ext = 303447308;
+  }
+
+  // If set, we will attempt to automatically apply the orientation specified by
+  // the image's EXIF data when loading the image. Otherwise, the image data
+  // will be loaded as-is.
+  optional bool apply_orientation_from_exif_data = 1 [default = false];
+}

mediapipe/calculators/image/recolor_calculator.cc

@@ -17,6 +17,9 @@
 #include "mediapipe/calculators/image/recolor_calculator.pb.h"
 #include "mediapipe/framework/calculator_framework.h"
 #include "mediapipe/framework/formats/image_frame.h"
+#include "mediapipe/framework/formats/image_frame_opencv.h"
+#include "mediapipe/framework/port/opencv_core_inc.h"
+#include "mediapipe/framework/port/opencv_imgproc_inc.h"
 #include "mediapipe/framework/port/ret_check.h"
 #include "mediapipe/framework/port/status.h"
 #include "mediapipe/util/color.pb.h"
@@ -39,8 +42,6 @@ namespace mediapipe {
 // The luminance of the input image is used to adjust the blending weight,
 // to help preserve image textures.
 //
-// TODO implement cpu support.
-//
 // Inputs:
 //   One of the following IMAGE tags:
 //   IMAGE: An ImageFrame input image, RGB or RGBA.
@@ -71,6 +72,8 @@ namespace mediapipe {
 //    }
 //  }
 //
+// Note: Cannot mix-match CPU & GPU inputs/outputs.
+//       CPU-in & CPU-out <or> GPU-in & GPU-out
 class RecolorCalculator : public CalculatorBase {
  public:
   RecolorCalculator() = default;
@@ -138,6 +141,11 @@ REGISTER_CALCULATOR(RecolorCalculator);
     cc->Outputs().Tag("IMAGE").Set<ImageFrame>();
   }
 
+  // Confirm only one of the input streams is present.
+  RET_CHECK(cc->Inputs().HasTag("IMAGE") ^ cc->Inputs().HasTag("IMAGE_GPU"));
+  // Confirm only one of the output streams is present.
+  RET_CHECK(cc->Outputs().HasTag("IMAGE") ^ cc->Outputs().HasTag("IMAGE_GPU"));
+
   if (use_gpu) {
 #if !defined(MEDIAPIPE_DISABLE_GPU)
     MP_RETURN_IF_ERROR(mediapipe::GlCalculatorHelper::UpdateContract(cc));
@@ -193,7 +201,62 @@ REGISTER_CALCULATOR(RecolorCalculator);
 }
 
 ::mediapipe::Status RecolorCalculator::RenderCpu(CalculatorContext* cc) {
-  return ::mediapipe::UnimplementedError("CPU support is not implemented yet.");
+  if (cc->Inputs().Tag("MASK").IsEmpty()) {
+    return ::mediapipe::OkStatus();
+  }
+  // Get inputs and setup output.
+  const auto& input_img = cc->Inputs().Tag("IMAGE").Get<ImageFrame>();
+  const auto& mask_img = cc->Inputs().Tag("MASK").Get<ImageFrame>();
+
+  cv::Mat input_mat = formats::MatView(&input_img);
+  cv::Mat mask_mat = formats::MatView(&mask_img);
+
+  RET_CHECK(input_mat.channels() == 3);  // RGB only.
+
+  if (mask_mat.channels() > 1) {
+    std::vector<cv::Mat> channels;
+    cv::split(mask_mat, channels);
+    if (mask_channel_ == mediapipe::RecolorCalculatorOptions_MaskChannel_ALPHA)
+      mask_mat = channels[3];
+    else
+      mask_mat = channels[0];
+  }
+  cv::Mat mask_full;
+  cv::resize(mask_mat, mask_full, input_mat.size());
+
+  auto output_img = absl::make_unique<ImageFrame>(
+      input_img.Format(), input_mat.cols, input_mat.rows);
+  cv::Mat output_mat = mediapipe::formats::MatView(output_img.get());
+
+  // From GPU shader:
+  /*
+      vec4 weight = texture2D(mask, sample_coordinate);
+      vec4 color1 = texture2D(frame, sample_coordinate);
+      vec4 color2 = vec4(recolor, 1.0);
+
+      float luminance = dot(color1.rgb, vec3(0.299, 0.587, 0.114));
+      float mix_value = weight.MASK_COMPONENT * luminance;
+
+      fragColor = mix(color1, color2, mix_value);
+  */
+  for (int i = 0; i < output_mat.rows; ++i) {
+    for (int j = 0; j < output_mat.cols; ++j) {
+      float weight = mask_full.at<uchar>(i, j) * (1.0 / 255.0);
+      cv::Vec3f color1 = input_mat.at<cv::Vec3b>(i, j);
+      cv::Vec3f color2 = {color_[0], color_[1], color_[2]};
+
+      float luminance =
+          (color1[0] * 0.299 + color1[1] * 0.587 + color1[2] * 0.114) / 255;
+      float mix_value = weight * luminance;
+
+      cv::Vec3b mix_color = color1 * (1.0 - mix_value) + color2 * mix_value;
+      output_mat.at<cv::Vec3b>(i, j) = mix_color;
+    }
+  }
+
+  cc->Outputs().Tag("IMAGE").Add(output_img.release(), cc->InputTimestamp());
+
+  return ::mediapipe::OkStatus();
 }
 
 ::mediapipe::Status RecolorCalculator::RenderGpu(CalculatorContext* cc) {
@@ -303,9 +366,9 @@ void RecolorCalculator::GlRender() {
 
   if (!options.has_color()) RET_CHECK_FAIL() << "Missing color option.";
 
-  color_.push_back(options.color().r() / 255.0);
-  color_.push_back(options.color().g() / 255.0);
-  color_.push_back(options.color().b() / 255.0);
+  color_.push_back(options.color().r());
+  color_.push_back(options.color().g());
+  color_.push_back(options.color().b());
 
   return ::mediapipe::OkStatus();
 }
@@ -378,8 +441,8 @@ void RecolorCalculator::GlRender() {
   glUseProgram(program_);
   glUniform1i(glGetUniformLocation(program_, "frame"), 1);
   glUniform1i(glGetUniformLocation(program_, "mask"), 2);
-  glUniform3f(glGetUniformLocation(program_, "recolor"), color_[0], color_[1],
-              color_[2]);
+  glUniform3f(glGetUniformLocation(program_, "recolor"), color_[0] / 255.0,
+              color_[1] / 255.0, color_[2] / 255.0);
 #endif  //  !MEDIAPIPE_DISABLE_GPU
 
   return ::mediapipe::OkStatus();

mediapipe/calculators/tensorflow/BUILD

@@ -1110,6 +1110,7 @@ cc_test(
         ],
         "//mediapipe:android": [
             "@org_tensorflow//tensorflow/core:android_tensorflow_lib_with_ops_lite_proto_no_rtti_lib",
+            "@org_tensorflow//tensorflow/core:android_tensorflow_test_lib",
         ],
         "//mediapipe:ios": [
             "@org_tensorflow//tensorflow/core:ios_tensorflow_test_lib",

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_calculator.cc

@@ -51,10 +51,11 @@ static constexpr char kStringSavedModelPath[] = "STRING_SAVED_MODEL_PATH";
 #endif
 }
 
-// If options.convert_signature_to_tags() will convert letters to uppercase
-// and replace /'s with _'s. If set, this enables the standard SavedModel
-// classification, regression, and prediction signatures to be used as
-// uppercase INPUTS and OUTPUTS tags for streams.
+// If options.convert_signature_to_tags() is set, will convert letters to
+// uppercase and replace /'s and -'s with _'s. This enables the standard
+// SavedModel classification, regression, and prediction signatures to be used
+// as uppercase INPUTS and OUTPUTS tags for streams and supports other common
+// patterns.
 const std::string MaybeConvertSignatureToTag(
     const std::string& name,
     const TensorFlowSessionFromSavedModelCalculatorOptions& options) {
@@ -64,6 +65,7 @@ const std::string MaybeConvertSignatureToTag(
     std::transform(name.begin(), name.end(), output.begin(),
                    [](unsigned char c) { return std::toupper(c); });
     output = absl::StrReplaceAll(output, {{"/", "_"}});
+    output = absl::StrReplaceAll(output, {{"-", "_"}});
     return output;
   } else {
     return name;

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_calculator.proto

@@ -32,8 +32,8 @@ message TensorFlowSessionFromSavedModelCalculatorOptions {
   // The name of the generic signature to load into the mapping from tags to
   // tensor names.
   optional string signature_name = 2 [default = "serving_default"];
-  // Whether to convert the signature keys to uppercase and switch /'s to
-  // _'s, which enables standard signatures to be used as Tags.
+  // Whether to convert the signature keys to uppercase as well as switch /'s
+  // and -'s to _'s, which enables common signatures to be used as Tags.
   optional bool convert_signature_to_tags = 3 [default = true];
   // If true, saved_model_path can have multiple exported models in
   // subdirectories saved_model_path/%08d and the alphabetically last (i.e.,

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_generator.cc

@@ -53,10 +53,11 @@ static constexpr char kStringSavedModelPath[] = "STRING_SAVED_MODEL_PATH";
 #endif
 }
 
-// If options.convert_signature_to_tags() will convert letters to uppercase
-// and replace /'s with _'s. If set, this enables the standard SavedModel
-// classification, regression, and prediction signatures to be used as
-// uppercase INPUTS and OUTPUTS tags for streams.
+// If options.convert_signature_to_tags() is set, will convert letters to
+// uppercase and replace /'s and -'s with _'s. This enables the standard
+// SavedModel classification, regression, and prediction signatures to be used
+// as uppercase INPUTS and OUTPUTS tags for streams and supports other common
+// patterns.
 const std::string MaybeConvertSignatureToTag(
     const std::string& name,
     const TensorFlowSessionFromSavedModelGeneratorOptions& options) {
@@ -66,6 +67,7 @@ const std::string MaybeConvertSignatureToTag(
     std::transform(name.begin(), name.end(), output.begin(),
                    [](unsigned char c) { return std::toupper(c); });
     output = absl::StrReplaceAll(output, {{"/", "_"}});
+    output = absl::StrReplaceAll(output, {{"-", "_"}});
     return output;
   } else {
     return name;

mediapipe/calculators/tensorflow/tensorflow_session_from_saved_model_generator.proto

@@ -32,8 +32,8 @@ message TensorFlowSessionFromSavedModelGeneratorOptions {
   // The name of the generic signature to load into the mapping from tags to
   // tensor names.
   optional string signature_name = 2 [default = "serving_default"];
-  // Whether to convert the signature keys to uppercase and switch /'s to
-  // _'s, which enables standard signatures to be used as Tags.
+  // Whether to convert the signature keys to uppercase as well as switch /'s
+  // and -'s to _'s, which enables common signatures to be used as Tags.
   optional bool convert_signature_to_tags = 3 [default = true];
   // If true, saved_model_path can have multiple exported models in
   // subdirectories saved_model_path/%08d and the alphabetically last (i.e.,

mediapipe/calculators/tflite/BUILD

@@ -222,9 +222,11 @@ cc_library(
     deps = [
         ":util",
         ":tflite_inference_calculator_cc_proto",
+        "@com_google_absl//absl/memory",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/util:resource_util",
         "@org_tensorflow//tensorflow/lite:framework",
+        "@org_tensorflow//tensorflow/lite/delegates/xnnpack:xnnpack_delegate",
         "@org_tensorflow//tensorflow/lite/kernels:builtin_ops",
         "//mediapipe/framework/stream_handler:fixed_size_input_stream_handler",
         "//mediapipe/framework/port:ret_check",
@@ -254,6 +256,10 @@ cc_library(
         "//mediapipe:android": [
             "@org_tensorflow//tensorflow/lite/delegates/nnapi:nnapi_delegate",
         ],
+    }) + select({
+        "//conditions:default": [
+            "//mediapipe/util:cpu_util",
+        ],
     }),
     alwayslink = 1,
 )
@@ -308,6 +314,20 @@ cc_library(
     alwayslink = 1,
 )
 
+cc_library(
+    name = "tflite_model_calculator",
+    srcs = ["tflite_model_calculator.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":util",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework:packet",
+        "//mediapipe/framework/port:ret_check",
+        "@org_tensorflow//tensorflow/lite:framework",
+    ],
+    alwayslink = 1,
+)
+
 cc_library(
     name = "tflite_tensors_to_segmentation_calculator",
     srcs = ["tflite_tensors_to_segmentation_calculator.cc"],
@@ -431,7 +451,7 @@ cc_library(
         "//mediapipe:android": [
             "//mediapipe/util/android/file/base",
         ],
-        "//mediapipe:apple": [
+        "//mediapipe:ios": [
             "//mediapipe/util/android/file/base",
         ],
         "//mediapipe:macos": [
@@ -478,6 +498,9 @@ cc_test(
     deps = [
         ":tflite_inference_calculator",
         ":tflite_inference_calculator_cc_proto",
+        ":tflite_model_calculator",
+        "//mediapipe/calculators/core:constant_side_packet_calculator",
+        "//mediapipe/calculators/util:local_file_contents_calculator",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework:calculator_runner",
         "//mediapipe/framework/deps:file_path",
@@ -485,7 +508,9 @@ cc_test(
         "//mediapipe/framework/port:integral_types",
         "//mediapipe/framework/port:parse_text_proto",
         "//mediapipe/framework/tool:validate_type",
+        "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/types:optional",
         "@org_tensorflow//tensorflow/lite:framework",
         "@org_tensorflow//tensorflow/lite/kernels:builtin_ops",
     ],
@@ -511,3 +536,19 @@ cc_test(
         "@org_tensorflow//tensorflow/lite/kernels:builtin_ops",
     ],
 )
+
+cc_test(
+    name = "tflite_model_calculator_test",
+    srcs = ["tflite_model_calculator_test.cc"],
+    data = ["testdata/add.bin"],
+    deps = [
+        ":tflite_model_calculator",
+        "//mediapipe/calculators/core:constant_side_packet_calculator",
+        "//mediapipe/calculators/util:local_file_contents_calculator",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework:calculator_runner",
+        "//mediapipe/framework/port:gtest_main",
+        "//mediapipe/framework/port:parse_text_proto",
+        "@org_tensorflow//tensorflow/lite:framework",
+    ],
+)

mediapipe/calculators/tflite/tflite_inference_calculator.cc

@@ -17,10 +17,16 @@
 #include <string>
 #include <vector>
 
+#include "absl/memory/memory.h"
 #include "mediapipe/calculators/tflite/tflite_inference_calculator.pb.h"
 #include "mediapipe/calculators/tflite/util.h"
 #include "mediapipe/framework/calculator_framework.h"
 #include "mediapipe/framework/port/ret_check.h"
+
+#if !defined(__EMSCRIPTEN__)
+#include "mediapipe/util/cpu_util.h"
+#endif  // !__EMSCRIPTEN__
+
 #include "mediapipe/util/resource_util.h"
 #include "tensorflow/lite/error_reporter.h"
 #include "tensorflow/lite/interpreter.h"
@@ -50,7 +56,7 @@
 #include "tensorflow/lite/delegates/gpu/metal_delegate.h"
 #include "tensorflow/lite/delegates/gpu/metal_delegate_internal.h"
 #endif  // iOS
-
+#include "tensorflow/lite/delegates/xnnpack/xnnpack_delegate.h"
 #if defined(MEDIAPIPE_ANDROID)
 #include "tensorflow/lite/delegates/nnapi/nnapi_delegate.h"
 #endif  // ANDROID
@@ -113,6 +119,23 @@ struct GPUData {
 };
 #endif
 
+// Returns number of threads to configure XNNPACK delegate with.
+// (Equal to user provided value if specified.  Otherwise, it returns number of
+// high cores (hard-coded to 1 for __EMSCRIPTEN__))
+int GetXnnpackNumThreads(
+    const mediapipe::TfLiteInferenceCalculatorOptions& opts) {
+  static constexpr int kDefaultNumThreads = -1;
+  if (opts.has_delegate() && opts.delegate().has_xnnpack() &&
+      opts.delegate().xnnpack().num_threads() != kDefaultNumThreads) {
+    return opts.delegate().xnnpack().num_threads();
+  }
+#if !defined(__EMSCRIPTEN__)
+  return InferHigherCoreIds().size();
+#else
+  return 1;
+#endif  // !__EMSCRIPTEN__
+}
+
 // Calculator Header Section
 
 // Runs inference on the provided input TFLite tensors and TFLite model.
@@ -139,6 +162,9 @@ struct GPUData {
 // Input side packet:
 //  CUSTOM_OP_RESOLVER (optional) - Use a custom op resolver,
 //                                  instead of the builtin one.
+//  MODEL (optional) - Use to specify TfLite model
+//                     (std::unique_ptr<tflite::FlatBufferModel,
+//                       std::function<void(tflite::FlatBufferModel*)>>)
 //
 // Example use:
 // node {
@@ -153,6 +179,20 @@ struct GPUData {
 //   }
 // }
 //
+// or
+//
+// node {
+//   calculator: "TfLiteInferenceCalculator"
+//   input_stream: "TENSORS:tensor_image"
+//   input_side_packet: "MODEL:model"
+//   output_stream: "TENSORS:tensors"
+//   options: {
+//     [mediapipe.TfLiteInferenceCalculatorOptions.ext] {
+//       delegate { gpu {} }
+//     }
+//   }
+// }
+//
 // IMPORTANT Notes:
 //  Tensors are assumed to be ordered correctly (sequentially added to model).
 //  Input tensors are assumed to be of the correct size and already normalized.
@@ -165,6 +205,9 @@ class TfLiteInferenceCalculator : public CalculatorBase {
  public:
   using TfLiteDelegatePtr =
       std::unique_ptr<TfLiteDelegate, std::function<void(TfLiteDelegate*)>>;
+  using TfLiteModelPtr =
+      std::unique_ptr<tflite::FlatBufferModel,
+                      std::function<void(tflite::FlatBufferModel*)>>;
 
   static ::mediapipe::Status GetContract(CalculatorContract* cc);
 
@@ -173,12 +216,12 @@ class TfLiteInferenceCalculator : public CalculatorBase {
   ::mediapipe::Status Close(CalculatorContext* cc) override;
 
  private:
-  ::mediapipe::Status LoadOptions(CalculatorContext* cc);
   ::mediapipe::Status LoadModel(CalculatorContext* cc);
+  ::mediapipe::StatusOr<Packet> GetModelAsPacket(const CalculatorContext& cc);
   ::mediapipe::Status LoadDelegate(CalculatorContext* cc);
 
+  Packet model_packet_;
   std::unique_ptr<tflite::Interpreter> interpreter_;
-  std::unique_ptr<tflite::FlatBufferModel> model_;
   TfLiteDelegatePtr delegate_;
 
 #if !defined(MEDIAPIPE_DISABLE_GL_COMPUTE)
@@ -198,7 +241,6 @@ class TfLiteInferenceCalculator : public CalculatorBase {
       edgetpu::EdgeTpuManager::GetSingleton()->OpenDevice();
 #endif
 
-  std::string model_path_ = "";
   bool gpu_inference_ = false;
   bool gpu_input_ = false;
   bool gpu_output_ = false;
@@ -217,6 +259,10 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
 
   const auto& options =
       cc->Options<::mediapipe::TfLiteInferenceCalculatorOptions>();
+  RET_CHECK(!options.model_path().empty() ^
+            cc->InputSidePackets().HasTag("MODEL"))
+      << "Either model as side packet or model path in options is required.";
+
   bool use_gpu =
       options.has_delegate() ? options.delegate().has_gpu() : options.use_gpu();
 
@@ -249,6 +295,9 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
         .Tag("CUSTOM_OP_RESOLVER")
         .Set<tflite::ops::builtin::BuiltinOpResolver>();
   }
+  if (cc->InputSidePackets().HasTag("MODEL")) {
+    cc->InputSidePackets().Tag("MODEL").Set<TfLiteModelPtr>();
+  }
 
   if (use_gpu) {
 #if !defined(MEDIAPIPE_DISABLE_GL_COMPUTE)
@@ -267,7 +316,9 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
 ::mediapipe::Status TfLiteInferenceCalculator::Open(CalculatorContext* cc) {
   cc->SetOffset(TimestampDiff(0));
 
-  MP_RETURN_IF_ERROR(LoadOptions(cc));
+  const auto& options =
+      cc->Options<::mediapipe::TfLiteInferenceCalculatorOptions>();
+  gpu_inference_ = options.use_gpu();
 
   if (cc->Inputs().HasTag("TENSORS_GPU")) {
 #if !defined(MEDIAPIPE_DISABLE_GPU) && !defined(__EMSCRIPTEN__)
@@ -492,34 +543,10 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
 
 // Calculator Auxiliary Section
 
-::mediapipe::Status TfLiteInferenceCalculator::LoadOptions(
-    CalculatorContext* cc) {
-  // Get calculator options specified in the graph.
-  const auto& options =
-      cc->Options<::mediapipe::TfLiteInferenceCalculatorOptions>();
-
-  // Get model name.
-  if (!options.model_path().empty()) {
-    std::string model_path = options.model_path();
-
-    ASSIGN_OR_RETURN(model_path_, mediapipe::PathToResourceAsFile(model_path));
-  } else {
-    LOG(ERROR) << "Must specify path to TFLite model.";
-    return ::mediapipe::Status(::mediapipe::StatusCode::kNotFound,
-                               "Must specify path to TFLite model.");
-  }
-
-  // Get execution modes.
-  gpu_inference_ =
-      options.has_delegate() ? options.delegate().has_gpu() : options.use_gpu();
-
-  return ::mediapipe::OkStatus();
-}
-
 ::mediapipe::Status TfLiteInferenceCalculator::LoadModel(
     CalculatorContext* cc) {
-  model_ = tflite::FlatBufferModel::BuildFromFile(model_path_.c_str());
-  RET_CHECK(model_);
+  ASSIGN_OR_RETURN(model_packet_, GetModelAsPacket(*cc));
+  const auto& model = *model_packet_.Get<TfLiteModelPtr>();
 
   tflite::ops::builtin::BuiltinOpResolver op_resolver;
   if (cc->InputSidePackets().HasTag("CUSTOM_OP_RESOLVER")) {
@@ -529,9 +556,9 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
   }
 #if defined(MEDIAPIPE_EDGE_TPU)
   interpreter_ =
-      BuildEdgeTpuInterpreter(*model_, &op_resolver, edgetpu_context_.get());
+      BuildEdgeTpuInterpreter(model, &op_resolver, edgetpu_context_.get());
 #else
-  tflite::InterpreterBuilder(*model_, op_resolver)(&interpreter_);
+  tflite::InterpreterBuilder(model, op_resolver)(&interpreter_);
 #endif  // MEDIAPIPE_EDGE_TPU
 
   RET_CHECK(interpreter_);
@@ -557,6 +584,28 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
   return ::mediapipe::OkStatus();
 }
 
+::mediapipe::StatusOr<Packet> TfLiteInferenceCalculator::GetModelAsPacket(
+    const CalculatorContext& cc) {
+  const auto& options =
+      cc.Options<mediapipe::TfLiteInferenceCalculatorOptions>();
+  if (!options.model_path().empty()) {
+    std::string model_path = options.model_path();
+
+    ASSIGN_OR_RETURN(model_path, mediapipe::PathToResourceAsFile(model_path));
+
+    auto model = tflite::FlatBufferModel::BuildFromFile(model_path.c_str());
+    RET_CHECK(model) << "Failed to load model from path.";
+    return MakePacket<TfLiteModelPtr>(TfLiteModelPtr(
+        model.release(), [](tflite::FlatBufferModel* model) { delete model; }));
+  }
+  if (cc.InputSidePackets().HasTag("MODEL")) {
+    return cc.InputSidePackets().Tag("MODEL");
+  }
+  return ::mediapipe::Status(
+      ::mediapipe::StatusCode::kNotFound,
+      "Must specify TFLite model as path or loaded model.");
+}
+
 ::mediapipe::Status TfLiteInferenceCalculator::LoadDelegate(
     CalculatorContext* cc) {
   const auto& calculator_opts =
@@ -587,6 +636,22 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
     }
 #endif  // MEDIAPIPE_ANDROID
 
+#if defined(__EMSCRIPTEN__)
+    const bool xnnpack_requested = true;
+#else
+    const bool xnnpack_requested = calculator_opts.has_delegate() &&
+                                   calculator_opts.delegate().has_xnnpack();
+#endif  // __EMSCRIPTEN__
+
+    if (xnnpack_requested) {
+      TfLiteXNNPackDelegateOptions xnnpack_opts{};
+      xnnpack_opts.num_threads = GetXnnpackNumThreads(calculator_opts);
+      delegate_ = TfLiteDelegatePtr(TfLiteXNNPackDelegateCreate(&xnnpack_opts),
+                                    &TfLiteXNNPackDelegateDelete);
+      RET_CHECK_EQ(interpreter_->ModifyGraphWithDelegate(delegate_.get()),
+                   kTfLiteOk);
+    }
+
     // Return, no need for GPU delegate below.
     return ::mediapipe::OkStatus();
   }
@@ -608,7 +673,7 @@ REGISTER_CALCULATOR(TfLiteInferenceCalculator);
     const auto& input_indices = interpreter_->inputs();
     gpu_data_in_.resize(input_indices.size());
     for (int i = 0; i < input_indices.size(); ++i) {
-      const TfLiteTensor* tensor = interpreter_->tensor(input_indices[0]);
+      const TfLiteTensor* tensor = interpreter_->tensor(input_indices[i]);
       gpu_data_in_[i] = absl::make_unique<GPUData>();
       gpu_data_in_[i]->elements = 1;
       for (int d = 0; d < tensor->dims->size; ++d) {

mediapipe/calculators/tflite/tflite_inference_calculator.proto

@@ -45,11 +45,17 @@ message TfLiteInferenceCalculatorOptions {
     message Gpu {}
     // Android only.
     message Nnapi {}
+    message Xnnpack {
+      // Number of threads for XNNPACK delegate. (By default, calculator tries
+      // to choose optimal number of threads depending on the device.)
+      optional int32 num_threads = 1 [default = -1];
+    }
 
     oneof delegate {
       TfLite tflite = 1;
       Gpu gpu = 2;
       Nnapi nnapi = 3;
+      Xnnpack xnnpack = 4;
     }
   }
 

mediapipe/calculators/tflite/tflite_inference_calculator_test.cc

@@ -41,7 +41,7 @@ namespace mediapipe {
 
 using ::tflite::Interpreter;
 
-void DoSmokeTest(absl::string_view delegate) {
+void DoSmokeTest(const std::string& graph_proto) {
   const int width = 8;
   const int height = 8;
   const int channels = 3;
@@ -69,24 +69,9 @@ void DoSmokeTest(absl::string_view delegate) {
   auto input_vec = absl::make_unique<std::vector<TfLiteTensor>>();
   input_vec->emplace_back(*tensor);
 
-  std::string graph_proto = R"(
-    input_stream: "tensor_in"
-    node {
-      calculator: "TfLiteInferenceCalculator"
-      input_stream: "TENSORS:tensor_in"
-      output_stream: "TENSORS:tensor_out"
-      options {
-        [mediapipe.TfLiteInferenceCalculatorOptions.ext] {
-          model_path: "mediapipe/calculators/tflite/testdata/add.bin"
-          $delegate
-        }
-      }
-    }
-  )";
-  ASSERT_EQ(absl::StrReplaceAll({{"$delegate", delegate}}, &graph_proto), 1);
   // Prepare single calculator graph to and wait for packets.
   CalculatorGraphConfig graph_config =
-      ::mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(graph_proto);
+      ParseTextProtoOrDie<CalculatorGraphConfig>(graph_proto);
   std::vector<Packet> output_packets;
   tool::AddVectorSink("tensor_out", &graph_config, &output_packets);
   CalculatorGraph graph(graph_config);
@@ -119,8 +104,70 @@ void DoSmokeTest(absl::string_view delegate) {
 
 // Tests a simple add model that adds an input tensor to itself.
 TEST(TfLiteInferenceCalculatorTest, SmokeTest) {
-  DoSmokeTest(/*delegate=*/"");
-  DoSmokeTest(/*delegate=*/"delegate { tflite {} }");
+  std::string graph_proto = R"(
+    input_stream: "tensor_in"
+    node {
+      calculator: "TfLiteInferenceCalculator"
+      input_stream: "TENSORS:tensor_in"
+      output_stream: "TENSORS:tensor_out"
+      options {
+        [mediapipe.TfLiteInferenceCalculatorOptions.ext] {
+          model_path: "mediapipe/calculators/tflite/testdata/add.bin"
+          $delegate
+        }
+      }
+    }
+  )";
+  DoSmokeTest(
+      /*graph_proto=*/absl::StrReplaceAll(graph_proto, {{"$delegate", ""}}));
+  DoSmokeTest(/*graph_proto=*/absl::StrReplaceAll(
+      graph_proto, {{"$delegate", "delegate { tflite {} }"}}));
+  DoSmokeTest(/*graph_proto=*/absl::StrReplaceAll(
+      graph_proto, {{"$delegate", "delegate { xnnpack {} }"}}));
+  DoSmokeTest(/*graph_proto=*/absl::StrReplaceAll(
+      graph_proto,
+      {{"$delegate", "delegate { xnnpack { num_threads: 10 } }"}}));
+}
+
+TEST(TfLiteInferenceCalculatorTest, SmokeTest_ModelAsInputSidePacket) {
+  std::string graph_proto = R"(
+    input_stream: "tensor_in"
+
+    node {
+      calculator: "ConstantSidePacketCalculator"
+      output_side_packet: "PACKET:model_path"
+      options: {
+        [mediapipe.ConstantSidePacketCalculatorOptions.ext]: {
+          packet { string_value: "mediapipe/calculators/tflite/testdata/add.bin" }
+        }
+      }
+    }
+
+    node {
+      calculator: "LocalFileContentsCalculator"
+      input_side_packet: "FILE_PATH:model_path"
+      output_side_packet: "CONTENTS:model_blob"
+    }
+
+    node {
+      calculator: "TfLiteModelCalculator"
+      input_side_packet: "MODEL_BLOB:model_blob"
+      output_side_packet: "MODEL:model"
+    }
+
+    node {
+      calculator: "TfLiteInferenceCalculator"
+      input_stream: "TENSORS:tensor_in"
+      output_stream: "TENSORS:tensor_out"
+      input_side_packet: "MODEL:model"
+      options {
+        [mediapipe.TfLiteInferenceCalculatorOptions.ext] {
+          use_gpu: false
+        }
+      }
+    }
+  )";
+  DoSmokeTest(graph_proto);
 }
 
 }  // namespace mediapipe

mediapipe/calculators/tflite/tflite_model_calculator.cc

@@ -0,0 +1,86 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <functional>
+#include <memory>
+#include <string>
+
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/packet.h"
+#include "mediapipe/framework/port/ret_check.h"
+#include "tensorflow/lite/model.h"
+
+namespace mediapipe {
+
+// Loads TfLite model from model blob specified as input side packet and outputs
+// corresponding side packet.
+//
+// Input side packets:
+//   MODEL_BLOB - TfLite model blob/file-contents (std::string). You can read
+//                model blob from file (using whatever APIs you have) and pass
+//                it to the graph as input side packet or you can use some of
+//                calculators like LocalFileContentsCalculator to get model
+//                blob and use it as input here.
+//
+// Output side packets:
+//   MODEL - TfLite model. (std::unique_ptr<tflite::FlatBufferModel,
+//           std::function<void(tflite::FlatBufferModel*)>>)
+//
+// Example use:
+//
+// node {
+//   calculator: "TfLiteModelCalculator"
+//   input_side_packet: "MODEL_BLOB:model_blob"
+//   output_side_packet: "MODEL:model"
+// }
+//
+class TfLiteModelCalculator : public CalculatorBase {
+ public:
+  using TfLiteModelPtr =
+      std::unique_ptr<tflite::FlatBufferModel,
+                      std::function<void(tflite::FlatBufferModel*)>>;
+
+  static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    cc->InputSidePackets().Tag("MODEL_BLOB").Set<std::string>();
+    cc->OutputSidePackets().Tag("MODEL").Set<TfLiteModelPtr>();
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Open(CalculatorContext* cc) override {
+    const Packet& model_packet = cc->InputSidePackets().Tag("MODEL_BLOB");
+    const std::string& model_blob = model_packet.Get<std::string>();
+    std::unique_ptr<tflite::FlatBufferModel> model =
+        tflite::FlatBufferModel::BuildFromBuffer(model_blob.data(),
+                                                 model_blob.size());
+    RET_CHECK(model) << "Failed to load TfLite model from blob.";
+
+    cc->OutputSidePackets().Tag("MODEL").Set(
+        MakePacket<TfLiteModelPtr>(TfLiteModelPtr(
+            model.release(), [model_packet](tflite::FlatBufferModel* model) {
+              // Keeping model_packet in order to keep underlying model blob
+              // which can be released only after TfLite model is not needed
+              // anymore (deleted).
+              delete model;
+            })));
+
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Process(CalculatorContext* cc) override {
+    return ::mediapipe::OkStatus();
+  }
+};
+REGISTER_CALCULATOR(TfLiteModelCalculator);
+
+}  // namespace mediapipe

mediapipe/calculators/tflite/tflite_model_calculator_test.cc

@@ -0,0 +1,88 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <memory>
+
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/calculator_runner.h"
+#include "mediapipe/framework/port/gmock.h"
+#include "mediapipe/framework/port/gtest.h"
+#include "mediapipe/framework/port/parse_text_proto.h"
+#include "mediapipe/framework/port/status_matchers.h"  // NOLINT
+#include "tensorflow/lite/model.h"
+
+namespace mediapipe {
+
+TEST(TfLiteModelCalculatorTest, SmokeTest) {
+  // Prepare single calculator graph to and wait for packets.
+  CalculatorGraphConfig graph_config = ParseTextProtoOrDie<
+      CalculatorGraphConfig>(
+      R"(
+        node {
+          calculator: "ConstantSidePacketCalculator"
+          output_side_packet: "PACKET:model_path"
+          options: {
+            [mediapipe.ConstantSidePacketCalculatorOptions.ext]: {
+              packet {
+                string_value: "mediapipe/calculators/tflite/testdata/add.bin"
+              }
+            }
+          }
+        }
+
+        node {
+          calculator: "LocalFileContentsCalculator"
+          input_side_packet: "FILE_PATH:model_path"
+          output_side_packet: "CONTENTS:model_blob"
+        }
+
+        node {
+          calculator: "TfLiteModelCalculator"
+          input_side_packet: "MODEL_BLOB:model_blob"
+          output_side_packet: "MODEL:model"
+        }
+      )");
+  CalculatorGraph graph(graph_config);
+  MP_ASSERT_OK(graph.StartRun({}));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+  auto status_or_packet = graph.GetOutputSidePacket("model");
+  MP_ASSERT_OK(status_or_packet);
+  auto model_packet = status_or_packet.ValueOrDie();
+  const auto& model = model_packet.Get<
+      std::unique_ptr<tflite::FlatBufferModel,
+                      std::function<void(tflite::FlatBufferModel*)>>>();
+
+  auto expected_model = tflite::FlatBufferModel::BuildFromFile(
+      "mediapipe/calculators/tflite/testdata/add.bin");
+
+  EXPECT_EQ(model->GetModel()->version(),
+            expected_model->GetModel()->version());
+  EXPECT_EQ(model->GetModel()->buffers()->size(),
+            expected_model->GetModel()->buffers()->size());
+  const int num_subgraphs = expected_model->GetModel()->subgraphs()->size();
+  EXPECT_EQ(model->GetModel()->subgraphs()->size(), num_subgraphs);
+  for (int i = 0; i < num_subgraphs; ++i) {
+    const auto* expected_subgraph =
+        expected_model->GetModel()->subgraphs()->Get(i);
+    const auto* subgraph = model->GetModel()->subgraphs()->Get(i);
+    const int num_tensors = expected_subgraph->tensors()->size();
+    EXPECT_EQ(subgraph->tensors()->size(), num_tensors);
+    for (int j = 0; j < num_tensors; ++j) {
+      EXPECT_EQ(subgraph->tensors()->Get(j)->name()->str(),
+                expected_subgraph->tensors()->Get(j)->name()->str());
+    }
+  }
+}
+
+}  // namespace mediapipe

mediapipe/calculators/tflite/tflite_tensors_to_classification_calculator.cc

@@ -129,22 +129,43 @@ REGISTER_CALCULATOR(TfLiteTensorsToClassificationCalculator);
     num_classes *= raw_score_tensor->dims->data[i];
   }
 
+  if (options_.binary_classification()) {
+    RET_CHECK_EQ(num_classes, 1);
+    // Number of classes for binary classification.
+    num_classes = 2;
+  }
   if (label_map_loaded_) {
     RET_CHECK_EQ(num_classes, label_map_.size());
   }
   const float* raw_scores = raw_score_tensor->data.f;
 
   auto classification_list = absl::make_unique<ClassificationList>();
-  for (int i = 0; i < num_classes; ++i) {
-    if (options_.has_min_score_threshold() &&
-        raw_scores[i] < options_.min_score_threshold()) {
-      continue;
-    }
-    Classification* classification = classification_list->add_classification();
-    classification->set_index(i);
-    classification->set_score(raw_scores[i]);
+  if (options_.binary_classification()) {
+    Classification* class_first = classification_list->add_classification();
+    Classification* class_second = classification_list->add_classification();
+    class_first->set_index(0);
+    class_second->set_index(1);
+    class_first->set_score(raw_scores[0]);
+    class_second->set_score(1. - raw_scores[0]);
+
     if (label_map_loaded_) {
-      classification->set_label(label_map_[i]);
+      class_first->set_label(label_map_[0]);
+      class_second->set_label(label_map_[1]);
+    }
+  } else {
+    for (int i = 0; i < num_classes; ++i) {
+      if (options_.has_min_score_threshold() &&
+          raw_scores[i] < options_.min_score_threshold()) {
+        continue;
+      }
+      Classification* classification =
+          classification_list->add_classification();
+      classification->set_index(i);
+      classification->set_score(raw_scores[i]);
+
+      if (label_map_loaded_) {
+        classification->set_label(label_map_[i]);
+      }
     }
   }
 

mediapipe/calculators/tflite/tflite_tensors_to_classification_calculator.proto

@@ -32,4 +32,10 @@ message TfLiteTensorsToClassificationCalculatorOptions {
   optional int32 top_k = 2;
   // Path to a label map file for getting the actual name of class ids.
   optional string label_map_path = 3;
+  // Whether the input is a single float for binary classification.
+  // When true, only a single float is expected in the input tensor and the
+  // label map, if provided, is expected to have exactly two labels.
+  // The single score(float) represent the probability of first label, and
+  // 1 - score is the probabilility of the second label.
+  optional bool binary_classification = 4;
 }

mediapipe/calculators/tflite/tflite_tensors_to_landmarks_calculator.cc

@@ -145,7 +145,7 @@ REGISTER_CALCULATOR(TfLiteTensorsToLandmarksCalculator);
           ? cc->InputSidePackets().Tag("FLIP_HORIZONTALLY").Get<bool>()
           : options_.flip_horizontally();
 
-  flip_horizontally_ =
+  flip_vertically_ =
       cc->InputSidePackets().HasTag("FLIP_VERTICALLY")
           ? cc->InputSidePackets().Tag("FLIP_VERTICALLY").Get<bool>()
           : options_.flip_vertically();

mediapipe/calculators/tflite/util.h

@@ -15,11 +15,11 @@
 #ifndef MEDIAPIPE_CALCULATORS_TFLITE_UTIL_H_
 #define MEDIAPIPE_CALCULATORS_TFLITE_UTIL_H_
 
-#define RET_CHECK_CALL(call)                                     \
-  do {                                                           \
-    const auto status = (call);                                  \
-    if (ABSL_PREDICT_FALSE(!status.ok()))                        \
-      return ::mediapipe::InternalError(status.error_message()); \
+#define RET_CHECK_CALL(call)                               \
+  do {                                                     \
+    const auto status = (call);                            \
+    if (ABSL_PREDICT_FALSE(!status.ok()))                  \
+      return ::mediapipe::InternalError(status.message()); \
   } while (0);
 
 #endif  // MEDIAPIPE_CALCULATORS_TFLITE_UTIL_H_

mediapipe/calculators/util/BUILD

@@ -321,7 +321,7 @@ cc_library(
         "//mediapipe:android": [
             "//mediapipe/util/android/file/base",
         ],
-        "//mediapipe:apple": [
+        "//mediapipe:ios": [
             "//mediapipe/util/android/file/base",
         ],
         "//mediapipe:macos": [
@@ -349,7 +349,7 @@ cc_library(
         "//mediapipe:android": [
             "//mediapipe/util/android/file/base",
         ],
-        "//mediapipe:apple": [
+        "//mediapipe:ios": [
             "//mediapipe/util/android/file/base",
         ],
         "//mediapipe:macos": [
@@ -926,7 +926,7 @@ cc_library(
         "//mediapipe:android": [
             "//mediapipe/util/android/file/base",
         ],
-        "//mediapipe:apple": [
+        "//mediapipe:ios": [
             "//mediapipe/util/android/file/base",
         ],
         "//mediapipe:macos": [
@@ -971,9 +971,9 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         "//mediapipe/framework:calculator_framework",
-        "//mediapipe/framework/port:file_helpers",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/framework/port:status",
+        "//mediapipe/util:resource_util",
     ],
     alwayslink = 1,
 )
@@ -998,6 +998,7 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/formats:classification_cc_proto",
         "//mediapipe/framework/formats:landmark_cc_proto",
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/framework/port:ret_check",
@@ -1015,6 +1016,7 @@ cc_library(
     deps = [
         ":collection_has_min_size_calculator_cc_proto",
         "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/formats:landmark_cc_proto",
         "//mediapipe/framework/formats:rect_cc_proto",
         "//mediapipe/framework/port:ret_check",
         "//mediapipe/framework/port:status",
@@ -1022,6 +1024,18 @@ cc_library(
     alwayslink = 1,
 )
 
+cc_test(
+    name = "collection_has_min_size_calculator_test",
+    srcs = ["collection_has_min_size_calculator_test.cc"],
+    deps = [
+        ":collection_has_min_size_calculator",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework:calculator_runner",
+        "//mediapipe/framework/port:gtest_main",
+        "//mediapipe/framework/port:parse_text_proto",
+    ],
+)
+
 cc_library(
     name = "association_calculator",
     hdrs = ["association_calculator.h"],

mediapipe/calculators/util/annotation_overlay_calculator.cc

@@ -55,7 +55,7 @@ size_t RoundUp(size_t n, size_t m) { return ((n + m - 1) / m) * m; }  // NOLINT
 // When using GPU, this color will become transparent when the calculator
 // merges the annotation overlay with the image frame. As a result, drawing in
 // this color is not supported and it should be set to something unlikely used.
-constexpr int kAnnotationBackgroundColor[] = {100, 101, 102};
+constexpr uchar kAnnotationBackgroundColor = 2;  // Grayscale value.
 }  // namespace
 
 // A calculator for rendering data on images.
@@ -491,11 +491,9 @@ REGISTER_CALCULATOR(AnnotationOverlayCalculator);
     if (format != mediapipe::ImageFormat::SRGBA &&
         format != mediapipe::ImageFormat::SRGB)
       RET_CHECK_FAIL() << "Unsupported GPU input format: " << format;
-
-    image_mat = absl::make_unique<cv::Mat>(
-        height_, width_, CV_8UC3,
-        cv::Scalar(kAnnotationBackgroundColor[0], kAnnotationBackgroundColor[1],
-                   kAnnotationBackgroundColor[2]));
+    image_mat = absl::make_unique<cv::Mat>(height_, width_, CV_8UC3);
+    memset(image_mat->data, kAnnotationBackgroundColor,
+           height_ * width_ * image_mat->elemSize());
   } else {
     image_mat = absl::make_unique<cv::Mat>(
         options_.canvas_height_px(), options_.canvas_width_px(), CV_8UC3,
@@ -617,9 +615,9 @@ REGISTER_CALCULATOR(AnnotationOverlayCalculator);
   glUniform1i(glGetUniformLocation(program_, "input_frame"), 1);
   glUniform1i(glGetUniformLocation(program_, "overlay"), 2);
   glUniform3f(glGetUniformLocation(program_, "transparent_color"),
-              kAnnotationBackgroundColor[0] / 255.0,
-              kAnnotationBackgroundColor[1] / 255.0,
-              kAnnotationBackgroundColor[2] / 255.0);
+              kAnnotationBackgroundColor / 255.0,
+              kAnnotationBackgroundColor / 255.0,
+              kAnnotationBackgroundColor / 255.0);
 
   // Init texture for opencv rendered frame.
   const auto& input_frame =

mediapipe/calculators/util/collection_has_min_size_calculator.cc

@@ -15,6 +15,9 @@
 
 #include "mediapipe/calculators/util/collection_has_min_size_calculator.h"
 
+#include <vector>
+
+#include "mediapipe/framework/formats/landmark.pb.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 
 namespace mediapipe {
@@ -23,4 +26,9 @@ typedef CollectionHasMinSizeCalculator<std::vector<::mediapipe::NormalizedRect>>
     NormalizedRectVectorHasMinSizeCalculator;
 REGISTER_CALCULATOR(NormalizedRectVectorHasMinSizeCalculator);
 
+typedef CollectionHasMinSizeCalculator<
+    std::vector<::mediapipe::NormalizedLandmarkList>>
+    NormalizedLandmarkListVectorHasMinSizeCalculator;
+REGISTER_CALCULATOR(NormalizedLandmarkListVectorHasMinSizeCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/util/collection_has_min_size_calculator_test.cc

@@ -0,0 +1,156 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "mediapipe/calculators/util/collection_has_min_size_calculator.h"
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/calculator_runner.h"
+#include "mediapipe/framework/port/gmock.h"
+#include "mediapipe/framework/port/gtest.h"
+#include "mediapipe/framework/port/parse_text_proto.h"
+#include "mediapipe/framework/port/status_matchers.h"  // NOLINT
+
+namespace mediapipe {
+
+typedef CollectionHasMinSizeCalculator<std::vector<int>>
+    TestIntCollectionHasMinSizeCalculator;
+REGISTER_CALCULATOR(TestIntCollectionHasMinSizeCalculator);
+
+void AddInputVector(const std::vector<int>& input, int64 timestamp,
+                    CalculatorRunner* runner) {
+  runner->MutableInputs()
+      ->Tag("ITERABLE")
+      .packets.push_back(
+          MakePacket<std::vector<int>>(input).At(Timestamp(timestamp)));
+}
+
+TEST(TestIntCollectionHasMinSizeCalculator, DoesHaveMinSize) {
+  CalculatorGraphConfig::Node node_config =
+      ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"(
+        calculator: "TestIntCollectionHasMinSizeCalculator"
+        input_stream: "ITERABLE:input_vector"
+        output_stream: "output_vector"
+        options {
+          [mediapipe.CollectionHasMinSizeCalculatorOptions.ext] { min_size: 2 }
+        }
+      )");
+  CalculatorRunner runner(node_config);
+  const std::vector<Packet>& outputs = runner.Outputs().Index(0).packets;
+
+  AddInputVector({1, 2}, /*timestamp=*/1, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(1, outputs.size());
+  EXPECT_EQ(Timestamp(1), outputs[0].Timestamp());
+  EXPECT_TRUE(outputs[0].Get<bool>());
+
+  AddInputVector({1, 2, 3}, /*timestamp=*/2, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(2, outputs.size());
+  EXPECT_EQ(Timestamp(2), outputs[1].Timestamp());
+  EXPECT_TRUE(outputs[1].Get<bool>());
+}
+
+TEST(TestIntCollectionHasMinSizeCalculator,
+     DoesHaveMinSize_MinSizeAsSidePacket) {
+  CalculatorGraphConfig::Node node_config =
+      ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"(
+        calculator: "TestIntCollectionHasMinSizeCalculator"
+        input_stream: "ITERABLE:input_vector"
+        input_side_packet: "min_size"
+        output_stream: "output_vector"
+      )");
+  CalculatorRunner runner(node_config);
+  const std::vector<Packet>& outputs = runner.Outputs().Index(0).packets;
+
+  runner.MutableSidePackets()->Index(0) = MakePacket<int>(2);
+
+  AddInputVector({1, 2}, /*timestamp=*/1, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(1, outputs.size());
+  EXPECT_EQ(Timestamp(1), outputs[0].Timestamp());
+  EXPECT_TRUE(outputs[0].Get<bool>());
+
+  AddInputVector({1, 2, 3}, /*timestamp=*/2, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(2, outputs.size());
+  EXPECT_EQ(Timestamp(2), outputs[1].Timestamp());
+  EXPECT_TRUE(outputs[1].Get<bool>());
+}
+
+TEST(TestIntCollectionHasMinSizeCalculator, DoesNotHaveMinSize) {
+  CalculatorGraphConfig::Node node_config =
+      ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"(
+        calculator: "TestIntCollectionHasMinSizeCalculator"
+        input_stream: "ITERABLE:input_vector"
+        output_stream: "output_vector"
+        options {
+          [mediapipe.CollectionHasMinSizeCalculatorOptions.ext] { min_size: 3 }
+        }
+      )");
+  CalculatorRunner runner(node_config);
+  const std::vector<Packet>& outputs = runner.Outputs().Index(0).packets;
+
+  AddInputVector({1}, /*timestamp=*/1, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(1, outputs.size());
+  EXPECT_EQ(Timestamp(1), outputs[0].Timestamp());
+  EXPECT_FALSE(outputs[0].Get<bool>());
+
+  AddInputVector({1, 2}, /*timestamp=*/2, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(2, outputs.size());
+  EXPECT_EQ(Timestamp(2), outputs[1].Timestamp());
+  EXPECT_FALSE(outputs[1].Get<bool>());
+}
+
+TEST(TestIntCollectionHasMinSizeCalculator,
+     DoesNotHaveMinSize_MinSizeAsSidePacket) {
+  CalculatorGraphConfig::Node node_config =
+      ParseTextProtoOrDie<CalculatorGraphConfig::Node>(R"(
+        calculator: "TestIntCollectionHasMinSizeCalculator"
+        input_stream: "ITERABLE:input_vector"
+        input_side_packet: "min_size"
+        output_stream: "output_vector"
+      )");
+  CalculatorRunner runner(node_config);
+  const std::vector<Packet>& outputs = runner.Outputs().Index(0).packets;
+
+  runner.MutableSidePackets()->Index(0) = MakePacket<int>(3);
+
+  AddInputVector({1}, /*timestamp=*/1, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(1, outputs.size());
+  EXPECT_EQ(Timestamp(1), outputs[0].Timestamp());
+  EXPECT_FALSE(outputs[0].Get<bool>());
+
+  AddInputVector({1, 2}, /*timestamp=*/2, &runner);
+  MP_ASSERT_OK(runner.Run());
+
+  EXPECT_EQ(2, outputs.size());
+  EXPECT_EQ(Timestamp(2), outputs[1].Timestamp());
+  EXPECT_FALSE(outputs[1].Get<bool>());
+}
+
+}  // namespace mediapipe

mediapipe/calculators/util/filter_collection_calculator.cc

@@ -17,6 +17,7 @@
 
 #include <vector>
 
+#include "mediapipe/framework/formats/classification.pb.h"
 #include "mediapipe/framework/formats/landmark.pb.h"
 #include "mediapipe/framework/formats/rect.pb.h"
 
@@ -31,4 +32,8 @@ typedef FilterCollectionCalculator<
     FilterLandmarkListCollectionCalculator;
 REGISTER_CALCULATOR(FilterLandmarkListCollectionCalculator);
 
+typedef FilterCollectionCalculator<std::vector<::mediapipe::ClassificationList>>
+    FilterClassificationListCollectionCalculator;
+REGISTER_CALCULATOR(FilterClassificationListCollectionCalculator);
+
 }  // namespace mediapipe

mediapipe/calculators/util/labels_to_render_data_calculator.cc

@@ -128,16 +128,19 @@ REGISTER_CALCULATOR(LabelsToRenderDataCalculator);
   } else {
     const std::vector<std::string>& label_vector =
         cc->Inputs().Tag("LABELS").Get<std::vector<std::string>>();
-    std::vector<float> score_vector;
-    if (cc->Inputs().HasTag("SCORES")) {
-      score_vector = cc->Inputs().Tag("SCORES").Get<std::vector<float>>();
-    }
-    CHECK_EQ(label_vector.size(), score_vector.size());
     labels.resize(label_vector.size());
-    scores.resize(label_vector.size());
     for (int i = 0; i < label_vector.size(); ++i) {
       labels[i] = label_vector[i];
-      scores[i] = score_vector[i];
+    }
+
+    if (cc->Inputs().HasTag("SCORES")) {
+      std::vector<float> score_vector =
+          cc->Inputs().Tag("SCORES").Get<std::vector<float>>();
+      CHECK_EQ(label_vector.size(), score_vector.size());
+      scores.resize(label_vector.size());
+      for (int i = 0; i < label_vector.size(); ++i) {
+        scores[i] = score_vector[i];
+      }
     }
   }
 

mediapipe/calculators/util/landmarks_to_render_data_calculator.cc

@@ -29,6 +29,7 @@ namespace {
 
 constexpr char kLandmarksTag[] = "LANDMARKS";
 constexpr char kNormLandmarksTag[] = "NORM_LANDMARKS";
+constexpr char kRenderScaleTag[] = "RENDER_SCALE";
 constexpr char kRenderDataTag[] = "RENDER_DATA";
 constexpr char kLandmarkLabel[] = "KEYPOINT";
 constexpr int kMaxLandmarkThickness = 18;
@@ -71,6 +72,83 @@ void SetColorSizeValueFromZ(float z, float z_min, float z_max,
   render_annotation->set_thickness(thickness);
 }
 
+template <class LandmarkType>
+void AddConnectionToRenderData(const LandmarkType& start,
+                               const LandmarkType& end, int gray_val1,
+                               int gray_val2, float thickness, bool normalized,
+                               RenderData* render_data) {
+  auto* connection_annotation = render_data->add_render_annotations();
+  RenderAnnotation::GradientLine* line =
+      connection_annotation->mutable_gradient_line();
+  line->set_x_start(start.x());
+  line->set_y_start(start.y());
+  line->set_x_end(end.x());
+  line->set_y_end(end.y());
+  line->set_normalized(normalized);
+  line->mutable_color1()->set_r(gray_val1);
+  line->mutable_color1()->set_g(gray_val1);
+  line->mutable_color1()->set_b(gray_val1);
+  line->mutable_color2()->set_r(gray_val2);
+  line->mutable_color2()->set_g(gray_val2);
+  line->mutable_color2()->set_b(gray_val2);
+  connection_annotation->set_thickness(thickness);
+}
+
+template <class LandmarkListType, class LandmarkType>
+void AddConnectionsWithDepth(const LandmarkListType& landmarks,
+                             const std::vector<int>& landmark_connections,
+                             float thickness, bool normalized, float min_z,
+                             float max_z, RenderData* render_data) {
+  for (int i = 0; i < landmark_connections.size(); i += 2) {
+    const auto& ld0 = landmarks.landmark(landmark_connections[i]);
+    const auto& ld1 = landmarks.landmark(landmark_connections[i + 1]);
+    const int gray_val1 =
+        255 - static_cast<int>(Remap(ld0.z(), min_z, max_z, 255));
+    const int gray_val2 =
+        255 - static_cast<int>(Remap(ld1.z(), min_z, max_z, 255));
+    AddConnectionToRenderData<LandmarkType>(ld0, ld1, gray_val1, gray_val2,
+                                            thickness, normalized, render_data);
+  }
+}
+
+template <class LandmarkType>
+void AddConnectionToRenderData(const LandmarkType& start,
+                               const LandmarkType& end,
+                               const Color& connection_color, float thickness,
+                               bool normalized, RenderData* render_data) {
+  auto* connection_annotation = render_data->add_render_annotations();
+  RenderAnnotation::Line* line = connection_annotation->mutable_line();
+  line->set_x_start(start.x());
+  line->set_y_start(start.y());
+  line->set_x_end(end.x());
+  line->set_y_end(end.y());
+  line->set_normalized(normalized);
+  SetColor(connection_annotation, connection_color);
+  connection_annotation->set_thickness(thickness);
+}
+
+template <class LandmarkListType, class LandmarkType>
+void AddConnections(const LandmarkListType& landmarks,
+                    const std::vector<int>& landmark_connections,
+                    const Color& connection_color, float thickness,
+                    bool normalized, RenderData* render_data) {
+  for (int i = 0; i < landmark_connections.size(); i += 2) {
+    const auto& ld0 = landmarks.landmark(landmark_connections[i]);
+    const auto& ld1 = landmarks.landmark(landmark_connections[i + 1]);
+    AddConnectionToRenderData<LandmarkType>(ld0, ld1, connection_color,
+                                            thickness, normalized, render_data);
+  }
+}
+
+RenderAnnotation* AddPointRenderData(const Color& landmark_color,
+                                     float thickness, RenderData* render_data) {
+  auto* landmark_data_annotation = render_data->add_render_annotations();
+  landmark_data_annotation->set_scene_tag(kLandmarkLabel);
+  SetColor(landmark_data_annotation, landmark_color);
+  landmark_data_annotation->set_thickness(thickness);
+  return landmark_data_annotation;
+}
+
 }  // namespace
 
 // A calculator that converts Landmark proto to RenderData proto for
@@ -107,29 +185,6 @@ class LandmarksToRenderDataCalculator : public CalculatorBase {
   ::mediapipe::Status Process(CalculatorContext* cc) override;
 
  private:
-  static void AddConnectionToRenderData(
-      float start_x, float start_y, float end_x, float end_y,
-      const LandmarksToRenderDataCalculatorOptions& options, bool normalized,
-      RenderData* render_data);
-  static void SetRenderAnnotationColorThickness(
-      const LandmarksToRenderDataCalculatorOptions& options,
-      RenderAnnotation* render_annotation);
-  static RenderAnnotation* AddPointRenderData(
-      const LandmarksToRenderDataCalculatorOptions& options,
-      RenderData* render_data);
-  static void AddConnectionToRenderData(
-      float start_x, float start_y, float end_x, float end_y,
-      const LandmarksToRenderDataCalculatorOptions& options, bool normalized,
-      int gray_val1, int gray_val2, RenderData* render_data);
-
-  template <class LandmarkListType>
-  void AddConnections(const LandmarkListType& landmarks, bool normalized,
-                      RenderData* render_data);
-  template <class LandmarkListType>
-  void AddConnectionsWithDepth(const LandmarkListType& landmarks,
-                               bool normalized, float min_z, float max_z,
-                               RenderData* render_data);
-
   LandmarksToRenderDataCalculatorOptions options_;
 };
 REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
@@ -150,6 +205,9 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
   if (cc->Inputs().HasTag(kNormLandmarksTag)) {
     cc->Inputs().Tag(kNormLandmarksTag).Set<NormalizedLandmarkList>();
   }
+  if (cc->Inputs().HasTag(kRenderScaleTag)) {
+    cc->Inputs().Tag(kRenderScaleTag).Set<float>();
+  }
   cc->Outputs().Tag(kRenderDataTag).Set<RenderData>();
   return ::mediapipe::OkStatus();
 }
@@ -169,11 +227,26 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
   float z_min = 0.f;
   float z_max = 0.f;
 
+  // Apply scale to `thickness` of rendered landmarks and connections to make
+  // them bigger when object (e.g. pose, hand or face) is closer/bigger and
+  // snaller when object is further/smaller.
+  float thickness = options_.thickness();
+  if (cc->Inputs().HasTag(kRenderScaleTag)) {
+    const float render_scale = cc->Inputs().Tag(kRenderScaleTag).Get<float>();
+    thickness *= render_scale;
+  }
+
+  // Parse landmarks connections to a vector.
+  RET_CHECK_EQ(options_.landmark_connections_size() % 2, 0)
+      << "Number of entries in landmark connections must be a multiple of 2";
+  std::vector<int> landmark_connections;
+  for (int i = 0; i < options_.landmark_connections_size(); i += 1) {
+    landmark_connections.push_back(options_.landmark_connections(i));
+  }
+
   if (cc->Inputs().HasTag(kLandmarksTag)) {
     const LandmarkList& landmarks =
         cc->Inputs().Tag(kLandmarksTag).Get<LandmarkList>();
-    RET_CHECK_EQ(options_.landmark_connections_size() % 2, 0)
-        << "Number of entries in landmark connections must be a multiple of 2";
     if (visualize_depth) {
       GetMinMaxZ<LandmarkList, Landmark>(landmarks, &z_min, &z_max);
     }
@@ -181,8 +254,8 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
     visualize_depth &= ((z_max - z_min) > 1e-3);
     for (int i = 0; i < landmarks.landmark_size(); ++i) {
       const Landmark& landmark = landmarks.landmark(i);
-      auto* landmark_data_render =
-          AddPointRenderData(options_, render_data.get());
+      auto* landmark_data_render = AddPointRenderData(
+          options_.landmark_color(), thickness, render_data.get());
       if (visualize_depth) {
         SetColorSizeValueFromZ(landmark.z(), z_min, z_max,
                                landmark_data_render);
@@ -193,19 +266,19 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
       landmark_data->set_y(landmark.y());
     }
     if (visualize_depth) {
-      AddConnectionsWithDepth<LandmarkList>(landmarks, /*normalized=*/false,
-                                            z_min, z_max, render_data.get());
+      AddConnectionsWithDepth<LandmarkList, Landmark>(
+          landmarks, landmark_connections, thickness, /*normalized=*/false,
+          z_min, z_max, render_data.get());
     } else {
-      AddConnections<LandmarkList>(landmarks, /*normalized=*/false,
-                                   render_data.get());
+      AddConnections<LandmarkList, Landmark>(
+          landmarks, landmark_connections, options_.connection_color(),
+          thickness, /*normalized=*/false, render_data.get());
     }
   }
 
   if (cc->Inputs().HasTag(kNormLandmarksTag)) {
     const NormalizedLandmarkList& landmarks =
         cc->Inputs().Tag(kNormLandmarksTag).Get<NormalizedLandmarkList>();
-    RET_CHECK_EQ(options_.landmark_connections_size() % 2, 0)
-        << "Number of entries in landmark connections must be a multiple of 2";
     if (visualize_depth) {
       GetMinMaxZ<NormalizedLandmarkList, NormalizedLandmark>(landmarks, &z_min,
                                                              &z_max);
@@ -214,8 +287,8 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
     visualize_depth &= ((z_max - z_min) > 1e-3);
     for (int i = 0; i < landmarks.landmark_size(); ++i) {
       const NormalizedLandmark& landmark = landmarks.landmark(i);
-      auto* landmark_data_render =
-          AddPointRenderData(options_, render_data.get());
+      auto* landmark_data_render = AddPointRenderData(
+          options_.landmark_color(), thickness, render_data.get());
       if (visualize_depth) {
         SetColorSizeValueFromZ(landmark.z(), z_min, z_max,
                                landmark_data_render);
@@ -226,11 +299,13 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
       landmark_data->set_y(landmark.y());
     }
     if (visualize_depth) {
-      AddConnectionsWithDepth<NormalizedLandmarkList>(
-          landmarks, /*normalized=*/true, z_min, z_max, render_data.get());
+      AddConnectionsWithDepth<NormalizedLandmarkList, NormalizedLandmark>(
+          landmarks, landmark_connections, thickness, /*normalized=*/true,
+          z_min, z_max, render_data.get());
     } else {
-      AddConnections<NormalizedLandmarkList>(landmarks, /*normalized=*/true,
-                                             render_data.get());
+      AddConnections<NormalizedLandmarkList, NormalizedLandmark>(
+          landmarks, landmark_connections, options_.connection_color(),
+          thickness, /*normalized=*/true, render_data.get());
     }
   }
 
@@ -240,84 +315,4 @@ REGISTER_CALCULATOR(LandmarksToRenderDataCalculator);
   return ::mediapipe::OkStatus();
 }
 
-template <class LandmarkListType>
-void LandmarksToRenderDataCalculator::AddConnectionsWithDepth(
-    const LandmarkListType& landmarks, bool normalized, float min_z,
-    float max_z, RenderData* render_data) {
-  for (int i = 0; i < options_.landmark_connections_size(); i += 2) {
-    const auto& ld0 = landmarks.landmark(options_.landmark_connections(i));
-    const auto& ld1 = landmarks.landmark(options_.landmark_connections(i + 1));
-    const int gray_val1 =
-        255 - static_cast<int>(Remap(ld0.z(), min_z, max_z, 255));
-    const int gray_val2 =
-        255 - static_cast<int>(Remap(ld1.z(), min_z, max_z, 255));
-    AddConnectionToRenderData(ld0.x(), ld0.y(), ld1.x(), ld1.y(), options_,
-                              normalized, gray_val1, gray_val2, render_data);
-  }
-}
-
-void LandmarksToRenderDataCalculator::AddConnectionToRenderData(
-    float start_x, float start_y, float end_x, float end_y,
-    const LandmarksToRenderDataCalculatorOptions& options, bool normalized,
-    int gray_val1, int gray_val2, RenderData* render_data) {
-  auto* connection_annotation = render_data->add_render_annotations();
-  RenderAnnotation::GradientLine* line =
-      connection_annotation->mutable_gradient_line();
-  line->set_x_start(start_x);
-  line->set_y_start(start_y);
-  line->set_x_end(end_x);
-  line->set_y_end(end_y);
-  line->set_normalized(normalized);
-  line->mutable_color1()->set_r(gray_val1);
-  line->mutable_color1()->set_g(gray_val1);
-  line->mutable_color1()->set_b(gray_val1);
-  line->mutable_color2()->set_r(gray_val2);
-  line->mutable_color2()->set_g(gray_val2);
-  line->mutable_color2()->set_b(gray_val2);
-  connection_annotation->set_thickness(options.thickness());
-}
-
-template <class LandmarkListType>
-void LandmarksToRenderDataCalculator::AddConnections(
-    const LandmarkListType& landmarks, bool normalized,
-    RenderData* render_data) {
-  for (int i = 0; i < options_.landmark_connections_size(); i += 2) {
-    const auto& ld0 = landmarks.landmark(options_.landmark_connections(i));
-    const auto& ld1 = landmarks.landmark(options_.landmark_connections(i + 1));
-    AddConnectionToRenderData(ld0.x(), ld0.y(), ld1.x(), ld1.y(), options_,
-                              normalized, render_data);
-  }
-}
-
-void LandmarksToRenderDataCalculator::AddConnectionToRenderData(
-    float start_x, float start_y, float end_x, float end_y,
-    const LandmarksToRenderDataCalculatorOptions& options, bool normalized,
-    RenderData* render_data) {
-  auto* connection_annotation = render_data->add_render_annotations();
-  RenderAnnotation::Line* line = connection_annotation->mutable_line();
-  line->set_x_start(start_x);
-  line->set_y_start(start_y);
-  line->set_x_end(end_x);
-  line->set_y_end(end_y);
-  line->set_normalized(normalized);
-  SetColor(connection_annotation, options.connection_color());
-  connection_annotation->set_thickness(options.thickness());
-}
-
-RenderAnnotation* LandmarksToRenderDataCalculator::AddPointRenderData(
-    const LandmarksToRenderDataCalculatorOptions& options,
-    RenderData* render_data) {
-  auto* landmark_data_annotation = render_data->add_render_annotations();
-  landmark_data_annotation->set_scene_tag(kLandmarkLabel);
-  SetRenderAnnotationColorThickness(options, landmark_data_annotation);
-  return landmark_data_annotation;
-}
-
-void LandmarksToRenderDataCalculator::SetRenderAnnotationColorThickness(
-    const LandmarksToRenderDataCalculatorOptions& options,
-    RenderAnnotation* render_annotation) {
-  SetColor(render_annotation, options.landmark_color());
-  render_annotation->set_thickness(options.thickness());
-}
-
 }  // namespace mediapipe

mediapipe/calculators/util/local_file_contents_calculator.cc

@@ -16,34 +16,80 @@
 #include <string>
 
 #include "mediapipe/framework/calculator_framework.h"
-#include "mediapipe/framework/port/file_helpers.h"
 #include "mediapipe/framework/port/status.h"
+#include "mediapipe/util/resource_util.h"
 
 namespace mediapipe {
+
+namespace {
+
+constexpr char kFilePathTag[] = "FILE_PATH";
+constexpr char kContentsTag[] = "CONTENTS";
+
+}  // namespace
+
 // The calculator takes the path to the local file as an input side packet and
 // outputs the contents of that file.
 //
+// NOTE: file loading can be batched by providing multiple input/output side
+// packets.
+//
 // Example config:
 // node {
 //   calculator: "LocalFileContentsCalculator"
 //   input_side_packet: "FILE_PATH:file_path"
 //   output_side_packet: "CONTENTS:contents"
 // }
+//
+// node {
+//   calculator: "LocalFileContentsCalculator"
+//   input_side_packet: "FILE_PATH:0:file_path1"
+//   input_side_packet: "FILE_PATH:1:file_path2"
+//   ...
+//   output_side_packet: "CONTENTS:0:contents1"
+//   output_side_packet: "CONTENTS:1:contents2"
+//   ...
+// }
 class LocalFileContentsCalculator : public CalculatorBase {
  public:
   static ::mediapipe::Status GetContract(CalculatorContract* cc) {
-    cc->InputSidePackets().Tag("FILE_PATH").Set<std::string>();
-    cc->OutputSidePackets().Tag("CONTENTS").Set<std::string>();
+    RET_CHECK(cc->InputSidePackets().HasTag(kFilePathTag))
+        << "Missing PATH input side packet(s)";
+    RET_CHECK(cc->OutputSidePackets().HasTag(kContentsTag))
+        << "Missing CONTENTS output side packet(s)";
+
+    RET_CHECK_EQ(cc->InputSidePackets().NumEntries(kFilePathTag),
+                 cc->OutputSidePackets().NumEntries(kContentsTag))
+        << "Same number of input streams and output streams is required.";
+
+    for (CollectionItemId id = cc->InputSidePackets().BeginId(kFilePathTag);
+         id != cc->InputSidePackets().EndId(kFilePathTag); ++id) {
+      cc->InputSidePackets().Get(id).Set<std::string>();
+    }
+
+    for (CollectionItemId id = cc->OutputSidePackets().BeginId(kContentsTag);
+         id != cc->OutputSidePackets().EndId(kContentsTag); ++id) {
+      cc->OutputSidePackets().Get(id).Set<std::string>();
+    }
+
     return ::mediapipe::OkStatus();
   }
 
   ::mediapipe::Status Open(CalculatorContext* cc) override {
-    std::string contents;
-    MP_RETURN_IF_ERROR(mediapipe::file::GetContents(
-        cc->InputSidePackets().Tag("FILE_PATH").Get<std::string>(), &contents));
-    cc->OutputSidePackets()
-        .Tag("CONTENTS")
-        .Set(MakePacket<std::string>(std::move(contents)));
+    CollectionItemId input_id = cc->InputSidePackets().BeginId(kFilePathTag);
+    CollectionItemId output_id = cc->OutputSidePackets().BeginId(kContentsTag);
+    // Number of inputs and outpus is the same according to the contract.
+    for (; input_id != cc->InputSidePackets().EndId(kFilePathTag);
+         ++input_id, ++output_id) {
+      std::string file_path =
+          cc->InputSidePackets().Get(input_id).Get<std::string>();
+      ASSIGN_OR_RETURN(file_path, PathToResourceAsFile(file_path));
+
+      std::string contents;
+      MP_RETURN_IF_ERROR(GetResourceContents(file_path, &contents));
+      cc->OutputSidePackets().Get(output_id).Set(
+          MakePacket<std::string>(std::move(contents)));
+    }
     return ::mediapipe::OkStatus();
   }
 

mediapipe/calculators/util/packet_latency_calculator_test.cc

@@ -276,6 +276,7 @@ TEST_F(PacketLatencyCalculatorTest, DoesNotOutputUntilReferencePacketReceived) {
       "delayed_packet_0", Adopt(new double()).At(Timestamp(2))));
 
   // Send a reference packet with timestamp 10 usec.
+  simulation_clock_->Sleep(absl::Microseconds(1));
   MP_ASSERT_OK(graph_.AddPacketToInputStream(
       "camera_frames", Adopt(new double()).At(Timestamp(10))));
   simulation_clock_->Sleep(absl::Microseconds(1));

mediapipe/calculators/util/timed_box_list_to_render_data_calculator.cc

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <algorithm>
+
 #include "absl/memory/memory.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_join.h"
@@ -76,14 +78,16 @@ void AddTimedBoxProtoToRenderData(
     RenderAnnotation::Text* text = label_annotation->mutable_text();
     text->set_display_text(box_proto.label());
     text->set_normalized(true);
-    constexpr float text_left_start = 0.3f;
+    constexpr float text_left_start = 0.2f;
     text->set_left((1.0f - text_left_start) * box_proto.left() +
                    text_left_start * box_proto.right());
     constexpr float text_baseline = 0.6f;
     text->set_baseline(text_baseline * box_proto.bottom() +
                        (1.0f - text_baseline) * box_proto.top());
-    constexpr float text_height = 0.2f;
-    text->set_font_height((box_proto.bottom() - box_proto.top()) * text_height);
+    constexpr float text_height = 0.1f;
+    text->set_font_height(std::min(box_proto.bottom() - box_proto.top(),
+                                   box_proto.right() - box_proto.left()) *
+                          text_height);
   }
 }
 

mediapipe/calculators/video/BUILD

@@ -65,6 +65,26 @@ proto_library(
     ],
 )
 
+proto_library(
+    name = "tracked_detection_manager_calculator_proto",
+    srcs = ["tracked_detection_manager_calculator.proto"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//mediapipe/framework:calculator_proto",
+        "//mediapipe/util/tracking:tracked_detection_manager_config_proto",
+    ],
+)
+
+proto_library(
+    name = "box_detector_calculator_proto",
+    srcs = ["box_detector_calculator.proto"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//mediapipe/framework:calculator_proto",
+        "//mediapipe/util/tracking:box_detector_proto",
+    ],
+)
+
 proto_library(
     name = "video_pre_stream_calculator_proto",
     srcs = ["video_pre_stream_calculator.proto"],
@@ -107,6 +127,28 @@ mediapipe_cc_proto_library(
     deps = [":box_tracker_calculator_proto"],
 )
 
+mediapipe_cc_proto_library(
+    name = "tracked_detection_manager_calculator_cc_proto",
+    srcs = ["tracked_detection_manager_calculator.proto"],
+    cc_deps = [
+        "//mediapipe/framework:calculator_cc_proto",
+        "//mediapipe/util/tracking:tracked_detection_manager_config_cc_proto",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [":tracked_detection_manager_calculator_proto"],
+)
+
+mediapipe_cc_proto_library(
+    name = "box_detector_calculator_cc_proto",
+    srcs = ["box_detector_calculator.proto"],
+    cc_deps = [
+        "//mediapipe/framework:calculator_cc_proto",
+        "//mediapipe/util/tracking:box_detector_cc_proto",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [":box_detector_calculator_proto"],
+)
+
 mediapipe_cc_proto_library(
     name = "video_pre_stream_calculator_cc_proto",
     srcs = ["video_pre_stream_calculator.proto"],
@@ -138,7 +180,7 @@ cc_library(
     srcs = ["flow_to_image_calculator.cc"],
     visibility = ["//visibility:public"],
     deps = [
-        "//mediapipe/calculators/video:flow_to_image_calculator_cc_proto",
+        ":flow_to_image_calculator_cc_proto",
         "//mediapipe/calculators/video/tool:flow_quantizer_model",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework/formats:image_format_cc_proto",
@@ -279,11 +321,54 @@ cc_library(
     alwayslink = 1,
 )
 
+cc_library(
+    name = "box_detector_calculator",
+    srcs = ["box_detector_calculator.cc"],
+    visibility = ["//visibility:public"],
+    deps = [
+        ":box_detector_calculator_cc_proto",
+        "@com_google_absl//absl/memory",
+        "@com_google_absl//absl/strings",
+        "//mediapipe/framework:calculator_framework",
+        "//mediapipe/framework/formats:image_frame",
+        "//mediapipe/framework/formats:image_frame_opencv",
+        "//mediapipe/framework/formats:video_stream_header",  # fixdeps: keep -- required for exobazel build.
+        "//mediapipe/framework/port:integral_types",
+        "//mediapipe/framework/port:logging",
+        "//mediapipe/framework/port:opencv_core",
+        "//mediapipe/framework/port:opencv_features2d",
+        "//mediapipe/framework/port:ret_check",
+        "//mediapipe/framework/port:status",
+        "//mediapipe/util:resource_util",
+        "//mediapipe/util/tracking",
+        "//mediapipe/util/tracking:box_detector",
+        "//mediapipe/util/tracking:box_tracker",
+        "//mediapipe/util/tracking:box_tracker_cc_proto",
+        "//mediapipe/util/tracking:flow_packager_cc_proto",
+        "//mediapipe/util/tracking:tracking_visualization_utilities",
+    ] + select({
+        "//mediapipe:android": [
+            "//mediapipe/util/android/file/base",
+        ],
+        "//mediapipe:ios": [
+            "//mediapipe/util/android/file/base",
+        ],
+        "//mediapipe:macos": [
+            "//mediapipe/framework/port:file_helpers",
+        ],
+        "//conditions:default": [
+            "//mediapipe/framework/port:file_helpers",
+        ],
+    }),
+    alwayslink = 1,
+)
+
 cc_library(
     name = "tracked_detection_manager_calculator",
     srcs = ["tracked_detection_manager_calculator.cc"],
     visibility = ["//visibility:public"],
     deps = [
+        ":tracked_detection_manager_calculator_cc_proto",
         "//mediapipe/framework:calculator_framework",
         "//mediapipe/framework/formats:detection_cc_proto",
         "//mediapipe/framework/formats:location_data_cc_proto",
@@ -384,20 +469,18 @@ cc_test(
     ],
 )
 
-MEDIAPIPE_DEPS = [
-    "//mediapipe/calculators/video:box_tracker_calculator",
-    "//mediapipe/calculators/video:flow_packager_calculator",
-    "//mediapipe/calculators/video:motion_analysis_calculator",
-    "//mediapipe/framework/stream_handler:fixed_size_input_stream_handler",
-    "//mediapipe/framework/stream_handler:sync_set_input_stream_handler",
-]
-
 mediapipe_binary_graph(
     name = "parallel_tracker_binarypb",
     graph = "testdata/parallel_tracker_graph.pbtxt",
     output_name = "testdata/parallel_tracker.binarypb",
     visibility = ["//visibility:public"],
-    deps = MEDIAPIPE_DEPS,
+    deps = [
+        ":box_tracker_calculator",
+        ":flow_packager_calculator",
+        ":motion_analysis_calculator",
+        "//mediapipe/framework/stream_handler:fixed_size_input_stream_handler",
+        "//mediapipe/framework/stream_handler:sync_set_input_stream_handler",
+    ],
 )
 
 mediapipe_binary_graph(
@@ -405,7 +488,13 @@ mediapipe_binary_graph(
     graph = "testdata/tracker_graph.pbtxt",
     output_name = "testdata/tracker.binarypb",
     visibility = ["//visibility:public"],
-    deps = MEDIAPIPE_DEPS,
+    deps = [
+        ":box_tracker_calculator",
+        ":flow_packager_calculator",
+        ":motion_analysis_calculator",
+        "//mediapipe/framework/stream_handler:fixed_size_input_stream_handler",
+        "//mediapipe/framework/stream_handler:sync_set_input_stream_handler",
+    ],
 )
 
 cc_test(

mediapipe/calculators/video/box_detector_calculator.cc

@@ -0,0 +1,393 @@
+// Copyright 2019 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdio.h>
+
+#include <memory>
+#include <unordered_set>
+
+#include "absl/memory/memory.h"
+#include "absl/strings/numbers.h"
+#include "mediapipe/calculators/video/box_detector_calculator.pb.h"
+#include "mediapipe/framework/calculator_framework.h"
+#include "mediapipe/framework/formats/image_frame.h"
+#include "mediapipe/framework/formats/image_frame_opencv.h"
+#include "mediapipe/framework/formats/video_stream_header.h"
+#include "mediapipe/framework/port/integral_types.h"
+#include "mediapipe/framework/port/logging.h"
+#include "mediapipe/framework/port/opencv_core_inc.h"
+#include "mediapipe/framework/port/opencv_features2d_inc.h"
+#include "mediapipe/framework/port/ret_check.h"
+#include "mediapipe/framework/port/status.h"
+#include "mediapipe/util/resource_util.h"
+#include "mediapipe/util/tracking/box_detector.h"
+#include "mediapipe/util/tracking/box_tracker.h"
+#include "mediapipe/util/tracking/box_tracker.pb.h"
+#include "mediapipe/util/tracking/flow_packager.pb.h"
+#include "mediapipe/util/tracking/tracking.h"
+#include "mediapipe/util/tracking/tracking_visualization_utilities.h"
+
+#if defined(MEDIAPIPE_MOBILE)
+#include "mediapipe/util/android/file/base/file.h"
+#include "mediapipe/util/android/file/base/helpers.h"
+#else
+#include "mediapipe/framework/port/file_helpers.h"
+#endif
+
+namespace mediapipe {
+
+// A calculator to detect reappeared box positions from single frame.
+//
+// Input stream:
+//   TRACKING: Input tracking data (proto TrackingData) containing features and
+//             descriptors.
+//   VIDEO:    Optional input video stream tracked boxes are rendered over
+//             (Required if VIZ is specified).
+//   FEATURES: Input feature points (std::vector<cv::KeyPoint>) in the original
+//             pixel space.
+//   DESCRIPTORS: Input feature descriptors (std::vector<float>). Actual feature
+//             dimension needs to be specified in detector_options.
+//   IMAGE_SIZE: Input image dimension.
+//   TRACKED_BOXES : input box tracking result (proto TimedBoxProtoList) from
+//             BoxTrackerCalculator.
+//   ADD_INDEX: Optional std::string containing binary format proto of type
+//             BoxDetectorIndex. Used for adding target index to the detector
+//             search index during runtime.
+//   CANCEL_OBJECT_ID: Optional id of box to be removed. This is recommended
+//             to be used with SyncSetInputStreamHandler.
+//   REACQ_SWITCH: Optional bool for swithcing on and off reacquisition
+//             functionality. User should initialize a graph with box detector
+//             calculator and be able to switch it on and off in runtime.
+//
+// Output streams:
+//   VIZ:   Optional output video stream with rendered box positions
+//          (requires VIDEO to be present)
+//   BOXES: Optional output stream of type TimedBoxProtoList for each lost box.
+//
+// Imput side packets:
+//   INDEX_PROTO_STRING: Optional std::string containing binary format proto of
+//   type
+//                       BoxDetectorIndex. Used for initializing box_detector
+//                       with predefined template images.
+//   FRAME_ALIGNMENT:    Optional integer to indicate alignment_boundary for
+//                       outputing ImageFrame in "VIZ" stream.
+//                       Set to ImageFrame::kDefaultAlignmentBoundary for
+//                       offline pipeline to be compatible with FFmpeg.
+//                       Set to ImageFrame::kGlDefaultAlignmentBoundary for Apps
+//                       to be compatible with GL renderer.
+//   OUTPUT_INDEX_FILENAME: File path to the output index file.
+
+class BoxDetectorCalculator : public CalculatorBase {
+ public:
+  ~BoxDetectorCalculator() override = default;
+
+  static ::mediapipe::Status GetContract(CalculatorContract* cc);
+
+  ::mediapipe::Status Open(CalculatorContext* cc) override;
+  ::mediapipe::Status Process(CalculatorContext* cc) override;
+  ::mediapipe::Status Close(CalculatorContext* cc) override;
+
+ private:
+  BoxDetectorCalculatorOptions options_;
+  std::unique_ptr<BoxDetectorInterface> box_detector_;
+  bool detector_switch_ = true;
+  uint32 frame_alignment_ = ImageFrame::kDefaultAlignmentBoundary;
+  bool write_index_ = false;
+  int box_id_ = 0;
+};
+
+REGISTER_CALCULATOR(BoxDetectorCalculator);
+
+::mediapipe::Status BoxDetectorCalculator::GetContract(CalculatorContract* cc) {
+  if (cc->Inputs().HasTag("TRACKING")) {
+    cc->Inputs().Tag("TRACKING").Set<TrackingData>();
+  }
+
+  if (cc->Inputs().HasTag("TRACKED_BOXES")) {
+    cc->Inputs().Tag("TRACKED_BOXES").Set<TimedBoxProtoList>();
+  }
+
+  if (cc->Inputs().HasTag("VIDEO")) {
+    cc->Inputs().Tag("VIDEO").Set<ImageFrame>();
+  }
+
+  if (cc->Inputs().HasTag("FEATURES")) {
+    RET_CHECK(cc->Inputs().HasTag("DESCRIPTORS"))
+        << "FEATURES and DESCRIPTORS need to be specified together.";
+    cc->Inputs().Tag("FEATURES").Set<std::vector<cv::KeyPoint>>();
+  }
+
+  if (cc->Inputs().HasTag("DESCRIPTORS")) {
+    RET_CHECK(cc->Inputs().HasTag("FEATURES"))
+        << "FEATURES and DESCRIPTORS need to be specified together.";
+    cc->Inputs().Tag("DESCRIPTORS").Set<std::vector<float>>();
+  }
+
+  if (cc->Inputs().HasTag("IMAGE_SIZE")) {
+    cc->Inputs().Tag("IMAGE_SIZE").Set<std::pair<int, int>>();
+  }
+
+  if (cc->Inputs().HasTag("ADD_INDEX")) {
+    cc->Inputs().Tag("ADD_INDEX").Set<std::string>();
+  }
+
+  if (cc->Inputs().HasTag("CANCEL_OBJECT_ID")) {
+    cc->Inputs().Tag("CANCEL_OBJECT_ID").Set<int>();
+  }
+
+  if (cc->Inputs().HasTag("REACQ_SWITCH")) {
+    cc->Inputs().Tag("REACQ_SWITCH").Set<bool>();
+  }
+
+  if (cc->Outputs().HasTag("BOXES")) {
+    cc->Outputs().Tag("BOXES").Set<TimedBoxProtoList>();
+  }
+
+  if (cc->Outputs().HasTag("VIZ")) {
+    RET_CHECK(cc->Inputs().HasTag("VIDEO"))
+        << "Output stream VIZ requires VIDEO to be present.";
+    cc->Outputs().Tag("VIZ").Set<ImageFrame>();
+  }
+
+  if (cc->InputSidePackets().HasTag("INDEX_PROTO_STRING")) {
+    cc->InputSidePackets().Tag("INDEX_PROTO_STRING").Set<std::string>();
+  }
+
+  if (cc->InputSidePackets().HasTag("OUTPUT_INDEX_FILENAME")) {
+    cc->InputSidePackets().Tag("OUTPUT_INDEX_FILENAME").Set<std::string>();
+  }
+
+  if (cc->InputSidePackets().HasTag("FRAME_ALIGNMENT")) {
+    cc->InputSidePackets().Tag("FRAME_ALIGNMENT").Set<int>();
+  }
+
+  return ::mediapipe::OkStatus();
+}
+
+::mediapipe::Status BoxDetectorCalculator::Open(CalculatorContext* cc) {
+  options_ = cc->Options<BoxDetectorCalculatorOptions>();
+  box_detector_ = BoxDetectorInterface::Create(options_.detector_options());
+
+  if (cc->InputSidePackets().HasTag("INDEX_PROTO_STRING")) {
+    BoxDetectorIndex predefined_index;
+    if (!predefined_index.ParseFromString(cc->InputSidePackets()
+                                              .Tag("INDEX_PROTO_STRING")
+                                              .Get<std::string>())) {
+      LOG(FATAL) << "failed to parse BoxDetectorIndex from INDEX_PROTO_STRING";
+    }
+    box_detector_->AddBoxDetectorIndex(predefined_index);
+  }
+
+  for (const auto& filename : options_.index_proto_filename()) {
+    std::string string_path;
+    ASSIGN_OR_RETURN(string_path, PathToResourceAsFile(filename));
+    std::string index_string;
+    MP_RETURN_IF_ERROR(file::GetContents(string_path, &index_string));
+    BoxDetectorIndex predefined_index;
+    if (!predefined_index.ParseFromString(index_string)) {
+      LOG(FATAL)
+          << "failed to parse BoxDetectorIndex from index_proto_filename";
+    }
+    box_detector_->AddBoxDetectorIndex(predefined_index);
+  }
+
+  if (cc->InputSidePackets().HasTag("OUTPUT_INDEX_FILENAME")) {
+    write_index_ = true;
+  }
+
+  if (cc->InputSidePackets().HasTag("FRAME_ALIGNMENT")) {
+    frame_alignment_ = cc->InputSidePackets().Tag("FRAME_ALIGNMENT").Get<int>();
+  }
+
+  return ::mediapipe::OkStatus();
+}
+
+::mediapipe::Status BoxDetectorCalculator::Process(CalculatorContext* cc) {
+  const Timestamp timestamp = cc->InputTimestamp();
+  const int64 timestamp_msec = timestamp.Value() / 1000;
+
+  InputStream* cancel_object_id_stream =
+      cc->Inputs().HasTag("CANCEL_OBJECT_ID")
+          ? &(cc->Inputs().Tag("CANCEL_OBJECT_ID"))
+          : nullptr;
+  if (cancel_object_id_stream && !cancel_object_id_stream->IsEmpty()) {
+    const int cancel_object_id = cancel_object_id_stream->Get<int>();
+    box_detector_->CancelBoxDetection(cancel_object_id);
+  }
+
+  InputStream* add_index_stream = cc->Inputs().HasTag("ADD_INDEX")
+                                      ? &(cc->Inputs().Tag("ADD_INDEX"))
+                                      : nullptr;
+  if (add_index_stream && !add_index_stream->IsEmpty()) {
+    BoxDetectorIndex predefined_index;
+    if (!predefined_index.ParseFromString(
+            add_index_stream->Get<std::string>())) {
+      LOG(FATAL) << "failed to parse BoxDetectorIndex from ADD_INDEX";
+    }
+    box_detector_->AddBoxDetectorIndex(predefined_index);
+  }
+
+  InputStream* reacq_switch_stream = cc->Inputs().HasTag("REACQ_SWITCH")
+                                         ? &(cc->Inputs().Tag("REACQ_SWITCH"))
+                                         : nullptr;
+  if (reacq_switch_stream && !reacq_switch_stream->IsEmpty()) {
+    detector_switch_ = reacq_switch_stream->Get<bool>();
+  }
+
+  if (!detector_switch_) {
+    return ::mediapipe::OkStatus();
+  }
+
+  InputStream* track_stream = cc->Inputs().HasTag("TRACKING")
+                                  ? &(cc->Inputs().Tag("TRACKING"))
+                                  : nullptr;
+  InputStream* video_stream =
+      cc->Inputs().HasTag("VIDEO") ? &(cc->Inputs().Tag("VIDEO")) : nullptr;
+  InputStream* feature_stream = cc->Inputs().HasTag("FEATURES")
+                                    ? &(cc->Inputs().Tag("FEATURES"))
+                                    : nullptr;
+  InputStream* descriptor_stream = cc->Inputs().HasTag("DESCRIPTORS")
+                                       ? &(cc->Inputs().Tag("DESCRIPTORS"))
+                                       : nullptr;
+
+  CHECK(track_stream != nullptr || video_stream != nullptr ||
+        (feature_stream != nullptr && descriptor_stream != nullptr))
+      << "One and only one of {tracking_data, input image frame, "
+         "feature/descriptor} need to be valid.";
+
+  InputStream* tracked_boxes_stream = cc->Inputs().HasTag("TRACKED_BOXES")
+                                          ? &(cc->Inputs().Tag("TRACKED_BOXES"))
+                                          : nullptr;
+  std::unique_ptr<TimedBoxProtoList> detected_boxes(new TimedBoxProtoList());
+
+  if (track_stream != nullptr) {
+    // Detect from tracking data
+    if (track_stream->IsEmpty()) {
+      return ::mediapipe::OkStatus();
+    }
+
+    const TrackingData& tracking_data = track_stream->Get<TrackingData>();
+
+    CHECK(tracked_boxes_stream != nullptr) << "tracked_boxes needed.";
+
+    const TimedBoxProtoList tracked_boxes =
+        tracked_boxes_stream->Get<TimedBoxProtoList>();
+
+    box_detector_->DetectAndAddBox(tracking_data, tracked_boxes, timestamp_msec,
+                                   detected_boxes.get());
+  } else if (video_stream != nullptr) {
+    // Detect from input frame
+    if (video_stream->IsEmpty()) {
+      return ::mediapipe::OkStatus();
+    }
+
+    TimedBoxProtoList tracked_boxes;
+    if (tracked_boxes_stream != nullptr && !tracked_boxes_stream->IsEmpty()) {
+      tracked_boxes = tracked_boxes_stream->Get<TimedBoxProtoList>();
+    }
+
+    // Just directly pass along the image frame data as-is for detection; we
+    // don't need to worry about conforming to a specific alignment here.
+    const cv::Mat input_view =
+        formats::MatView(&video_stream->Get<ImageFrame>());
+    box_detector_->DetectAndAddBox(input_view, tracked_boxes, timestamp_msec,
+                                   detected_boxes.get());
+  } else {
+    if (feature_stream->IsEmpty() || descriptor_stream->IsEmpty()) {
+      return ::mediapipe::OkStatus();
+    }
+
+    const auto& image_size =
+        cc->Inputs().Tag("IMAGE_SIZE").Get<std::pair<int, int>>();
+    float inv_scale = 1.0f / std::max(image_size.first, image_size.second);
+
+    TimedBoxProtoList tracked_boxes;
+    if (tracked_boxes_stream != nullptr && !tracked_boxes_stream->IsEmpty()) {
+      tracked_boxes = tracked_boxes_stream->Get<TimedBoxProtoList>();
+    } else if (write_index_) {
+      auto* box_ptr = tracked_boxes.add_box();
+      box_ptr->set_id(box_id_);
+      box_ptr->set_reacquisition(true);
+      box_ptr->set_aspect_ratio((float)image_size.first /
+                                (float)image_size.second);
+
+      box_ptr->mutable_quad()->add_vertices(0);
+      box_ptr->mutable_quad()->add_vertices(0);
+
+      box_ptr->mutable_quad()->add_vertices(0);
+      box_ptr->mutable_quad()->add_vertices(1);
+
+      box_ptr->mutable_quad()->add_vertices(1);
+      box_ptr->mutable_quad()->add_vertices(1);
+
+      box_ptr->mutable_quad()->add_vertices(1);
+      box_ptr->mutable_quad()->add_vertices(0);
+
+      ++box_id_;
+    }
+
+    const auto& features = feature_stream->Get<std::vector<cv::KeyPoint>>();
+    const int feature_size = features.size();
+    std::vector<Vector2_f> features_vec(feature_size);
+
+    const auto& descriptors = descriptor_stream->Get<std::vector<float>>();
+    const int dims = options_.detector_options().descriptor_dims();
+    CHECK_GE(descriptors.size(), feature_size * dims);
+    cv::Mat descriptors_mat(feature_size, dims, CV_32F);
+    for (int j = 0; j < feature_size; ++j) {
+      features_vec[j].Set(features[j].pt.x * inv_scale,
+                          features[j].pt.y * inv_scale);
+      for (int i = 0; i < dims; ++i) {
+        descriptors_mat.at<float>(j, i) = descriptors[j * dims + i];
+      }
+    }
+
+    box_detector_->DetectAndAddBoxFromFeatures(
+        features_vec, descriptors_mat, tracked_boxes, timestamp_msec,
+        image_size.first * inv_scale, image_size.second * inv_scale,
+        detected_boxes.get());
+  }
+
+  if (cc->Outputs().HasTag("VIZ")) {
+    cv::Mat viz_view;
+    std::unique_ptr<ImageFrame> viz_frame;
+    if (video_stream != nullptr && !video_stream->IsEmpty()) {
+      viz_frame = absl::make_unique<ImageFrame>();
+      viz_frame->CopyFrom(video_stream->Get<ImageFrame>(), frame_alignment_);
+      viz_view = formats::MatView(viz_frame.get());
+    }
+    for (const auto& box : detected_boxes->box()) {
+      RenderBox(box, &viz_view);
+    }
+    cc->Outputs().Tag("VIZ").Add(viz_frame.release(), timestamp);
+  }
+
+  if (cc->Outputs().HasTag("BOXES")) {
+    cc->Outputs().Tag("BOXES").Add(detected_boxes.release(), timestamp);
+  }
+
+  return ::mediapipe::OkStatus();
+}
+
+::mediapipe::Status BoxDetectorCalculator::Close(CalculatorContext* cc) {
+  if (write_index_) {
+    BoxDetectorIndex index = box_detector_->ObtainBoxDetectorIndex();
+    MEDIAPIPE_CHECK_OK(mediapipe::file::SetContents(
+        cc->InputSidePackets().Tag("OUTPUT_INDEX_FILENAME").Get<std::string>(),
+        index.SerializeAsString()));
+  }
+  return ::mediapipe::OkStatus();
+}
+
+}  // namespace mediapipe

mediapipe/calculators/video/box_detector_calculator.proto

@@ -0,0 +1,31 @@
+// Copyright 2019 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto2";
+
+package mediapipe;
+
+import "mediapipe/framework/calculator.proto";
+import "mediapipe/util/tracking/box_detector.proto";
+
+message BoxDetectorCalculatorOptions {
+  extend CalculatorOptions {
+    optional BoxDetectorCalculatorOptions ext = 289746530;
+  }
+
+  optional BoxDetectorOptions detector_options = 1;
+
+  // File path to the template index files.
+  repeated string index_proto_filename = 2;
+}

mediapipe/calculators/video/tracked_detection_manager_calculator.cc

@@ -18,6 +18,7 @@
 #include <vector>
 
 #include "absl/container/node_hash_map.h"
+#include "mediapipe/calculators/video/tracked_detection_manager_calculator.pb.h"
 #include "mediapipe/framework/calculator_framework.h"
 #include "mediapipe/framework/formats/detection.pb.h"
 #include "mediapipe/framework/formats/location_data.pb.h"
@@ -139,6 +140,7 @@ Detection GetAxisAlignedDetectionFromTrackedDetection(
 class TrackedDetectionManagerCalculator : public CalculatorBase {
  public:
   static ::mediapipe::Status GetContract(CalculatorContract* cc);
+  ::mediapipe::Status Open(CalculatorContext* cc) override;
 
   ::mediapipe::Status Process(CalculatorContext* cc) override;
 
@@ -184,6 +186,15 @@ REGISTER_CALCULATOR(TrackedDetectionManagerCalculator);
   return ::mediapipe::OkStatus();
 }
 
+::mediapipe::Status TrackedDetectionManagerCalculator::Open(
+    CalculatorContext* cc) {
+  mediapipe::TrackedDetectionManagerCalculatorOptions options =
+      cc->Options<mediapipe::TrackedDetectionManagerCalculatorOptions>();
+  tracked_detection_manager_.SetConfig(
+      options.tracked_detection_manager_options());
+  return ::mediapipe::OkStatus();
+}
+
 ::mediapipe::Status TrackedDetectionManagerCalculator::Process(
     CalculatorContext* cc) {
   if (cc->Inputs().HasTag("TRACKING_BOXES")) {

mediapipe/calculators/video/tracked_detection_manager_calculator.proto

@@ -0,0 +1,28 @@
+// Copyright 2020 The MediaPipe Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto2";
+
+package mediapipe;
+
+import "mediapipe/framework/calculator.proto";
+import "mediapipe/util/tracking/tracked_detection_manager_config.proto";
+
+message TrackedDetectionManagerCalculatorOptions {
+  extend CalculatorOptions {
+    optional TrackedDetectionManagerCalculatorOptions ext = 301970230;
+  }
+
+  optional TrackedDetectionManagerConfig tracked_detection_manager_options = 1;
+}

mediapipe/docs/face_detection_desktop.md

@@ -51,7 +51,7 @@ To build and run the TensorFlow Lite example on desktop (GPU) with Webcam, run:
 ```bash
 # Video from webcam running on desktop GPU
 # This works only for linux currently
-$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS \
+$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
     mediapipe/examples/desktop/face_detection:face_detection_gpu
 
 # It should print:

mediapipe/docs/gpu.md

@@ -190,10 +190,10 @@ within the MediaPipe framework:
 bazel build --define MEDIAPIPE_DISABLE_GPU=1  <my-target>
 
 # to enable full GPU support (OpenGL ES 3.1+ & Metal)
-bazel build --copt -DMESA_EGL_NO_X11_HEADERS  <my-target>
+bazel build --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 <my-target>
 
 # to enable only OpenGL ES 3.0 and below (no GLES 3.1+ features)
-bazel build --copt -DMESA_EGL_NO_X11_HEADERS --copt -DMEDIAPIPE_DISABLE_GL_COMPUTE  <my-target>
+bazel build --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 --copt -DMEDIAPIPE_DISABLE_GL_COMPUTE  <my-target>
 ```
 
 Note *MEDIAPIPE_DISABLE_GL_COMPUTE* is automatically defined on all Apple

mediapipe/docs/hair_segmentation_desktop.md

@@ -26,7 +26,7 @@ To build and run the TensorFlow Lite example on desktop (GPU) with Webcam, run:
 ```bash
 # Video from webcam running on desktop GPU
 # This works only for linux currently
-$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS \
+$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
     mediapipe/examples/desktop/hair_segmentation:hair_segmentation_gpu
 
 # It should print:

mediapipe/docs/hand_tracking_desktop.md

@@ -48,7 +48,7 @@ To build and run the TensorFlow Lite example on desktop (GPU) with Webcam, run:
 ```bash
 # Video from webcam running on desktop GPU
 # This works only for linux currently
-$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS \
+$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
     mediapipe/examples/desktop/hand_tracking:hand_tracking_gpu
 
 # It should print:

mediapipe/docs/install.md

@@ -40,12 +40,11 @@ To build and run iOS apps:
     $ cd mediapipe
     ```
 
-2.  Install Bazel (version between 1.0.0 and 1.2.1).
+2.  Install Bazel.
 
     Follow the official
     [Bazel documentation](https://docs.bazel.build/versions/master/install-ubuntu.html)
-    to install Bazel manually. Note that MediaPipe doesn't support Bazel 2.0.0+
-    yet.
+    to install Bazel 2.0 or higher.
 
 3.  Install OpenCV and FFmpeg.
 
@@ -111,7 +110,7 @@ To build and run iOS apps:
     # To compile with GPU support, replace
     --define MEDIAPIPE_DISABLE_GPU=1
     # with
-    --copt -DMESA_EGL_NO_X11_HEADERS
+    --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11
     # when building GPU examples.
     ```
 
@@ -125,7 +124,7 @@ To build and run iOS apps:
         mediapipe/examples/desktop/hello_world:hello_world
 
     # If you are running on Linux desktop with GPU support enabled (via mesa drivers)
-    $ bazel run --copt -DMESA_EGL_NO_X11_HEADERS \
+    $ bazel run --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
         mediapipe/examples/desktop/hello_world:hello_world
 
     # Should print:
@@ -152,12 +151,11 @@ To build and run iOS apps:
     $ cd mediapipe
     ```
 
-2.  Install Bazel (version between 1.0.0 and 1.2.1).
+2.  Install Bazel.
 
     Follow the official
     [Bazel documentation](https://docs.bazel.build/versions/master/install-redhat.html)
-    to install Bazel manually. Note that MediaPipe doesn't support Bazel 2.0.0+
-    yet.
+    to install Bazel 2.0 or higher.
 
 3.  Install OpenCV.
 
@@ -241,23 +239,18 @@ To build and run iOS apps:
     $ cd mediapipe
     ```
 
-3.  Install Bazel (version between 1.0.0 and 1.1.0).
+3.  Install Bazel.
 
-    Option 1. Use package manager tool to install Bazel 1.1.0
+    Option 1. Use package manager tool to install Bazel
 
     ```bash
-    # If Bazel 1.1.0+ was installed.
-    $ brew uninstall bazel
-    # Install Bazel 1.1.0
-    $ brew install https://raw.githubusercontent.com/bazelbuild/homebrew-tap/f8a0fa981bcb1784a0d0823e14867b844e94fb3d/Formula/bazel.rb
-    $ brew link bazel
+    $ brew install bazel
     # Run 'bazel version' to check version of bazel
     ```
 
     Option 2. Follow the official
     [Bazel documentation](https://docs.bazel.build/versions/master/install-os-x.html#install-with-installer-mac-os-x)
-    to install any version of Bazel manually. Note that MediaPipe doesn't
-    support Bazel 1.1.0+ on macOS yet.
+    to install Bazel 2.0 or higher.
 
 4.  Install OpenCV and FFmpeg.
 
@@ -391,18 +384,18 @@ cameras. Alternatively, you use a video file as input.
     username@DESKTOP-TMVLBJ1:~$ sudo apt-get update && sudo apt-get install -y build-essential git python zip adb openjdk-8-jdk
     ```
 
-5.  Install Bazel (version between 1.0.0 and 1.2.1).
+5.  Install Bazel.
 
     ```bash
     username@DESKTOP-TMVLBJ1:~$ curl -sLO --retry 5 --retry-max-time 10 \
-    https://storage.googleapis.com/bazel/1.0.0/release/bazel-1.0.0-installer-linux-x86_64.sh && \
-    sudo mkdir -p /usr/local/bazel/1.0.0 && \
-    chmod 755 bazel-1.0.0-installer-linux-x86_64.sh && \
-    sudo ./bazel-1.0.0-installer-linux-x86_64.sh --prefix=/usr/local/bazel/1.0.0 && \
-    source /usr/local/bazel/1.0.0/lib/bazel/bin/bazel-complete.bash
+    https://storage.googleapis.com/bazel/2.0.0/release/bazel-2.0.0-installer-linux-x86_64.sh && \
+    sudo mkdir -p /usr/local/bazel/2.0.0 && \
+    chmod 755 bazel-2.0.0-installer-linux-x86_64.sh && \
+    sudo ./bazel-2.0.0-installer-linux-x86_64.sh --prefix=/usr/local/bazel/2.0.0 && \
+    source /usr/local/bazel/2.0.0/lib/bazel/bin/bazel-complete.bash
 
-    username@DESKTOP-TMVLBJ1:~$ /usr/local/bazel/1.0.0/lib/bazel/bin/bazel version && \
-    alias bazel='/usr/local/bazel/1.0.0/lib/bazel/bin/bazel'
+    username@DESKTOP-TMVLBJ1:~$ /usr/local/bazel/2.0.0/lib/bazel/bin/bazel version && \
+    alias bazel='/usr/local/bazel/2.0.0/lib/bazel/bin/bazel'
     ```
 
 6.  Checkout MediaPipe repository.

mediapipe/docs/media_sequence.md

@@ -89,11 +89,11 @@ process new data sets, in the documentation of
        dataset = d.as_dataset('test')
        # implement additional processing and batching here
        dataset_output = dataset.make_one_shot_iterator().get_next()
-       images = dataset_output=['images']
-       labels = dataset_output=['labels']
+       images = dataset_output['images']
+       labels = dataset_output['labels']
 
        with tf.Session() as sess:
-         images_, labels_ = sess.run(images, labels)
+         images_, labels_ = sess.run([images, labels])
        print('The shape of images_ is %s' % str(images_.shape))
        print('The shape of labels_ is %s' % str(labels_.shape))
     ```

mediapipe/docs/mediapipe_ios_setup.md

@@ -76,6 +76,10 @@ in the next section.
 
 2.  Open `mediapipe/Mediapipe.tulsiproj` using the Tulsi app.
 
+    Important: If Tulsi displays an error saying "Bazel could not be found",
+    press the "Bazel..." button in the Packages tab and select the `bazel`
+    executable in your homebrew `/bin/` directory.
+
 3.  Select the MediaPipe config in the Configs tab, then press the Generate
     button below. You will be asked for a location to save the Xcode project.
     Once the project is generated, it will be opened in Xcode.

mediapipe/docs/multi_hand_tracking_desktop.md

@@ -48,7 +48,7 @@ To build and run the TensorFlow Lite example on desktop (GPU) with Webcam, run:
 ```bash
 # Video from webcam running on desktop GPU
 # This works only for linux currently
-$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS \
+$ bazel build -c opt --copt -DMESA_EGL_NO_X11_HEADERS --copt -DEGL_NO_X11 \
     mediapipe/examples/desktop/multi_hand_tracking:multi_hand_tracking_gpu
 
 # It should print:

mediapipe/examples/android/src/java/com/google/mediapipe/apps/METADATA

@@ -0,0 +1,7 @@
+tricorder: {
+  options: {
+    builder: {
+      config: "android_arm64"
+    }
+  }
+}

mediapipe/examples/android/src/java/com/google/mediapipe/apps/edgedetectiongpu/BUILD

@@ -60,8 +60,8 @@ android_library(
         "//third_party:androidx_appcompat",
         "//third_party:androidx_constraint_layout",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/facedetectioncpu/BUILD

@@ -64,10 +64,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/facedetectiongpu/BUILD

@@ -64,10 +64,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/hairsegmentationgpu/BUILD

@@ -63,10 +63,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/handdetectiongpu/BUILD

@@ -64,10 +64,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/handtrackinggpu/BUILD

@@ -85,10 +85,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/multihandtrackinggpu/BUILD

@@ -85,10 +85,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/objectdetection3d/BUILD

@@ -97,10 +97,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/objectdetectioncpu/BUILD

@@ -64,10 +64,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/objectdetectiongpu/BUILD

@@ -65,10 +65,10 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_code_findbugs//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_code_findbugs_jsr305",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/android/src/java/com/google/mediapipe/apps/objecttrackinggpu/BUILD

@@ -64,9 +64,9 @@ android_library(
         "//third_party:androidx_legacy_support_v4",
         "//third_party:androidx_recyclerview",
         "//third_party:opencv",
-        "@androidx_concurrent_futures//jar",
-        "@androidx_lifecycle//jar",
-        "@com_google_guava_android//jar",
+        "@maven//:androidx_concurrent_concurrent_futures",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:com_google_guava_guava",
     ],
 )
 

mediapipe/examples/coral/Dockerfile

@@ -35,10 +35,8 @@ RUN dpkg --add-architecture arm64
 RUN apt-get update && apt-get install -y \
   build-essential \
   crossbuild-essential-arm64 \
-  libusb-1.0-0-dev \
   libusb-1.0-0-dev:arm64 \
-  zlib1g-dev \
-  zlib1g-dev:arm64 \
+  zlibc:arm64 \
   pkg-config \
   zip \
   unzip \
@@ -62,8 +60,8 @@ RUN pip3 install six
 COPY . /mediapipe/
 
 # Install bazel
-
-ARG BAZEL_VERSION=1.1.0
+# Please match the current MediaPipe Bazel requirements according to docs.
+ARG BAZEL_VERSION=2.0.0
 RUN mkdir /bazel && \
     wget --no-check-certificate -O /bazel/installer.sh "https://github.com/bazelbuild/bazel/releases/download/${BAZEL_VERSION}/bazel-${BAZEL_VERSION}-installer-linux-x86_64.sh" && \
     wget --no-check-certificate -O  /bazel/LICENSE.txt "https://raw.githubusercontent.com/bazelbuild/bazel/master/LICENSE" && \

mediapipe/examples/coral/WORKSPACE

@@ -1,356 +0,0 @@
-workspace(name = "mediapipe")
-
-load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
-
-skylib_version = "0.8.0"
-http_archive(
-    name = "bazel_skylib",
-    type = "tar.gz",
-    url = "https://github.com/bazelbuild/bazel-skylib/releases/download/{}/bazel-skylib.{}.tar.gz".format (skylib_version, skylib_version),
-    sha256 = "2ef429f5d7ce7111263289644d233707dba35e39696377ebab8b0bc701f7818e",
-)
-load("@bazel_skylib//lib:versions.bzl", "versions")
-versions.check(minimum_bazel_version = "1.0.0",
-               maximum_bazel_version = "1.2.1")
-
-
-# ABSL cpp library lts_2020_02_25
-http_archive(
-    name = "com_google_absl",
-    urls = [
-        "https://github.com/abseil/abseil-cpp/archive/20200225.tar.gz",
-    ],
-    # Remove after https://github.com/abseil/abseil-cpp/issues/326 is solved.
-    patches = [
-        "@//third_party:com_google_absl_f863b622fe13612433fdf43f76547d5edda0c93001.diff"
-    ],
-    patch_args = [
-        "-p1",
-    ],
-    strip_prefix = "abseil-cpp-20200225",
-    sha256 = "728a813291bdec2aa46eab8356ace9f75ac2ed9dfe2df5ab603c4e6c09f1c353"
-)
-
-http_archive(
-    name = "rules_cc",
-    strip_prefix = "rules_cc-master",
-    urls = ["https://github.com/bazelbuild/rules_cc/archive/master.zip"],
-)
-
-# GoogleTest/GoogleMock framework. Used by most unit-tests.
-http_archive(
-     name = "com_google_googletest",
-     urls = ["https://github.com/google/googletest/archive/master.zip"],
-     strip_prefix = "googletest-master",
-)
-
-# Google Benchmark library.
-http_archive(
-    name = "com_google_benchmark",
-    urls = ["https://github.com/google/benchmark/archive/master.zip"],
-    strip_prefix = "benchmark-master",
-    build_file = "@//third_party:benchmark.BUILD",
-)
-
-# gflags needed by glog
-http_archive(
-    name = "com_github_gflags_gflags",
-    sha256 = "6e16c8bc91b1310a44f3965e616383dbda48f83e8c1eaa2370a215057b00cabe",
-    strip_prefix = "gflags-77592648e3f3be87d6c7123eb81cbad75f9aef5a",
-    urls = [
-        "https://mirror.bazel.build/github.com/gflags/gflags/archive/77592648e3f3be87d6c7123eb81cbad75f9aef5a.tar.gz",
-        "https://github.com/gflags/gflags/archive/77592648e3f3be87d6c7123eb81cbad75f9aef5a.tar.gz",
-    ],
-)
-
-# glog
-http_archive(
-    name = "com_github_glog_glog",
-    url = "https://github.com/google/glog/archive/v0.3.5.zip",
-    sha256 = "267103f8a1e9578978aa1dc256001e6529ef593e5aea38193d31c2872ee025e8",
-    strip_prefix = "glog-0.3.5",
-    build_file = "@//third_party:glog.BUILD",
-    patches = [
-        "@//third_party:com_github_glog_glog_9779e5ea6ef59562b030248947f787d1256132ae.diff"
-    ],
-    patch_args = [
-        "-p1",
-    ],
-)
-
-# easyexif
-http_archive(
-    name = "easyexif",
-    url = "https://github.com/mayanklahiri/easyexif/archive/master.zip",
-    strip_prefix = "easyexif-master",
-    build_file = "@//third_party:easyexif.BUILD",
-)
-
-# libyuv
-http_archive(
-    name = "libyuv",
-    urls = ["https://chromium.googlesource.com/libyuv/libyuv/+archive/refs/heads/master.tar.gz"],
-    build_file = "@//third_party:libyuv.BUILD",
-)
-
-http_archive(
-    name = "com_google_protobuf_javalite",
-    sha256 = "79d102c61e2a479a0b7e5fc167bcfaa4832a0c6aad4a75fa7da0480564931bcc",
-    strip_prefix = "protobuf-384989534b2246d413dbcd750744faab2607b516",
-    urls = ["https://github.com/google/protobuf/archive/384989534b2246d413dbcd750744faab2607b516.zip"],
-)
-
-http_archive(
-    name = "com_google_audio_tools",
-    strip_prefix = "multichannel-audio-tools-master",
-    urls = ["https://github.com/google/multichannel-audio-tools/archive/master.zip"],
-)
-
-# Needed by TensorFlow
-http_archive(
-    name = "io_bazel_rules_closure",
-    sha256 = "e0a111000aeed2051f29fcc7a3f83be3ad8c6c93c186e64beb1ad313f0c7f9f9",
-    strip_prefix = "rules_closure-cf1e44edb908e9616030cc83d085989b8e6cd6df",
-    urls = [
-        "http://mirror.tensorflow.org/github.com/bazelbuild/rules_closure/archive/cf1e44edb908e9616030cc83d085989b8e6cd6df.tar.gz",
-        "https://github.com/bazelbuild/rules_closure/archive/cf1e44edb908e9616030cc83d085989b8e6cd6df.tar.gz",  # 2019-04-04
-    ],
-)
-
-# 2020-02-12
-# The last commit before TensorFlow switched to Bazel 2.0
-_TENSORFLOW_GIT_COMMIT = "77e9ffb9b2bfb1a4f7056e62d84039626923e328"
-_TENSORFLOW_SHA256= "176ccd82f7dd17c5e117b50d353603b129c7a6ccbfebd522ca47cc2a40f33f13"
-http_archive(
-    name = "org_tensorflow",
-    urls = [
-      "https://mirror.bazel.build/github.com/tensorflow/tensorflow/archive/%s.tar.gz" % _TENSORFLOW_GIT_COMMIT,
-      "https://github.com/tensorflow/tensorflow/archive/%s.tar.gz" % _TENSORFLOW_GIT_COMMIT,
-    ],
-    # A compatibility patch
-    patches = [
-        "@//third_party:org_tensorflow_528e22eae8bf3206189a066032c66e9e5c9b4a61.diff"
-    ],
-    patch_args = [
-        "-p1",
-    ],
-    strip_prefix = "tensorflow-%s" % _TENSORFLOW_GIT_COMMIT,
-    sha256 = _TENSORFLOW_SHA256,
-)
-
-load("@org_tensorflow//tensorflow:workspace.bzl", "tf_workspace")
-tf_workspace(tf_repo_name = "org_tensorflow")
-
-http_archive(
-    name = "ceres_solver",
-    url = "https://github.com/ceres-solver/ceres-solver/archive/1.14.0.zip",
-    patches = [
-        "@//third_party:ceres_solver_9bf9588988236279e1262f75d7f4d85711dfa172.diff"
-    ],
-    patch_args = [
-        "-p1",
-    ],
-    strip_prefix = "ceres-solver-1.14.0",
-    sha256 = "5ba6d0db4e784621fda44a50c58bb23b0892684692f0c623e2063f9c19f192f1"
-)
-
-# Please run
-# $ sudo apt-get install libopencv-core-dev libopencv-highgui-dev \
-#                        libopencv-calib3d-dev libopencv-features2d-dev \
-#                        libopencv-imgproc-dev libopencv-video-dev
-new_local_repository(
-    name = "linux_opencv",
-    build_file = "@//third_party:opencv_linux.BUILD",
-    path = "/usr",
-)
-
-new_local_repository(
-    name = "linux_ffmpeg",
-    build_file = "@//third_party:ffmpeg_linux.BUILD",
-    path = "/usr"
-)
-
-# Please run $ brew install opencv@3
-new_local_repository(
-    name = "macos_opencv",
-    build_file = "@//third_party:opencv_macos.BUILD",
-    path = "/usr",
-)
-
-new_local_repository(
-    name = "macos_ffmpeg",
-    build_file = "@//third_party:ffmpeg_macos.BUILD",
-    path = "/usr",
-)
-
-http_archive(
-    name = "android_opencv",
-    build_file = "@//third_party:opencv_android.BUILD",
-    strip_prefix = "OpenCV-android-sdk",
-    type = "zip",
-    url = "https://github.com/opencv/opencv/releases/download/3.4.3/opencv-3.4.3-android-sdk.zip",
-)
-
-# After OpenCV 3.2.0, the pre-compiled opencv2.framework has google protobuf symbols, which will
-# trigger duplicate symbol errors in the linking stage of building a mediapipe ios app.
-# To get a higher version of OpenCV for iOS, opencv2.framework needs to be built from source with
-# '-DBUILD_PROTOBUF=OFF -DBUILD_opencv_dnn=OFF'.
-http_archive(
-    name = "ios_opencv",
-    sha256 = "7dd536d06f59e6e1156b546bd581523d8df92ce83440002885ec5abc06558de2",
-    build_file = "@//third_party:opencv_ios.BUILD",
-    type = "zip",
-    url = "https://github.com/opencv/opencv/releases/download/3.2.0/opencv-3.2.0-ios-framework.zip",
-)
-
-RULES_JVM_EXTERNAL_TAG = "2.2"
-RULES_JVM_EXTERNAL_SHA = "f1203ce04e232ab6fdd81897cf0ff76f2c04c0741424d192f28e65ae752ce2d6"
-
-http_archive(
-    name = "rules_jvm_external",
-    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
-    sha256 = RULES_JVM_EXTERNAL_SHA,
-    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
-)
-
-load("@rules_jvm_external//:defs.bzl", "maven_install")
-
-maven_install(
-    artifacts = [
-        "androidx.annotation:annotation:aar:1.1.0",
-        "androidx.appcompat:appcompat:aar:1.1.0-rc01",
-        "androidx.camera:camera-core:aar:1.0.0-alpha06",
-        "androidx.camera:camera-camera2:aar:1.0.0-alpha06",
-        "androidx.constraintlayout:constraintlayout:aar:1.1.3",
-        "androidx.core:core:aar:1.1.0-rc03",
-        "androidx.legacy:legacy-support-v4:aar:1.0.0",
-        "androidx.recyclerview:recyclerview:aar:1.1.0-beta02",
-        "com.google.android.material:material:aar:1.0.0-rc01",
-    ],
-    repositories = [
-        "https://dl.google.com/dl/android/maven2",
-        "https://repo1.maven.org/maven2",
-    ],
-)
-
-maven_server(
-    name = "google_server",
-    url = "https://dl.google.com/dl/android/maven2",
-)
-
-maven_jar(
-    name = "androidx_lifecycle",
-    artifact = "androidx.lifecycle:lifecycle-common:2.0.0",
-    sha1 = "e070ffae07452331bc5684734fce6831d531785c",
-    server = "google_server",
-)
-
-maven_jar(
-    name = "androidx_concurrent_futures",
-    artifact = "androidx.concurrent:concurrent-futures:1.0.0-alpha03",
-    sha1 = "b528df95c7e2fefa2210c0c742bf3e491c1818ae",
-    server = "google_server",
-)
-
-maven_jar(
-    name = "com_google_guava_android",
-    artifact = "com.google.guava:guava:27.0.1-android",
-    sha1 = "b7e1c37f66ef193796ccd7ea6e80c2b05426182d",
-)
-
-maven_jar(
-    name = "com_google_common_flogger",
-    artifact = "com.google.flogger:flogger:0.3.1",
-    sha1 = "585030fe1ec709760cbef997a459729fb965df0e",
-)
-
-maven_jar(
-    name = "com_google_common_flogger_system_backend",
-    artifact = "com.google.flogger:flogger-system-backend:0.3.1",
-    sha1 = "287b569d76abcd82f9de87fe41829fbc7ebd8ac9",
-)
-
-maven_jar(
-    name = "com_google_code_findbugs",
-    artifact = "com.google.code.findbugs:jsr305:3.0.2",
-    sha1 = "25ea2e8b0c338a877313bd4672d3fe056ea78f0d",
-)
-
-# You may run setup_android.sh to install Android SDK and NDK.
-android_ndk_repository(
-    name = "androidndk",
-)
-
-android_sdk_repository(
-    name = "androidsdk",
-)
-
-# iOS basic build deps.
-
-http_archive(
-    name = "build_bazel_rules_apple",
-    sha256 = "bdc8e66e70b8a75da23b79f1f8c6207356df07d041d96d2189add7ee0780cf4e",
-    strip_prefix = "rules_apple-b869b0d3868d78a1d4ffd866ccb304fb68aa12c3",
-    url = "https://github.com/bazelbuild/rules_apple/archive/b869b0d3868d78a1d4ffd866ccb304fb68aa12c3.tar.gz",
-)
-
-load(
-    "@build_bazel_rules_apple//apple:repositories.bzl",
-    "apple_rules_dependencies",
-)
-
-apple_rules_dependencies()
-
-load(
-    "@build_bazel_rules_swift//swift:repositories.bzl",
-    "swift_rules_dependencies",
-)
-
-swift_rules_dependencies()
-
-load(
-    "@build_bazel_apple_support//lib:repositories.bzl",
-    "apple_support_dependencies",
-)
-
-apple_support_dependencies()
-
-# More iOS deps.
-
-http_archive(
-    name = "google_toolbox_for_mac",
-    url = "https://github.com/google/google-toolbox-for-mac/archive/v2.2.1.zip",
-    sha256 = "e3ac053813c989a88703556df4dc4466e424e30d32108433ed6beaec76ba4fdc",
-    strip_prefix = "google-toolbox-for-mac-2.2.1",
-    build_file = "@//third_party:google_toolbox_for_mac.BUILD",
-)
-
-### Coral ###
-
-#COMMIT=$(git ls-remote https://github.com/google-coral/crosstool master | awk '{print $1}')
-#SHA256=$(curl -L "https://github.com/google-coral/crosstool/archive/${COMMIT}.tar.gz" | sha256sum | awk '{print $1}')
-# Oct 2019
-#COMMIT=9e00d5be43bf001f883b5700f5d04882fea00229
-#SHA256=cb31b1417ccdcf7dd9fca5ec63e1571672372c30427730255997a547569d2feb
-http_archive(
-    name = "coral_crosstool",
-    sha256 = "cb31b1417ccdcf7dd9fca5ec63e1571672372c30427730255997a547569d2feb",
-    strip_prefix = "crosstool-9e00d5be43bf001f883b5700f5d04882fea00229",
-    urls = [
-        "https://github.com/google-coral/crosstool/archive/9e00d5be43bf001f883b5700f5d04882fea00229.tar.gz",
-    ],
-)
-load("@coral_crosstool//:configure.bzl", "cc_crosstool")
-cc_crosstool(name = "crosstool")
-
-# EdgeTPU
-new_local_repository(
-    name = "edgetpu",
-    path = "/edgetpu/libedgetpu",
-    build_file = "/edgetpu/libedgetpu/BUILD"
-)
-new_local_repository(
-    name = "libedgetpu",
-    path = "/usr/lib/aarch64-linux-gnu",
-    build_file = "/edgetpu/libedgetpu/BUILD"
-)

mediapipe/examples/coral/WORKSPACE.coral

@@ -0,0 +1,30 @@
+
+### Coral additions to MediaPipe WORKSPACE ###
+
+#COMMIT=$(git ls-remote https://github.com/google-coral/crosstool master | awk '{print $1}')
+#SHA256=$(curl -L "https://github.com/google-coral/crosstool/archive/${COMMIT}.tar.gz" | sha256sum | awk '{print $1}')
+# Oct 2019
+#COMMIT=9e00d5be43bf001f883b5700f5d04882fea00229
+#SHA256=cb31b1417ccdcf7dd9fca5ec63e1571672372c30427730255997a547569d2feb
+http_archive(
+    name = "coral_crosstool",
+    sha256 = "cb31b1417ccdcf7dd9fca5ec63e1571672372c30427730255997a547569d2feb",
+    strip_prefix = "crosstool-9e00d5be43bf001f883b5700f5d04882fea00229",
+    urls = [
+        "https://github.com/google-coral/crosstool/archive/9e00d5be43bf001f883b5700f5d04882fea00229.tar.gz",
+    ],
+)
+load("@coral_crosstool//:configure.bzl", "cc_crosstool")
+cc_crosstool(name = "crosstool")
+
+# EdgeTPU
+new_local_repository(
+    name = "edgetpu",
+    path = "/edgetpu/libedgetpu",
+    build_file = "/edgetpu/libedgetpu/BUILD"
+)
+new_local_repository(
+    name = "libedgetpu",
+    path = "/usr/lib/aarch64-linux-gnu",
+    build_file = "/edgetpu/libedgetpu/BUILD"
+)

mediapipe/examples/coral/setup.sh

@@ -10,12 +10,25 @@ sleep 3
 
 mkdir -p opencv32_arm64_libs
 
+# prepare docker aux script
 cp mediapipe/examples/coral/update_sources.sh update_sources.sh
 chmod +x update_sources.sh
 
+# backup non-coral Dockerfile
 mv Dockerfile Dockerfile.orig
 cp mediapipe/examples/coral/Dockerfile Dockerfile
 
+# backup non-coral workspace
 cp WORKSPACE WORKSPACE.orig
-cp mediapipe/examples/coral/WORKSPACE WORKSPACE
 
+# create temps
+cp WORKSPACE WORKSPACE.1
+cp mediapipe/examples/coral/WORKSPACE.coral WORKSPACE.2
+
+# merge (shell decides concat order, unless numbered appropriately)
+cat WORKSPACE.1 WORKSPACE.2 > WORKSPACE
+
+# cleanup
+rm WORKSPACE.1 WORKSPACE.2
+
+echo 'done'

mediapipe/examples/desktop/autoflip/calculators/shot_boundary_calculator.cc

@@ -85,7 +85,7 @@ REGISTER_CALCULATOR(ShotBoundaryCalculator);
 void ShotBoundaryCalculator::ComputeHistogram(const cv::Mat& image,
                                               cv::Mat* image_histogram) {
   cv::Mat equalized_image;
-  cv::cvtColor(image.clone(), equalized_image, CV_RGB2GRAY);
+  cv::cvtColor(image.clone(), equalized_image, cv::COLOR_RGB2GRAY);
 
   double min, max;
   cv::minMaxLoc(equalized_image, &min, &max);

mediapipe/examples/desktop/autoflip/quality/polynomial_regression_path_solver.cc

@@ -95,7 +95,7 @@ void PolynomialRegressionPathSolver::AddCostFunctionToProblem(
     const std::vector<FocusPointFrame>& focus_point_frames,
     const std::vector<FocusPointFrame>& prior_focus_point_frames,
     const int original_width, const int original_height, const int output_width,
-    const int output_height, std::vector<cv::Mat>* all_xforms) {
+    const int output_height, std::vector<cv::Mat>* all_transforms) {
   RET_CHECK_GE(original_width, output_width);
   RET_CHECK_GE(original_height, output_height);
   const bool should_solve_x_problem = original_width != output_width;
@@ -138,9 +138,10 @@ void PolynomialRegressionPathSolver::AddCostFunctionToProblem(
   Solver::Options options;
   options.linear_solver_type = ceres::DENSE_QR;
 
-  Solver::Summary summary;
-  Solve(options, &problem_x, &summary);
-  all_xforms->clear();
+  Solver::Summary summary_x, summary_y;
+  Solve(options, &problem_x, &summary_x);
+  Solve(options, &problem_y, &summary_y);
+  all_transforms->clear();
   for (int i = 0;
        i < focus_point_frames.size() + prior_focus_point_frames.size(); i++) {
     // Code below assigns values into an affine model, defined as:
@@ -160,7 +161,7 @@ void PolynomialRegressionPathSolver::AddCostFunctionToProblem(
                                        yb_, yc_, yd_, yk_);
       transform.at<float>(1, 2) = delta;
     }
-    all_xforms->push_back(transform);
+    all_transforms->push_back(transform);
   }
   return mediapipe::OkStatus();
 }

mediapipe/examples/desktop/autoflip/quality/polynomial_regression_path_solver.h

@@ -40,14 +40,14 @@ class PolynomialRegressionPathSolver {
   // Given a series of focus points on frames, uses polynomial regression to
   // compute a best guess of a 1D camera movement trajectory along x-axis and
   // y-axis, such that focus points can be preserved as much as possible. The
-  // returned |all_xforms| hold the camera location at each timestamp
+  // returned |all_transforms| hold the camera location at each timestamp
   // corresponding to each input frame.
   ::mediapipe::Status ComputeCameraPath(
       const std::vector<FocusPointFrame>& focus_point_frames,
       const std::vector<FocusPointFrame>& prior_focus_point_frames,
       const int original_width, const int original_height,
       const int output_width, const int output_height,
-      std::vector<cv::Mat>* all_xforms);
+      std::vector<cv::Mat>* all_transforms);
 
  private:
   // Adds a new cost function, constructed using |in| and |out|, into |problem|.

mediapipe/examples/desktop/hair_segmentation/BUILD

@@ -24,3 +24,17 @@ cc_binary(
         "//mediapipe/graphs/hair_segmentation:mobile_calculators",
     ],
 )
+
+cc_binary(
+    name = "hair_segmentation_cpu",
+    deps = [
+        "//mediapipe/examples/desktop:demo_run_graph_main",
+    ] + select({
+        "//mediapipe/gpu:disable_gpu": [
+            "//mediapipe/graphs/hair_segmentation:desktop_calculators",
+        ],
+        "//conditions:default": [
+            "//mediapipe/graphs/hair_segmentation:mobile_calculators",
+        ],
+    }),
+)

mediapipe/framework/BUILD

@@ -361,6 +361,7 @@ cc_library(
         "//mediapipe/framework:mediapipe_options_cc_proto",
         "//mediapipe/framework:packet_generator_cc_proto",
         "//mediapipe/framework:status_handler_cc_proto",
+        "//mediapipe/framework:stream_handler_cc_proto",
         "//mediapipe/framework/port:any_proto",
         "//mediapipe/framework/port:status",
         "//mediapipe/framework/tool:options_util",
@@ -1495,13 +1496,17 @@ cc_test(
         "//mediapipe/framework/port:status",
         "//mediapipe/framework/stream_handler:barrier_input_stream_handler",
         "//mediapipe/framework/stream_handler:early_close_input_stream_handler",
+        "//mediapipe/framework/stream_handler:fixed_size_input_stream_handler",
         "//mediapipe/framework/stream_handler:immediate_input_stream_handler",
         "//mediapipe/framework/stream_handler:mux_input_stream_handler",
+        "//mediapipe/framework/stream_handler:sync_set_input_stream_handler",
+        "//mediapipe/framework/stream_handler:timestamp_align_input_stream_handler",
         "//mediapipe/framework/tool:sink",
         "//mediapipe/framework/tool:status_util",
         "@com_google_absl//absl/container:fixed_array",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:str_format",
         "@com_google_absl//absl/time",
     ],
 )

mediapipe/framework/calculator_contract.h

@@ -84,7 +84,7 @@ class CalculatorContract {
     return *output_side_packets_;
   }
 
-  // Set this Node's default InputStreamHandler.
+  // Specifies the preferred InputStreamHandler for this Node.
   // If there is an InputStreamHandler specified in the graph (.pbtxt) for this
   // Node, then the graph's InputStreamHandler will take priority.
   void SetInputStreamHandler(const std::string& name) {
@@ -104,6 +104,29 @@ class CalculatorContract {
     return input_stream_handler_options_;
   }
 
+  // The next few methods are concerned with timestamp bound propagation
+  // (see scheduling_sync.md#input-policies). Every calculator that processes
+  // live inputs should specify either ProcessTimestampBounds or
+  // TimestampOffset.  Calculators that produce output at the same timestamp as
+  // the input, or with a fixed offset, should declare this fact using
+  // SetTimestampOffset.  Calculators that require custom timestamp bound
+  // calculations should use SetProcessTimestampBounds.
+
+  // When true, Process is called for every new timestamp bound, with or without
+  // new packets.  A call to Process with only an input timestamp bound is
+  // normally used to compute a new output timestamp bound.
+  void SetProcessTimestampBounds(bool process_timestamps) {
+    process_timestamps_ = process_timestamps;
+  }
+  bool GetProcessTimestampBounds() const { return process_timestamps_; }
+
+  // Specifies the maximum difference between input and output timestamps.
+  // When specified, the mediapipe framework automatically computes output
+  // timestamp bounds based on input timestamps.  The special value
+  // TimestampDiff::Unset disables the timestamp offset.
+  void SetTimestampOffset(TimestampDiff offset) { timestamp_offset_ = offset; }
+  TimestampDiff GetTimestampOffset() const { return timestamp_offset_; }
+
   class GraphServiceRequest {
    public:
     // APIs that should be used by calculators.
@@ -147,6 +170,8 @@ class CalculatorContract {
   MediaPipeOptions input_stream_handler_options_;
   std::string node_name_;
   std::map<std::string, GraphServiceRequest> service_requests_;
+  bool process_timestamps_ = false;
+  TimestampDiff timestamp_offset_ = TimestampDiff::Unset();
 };
 
 }  // namespace mediapipe

mediapipe/framework/calculator_graph.h

@@ -143,7 +143,7 @@ class CalculatorGraph {
       const std::string& graph_type = "",
       const Subgraph::SubgraphOptions* options = nullptr);
 
-  // Resturns the canonicalized CalculatorGraphConfig for this graph.
+  // Returns the canonicalized CalculatorGraphConfig for this graph.
   const CalculatorGraphConfig& Config() const {
     return validated_graph_->Config();
   }

mediapipe/framework/calculator_graph_bounds_test.cc

@@ -31,6 +31,17 @@ namespace {
 typedef std::function<::mediapipe::Status(CalculatorContext* cc)>
     CalculatorContextFunction;
 
+// Returns the contents of a set of Packets.
+// The contents must be copyable.
+template <typename T>
+std::vector<T> GetContents(const std::vector<Packet>& packets) {
+  std::vector<T> result;
+  for (Packet p : packets) {
+    result.push_back(p.Get<T>());
+  }
+  return result;
+}
+
 // A simple Semaphore for synchronizing test threads.
 class AtomicSemaphore {
  public:
@@ -671,9 +682,9 @@ REGISTER_CALCULATOR(BoundToPacketCalculator);
 
 // A Calculator that produces packets at timestamps beyond the input timestamp.
 class FuturePacketCalculator : public CalculatorBase {
+ public:
   static constexpr int64 kOutputFutureMicros = 3;
 
- public:
   static ::mediapipe::Status GetContract(CalculatorContract* cc) {
     cc->Inputs().Index(0).Set<int>();
     cc->Outputs().Index(0).Set<int>();
@@ -742,9 +753,8 @@ TEST(CalculatorGraphBoundsTest, OffsetBoundPropagation) {
   MP_ASSERT_OK(graph.WaitUntilDone());
 }
 
-// Shows that bounds changes alone do not invoke Process.
-// Note: Bounds changes alone will invoke Process eventually
-// when SetOffset is cleared, see: go/mediapipe-realtime-graph.
+// Shows that timestamp bounds changes alone do not invoke Process,
+// without SetProcessTimestampBounds(true).
 TEST(CalculatorGraphBoundsTest, BoundWithoutInputPackets) {
   // OffsetBoundCalculator produces only timestamp bounds.
   // The BoundToPacketCalculator delivers an output packet whenever the
@@ -753,8 +763,13 @@ TEST(CalculatorGraphBoundsTest, BoundWithoutInputPackets) {
       ::mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(R"(
         input_stream: 'input'
         node {
-          calculator: 'OffsetBoundCalculator'
+          calculator: 'FuturePacketCalculator'
           input_stream: 'input'
+          output_stream: 'input_2'
+        }
+        node {
+          calculator: 'OffsetBoundCalculator'
+          input_stream: 'input_2'
           output_stream: 'bounds'
         }
         node {
@@ -778,6 +793,7 @@ TEST(CalculatorGraphBoundsTest, BoundWithoutInputPackets) {
   for (int i = 0; i < kNumInputs; ++i) {
     Packet p = MakePacket<int>(33).At(Timestamp(i));
     MP_ASSERT_OK(graph.AddPacketToInputStream("input", p));
+    MP_ASSERT_OK(graph.WaitUntilIdle());
   }
 
   // No packets arrive, because updated timestamp bounds do not invoke
@@ -1104,5 +1120,254 @@ TEST(CalculatorGraphBoundsTest, BoundsForEmptyInputs_SyncSets) {
     )");
 }
 
+// A Calculator that produces a packet for each timestamp bounds update.
+class ProcessBoundToPacketCalculator : public CalculatorBase {
+ public:
+  static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    for (int i = 0; i < cc->Inputs().NumEntries(); ++i) {
+      cc->Inputs().Index(i).SetAny();
+    }
+    for (int i = 0; i < cc->Outputs().NumEntries(); ++i) {
+      cc->Outputs().Index(i).Set<Timestamp>();
+    }
+    cc->SetInputStreamHandler("ImmediateInputStreamHandler");
+    cc->SetProcessTimestampBounds(true);
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Process(CalculatorContext* cc) final {
+    for (int i = 0; i < cc->Outputs().NumEntries(); ++i) {
+      Timestamp t = cc->Inputs().Index(i).Value().Timestamp();
+      if (t == cc->InputTimestamp() &&
+          t >= cc->Outputs().Index(i).NextTimestampBound()) {
+        cc->Outputs().Index(i).Add(new auto(t), t);
+      }
+    }
+    return ::mediapipe::OkStatus();
+  }
+};
+REGISTER_CALCULATOR(ProcessBoundToPacketCalculator);
+
+// A Calculator that passes through each packet and timestamp immediately.
+class ImmediatePassthroughCalculator : public CalculatorBase {
+ public:
+  static ::mediapipe::Status GetContract(CalculatorContract* cc) {
+    for (int i = 0; i < cc->Inputs().NumEntries(); ++i) {
+      cc->Inputs().Index(i).SetAny();
+    }
+    for (int i = 0; i < cc->Outputs().NumEntries(); ++i) {
+      cc->Outputs().Index(i).SetSameAs(&cc->Inputs().Index(i));
+    }
+    cc->SetInputStreamHandler("ImmediateInputStreamHandler");
+    cc->SetProcessTimestampBounds(true);
+    return ::mediapipe::OkStatus();
+  }
+
+  ::mediapipe::Status Process(CalculatorContext* cc) final {
+    for (int i = 0; i < cc->Outputs().NumEntries(); ++i) {
+      if (!cc->Inputs().Index(i).IsEmpty()) {
+        cc->Outputs().Index(i).AddPacket(cc->Inputs().Index(i).Value());
+      } else {
+        Timestamp input_bound =
+            cc->Inputs().Index(i).Value().Timestamp().NextAllowedInStream();
+        if (cc->Outputs().Index(i).NextTimestampBound() < input_bound) {
+          cc->Outputs().Index(i).SetNextTimestampBound(input_bound);
+        }
+      }
+    }
+    return ::mediapipe::OkStatus();
+  }
+};
+REGISTER_CALCULATOR(ImmediatePassthroughCalculator);
+
+// Shows that Process is called for input-sets without input packets.
+void TestProcessForEmptyInputs(const std::string& input_stream_handler) {
+  // FuturePacketCalculator and OffsetBoundCalculator produce only ts bounds,
+  // The ProcessBoundToPacketCalculator has SetProcessTimestampBounds(true),
+  // and produces an output packet for every timestamp bound update.
+  std::string config_str = R"(
+            input_stream: 'input'
+            node {
+              calculator: 'FuturePacketCalculator'
+              input_stream: 'input'
+              output_stream: 'futures'
+            }
+            node {
+              calculator: 'OffsetBoundCalculator'
+              input_stream: 'futures'
+              output_stream: 'bounds'
+            }
+            node {
+              calculator: 'ProcessBoundToPacketCalculator'
+              input_stream: 'bounds'
+              output_stream: 'bounds_ts'
+              input_stream_handler { $input_stream_handler }
+            }
+          )";
+  absl::StrReplaceAll({{"$input_stream_handler", input_stream_handler}},
+                      &config_str);
+  CalculatorGraphConfig config =
+      ::mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(config_str);
+  CalculatorGraph graph;
+  std::vector<Packet> input_ts_packets;
+  std::vector<Packet> bounds_ts_packets;
+  MP_ASSERT_OK(graph.Initialize(config));
+  MP_ASSERT_OK(graph.ObserveOutputStream("bounds_ts", [&](const Packet& p) {
+    bounds_ts_packets.push_back(p);
+    return ::mediapipe::OkStatus();
+  }));
+  MP_ASSERT_OK(graph.StartRun({}));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  // Add four packets into the graph.
+  constexpr int kFutureMicros = FuturePacketCalculator::kOutputFutureMicros;
+  Packet p;
+  p = MakePacket<int>(33).At(Timestamp(0));
+  MP_ASSERT_OK(graph.AddPacketToInputStream("input", p));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  p = MakePacket<int>(33).At(Timestamp(10));
+  MP_ASSERT_OK(graph.AddPacketToInputStream("input", p));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  p = MakePacket<int>(33).At(Timestamp(20));
+  MP_ASSERT_OK(graph.AddPacketToInputStream("input", p));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  p = MakePacket<int>(33).At(Timestamp(30));
+  MP_ASSERT_OK(graph.AddPacketToInputStream("input", p));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  // Packets arrive.
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+  EXPECT_EQ(bounds_ts_packets.size(), 4);
+
+  std::vector<Timestamp> expected = {
+      Timestamp(0 + kFutureMicros), Timestamp(10 + kFutureMicros),
+      Timestamp(20 + kFutureMicros), Timestamp(30 + kFutureMicros)};
+  EXPECT_EQ(GetContents<Timestamp>(bounds_ts_packets), expected);
+
+  // Shutdown the graph.
+  MP_ASSERT_OK(graph.CloseAllPacketSources());
+  MP_ASSERT_OK(graph.WaitUntilDone());
+}
+
+// Shows that Process is called for input-sets without input packets
+// using an DefaultInputStreamHandler.
+TEST(CalculatorGraphBoundsTest, ProcessTimestampBounds_Default) {
+  TestProcessForEmptyInputs(R"(
+      input_stream_handler: "DefaultInputStreamHandler")");
+}
+
+// Shows that Process is called for input-sets without input packets
+// using an ImmediateInputStreamHandler.
+TEST(CalculatorGraphBoundsTest, ProcessTimestampBounds_Immediate) {
+  TestProcessForEmptyInputs(R"(
+      input_stream_handler: "ImmediateInputStreamHandler")");
+}
+
+// Shows that Process is called for input-sets without input packets
+// using a SyncSetInputStreamHandler with a single sync-set.
+TEST(CalculatorGraphBoundsTest, ProcessTimestampBounds_SyncSet) {
+  TestProcessForEmptyInputs(R"(
+      input_stream_handler: "SyncSetInputStreamHandler")");
+}
+
+// Shows that Process is called for input-sets without input packets
+// using a SyncSetInputStreamHandler with multiple sync-sets.
+TEST(CalculatorGraphBoundsTest, ProcessTimestampBounds_SyncSets) {
+  TestProcessForEmptyInputs(R"(
+      input_stream_handler: "SyncSetInputStreamHandler"
+      options {
+        [mediapipe.SyncSetInputStreamHandlerOptions.ext] {
+          sync_set { tag_index: ":0" }
+        }
+      }
+    )");
+}
+
+// Demonstrates the functionality of an "ImmediatePassthroughCalculator".
+// The ImmediatePassthroughCalculator simply relays each input packet to
+// the corresponding output stream.  ProcessTimestampBounds is needed to
+// relay timestamp bounds as well as packets.
+TEST(CalculatorGraphBoundsTest, ProcessTimestampBounds_Passthrough) {
+  // OffsetBoundCalculator produces timestamp bounds.
+  // ImmediatePassthroughCalculator relays packets and bounds.
+  // ProcessBoundToPacketCalculator reports packets and bounds as packets.
+  std::string config_str = R"(
+            input_stream: "input_0"
+            input_stream: "input_1"
+            node {
+              calculator: "OffsetBoundCalculator"
+              input_stream: "input_1"
+              output_stream: "bound_1"
+            }
+            node {
+              calculator: "ImmediatePassthroughCalculator"
+              input_stream: "input_0"
+              input_stream: "bound_1"
+              output_stream: "same_0"
+              output_stream: "same_1"
+            }
+            node {
+              calculator: "ProcessBoundToPacketCalculator"
+              input_stream: "same_0"
+              input_stream: "same_1"
+              output_stream: "output_0"
+              output_stream: "output_1"
+            }
+          )";
+  CalculatorGraphConfig config =
+      ::mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(config_str);
+  CalculatorGraph graph;
+  std::vector<Packet> output_0_packets;
+  std::vector<Packet> output_1_packets;
+  MP_ASSERT_OK(graph.Initialize(config));
+  MP_ASSERT_OK(graph.ObserveOutputStream("output_0", [&](const Packet& p) {
+    output_0_packets.push_back(p);
+    return ::mediapipe::OkStatus();
+  }));
+  MP_ASSERT_OK(graph.ObserveOutputStream("output_1", [&](const Packet& p) {
+    output_1_packets.push_back(p);
+    return ::mediapipe::OkStatus();
+  }));
+  MP_ASSERT_OK(graph.StartRun({}));
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+
+  // Add four packets to input_0.
+  for (int i = 0; i < 4; ++i) {
+    Packet p = MakePacket<int>(33).At(Timestamp(i * 10));
+    MP_ASSERT_OK(graph.AddPacketToInputStream("input_0", p));
+    MP_ASSERT_OK(graph.WaitUntilIdle());
+  }
+
+  // Packets arrive.
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+  EXPECT_EQ(output_0_packets.size(), 4);
+  EXPECT_EQ(output_1_packets.size(), 0);
+  std::vector<Timestamp> expected =  //
+      {Timestamp(0), Timestamp(10), Timestamp(20), Timestamp(30)};
+  EXPECT_EQ(GetContents<Timestamp>(output_0_packets), expected);
+
+  // Add two timestamp bounds to bound_1.
+  for (int i = 0; i < 2; ++i) {
+    Packet p = MakePacket<int>(33).At(Timestamp(10 + i * 10));
+    MP_ASSERT_OK(graph.AddPacketToInputStream("input_1", p));
+    MP_ASSERT_OK(graph.WaitUntilIdle());
+  }
+
+  // Bounds arrive.
+  MP_ASSERT_OK(graph.WaitUntilIdle());
+  EXPECT_EQ(output_0_packets.size(), 4);
+  EXPECT_EQ(output_1_packets.size(), 2);
+  expected =  //
+      {Timestamp(10), Timestamp(20)};
+  EXPECT_EQ(GetContents<Timestamp>(output_1_packets), expected);
+
+  // Shutdown the graph.
+  MP_ASSERT_OK(graph.CloseAllPacketSources());
+  MP_ASSERT_OK(graph.WaitUntilDone());
+}
+
 }  // namespace
 }  // namespace mediapipe

mediapipe/framework/calculator_graph_test.cc

@@ -29,6 +29,7 @@
 #include "absl/memory/memory.h"
 #include "absl/strings/escaping.h"
 #include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 #include "absl/strings/substitute.h"
 #include "absl/time/clock.h"
@@ -4558,5 +4559,68 @@ TEST(CalculatorGraph, SimpleMuxCalculatorWithCustomInputStreamHandler) {
           testing::HasSubstr("ImmediateInputStreamHandler class comment")));
 }
 
+void DoTestMultipleGraphRuns(absl::string_view input_stream_handler,
+                             bool select_packet) {
+  std::string graph_proto = absl::StrFormat(R"(
+    input_stream: 'input'
+    input_stream: 'select'
+    node {
+      calculator: 'PassThroughCalculator'
+      input_stream: 'input'
+      input_stream: 'select'
+      input_stream_handler {
+        input_stream_handler: "%s"
+      }
+      output_stream: 'output'
+      output_stream: 'select_out'
+    }
+  )",
+                                            input_stream_handler.data());
+  CalculatorGraphConfig config =
+      ::mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(graph_proto);
+  std::vector<Packet> packet_dump;
+  tool::AddVectorSink("output", &config, &packet_dump);
+
+  CalculatorGraph graph;
+  MP_ASSERT_OK(graph.Initialize(config));
+
+  struct Run {
+    Timestamp timestamp;
+    int value;
+  };
+  std::vector<Run> runs = {{.timestamp = Timestamp(2000), .value = 2},
+                           {.timestamp = Timestamp(1000), .value = 1}};
+  for (const Run& run : runs) {
+    MP_ASSERT_OK(graph.StartRun({}));
+
+    if (select_packet) {
+      MP_EXPECT_OK(graph.AddPacketToInputStream(
+          "select", MakePacket<int>(0).At(run.timestamp)));
+    }
+    MP_EXPECT_OK(graph.AddPacketToInputStream(
+        "input", MakePacket<int>(run.value).At(run.timestamp)));
+    MP_ASSERT_OK(graph.WaitUntilIdle());
+    ASSERT_EQ(1, packet_dump.size());
+    EXPECT_EQ(run.value, packet_dump[0].Get<int>());
+    EXPECT_EQ(run.timestamp, packet_dump[0].Timestamp());
+
+    MP_ASSERT_OK(graph.CloseAllPacketSources());
+    MP_ASSERT_OK(graph.WaitUntilDone());
+
+    packet_dump.clear();
+  }
+}
+
+TEST(CalculatorGraph, MultipleRunsWithDifferentInputStreamHandlers) {
+  DoTestMultipleGraphRuns("BarrierInputStreamHandler", true);
+  DoTestMultipleGraphRuns("DefaultInputStreamHandler", true);
+  DoTestMultipleGraphRuns("EarlyCloseInputStreamHandler", true);
+  DoTestMultipleGraphRuns("FixedSizeInputStreamHandler", true);
+  DoTestMultipleGraphRuns("ImmediateInputStreamHandler", false);
+  DoTestMultipleGraphRuns("MuxInputStreamHandler", true);
+  DoTestMultipleGraphRuns("SyncSetInputStreamHandler", true);
+  DoTestMultipleGraphRuns("TimestampAlignInputStreamHandler", true);
+}
+
 }  // namespace
 }  // namespace mediapipe

mediapipe/framework/calculator_node.cc

@@ -97,6 +97,7 @@ Timestamp CalculatorNode::SourceProcessOrder(
 
   const NodeTypeInfo& node_type_info =
       validated_graph_->CalculatorInfos()[node_id_];
+  const CalculatorContract& contract = node_type_info.Contract();
 
   uses_gpu_ =
       node_type_info.InputSidePacketTypes().HasTag(kGpuSharedTagName) ||
@@ -147,6 +148,14 @@ Timestamp CalculatorNode::SourceProcessOrder(
       use_calc_specified ? handler_config : node_config.input_stream_handler(),
       node_type_info.InputStreamTypes()));
 
+  for (auto& stream : output_stream_handler_->OutputStreams()) {
+    stream->Spec()->offset_enabled =
+        (contract.GetTimestampOffset() != TimestampDiff::Unset());
+    stream->Spec()->offset = contract.GetTimestampOffset();
+  }
+  input_stream_handler_->SetProcessTimestampBounds(
+      contract.GetProcessTimestampBounds());
+
   return InitializeInputStreams(input_stream_managers, output_stream_managers);
 }
 
@@ -805,7 +814,8 @@ std::string CalculatorNode::DebugName() const {
         input_stream_handler_->FinalizeInputSet(input_timestamp, inputs);
         output_stream_handler_->PrepareOutputs(input_timestamp, outputs);
 
-        VLOG(2) << "Calling Calculator::Process() for node: " << DebugName();
+        VLOG(2) << "Calling Calculator::Process() for node: " << DebugName()
+                << " timestamp: " << input_timestamp;
 
         if (OutputsAreConstant(calculator_context)) {
           // Do nothing.
@@ -817,6 +827,9 @@ std::string CalculatorNode::DebugName() const {
           result = calculator_->Process(calculator_context);
         }
 
+        VLOG(2) << "Called Calculator::Process() for node: " << DebugName()
+                << " timestamp: " << input_timestamp;
+
         // Removes one packet from each shard and progresses to the next input
         // timestamp.
         input_stream_handler_->ClearCurrentInputs(calculator_context);

mediapipe/framework/calculator_profile.proto

@@ -113,7 +113,10 @@ message GraphTrace {
     optional int32 stream_id = 4;
 
     // The address of the packet contents.
-    optional int64 packet_id = 5;
+    optional int64 packet_id = 5 [deprecated = true];
+
+    // Data describing the event, such as the packet contents.
+    optional int64 event_data = 6;
   }
 
   // The kind of event recorded.
@@ -133,6 +136,7 @@ message GraphTrace {
     DSP_TASK = 12;
     TPU_TASK = 13;
     GPU_CALIBRATION = 14;
+    PACKET_QUEUED = 15;
   }
 
   // The timing for one packet set being processed at one caclulator node.

mediapipe/framework/deps/registration.cc

@@ -18,6 +18,10 @@ namespace mediapipe {
 
 namespace {
 
+// List of namespaces that can register calculators inside the namespace
+// and still refer to them using an unqualified name.  This whitelist
+// is meant to facilitate migration from unqualified to fully qualified
+// calculator names.
 constexpr char const* kTopNamespaces[] = {
     "mediapipe",
 };

mediapipe/framework/formats/BUILD

@@ -13,7 +13,7 @@
 # limitations under the License.
 #
 
-load("//mediapipe/framework/port:build_config.bzl", "mediapipe_cc_proto_library")
+load("//mediapipe/framework/port:build_config.bzl", "mediapipe_proto_library")
 
 package(
     default_visibility = ["//visibility:private"],
@@ -24,95 +24,45 @@ licenses(["notice"])  # Apache 2.0
 
 exports_files(["LICENSE"])
 
-proto_library(
+mediapipe_proto_library(
     name = "detection_proto",
     srcs = ["detection.proto"],
     visibility = ["//visibility:public"],
     deps = ["//mediapipe/framework/formats:location_data_proto"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "classification_proto",
     srcs = ["classification.proto"],
     visibility = ["//visibility:public"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "image_format_proto",
     srcs = ["image_format.proto"],
     visibility = ["//visibility:public"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "matrix_data_proto",
     srcs = ["matrix_data.proto"],
     visibility = ["//visibility:public"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "location_data_proto",
     srcs = ["location_data.proto"],
+    portable_deps = ["//mediapipe/framework/formats/annotation:rasterization_cc_proto"],
     visibility = ["//visibility:public"],
     deps = ["//mediapipe/framework/formats/annotation:rasterization_proto"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "time_series_header_proto",
     srcs = ["time_series_header.proto"],
     visibility = ["//visibility:public"],
 )
 
-mediapipe_cc_proto_library(
-    name = "detection_cc_proto",
-    srcs = ["detection.proto"],
-    cc_deps = [":location_data_cc_proto"],
-    visibility = ["//visibility:public"],
-    deps = [":detection_proto"],
-)
-
-java_lite_proto_library(
-    name = "detection_java_proto_lite",
-    strict_deps = 0,
-    visibility = ["//mediapipe:__subpackages__"],
-    deps = [":detection_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "classification_cc_proto",
-    srcs = ["classification.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":classification_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "image_format_cc_proto",
-    srcs = ["image_format.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":image_format_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "matrix_data_cc_proto",
-    srcs = ["matrix_data.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":matrix_data_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "location_data_cc_proto",
-    srcs = ["location_data.proto"],
-    cc_deps = ["//mediapipe/framework/formats/annotation:rasterization_cc_proto"],
-    visibility = ["//visibility:public"],
-    deps = [":location_data_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "time_series_header_cc_proto",
-    srcs = ["time_series_header.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":time_series_header_proto"],
-)
-
 cc_library(
     name = "deleting_file",
     srcs = ["deleting_file.cc"],
@@ -245,33 +195,14 @@ cc_test(
     ],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "rect_proto",
     srcs = ["rect.proto"],
-    visibility = [
-        "//visibility:public",
-    ],
+    visibility = ["//visibility:public"],
+    deps = ["//mediapipe/framework/formats:location_data_proto"],
 )
 
-mediapipe_cc_proto_library(
-    name = "rect_cc_proto",
-    srcs = ["rect.proto"],
-    visibility = [
-        "//visibility:public",
-    ],
-    deps = [":rect_proto"],
-)
-
-java_lite_proto_library(
-    name = "rect_java_proto_lite",
-    strict_deps = 0,
-    visibility = [
-        "//mediapipe:__subpackages__",
-    ],
-    deps = [":rect_proto"],
-)
-
-proto_library(
+mediapipe_proto_library(
     name = "landmark_proto",
     srcs = ["landmark.proto"],
     visibility = [
@@ -279,22 +210,6 @@ proto_library(
     ],
 )
 
-mediapipe_cc_proto_library(
-    name = "landmark_cc_proto",
-    srcs = ["landmark.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":landmark_proto"],
-)
-
-java_lite_proto_library(
-    name = "landmark_java_proto_lite",
-    strict_deps = 0,
-    visibility = [
-        "//mediapipe:__subpackages__",
-    ],
-    deps = [":landmark_proto"],
-)
-
 # Expose the proto source files for building mediapipe AAR.
 filegroup(
     name = "protos_src",

mediapipe/framework/formats/annotation/BUILD

@@ -14,38 +14,31 @@
 # limitations under the License.
 #
 
+load("//mediapipe/framework/port:build_config.bzl", "mediapipe_proto_library")
+
+package(default_visibility = ["//visibility:private"])
+
 licenses(["notice"])  # Apache 2.0
 
 exports_files(["LICENSE"])
 
-load("//mediapipe/framework/port:build_config.bzl", "mediapipe_cc_proto_library")
-
-package(default_visibility = ["//visibility:private"])
-
-proto_library(
+mediapipe_proto_library(
     name = "locus_proto",
     srcs = ["locus.proto"],
+    portable_deps = ["//mediapipe/framework/formats/annotation:rasterization_cc_proto"],
     visibility = ["//visibility:public"],
     deps = ["//mediapipe/framework/formats/annotation:rasterization_proto"],
 )
 
-proto_library(
+mediapipe_proto_library(
     name = "rasterization_proto",
     srcs = ["rasterization.proto"],
     visibility = ["//visibility:public"],
 )
 
-mediapipe_cc_proto_library(
-    name = "locus_cc_proto",
-    srcs = ["locus.proto"],
-    cc_deps = [":rasterization_cc_proto"],
-    visibility = ["//visibility:public"],
-    deps = [":locus_proto"],
-)
-
-mediapipe_cc_proto_library(
-    name = "rasterization_cc_proto",
-    srcs = ["rasterization.proto"],
-    visibility = ["//visibility:public"],
-    deps = [":rasterization_proto"],
+# Expose the proto source files for building mediapipe AAR.
+filegroup(
+    name = "protos_src",
+    srcs = glob(["*.proto"]),
+    visibility = ["//mediapipe:__subpackages__"],
 )

mediapipe/framework/formats/annotation/rasterization.proto

@@ -16,6 +16,9 @@ syntax = "proto2";
 
 package mediapipe;
 
+option java_package = "com.google.mediapipe.formats.annotation.proto";
+option java_outer_classname = "RasterizationProto";
+
 // A Region can be represented in each frame as a set of scanlines
 // (compressed RLE, similar to rasterization of polygons).
 // For each scanline with y-coordinate y, we save (possibly multiple) intervals

mediapipe/framework/formats/location_data.proto

@@ -23,6 +23,9 @@ package mediapipe;
 
 import "mediapipe/framework/formats/annotation/rasterization.proto";
 
+option java_package = "com.google.mediapipe.formats.proto";
+option java_outer_classname = "LocationDataProto";
+
 message LocationData {
   // The supported formats for representing location data. A single location
   // must store its data in exactly one way.

mediapipe/framework/input_stream_handler.cc

@@ -22,6 +22,8 @@
 
 namespace mediapipe {
 
+using SyncSet = InputStreamHandler::SyncSet;
+
 ::mediapipe::Status InputStreamHandler::InitializeInputStreamManagers(
     InputStreamManager* flat_input_stream_managers) {
   for (CollectionItemId id = input_stream_managers_.BeginId();
@@ -228,8 +230,36 @@ void InputStreamHandler::FinalizeInputSet(Timestamp timestamp,
   }
 }
 
+// Returns the default CalculatorContext.
+CalculatorContext* GetCalculatorContext(CalculatorContextManager* manager) {
+  return (manager && manager->HasDefaultCalculatorContext())
+             ? manager->GetDefaultCalculatorContext()
+             : nullptr;
+}
+
+// Logs the current queue size of an input stream.
+void LogQueuedPackets(CalculatorContext* context, InputStreamManager* stream,
+                      Packet queue_tail) {
+  if (context) {
+    TraceEvent event = TraceEvent(TraceEvent::PACKET_QUEUED)
+                           .set_node_id(context->NodeId())
+                           .set_input_ts(queue_tail.Timestamp())
+                           .set_stream_id(&stream->Name())
+                           .set_event_data(stream->QueueSize() + 1);
+    ::mediapipe::LogEvent(context->GetProfilingContext(),
+                          event.set_packet_ts(queue_tail.Timestamp()));
+    Packet queue_head = stream->QueueHead();
+    if (!queue_head.IsEmpty()) {
+      ::mediapipe::LogEvent(context->GetProfilingContext(),
+                            event.set_packet_ts(queue_head.Timestamp()));
+    }
+  }
+}
+
 void InputStreamHandler::AddPackets(CollectionItemId id,
                                     const std::list<Packet>& packets) {
+  LogQueuedPackets(GetCalculatorContext(calculator_context_manager_),
+                   input_stream_managers_.Get(id), packets.back());
   bool notify = false;
   ::mediapipe::Status result =
       input_stream_managers_.Get(id)->AddPackets(packets, &notify);
@@ -243,6 +273,8 @@ void InputStreamHandler::AddPackets(CollectionItemId id,
 
 void InputStreamHandler::MovePackets(CollectionItemId id,
                                      std::list<Packet>* packets) {
+  LogQueuedPackets(GetCalculatorContext(calculator_context_manager_),
+                   input_stream_managers_.Get(id), packets->back());
   bool notify = false;
   ::mediapipe::Status result =
       input_stream_managers_.Get(id)->MovePackets(packets, &notify);
@@ -300,4 +332,94 @@ void InputStreamHandler::SetLatePreparation(bool late_preparation) {
   late_preparation_ = late_preparation;
 }
 
+SyncSet::SyncSet(InputStreamHandler* input_stream_handler,
+                 std::vector<CollectionItemId> stream_ids)
+    : input_stream_handler_(input_stream_handler),
+      stream_ids_(std::move(stream_ids)) {}
+
+void SyncSet::PrepareForRun() { last_processed_ts_ = Timestamp::Unset(); }
+
+NodeReadiness SyncSet::GetReadiness(Timestamp* min_stream_timestamp) {
+  Timestamp min_bound = Timestamp::Done();
+  Timestamp min_packet = Timestamp::Done();
+  for (CollectionItemId id : stream_ids_) {
+    const auto& stream = input_stream_handler_->input_stream_managers_.Get(id);
+    bool empty;
+    Timestamp stream_timestamp = stream->MinTimestampOrBound(&empty);
+    if (empty) {
+      min_bound = std::min(min_bound, stream_timestamp);
+    } else {
+      min_packet = std::min(min_packet, stream_timestamp);
+    }
+  }
+  *min_stream_timestamp = std::min(min_packet, min_bound);
+  if (*min_stream_timestamp == Timestamp::Done()) {
+    last_processed_ts_ = Timestamp::Done().PreviousAllowedInStream();
+    return NodeReadiness::kReadyForClose;
+  }
+  if (!input_stream_handler_->process_timestamps_) {
+    // Only an input_ts with packets can be processed.
+    // Note that (min_bound - 1) is the highest fully settled timestamp.
+    if (min_bound > min_packet) {
+      last_processed_ts_ = *min_stream_timestamp;
+      return NodeReadiness::kReadyForProcess;
+    }
+  } else {
+    // Any unprocessed input_ts can be processed.
+    // Note that (min_bound - 1) is the highest fully settled timestamp.
+    Timestamp input_timestamp =
+        std::min(min_packet, min_bound.PreviousAllowedInStream());
+    if (input_timestamp >
+        std::max(last_processed_ts_, Timestamp::Unstarted())) {
+      *min_stream_timestamp = input_timestamp;
+      last_processed_ts_ = input_timestamp;
+      return NodeReadiness::kReadyForProcess;
+    }
+  }
+  return NodeReadiness::kNotReady;
+}
+
+Timestamp SyncSet::LastProcessed() const { return last_processed_ts_; }
+
+Timestamp SyncSet::MinPacketTimestamp() const {
+  Timestamp result = Timestamp::Done();
+  for (CollectionItemId id : stream_ids_) {
+    const auto& stream = input_stream_handler_->input_stream_managers_.Get(id);
+    bool empty;
+    Timestamp stream_timestamp = stream->MinTimestampOrBound(&empty);
+    if (!empty) {
+      result = std::min(result, stream_timestamp);
+    }
+  }
+  return result;
+}
+
+void SyncSet::FillInputSet(Timestamp input_timestamp,
+                           InputStreamShardSet* input_set) {
+  CHECK(input_timestamp.IsAllowedInStream());
+  CHECK(input_set);
+  for (CollectionItemId id : stream_ids_) {
+    const auto& stream = input_stream_handler_->input_stream_managers_.Get(id);
+    int num_packets_dropped = 0;
+    bool stream_is_done = false;
+    Packet current_packet = stream->PopPacketAtTimestamp(
+        input_timestamp, &num_packets_dropped, &stream_is_done);
+    CHECK_EQ(num_packets_dropped, 0)
+        << absl::Substitute("Dropped $0 packet(s) on input stream \"$1\".",
+                            num_packets_dropped, stream->Name());
+    input_stream_handler_->AddPacketToShard(
+        &input_set->Get(id), std::move(current_packet), stream_is_done);
+  }
+}
+
+void SyncSet::FillInputBounds(InputStreamShardSet* input_set) {
+  for (CollectionItemId id : stream_ids_) {
+    const auto* stream = input_stream_handler_->input_stream_managers_.Get(id);
+    Timestamp bound = stream->MinTimestampOrBound(nullptr);
+    input_stream_handler_->AddPacketToShard(
+        &input_set->Get(id), Packet().At(bound.PreviousAllowedInStream()),
+        bound == Timestamp::Done());
+  }
+}
+
 }  // namespace mediapipe

mediapipe/framework/input_stream_handler.h

@@ -74,9 +74,7 @@ class InputStreamHandler {
       : input_stream_managers_(std::move(tag_map)),
         calculator_context_manager_(calculator_context_manager),
         options_(options),
-        calculator_run_in_parallel_(calculator_run_in_parallel),
-        late_preparation_(false),
-        batch_size_(1) {}
+        calculator_run_in_parallel_(calculator_run_in_parallel) {}
 
   virtual ~InputStreamHandler() = default;
 
@@ -174,6 +172,60 @@ class InputStreamHandler {
     return unset_header_count_.load(std::memory_order_relaxed);
   }
 
+  // When true, Calculator::Process is called for any increase in the
+  // timestamp bound, whether or not any packets are available.
+  // Calculator::Process is called when the minimum timestamp bound
+  // increases for any synchronized set of input streams.
+  // DefaultInputStreamHandler groups all input streams into a single set.
+  // ImmediateInputStreamHandler treats each input stream as a separate set.
+  void SetProcessTimestampBounds(bool process_ts) {
+    process_timestamps_ = process_ts;
+  }
+
+  // When true, Calculator::Process is called for every input timestamp bound.
+  bool ProcessTimestampBounds() { return process_timestamps_; }
+
+  // A helper class to build input packet sets for a certain set of streams.
+  //
+  // ReadyForProcess requires all of the streams to be fully determined
+  // at the same input-timestamp.
+  // This is the readiness policy for all streams in DefaultInputStreamHandler.
+  // It is also the policy for each sync-set in SyncSetInputStreamHandler.
+  // It is also the policy for each input-stream in ImmediateInputStreamHandler.
+  //
+  // If ProcessTimestampBounds() is set, then a fully determined input timestamp
+  // with only empty input packets will qualify as ReadyForProcess.
+  class SyncSet {
+   public:
+    // Creates a SyncSet for a certain set of streams, |stream_ids|.
+    SyncSet(InputStreamHandler* input_stream_handler,
+            std::vector<CollectionItemId> stream_ids);
+
+    // Reinitializes this SyncSet before each CalculatorGraph run.
+    void PrepareForRun();
+
+    // Answers whether this stream is ready for Process or Close.
+    NodeReadiness GetReadiness(Timestamp* min_stream_timestamp);
+
+    // Returns the latest timestamp returned for processing.
+    Timestamp LastProcessed() const;
+
+    // The earliest available packet timestamp, or Timestamp::Done.
+    Timestamp MinPacketTimestamp() const;
+
+    // Moves packets from all input streams to the input_set.
+    void FillInputSet(Timestamp input_timestamp,
+                      InputStreamShardSet* input_set);
+
+    // Copies timestamp bounds from all input streams to the input_set.
+    void FillInputBounds(InputStreamShardSet* input_set);
+
+   private:
+    InputStreamHandler* input_stream_handler_;
+    std::vector<CollectionItemId> stream_ids_;
+    Timestamp last_processed_ts_ = Timestamp::Unset();
+  };
+
  protected:
   typedef internal::Collection<InputStreamManager*> InputStreamManagerSet;
 
@@ -240,11 +292,14 @@ class InputStreamHandler {
   // The variable is set to false by default. A subclass should set it to true
   // with SetLatePreparation(true) in the constructor if the input sets need to
   // be filled in ProcessNode().
-  bool late_preparation_;
+  bool late_preparation_ = false;
 
   // Determines how many sets of input packets are collected before a
   // CalculatorNode is scheduled.
-  int batch_size_;
+  int batch_size_ = 1;
+
+  // When true, any increase in timestamp bound invokes Calculator::Process.
+  bool process_timestamps_ = false;
 
   // A callback to notify the observer when all the input stream headers
   // (excluding headers of back edges) become available.

mediapipe/framework/input_stream_manager.cc

@@ -152,7 +152,7 @@ template <typename Container>
       // If the caller is MovePackets(), packet's underlying holder should be
       // transferred into queue_. Otherwise, queue_ keeps a copy of the packet.
       ++num_packets_added_;
-      VLOG(2) << "Input stream:" << name_
+      VLOG(3) << "Input stream:" << name_
               << " has added packet at time: " << packet.Timestamp();
       if (std::is_const<
               typename std::remove_reference<Container>::type>::value) {
@@ -163,15 +163,15 @@ template <typename Container>
     }
     queue_became_full = (!was_queue_full && max_queue_size_ != -1 &&
                          queue_.size() >= max_queue_size_);
-    VLOG_IF(2, queue_.size() > 1)
+    VLOG_IF(3, queue_.size() > 1)
         << "Queue size greater than 1: stream name: " << name_
         << " queue_size: " << queue_.size();
-    VLOG(2) << "Input stream:" << name_
+    VLOG(3) << "Input stream:" << name_
             << " becomes non-empty status:" << queue_became_non_empty
             << " Size: " << queue_.size();
   }
   if (queue_became_full) {
-    VLOG(2) << "Queue became full: " << Name();
+    VLOG(3) << "Queue became full: " << Name();
     becomes_full_callback_(this, &last_reported_stream_full_);
   }
   *notify = queue_became_non_empty;
@@ -257,7 +257,7 @@ Packet InputStreamManager::PopPacketAtTimestamp(Timestamp timestamp,
       next_timestamp_bound_ = timestamp.NextAllowedInStream();
     }
 
-    VLOG(2) << "Input stream " << name_
+    VLOG(3) << "Input stream " << name_
             << " selecting at timestamp:" << timestamp.Value()
             << " next timestamp bound: " << next_timestamp_bound_;
 
@@ -282,13 +282,13 @@ Packet InputStreamManager::PopPacketAtTimestamp(Timestamp timestamp,
       ++(*num_packets_dropped);
     }
 
-    VLOG(2) << "Input stream removed packets:" << name_
+    VLOG(3) << "Input stream removed packets:" << name_
             << " Size:" << queue_.size();
     queue_became_non_full = (was_queue_full && queue_.size() < max_queue_size_);
     *stream_is_done = IsDone();
   }
   if (queue_became_non_full) {
-    VLOG(2) << "Queue became non-full: " << Name();
+    VLOG(3) << "Queue became non-full: " << Name();
     becomes_not_full_callback_(this, &last_reported_stream_full_);
   }
   return packet;
@@ -302,7 +302,7 @@ Packet InputStreamManager::PopQueueHead(bool* stream_is_done) {
   {
     absl::MutexLock stream_lock(&stream_mutex_);
 
-    VLOG(2) << "Input stream " << name_ << " selecting at queue head";
+    VLOG(3) << "Input stream " << name_ << " selecting at queue head";
 
     // Check if queue is full.
     bool was_queue_full =
@@ -315,13 +315,13 @@ Packet InputStreamManager::PopQueueHead(bool* stream_is_done) {
       packet = Packet();
     }
 
-    VLOG(2) << "Input stream removed a packet:" << name_
+    VLOG(3) << "Input stream removed a packet:" << name_
             << " Size:" << queue_.size();
     queue_became_non_full = (was_queue_full && queue_.size() < max_queue_size_);
     *stream_is_done = IsDone();
   }
   if (queue_became_non_full) {
-    VLOG(2) << "Queue became non-full: " << Name();
+    VLOG(3) << "Queue became non-full: " << Name();
     becomes_not_full_callback_(this, &last_reported_stream_full_);
   }
   return packet;
@@ -349,10 +349,10 @@ void InputStreamManager::SetMaxQueueSize(int max_queue_size) {
 
   // QueueSizeCallback is called with no mutexes held.
   if (!was_full && is_full) {
-    VLOG(2) << "Queue became full: " << Name();
+    VLOG(3) << "Queue became full: " << Name();
     becomes_full_callback_(this, &last_reported_stream_full_);
   } else if (was_full && !is_full) {
-    VLOG(2) << "Queue became non-full: " << Name();
+    VLOG(3) << "Queue became non-full: " << Name();
     becomes_not_full_callback_(this, &last_reported_stream_full_);
   }
 }
@@ -382,12 +382,12 @@ void InputStreamManager::ErasePacketsEarlierThan(Timestamp timestamp) {
       queue_.pop_front();
     }
 
-    VLOG(2) << "Input stream removed packets:" << name_
+    VLOG(3) << "Input stream removed packets:" << name_
             << " Size:" << queue_.size();
     queue_became_non_full = (was_queue_full && queue_.size() < max_queue_size_);
   }
   if (queue_became_non_full) {
-    VLOG(2) << "Queue became non-full: " << Name();
+    VLOG(3) << "Queue became non-full: " << Name();
     becomes_not_full_callback_(this, &last_reported_stream_full_);
   }
 }

mediapipe/framework/legacy_calculator_support.h

@@ -107,6 +107,9 @@ CalculatorContext* LegacyCalculatorSupport::Scoped<CalculatorContext>::current_;
 template <>
 CalculatorContract*
     LegacyCalculatorSupport::Scoped<CalculatorContract>::current_;
+#elif _MSC_VER
+// MSVC interprets these declarations as definitions and during linking it
+// generates an error about multiple definitions of current_.
 #else
 template <>
 thread_local CalculatorContext*

mediapipe/framework/output_stream_handler.h

@@ -46,6 +46,7 @@ class OutputStreamHandler {
   // ids of upstream sources that affect it.
   typedef std::unordered_map<std::string, std::unordered_set<int>>
       OutputStreamToSourcesMap;
+  typedef internal::Collection<OutputStreamManager*> OutputStreamManagerSet;
 
   // The constructor of the OutputStreamHandler takes four arguments.
   // The tag_map argument holds the information needed for tag/index retrieval
@@ -119,9 +120,11 @@ class OutputStreamHandler {
   // collection for debugging purpose.
   std::string FirstStreamName() const;
 
- protected:
-  typedef internal::Collection<OutputStreamManager*> OutputStreamManagerSet;
+  const OutputStreamManagerSet& OutputStreams() {
+    return output_stream_managers_;
+  }
 
+ protected:
   // Checks if the given input bound should be propagated or not. If any output
   // streams with OffsetEnabled() need to have the timestamp bounds updated,
   // then propagates the timestamp bounds of all output streams with

mediapipe/framework/output_stream_manager.cc

@@ -164,9 +164,9 @@ void OutputStreamManager::PropagateUpdatesToMirrors(
     next_timestamp_bound_ = next_timestamp_bound;
   }
   std::list<Packet>* packets_to_propagate = output_stream_shard->OutputQueue();
-  VLOG(2) << "Output stream: " << Name()
+  VLOG(3) << "Output stream: " << Name()
           << " queue size: " << packets_to_propagate->size();
-  VLOG(2) << "Output stream: " << Name()
+  VLOG(3) << "Output stream: " << Name()
           << " next timestamp: " << next_timestamp_bound;
   bool add_packets = !packets_to_propagate->empty();
   bool set_bound =

mediapipe/framework/output_stream_poller.h

@@ -27,6 +27,9 @@ class OutputStreamPoller {
   OutputStreamPoller(const OutputStreamPoller&) = delete;
   OutputStreamPoller& operator=(const OutputStreamPoller&) = delete;
   OutputStreamPoller(OutputStreamPoller&&) = default;
+  // Move assignment needs to be explicitly defaulted to allow ASSIGN_OR_RETURN
+  // on `StatusOr<OutputStreamPoller>`.
+  OutputStreamPoller& operator=(OutputStreamPoller&&) = default;
 
   // Resets OutputStramPollerImpl and cleans the internal packet queue.
   void Reset() {

mediapipe/framework/packet.h

@@ -540,11 +540,11 @@ const Holder<T>* HolderBase::As() const {
 
 inline Packet::Packet(const Packet& packet)
     : holder_(packet.holder_), timestamp_(packet.timestamp_) {
-  VLOG(2) << "Using copy constructor of " << packet.DebugString();
+  VLOG(4) << "Using copy constructor of " << packet.DebugString();
 }
 
 inline Packet& Packet::operator=(const Packet& packet) {
-  VLOG(2) << "Using copy assignment operator of " << packet.DebugString();
+  VLOG(4) << "Using copy assignment operator of " << packet.DebugString();
   if (this != &packet) {
     holder_ = packet.holder_;
     timestamp_ = packet.timestamp_;
@@ -559,11 +559,11 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::Consume() {
   // Clients who use this function are responsible for ensuring that no
   // other thread is doing anything with this Packet.
   if (holder_.unique()) {
-    VLOG(1) << "Consuming the data of " << DebugString();
+    VLOG(2) << "Consuming the data of " << DebugString();
     ::mediapipe::StatusOr<std::unique_ptr<T>> release_result =
         holder_->As<T>()->Release();
     if (release_result.ok()) {
-      VLOG(1) << "Setting " << DebugString() << " to empty.";
+      VLOG(2) << "Setting " << DebugString() << " to empty.";
       holder_.reset();
     }
     return release_result;
@@ -582,11 +582,11 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
   // If holder is the sole owner of the underlying data, consumes this packet.
   if (!holder_->HolderIsOfType<packet_internal::ForeignHolder<T>>() &&
       holder_.unique()) {
-    VLOG(1) << "Consuming the data of " << DebugString();
+    VLOG(2) << "Consuming the data of " << DebugString();
     ::mediapipe::StatusOr<std::unique_ptr<T>> release_result =
         holder_->As<T>()->Release();
     if (release_result.ok()) {
-      VLOG(1) << "Setting " << DebugString() << " to empty.";
+      VLOG(2) << "Setting " << DebugString() << " to empty.";
       holder_.reset();
     }
     if (was_copied) {
@@ -594,9 +594,9 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
     }
     return release_result;
   }
-  VLOG(1) << "Copying the data of " << DebugString();
+  VLOG(2) << "Copying the data of " << DebugString();
   std::unique_ptr<T> data_ptr = absl::make_unique<T>(Get<T>());
-  VLOG(1) << "Setting " << DebugString() << " to empty.";
+  VLOG(2) << "Setting " << DebugString() << " to empty.";
   holder_.reset();
   if (was_copied) {
     *was_copied = true;
@@ -613,11 +613,11 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
   // If holder is the sole owner of the underlying data, consumes this packet.
   if (!holder_->HolderIsOfType<packet_internal::ForeignHolder<T>>() &&
       holder_.unique()) {
-    VLOG(1) << "Consuming the data of " << DebugString();
+    VLOG(2) << "Consuming the data of " << DebugString();
     ::mediapipe::StatusOr<std::unique_ptr<T>> release_result =
         holder_->As<T>()->Release();
     if (release_result.ok()) {
-      VLOG(1) << "Setting " << DebugString() << " to empty.";
+      VLOG(2) << "Setting " << DebugString() << " to empty.";
       holder_.reset();
     }
     if (was_copied) {
@@ -625,7 +625,7 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
     }
     return release_result;
   }
-  VLOG(1) << "Copying the data of " << DebugString();
+  VLOG(2) << "Copying the data of " << DebugString();
   const auto& original_array = Get<T>();
   // Type T is bounded array type, such as int[N] and float[M].
   // The new operator creates a new bounded array.
@@ -633,7 +633,7 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
   // Copies bounded array data into data_ptr.
   std::copy(std::begin(original_array), std::end(original_array),
             std::begin(*data_ptr));
-  VLOG(1) << "Setting " << DebugString() << " to empty.";
+  VLOG(2) << "Setting " << DebugString() << " to empty.";
   holder_.reset();
   if (was_copied) {
     *was_copied = true;
@@ -650,14 +650,14 @@ inline ::mediapipe::StatusOr<std::unique_ptr<T>> Packet::ConsumeOrCopy(
 }
 
 inline Packet::Packet(Packet&& packet) {
-  VLOG(2) << "Using move constructor of " << packet.DebugString();
+  VLOG(4) << "Using move constructor of " << packet.DebugString();
   holder_ = std::move(packet.holder_);
   timestamp_ = packet.timestamp_;
   packet.timestamp_ = Timestamp::Unset();
 }
 
 inline Packet& Packet::operator=(Packet&& packet) {
-  VLOG(2) << "Using move assignment operator of " << packet.DebugString();
+  VLOG(4) << "Using move assignment operator of " << packet.DebugString();
   if (this != &packet) {
     holder_ = std::move(packet.holder_);
     timestamp_ = packet.timestamp_;

mediapipe/framework/port/BUILD

@@ -246,6 +246,7 @@ cc_library(
     visibility = ["//visibility:public"],
     deps = [
         ":opencv_core",
+        "//mediapipe/framework:port",
         "//third_party:opencv",
     ],
 )

mediapipe/framework/port/build_config.bzl

@@ -5,6 +5,98 @@
 
 load("@com_google_protobuf//:protobuf.bzl", "cc_proto_library", "py_proto_library")
 
+def provided_args(**kwargs):
+    """Returns the keyword arguments omitting None arguments."""
+    return {k: v for k, v in kwargs.items() if v != None}
+
+def allowed_args(**kwargs):
+    """Returns the keyword arguments allowed for proto_library().
+
+    Args:
+      **kwargs: the specified keyword arguments.
+    Returns:
+      the allowed keyword arguments.
+    """
+    result = dict(kwargs)
+    result.pop("cc_api_version", None)
+    return result
+
+# TODO: load this macro from a common helper file.
+def mediapipe_proto_library(
+        name,
+        srcs,
+        deps = [],
+        visibility = None,
+        testonly = 0,
+        compatible_with = [],
+        def_proto = True,
+        def_cc_proto = True,
+        def_py_proto = True,
+        def_java_lite_proto = True,
+        def_portable_proto = True,
+        portable_deps = None):
+    """Defines the proto_library targets needed for all mediapipe platforms.
+
+    Args:
+      name: the new proto_library target name.
+      srcs: the ".proto" source files to compile.
+      deps: the proto_library targets for all referenced protobufs.
+      portable_deps: the portable_proto_library targets for all referenced protobufs.
+      visibility: visibility of this target.
+      testonly: true means the proto can be used for testing only.
+      compatible_with: see go/target-constraints.
+      def_proto: define the proto_library target
+      def_cc_proto: define the cc_proto_library target
+      def_py_proto: define the py_proto_library target
+      def_java_lite_proto: define the java_lite_proto_library target
+      def_portable_proto: define the portable_proto_library target
+    """
+    _ignore = [def_portable_proto, portable_deps]
+
+    # The proto_library targets for the compiled ".proto" source files.
+    proto_deps = [":" + name]
+
+    if def_proto:
+        native.proto_library(**allowed_args(**provided_args(
+            name = name,
+            srcs = srcs,
+            deps = deps,
+            visibility = visibility,
+            testonly = testonly,
+            cc_api_version = 2,
+            compatible_with = compatible_with,
+        )))
+
+    if def_cc_proto:
+        cc_deps = [dep.replace("_proto", "_cc_proto") for dep in deps]
+        mediapipe_cc_proto_library(**provided_args(
+            name = name.replace("_proto", "_cc_proto"),
+            srcs = srcs,
+            deps = proto_deps,
+            cc_deps = cc_deps,
+            visibility = visibility,
+            testonly = testonly,
+        ))
+
+    if def_py_proto:
+        py_deps = [dep.replace("_proto", "_py_pb2") for dep in deps]
+        mediapipe_py_proto_library(**provided_args(
+            name = name.replace("_proto", "_py_pb2"),
+            srcs = srcs,
+            proto_deps = proto_deps,
+            py_proto_deps = py_deps,
+            visibility = visibility,
+            api_version = 2,
+        ))
+
+    if def_java_lite_proto:
+        native.java_lite_proto_library(**provided_args(
+            name = name.replace("_proto", "_java_proto_lite"),
+            deps = proto_deps,
+            strict_deps = 0,
+            visibility = visibility,
+        ))
+
 def mediapipe_py_proto_library(
         name,
         srcs,
@@ -21,14 +113,14 @@ def mediapipe_py_proto_library(
       py_proto_deps: a list of dependency labels for Bazel use; must be py_proto_library.
     """
     _ignore = [api_version, proto_deps]
-    py_proto_library(
+    py_proto_library(**provided_args(
         name = name,
         srcs = srcs,
         visibility = visibility,
         default_runtime = "@com_google_protobuf//:protobuf_python",
         protoc = "@com_google_protobuf//:protoc",
         deps = py_proto_deps + ["@com_google_protobuf//:protobuf_python"],
-    )
+    ))
 
 def mediapipe_cc_proto_library(name, srcs, visibility, deps = [], cc_deps = [], testonly = 0):
     """Generate cc_proto_library for mediapipe open source version.
@@ -41,7 +133,7 @@ def mediapipe_cc_proto_library(name, srcs, visibility, deps = [], cc_deps = [],
         testonly: test only proto or not.
     """
     _ignore = [deps]
-    cc_proto_library(
+    cc_proto_library(**provided_args(
         name = name,
         srcs = srcs,
         visibility = visibility,
@@ -51,4 +143,4 @@ def mediapipe_cc_proto_library(name, srcs, visibility, deps = [], cc_deps = [],
         protoc = "@com_google_protobuf//:protoc",
         default_runtime = "@com_google_protobuf//:protobuf",
         alwayslink = 1,
-    )
+    ))