[FFmpeg-trac] #692(FFmpeg:new): Audio is not in sync with video, webcam capturing

[FFmpeg]

#692: Audio is not in sync with video, webcam capturing
--------------------------------+--------------------------------------
             Reporter:  burek   |                     Type:  defect
               Status:  new     |                 Priority:  important
            Component:  FFmpeg  |                  Version:  git-master
             Keywords:          |               Blocked By:
             Blocking:          |  Reproduced by developer:  0
Analyzed by developer:  0       |
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 This command:

 {{{
 ffmpeg -f alsa -ar 44100 -ac 1 -i front:CARD=U0x46d0x809,DEV=0 -f
 video4linux2 -r 25 -s vga -i /dev/video0 -vcodec libx264 -preset fast -crf
 20 -acodec libaacplus -ab 32k -f mpegts udp://burek:10001
 }}}

 produces such a stream that AUDIO is late (video comes before audio), and
 this command (just swapped a/v inputs):

 {{{
 ffmpeg -f video4linux2 -r 25 -s vga -i /dev/video0 -f alsa -ar 44100 -ac 1
 -i front:CARD=U0x46d0x809,DEV=0 -vcodec libx264 -preset fast -crf 20
 -acodec libaacplus -ab 32k -f mpegts udp://burek:10001
 }}}
 produces such a stream that VIDEO is late (audio comes before video).

 The sync time difference is less than a second, but it's noticable. Also,
 I've tried with -isync option (before, between and after both inputs) and
 it didn't have any effect.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/692>
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