[FFmpeg-user] ffmpeg record from usb webcam give huge sync problem
Carl Eugen Hoyos
cehoyos at ag.or.at
Mon Feb 23 19:42:16 CET 2015
Vlăduţ Frăţiman <fratiman.vladut <at> gmail.com> writes:
$ ./ffmpeg -y -f v4l2 -video_size 640x360 -framerate 5 \
> -ts mono2abs -i /dev/video0 \
> -f alsa -ac 1 -i hw:1,0 \
> Input #0, video4linux2,v4l2, from '/dev/video0':
> Duration: N/A, start: 1424715824.973374
> Input #1, alsa, from 'hw:1,0':
> Duration: N/A, start: 1424715814.786186
On my system, the start times are nearly identical,
the difference is <0.02 seconds.
If the difference is constant (when you run ffmpeg
several times), you can use -itsoffset or the setpts
filter to correct the timestamps.
I suspect this is an issue with the driver of your
multimedia (v4l2) device, but I don't know enough
Maybe -vsync 0 works better but this would be a
workaround, not a solution.
More information about the ffmpeg-user