[FFmpeg-user] synchronisation problem on encoding video files

Frank Häfemeier ffmpeg at frank.haefemeier.eu
Tue Jan 29 21:34:40 CET 2013

Am Sonntag, den 27.01.2013, 22:38 +0200 schrieb Andrei Danila:
> Hi,
> I am writing to you guys to see if somebody can help us figure out what are we doing wrong. We are working on a project that involves users uploading video files and then we make it available to viewers in different formats. A tube website :). No matter what we try we keep getting the same problem. The result files all have a de-syncronisation of 0.3-1s between sound and video. Here is the command line that we use:
> /usr/local/bin/ffmpeg -y -i input -isync -async 1 -f mp4 -threads 0 -b:v 2500k -s 1280x720 -c:v libx264 -pass 1 -preset veryslow -tune film -r 24000/1001 -an -map_metadata -1 output 
> /usr/local/bin/ffmpeg -y -i input -isync -async 1 -f mp4 -threads 0 -b:v 2500k -s 1280x720 -c:v libx264 -pass 2 -preset veryslow -tune film -r 24000/1001 -c:a libfaac -b:a 128k -ar 44100 -ac 2  -map_metadata -1 output
> Is it something that we are doing wrong? Is there any setting that we have overlooked? 
IMHO a better way to synchronize audio and video is to use filter like
'asyncts' (now deprecated) or 'avresample' (replaceent of avsyncts).
Sorry, but I can't tell you yet how to use the new filter. I am in the
same situation to sync audio and video and have to figure out how to do
it with the new filter.
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