[FFmpeg-devel] [Bug] Problem on remuxing AVC in mkv to mp4, how to fix it?

Michael Niedermayer michaelni
Thu Aug 6 01:01:49 CEST 2009

On Thu, Aug 06, 2009 at 12:46:08AM +0200, Aurelien Jacobs wrote:
> On Tue, Aug 04, 2009 at 03:09:18PM -0700, Baptiste Coudurier wrote:
> I guess your reply wasn't intended only for me ?
> > On 8/4/2009 3:00 PM, Aurelien Jacobs wrote:
> >> This is already known as issue807 [1].
> >>
> >>> Since matroska does not provide dts (mp4 does), ffmpeg assumes dts = pts, which is completely wrong if b-frames are used.
> >>> Is that where the problem is and can anybody give suggestions on how to fix that?
> >>
> >> IIRC the problem is that FFmpeg is missing a h264 parser that would
> >> generate dts for streams which don't have it.
> >
> > FFmpeg already has a h264_parser, it does not work with MKV bitstream  
> > however.
> I know we have a h264_parser but AFAIK it is not able to generate any dts.
> Is Matroska the only format storing h264 without dts ?

nut doesnt store dts either, but nut defines how one can calculate dts from
pts and the decoder delay that is a mandatory syntax element in nut.
This is of course independant of the used codec so the codec id or bitstream
never has to be touched for it ...


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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