[FFmpeg-devel] The v4l2 demuxer and the use of libv4l2

Stephan Hilb stephan at ecshi.net
Sun Dec 30 12:54:30 CET 2012


some time ago I contributed the cpia decoder for use with the v4l2
demuxer to get my old camera working.
To my surprise I noticed just now that when ffmpeg is build with the
"--enable-libv4l2" flag (and thereby using libv4l2 as an additional
layer between ffmpeg and the kernel api) my camera doesn't work as
expected and the cpia decoder isn't used (libv4l2 does the conversion

Now this leads me to the question why the libv4l2 userspace library is
used anyways when there is an appropriate decoder available for the
format (cpia in my case).
Also afaict there seem to be very few v4l2 formats not already
understood by ffmpeg. So is there any other benefit in using libv4l2
with ffmpeg?

I'd like to clean up things in the v4l2 demuxer and fix some small bugs
with ffplay-ing directly from /dev/video0. But I'm not sure whether to
do it inside the v4l2 demuxer or rather work on libv4l2.

To me it seems like a bit of a maintenance burden to support both ways.


Stephan Hilb
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