[FFmpeg-devel] Audio Video Sync issue with dvr-ms files

[Michael Niedermayer]

Hi

On Mon, Jun 11, 2007 at 03:15:03PM -0400, Jonathon Elwood wrote:
> On 6/10/07, Michael Niedermayer <michaelni at gmx.at> wrote:
> > [...]
> >
> > hmm, i dont think theres a clean way to detect it, and there also shouldnt
> > be any need to except for debuging (and for that a simple static int should
> > do)
> > or is there some case iam missing?
> > [...]
> Using your debug statement I'm able to see the real keyframes and this
> allowed me to learn two things about DVR-MS files.  First, dvr-ms
> files don't have timestamps on keyframes, there is always a timestamp
> on the segment right before a keyframe however.  Second, not all
> DVR-MS timestamps are sequencal.  The only reliable timestamps are the
> timestamps in the segment before the keyframes.

the timestamps are likely something like PTS, these are not sequential
in case of b frames, and they MUST NOT be sequential in case of b frames

mpeg with b frames does not store frames in display order, instead all non
b frames get delayed during decoding
so

PTS:            031254867
stored        : IPBBPBPBB
decoder output:  IBBPBPBBP

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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