Error using v4l2sink when combining 2 camera streams

[gotsring]

Assuming you're using v4l2loopback to create the loopback device, there seems
to be a hack to get this to work on the more recent GStreamer releases. Just
add identity drop-allocation=1 to the pipeline.

Example of using loopback (video1) using test sources:
gst-launch-1.0 videotestsrc ! video/x-raw, format=YUY2, framerate=30/1,
width=640, height=480 ! \
alpha alpha=1 ! videobox border-alpha=0 left=-640 ! compositor  name=Mix ! \
videoconvert ! video/x-raw, format=YUY2 ! identity drop-allocation=1 !
v4l2sink device=/dev/video1  \
videotestsrc pattern=ball ! video/x-raw, format=YUY2, framerate=30/1,
width=640, height=480 ! \
alpha alpha=1 ! videobox border-alpha=0 right=-640 ! Mix.


Solution gotten from the bottom of this page:
https://github.com/umlaeute/v4l2loopback/wiki/GStreamer

I typically use udpsink to send videos over network loopback, and then I can
play the videos as a network source on something like VLC. Probably not
great, but I've had no problems so far!



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