[FFmpeg-user] A/V synchronization question

[Elżbieta Jakubska]

Hi,

I have a small problem with A/V synchronization when saving live tv_stream
to avi. I would need to have very good synchronization, or in the worst
case - video before audio, but I have video a little bit after audio (video
goes about half of the video frame after audio, what makes that I can see
previous video frame wile the audio for next one is playing). I use the
following command for dumping the stream to file:

 ffmpeg -y -probesize 600 -threads 1 -i http://url -vf scale=640:360
-b:v 800k -acodec libmp3lame -b:a 128k -ac 1 -af aresample=async=1000 -ss 0
-threads 1 -t 120 -f avi test.avi


Please, could you help me to synchronize this? Is it maybe a way to push
video one frame forward? Or maybe using -vsync option would be useful? I
was already trying also with vsync option, but I haven't got good results.

Thank you for your answers,

Ela
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Re: [FFmpeg-user] A/V synchronization question

[Carl Eugen Hoyos]

Elżbieta Jakubska elzbieta.jakubska at gmail.com writes:

  ffmpeg -y -probesize 600 -threads 1 -i http://url 
 -vf scale=640:360 -b:v 800k -acodec libmp3lame -b:a 128k 
 -ac 1 -af aresample=async=1000 -ss 0 -threads 1 -t 120 
 -f avi test.avi

Complete, uncut console output missing.

Is your synchronization problem only reproducible if 
you transcode network input or is it also reproducible 
if you first save the http stream (with wget or 
MPlayer or another tool of your choice, not FFmpeg) 
and then transcode the saved stream with FFmpeg?

Note that some developers don't believe in one half 
frame A/V desync...

Carl Eugen

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