Sync motion-tracking from metro-analytics-catalog

README.md

@@ -259,7 +259,9 @@ from gstgva import VideoFrame
 
 Gst.init(None)
 
-# For GPU: change device=CPU to device=GPU and add vapostproc after decodebin3.
+# For GPU: change device=CPU to device=GPU, add vapostproc !
+# video/x-raw(memory:VASurface) after decodebin3, and set
+# pre-process-backend=vaapi-surface-sharing on gvadetect.
 # For NPU: change device=CPU to device=NPU (batch-size=1, nireq=4 recommended).
 pipeline_str = (
     "filesrc location=test_video.mp4 ! decodebin3 ! videoconvert ! "
@@ -348,7 +350,7 @@ print("Wrote output.mp4", flush=True)
 **Device targets:**
 
 - `device=CPU` -- default in the sample code.
-- `device=GPU` -- add `vapostproc` after `decodebin3` for zero-copy color conversion.
+- `device=GPU` -- add `vapostproc ! video/x-raw(memory:VASurface)` after `decodebin3` and set `pre-process-backend=vaapi-surface-sharing` on `gvadetect`.
 - `device=NPU` -- use `batch-size=1` and `nireq=4` for best NPU utilization.
 
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