[MPlayer-users] A/V sync with two-stage encoding

Ian Smith the.pond at dsl.pipex.com
Thu Apr 29 21:19:21 CEST 2004

Ian Smith wrote, on 29/04/04 10:01:
> Right, tried a 30-minute section, (with two passes identical, apart from 
> the pass number) and the problem is still there.
> I'm not really surprised, as I don't see the problem when the master 
> source is an MPEG or VOB file.
> Anyway, I shall continue to experiment . . .

Well, I removed all the mpeg4 high quality stuff, set up audio on both 
passes, and tried encoding a 30 minute stretch using:

mencoder grabbed.avi -ovc lavc -lavcopts 
vcodec=mpeg4:vbitrate=917504:vpass=1 -oac mp3lame -lameopts cbr:br=128 
-o compressed.avi

mencoder grabbed.avi -ovc lavc -lavcopts 
vcodec=mpeg4:vbitrate=917504:vpass=2 -oac mp3lame -lameopts cbr:br=128 
-o compressed.avi

also tried using abr for the audio just in case.  Whatever I try there 
seems to be a small initial A/V offset, which increases gradually with time.

Bearing in mind what I said about using MPEG as source, I can only 
assume that there is some effect at play that causes mencoder to 
misbehave in this way when fed with it's own output?

If anyone can think of any other tests I can do, please let me know.

Ian Smith
Worst . . . signature . . . ever !

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