Opening a webcam which is already in use by a gst-launch

Arjen Veenhuizen arjen at
Tue Aug 29 14:07:45 UTC 2017

What one typically would do is write a little app and use a combination of
tee and appsink:

gst-launch-1.0 -e v4l2src device=/dev/webcam ! videoconvert !
video/x-raw,width=544,height=288,framerate=10/1 ! v4l2h264enc ! h264parse !
tee name=t ! mp4mux ! filesink location=video.mp4 t. ! decodebin !
videoconvert ! "video/x-raw,format=I420" ! appsink

and wait for the appropriate callback from appsink to get the raw (in this
case) yuv420p frame and feed the data into opencv.

Alternatively, to get things running quick and dirty from the command line,
have it write the decoded output to a file / named pipe by replacing the
appsink element by a filesink element.

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