[FFmpeg-devel] Invalid and inefficient vfw-avi packed B frames detected

Michael Niedermayer michaelni
Sun Nov 2 23:35:00 CET 2008

On Sun, Nov 02, 2008 at 07:41:10PM +0100, Reimar D?ffinger wrote:
> On Sun, Nov 02, 2008 at 07:24:03PM +0100, Tobias Diedrich wrote:
> > Is this really an error for avis?
> Yes. To my knowledge this was only a workaround around the broken VfW
> subsystem, not even AVI needs that wrong and broken packed bitstream
> stuff.

1. not valid mpeg4
2. causes minor AV sync issues
3. requires 2x as much CPU to decode unless the player has some decoded
   picture que to compenate the 2,0,2,0 style frame decoding per frame.
4. will cause hell to break loose if copied into a standard container like
   mp4 or mpeg-ps/ts (thats because of 1. above, i mean its not mpeg4 so
   no mpeg4 decoder will know what to do with it)

> > I think it would be nice to do one of the following:
> > 1) Suppress this for avis (but I guess the codec knows nothing about
> > the container, so this might be a bit difficult :))
> > 2) Demote it to 'DEBUG' level so it's not that annoying.
> Since those files (again AFAIK) do not play right that is a bad idea.

ffmpeg/ffplay should play them, assuming you can live with a 1 frame av
sync error.

> > 4) Document it better :) (What does it mean / Why is it bad / What
> >    can $JOEUSER do about it)
> IMO just add "use avidemux to fix it and decrease file size for free in
> the process".

and a bitstream filter that fixes this in ffmpeg is welcome as well


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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