[FFmpeg-user] Comments about audio sync invited

James Linder jam at tigger.ws
Tue Jul 9 04:26:01 CEST 2013

Some years ago I setup a record-v4l-camera-from-interface with audio on line in using transcode. Perfect, but at kernel 2.6.32

I modernized the recording system only to find transcode still uses VIDIOC_S_PARM ioctls that were removed from kernel cica 2.6.33

I use ffmpeg now. All good except the audio is not synced. I apply -itsoffset and all is good for an hour or two then the recording hesitates every 5 or so seconds for say 100mS. I've looked at top, vmstat, iostat even gnome-system-monitor and can see nothing that would be causing it.

ffmpeg -f pulse -itsoffset 0.2 -i default -f v4l2 -i /dev/video0 -vtag divx -s svga -r pal -q:v 5 file.avi -s svga -f rawvideo - | ffplay -f rawvideo -i - -s svga

There is not any swap or obvious unusual disk activity.

Any ideas welcome

I tried avconv instead of ffmpeg and the stuttering ceased (joy, rapture) but I cannot sync audio (sad)
avplay stutters where ffplay does not

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