From 567e1a7a9c3f2c026df7da7d8c66c1dda126ce5e Mon Sep 17 00:00:00 2001
From: talksik <patel.arjun50@gmail.com>
Date: Sun, 23 Jul 2023 13:44:51 -0700
Subject: [PATCH] looks like seeing frames on new sample

---
 src/local_capture.cpp | 28 ++++++++++++++++++++++++----
 src/local_capture.h   |  4 +++-
 src/main.cpp          |  1 +
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/local_capture.cpp b/src/local_capture.cpp
index 82d1280..95d1311 100644
--- a/src/local_capture.cpp
+++ b/src/local_capture.cpp
@@ -11,17 +11,21 @@ LocalCapture::LocalCapture() {
   GstElement *video = gst_element_factory_make("v4l2src", "video");
   GstElement *videoconvert =
       gst_element_factory_make("videoconvert", "videoconvert");
-  gtksink = gst_element_factory_make("autovideosink", "sink");
+  sink = gst_element_factory_make("appsink", "sink");
 
-  if (!video || !videoconvert || !gtksink) {
+  // set callback for appsink
+  g_object_set(G_OBJECT(sink), "emit-signals", TRUE, "sync", FALSE, nullptr);
+  g_signal_connect(sink, "new-sample", G_CALLBACK(on_new_sample), this);
+
+  if (!video || !videoconvert || !sink) {
     std::cerr << "failed to create elements" << std::endl;
     return;
   }
 
   m_pipeline = gst_pipeline_new("local_capture");
 
-  gst_bin_add_many(GST_BIN(m_pipeline), video, videoconvert, gtksink, nullptr);
-  if (!gst_element_link_many(video, videoconvert, gtksink, nullptr)) {
+  gst_bin_add_many(GST_BIN(m_pipeline), video, videoconvert, sink, nullptr);
+  if (!gst_element_link_many(video, videoconvert, sink, nullptr)) {
     g_printerr("Elements could not be linked.\n");
   }
 
@@ -58,6 +62,22 @@ LocalCapture::LocalCapture() {
   std::cout << "local capture ready" << std::endl;
 }
 
+int LocalCapture::on_new_sample(GstElement *sink, gpointer data) {
+  GstSample *sample;
+
+  /* Retrieve the buffer */
+  g_signal_emit_by_name(sink, "pull-sample", &sample);
+  if (sample) {
+    /* The only thing we do in this example is print a * to indicate a received
+     * buffer */
+    g_print("*");
+    gst_sample_unref(sample);
+    return GST_FLOW_OK;
+  }
+
+  return GST_FLOW_ERROR;
+}
+
 void LocalCapture::start() {
   if (m_isRunning) {
     return;
diff --git a/src/local_capture.h b/src/local_capture.h
index 4a00623..6ff63ff 100644
--- a/src/local_capture.h
+++ b/src/local_capture.h
@@ -11,13 +11,15 @@ public:
     gst_object_unref(m_bus);
     gst_element_set_state(m_pipeline, GST_STATE_NULL);
     gst_object_unref(m_pipeline);
+    gst_object_unref(sink);
   }
   bool isRunning() const { return m_isRunning; }
-  GstElement *gtksink;
+  GstElement *sink;
 
 private:
   bool m_isRunning;
   gboolean bus_watch(GMainLoop *loop);
   GstElement *m_pipeline;
   GstBus *m_bus;
+  static int on_new_sample(GstElement *sink, gpointer data);
 };
diff --git a/src/main.cpp b/src/main.cpp
index e022084..55b1366 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -14,6 +14,7 @@ MyWindow::MyWindow() {
 
   m_localCapture = new LocalCapture();
 
+  // todo: show frames here
   //GtkWidget *area;
   // g_object_get(m_localCapture->gtksink, "widget", &area, NULL);
   // Gtk::Widget *widget = Glib::wrap(area);