chromium/third_party/mediapipe/src/mediapipe/modules/holistic_landmark/face_tracking.pbtxt

# Decides what ROI to use for face landmarks prediction: either previous frame
# landmarks ROI or the current frame face re-crop ROI.

type: "FaceTracking"

# Face landmarks from the current frame. They will be memorized for tracking on
# the next frame. (NormalizedLandmarkList)
input_stream: "LANDMARKS:face_landmarks"
# Face re-crop ROI from the current frame. (NormalizedRect)
input_stream: "FACE_RECROP_ROI:face_recrop_roi"
# Image size (width & height). (std::pair<int, int>)
input_stream: "IMAGE_SIZE:image_size"

# Face tracking ROI. Which is either face landmarks ROI from the previous frame
# if face is still tracked, or face re-crop ROI from the current frame
# otherwise. (NormalizedRect)
output_stream: "FACE_TRACKING_ROI:face_tracking_roi"

# Keeps track of face landmarks from the previous frame.
node {
  calculator: "PreviousLoopbackCalculator"
  input_stream: "MAIN:image_size"
  input_stream: "LOOP:face_landmarks"
  input_stream_info: {
    tag_index: "LOOP"
    back_edge: true
  }
  output_stream: "PREV_LOOP:prev_face_landmarks"
}

# Gets hand landarmsk rect.
node {
  calculator: "FaceLandmarksToRoi"
  input_stream: "LANDMARKS:prev_face_landmarks"
  input_stream: "IMAGE_SIZE:image_size"
  output_stream: "ROI:prev_face_landmarks_rect"
}

# Checks that all requirements for tracking are satisfied and use face rectangle
# from the previous frame in that case. Otherwise - use face re-crop rectangle
# from the current frame.
node {
  calculator: "RoiTrackingCalculator"
  input_stream: "PREV_LANDMARKS:prev_face_landmarks"
  input_stream: "PREV_LANDMARKS_RECT:prev_face_landmarks_rect"
  input_stream: "RECROP_RECT:face_recrop_roi"
  input_stream: "IMAGE_SIZE:image_size"
  output_stream: "TRACKING_RECT:face_tracking_roi"
  options: {
    [mediapipe.RoiTrackingCalculatorOptions.ext] {
      rect_requirements: {
        rotation_degrees: 15.0
        translation: 0.1
        scale: 0.3
      }
      landmarks_requirements: {
        recrop_rect_margin: -0.2
      }
    }
  }
}