[FFmpeg-user] problem with FFMPEG and USB WEBCAM: max resolution

Carl Eugen Hoyos cehoyos at ag.or.at
Sat Jun 18 16:35:47 CEST 2016

Juan M. Anera <juasmilla <at> gmail.com> writes:

>         ffmpeg version 3.0.2-2~bpo8+1

Please understand that generally only current FFmpeg git head 
is supported on this mailing list.

>     ffmpeg -y -f alsa -i hw:1 -i /dev/video0 -t 10  out12.avi

This is missing -qscale 2 or -qscale 10 or -vb 2000
(which is the reason for the bad quality).

>     Input #0, alsa, from 'hw:1':
>       Duration: N/A, start: 1466107437.084808, bitrate: 1024 kb/s

>     Input #1, video4linux2,v4l2, from '/dev/video0':
>       Duration: N/A, start: 1578.347093, bitrate: 147456 kb/s

The different start times mean that no recording can be in-sync.
Try the different sync options for v4l2, namely -ts abs or 
-ts mono2abs.

To set the resolution, use the -video_size option.

See ffmpeg -h demuxer=v4l2 to learn about the options.

Carl Eugen

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