# MediaPipe graph that performs face mesh with TensorFlow Lite on CPU.

# GPU buffer. (GpuBuffer)
input_stream: "input_video"

# Output image with rendered results. (GpuBuffer)
output_stream: "output_video"
# Detected faces. (std::vector<Detection>)
output_stream: "face_detections"

# Throttles the images flowing downstream for flow control. It passes through
# the very first incoming image unaltered, and waits for downstream nodes
# (calculators and subgraphs) in the graph to finish their tasks before it
# passes through another image. All images that come in while waiting are
# dropped, limiting the number of in-flight images in most part of the graph to
# 1. This prevents the downstream nodes from queuing up incoming images and data
# excessively, which leads to increased latency and memory usage, unwanted in
# real-time mobile applications. It also eliminates unnecessarily computation,
# e.g., the output produced by a node may get dropped downstream if the
# subsequent nodes are still busy processing previous inputs.
node {
  calculator: "FlowLimiterCalculator"
  input_stream: "input_video"
  input_stream: "FINISHED:output_video"
  input_stream_info: {
    tag_index: "FINISHED"
    back_edge: true
  }
  output_stream: "throttled_input_video"
}

# Transfers the input image from GPU to CPU memory for the purpose of
# demonstrating a CPU-based pipeline. Note that the input image on GPU has the
# origin defined at the bottom-left corner (OpenGL convention). As a result,
# the transferred image on CPU also shares the same representation.
node: {
  calculator: "GpuBufferToImageFrameCalculator"
  input_stream: "throttled_input_video"
  output_stream: "input_video_cpu"
}

# Subgraph that detects faces.
node {
  calculator: "FaceDetectionShortRangeCpu"
  input_stream: "IMAGE:input_video_cpu"
  output_stream: "DETECTIONS:face_detections"
}

# Converts the detections to drawing primitives for annotation overlay.
node {
  calculator: "DetectionsToRenderDataCalculator"
  input_stream: "DETECTIONS:face_detections"
  output_stream: "RENDER_DATA:render_data"
  node_options: {
    [type.googleapis.com/mediapipe.DetectionsToRenderDataCalculatorOptions] {
      thickness: 4.0
      color { r: 255 g: 0 b: 0 }
    }
  }
}

# Draws annotations and overlays them on top of the input images.
node {
  calculator: "AnnotationOverlayCalculator"
  input_stream: "IMAGE:input_video_cpu"
  input_stream: "render_data"
  output_stream: "IMAGE:output_video_cpu"
}

# Transfers the annotated image from CPU back to GPU memory, to be sent out of
# the graph.
node: {
  calculator: "ImageFrameToGpuBufferCalculator"
  input_stream: "output_video_cpu"
  output_stream: "output_video"
}
