[FFmpeg-user] Question about v4l2 controls and ffmpeg, also dts muxer problems

Goetz Dapp goetz.dapp at googlemail.com
Sat May 5 00:46:39 CEST 2012


I am currently trying to record two video streams with a script from two
webcams with ffmpeg. This works relatively well.

I am using the following command (with an adjusted -i /dev/videoX and
output file, of course):

ffmpeg -f video4linux2 -framerate 30 -video_size hd720 -input_format
mjpeg -fflags igndts -an -i /dev/video0 -c:v copy -an /HDD2/test1.mjpeg

I am curious though if there is any way of controlling the v4l2 control
ids through ffmpeg, i.e. things like V4L2_CID_WHITE_BALANCE_TEMPERATURE,
The autofocus particularly kicks in during recording and messes things up.

I also have another problem, namely that I am getting tons of errors
"/Application provided invalid, non monotonically //increasing dts to muxer"
I tried using "-fflags igndts" and "-an" but that does not seem to
change anything. If I tell it to save it as an .avi file it crashes
immediately, with the mjpeg it seems to record relatively OK. Is there a
way of solving this? Or, at the least, to turn off the error messages?

Thanks for your help - and for this awesome tool!

More information about the ffmpeg-user mailing list