Workaround for OpenCV on Raspberry PI OS 11 'Bullseye'

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#1

Hi,
I faced the problem that I want to use OpenCV on a RP 4B with 64 bit Raspberry Pi OS 11 ‘Bullseye’. The commands from the OpenCV library don’t work right with the new libcamera-based stack. Is there a proper workaround to run programs including OpenCV-commands with the new libcamera stack?

I read something about using a gstreamer pipeline… has anyone experience how it functions/can explain how to code it, maybe with example?

Thanks in advance

Jonas

#2

I’m not entirely sure how to do this from Python, but you can find out the gstreamer source we use in Edge Impulse for Linux via:

edge-impulse-linux --verbose

This’ll give you f.e. (Logitech C920 on bullseye):

gst-launch-1.0 uvch264src device=/dev/video0 ! video/x-raw,width=640,height=480 ! videoconvert ! jpegenc ! multifilesink location=test%05d.jpg

Reading through f.e. this article you should be able to replace everything after videoconvert ! with appsink and use that from Python:

camera = cv2.VideoCapture('uvch264src device=/dev/video0 ! video/x-raw,width=640,height=480 ! videoconvert ! appsink', cv2.CAP_GSTREAMER)

Maybe this works ^ ?

If so, please let me know and will see what we can do to hack something like this into the Python examples.