[Ffmpeg-devel] PTS / DTS with XViD

Rich Felker dalias
Sun Jul 23 19:50:46 CEST 2006

On Sat, Jul 22, 2006 at 10:28:19AM +0100, M?ns Rullg?rd wrote:
> Rich Felker said:
> > On Fri, Jul 21, 2006 at 08:01:13PM +0300, Jani Boutellier wrote:
> >> As a concluding remark, I'll have to state that the problem was not at all
> >> in the OGM format.
> >> After hours of trial and error I managed to get the XViD-encoded video into
> >> a MPEG4 -container (.mp4). Surprisingly the the abovementioned problem with
> >> OGM occurred also with mp4, so I figured that the true source of problems
> >> was XViD.
> >> Soon I discovered that the video clips I had used, contained a so-called
> >> "packed bitstream", which meant that the B-frames were crammed inside
> >> P-frames. After I changed this in encoding settings and re-encoded the
> >> video clips, the decoding worked well.
> >
> > Did ffmpeg generate these bitstreams? I sure hope it's not calling
> > xvid with packed bitstream enabled...
> FFmeg doesn't mux OGM so it can't have made those files.

Good point. :)

> >> This means that although the OGM format was labeled as a "broken format" in
> >> this thread, it probably would work well also with b-frames. However, I
> >> didn't try that in practice anymore, since I'm happy with mp4 now :)
> >
> > I imagine the timestamps would still be invalid but I'm not sure..
> Ogg only has frame count, no real timestamps.

A frame number is a timestamp in the time base of the stream. However
if they're always sequential/monotone then it's a DTS not a PTS.


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