[FFmpeg-devel] [RFC] dc value 0 legal for flv?

Michael Niedermayer michaelni
Sat Sep 12 23:41:19 CEST 2009

On Sat, Sep 12, 2009 at 10:40:20PM +0200, Reimar D?ffinger wrote:
> On Sat, Sep 12, 2009 at 07:50:22AM -0400, compn wrote:
> > On Sat, 12 Sep 2009 13:39:40 +0200, Reimar D?ffinger wrote:
> > >Hello,
> > >a user reported that
> > >http://study.fivebranches.edu/video_bank/gaoshuzhong200907/1_200907gaoshuzhong.flv
> > >does not play right in MPlayer.
> > >This is reproducible with "ffplay -er 2" (even without there are many
> > >warnings).
> > >Do you think it is possible that dc level of 0 is valid for flv?
> > 
> > does it play with flash player?

iam curious about that too as well as in what created it

> I'd sure expect so (I do not use flash player), though that doesn't really
> tell if the file is valid (if not, at least the warning should stay).

in h.263 such 0 values can lead to start code emulation, they are thus not
the flv spec i have which might not be the latest does not hint at any change
of dc coding
flv ver2 does replace the ac escape coding with a different one but it does
also explicitly list 0 as forbidden in the new table

btw, you did not mention it but does the file play correctly with your patch?

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Avoid a single point of failure, be that a person or equipment.
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