Re: [MPlayer-dev-eng] Revision 22879 causes AV sync problem with lavc option ‘keyint’

Nico Sabbi nicola_sabbi at
Fri Apr 6 23:41:46 CEST 2007

Jonathon Elwood wrote:
> In Revision 22879 a change was made to muxer_mpeg.c that is causing the AV
> sync to be incorrect if the lavc option 'keyint' is used.  If I reverse the
> changes made in Revision 22879 the AV sync is fine again with the keyint
> option.
> Below is an example command line:
> mencoder -oac lavc -of mpeg -mpegopts format=dvd -o "output file.mpg" -ovc
> lavc -vf scale=320:-2,harddup -lavcopts
> vcodec=mpeg2video:keyint=15:acodec=mp2:abitrate=192 -ofps 24000/1001 "input
> file.avi"
> This is only a problem if the keyint option is used.  If I remove this
> option from the command line the AV sync is fine.
> The description on this change is: "in flush_buffers() removed code that
> required the presence of an amount of audio data >= video data in the
> temporal domain", however, I don't know this code, so that doesn't mean 
> much
> to me.  It was obviously made because of another problem someone else was
> experiencing.  Since I'm not familiar, with this code, and any patch I try
> to make would probably break the original intent of this change.  Would
> anyone be willing to look at this and find a way for Revision 22879 to
> exist, but not affect the AV sync when the lavc option of keyint is used?

I'll give a look at it, but frankly removing that code shouldn't
affect synchrony in any way (timestamps assigned to frames don't 
change at all).
Are using a r22879 release or a fresh cvs checkout with only that diff 

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