[Ffmpeg-devel] Frame rates and time_base

Rich Felker dalias
Sat May 7 17:56:20 CEST 2005


On Sat, May 07, 2005 at 11:48:53AM +0200, M?ns Rullg?rd wrote:
> Rich Felker <dalias at aerifal.cx> writes:
> 
> > On Sat, May 07, 2005 at 01:48:50AM +0200, M?ns Rullg?rd wrote:
> >> castet.matthieu at free.fr writes:
> >> 
> >> > Hi,
> >> >
> >> > Selon M?ns Rullg?rd <mru at inprovide.com>:
> >> >
> >> >> After the latest framerate/pts related changes, I have a few
> >> >> questions:
> >> >>
> >> >> - Is it still possible to find the framerate in AVCodecContext?  How?
> >> >> - What is the proper way to synchronize the pts values with timestamps
> >> >>   from the containter?
> >> >> - What will the next incompatible change be? ;-)
> >> >>
> >> > just one offtopic question :
> >> > will you fix the ogg2 demuxer for video stream ?
> >> 
> >> Um, yeah... been a bit busy lately.  I just had a look at your patch.
> >> Unfortunately, the only theora samples I could easily locate
> >> (mplayerhq.ftp samples), doesn't want to decode at all.  Are some
> >> special incantations required to make theora decode with libavcodec?
> >
> > Yes, the demuxer somehow has to repack the "header packets" at the
> > beginning of the stream into "extradata"..
> 
> I get that, and that's also what I did, and got garbage results.
> Looking at the source code, I see it's not quite complete.  I'll try
> using libtheora instead.

There are several header packets which somehow need to be delimited in
extradata, and afaik no specification on how it's supposed to be done.
Leave it to Xiph to come up with something as idiotic as multiple
header packets just for the sake of making it hard to store Theora in
other containers than ogg...

Rich





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