[MPlayer-users] Concatenating AVI files - audio sync problem

Dariusz Andziak dandziak at kikom.pl
Fri Feb 25 05:52:02 CET 2005

Try to use option -nobps to your second example. I have repaired some 
AVI files with A-V synchronisation problems using this option. Probably 
you will have to re-encode your file, it means -ovc lavc -lavcopts .... 
instead of -ovc copy.


Ian Pickworth napisał(a):

> I have two AVI files, and I want to concatenate them to make one AVI 
> file, however, I cannot get the sound in the second file to be 
> properly syncronised in the concatenated version, its always about a 
> second out of sync.
> Both files are encoded identically (MJPEG), having been created using 
> mencoder -ss and -endpos options from an original AVI file (also 
> recorded using mencoder).
> eg:
> mencoder -oac copy -ovc copy -ss 186 -o 2.avi 2005-02-13_21-46_CH4.avi
> I have tried the following:
> 1)
> cat 1.avi 2.avi | mencoder -noidx -ovc copy -oac copy -o output.avi -
> This stops at the end of 1.avi, so no concatenation. (I saw this on 
> Google as an example of concatenating AVI files, which implied it 
> should work.)
> 2)
> cat 1.avi 2.avi >cat.avi
> mencoder -noidx -ovc copy -oac copy -o output.avi cat.avi
> This gives a concatenated file, but the audio is out of sync by about 
> a second from the start of the second part. I also tried -forceidx 
> instead of -noidx and that made no difference.
> 3)
> cat 1.avi 2.avi >cat.avi
> cat cat.avi | mencoder -noidx -ovc copy -oac copy -o output.avi -
> Same result as 1), ie stops at end of 1.avi.
> If I play back (using either mplayer or xine) 1.avi and 2.avi 
> separately, the sound is in sync for both.
> Is there a way of concatenating two AVI files in this way and keeping 
> the sound in sync for the second (third etc) parts?
> Thanks
> Ian
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