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

Jonathon Elwood jaelwood at
Sat Apr 7 02:16:10 CEST 2007

On 4/6/07, Nico Sabbi <nicola_sabbi at> wrote:
> 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
> reversed?

I tried it both using r22879, and using the latest SVN with that change
removed.  If there is anything I can do to help let me know and I'll be glad
to assist any way I can.

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