[Ffmpeg-devel] Re: Re: Re: [theora-dev] Theora encoding
paul.richards at gmail.com
Mon Jan 1 12:37:00 PST 2007
On 01/01/07, Rich Felker <dalias at aerifal.cx> wrote:
> On Sun, Dec 31, 2006 at 08:09:54PM +0000, Paul Richards wrote:
> > On 31/12/06, Michael Niedermayer <michaelni at gmx.at> wrote:
> > >On Sun, Dec 31, 2006 at 05:56:11PM +0000, Paul Richards wrote:
> > >> And on a deeper level..
> > >>
> > >> Why is all this special packing of the output from theora_encode_***()
> > >> into the extradata required? I naively assumed that any packing like
> > >> this would be the responsibility of the muxer...
> > >
> > >no of course not, just think about this for a moment, should the avi muxer
> > >contain code to repackage theora, vorbis, ... headers? then what about
> > >matroska, nut, asf, mov, mp4, ... ? should every muxer contain (duplicated)
> > >code to pack all the codec specific xiph headers into a single packet?
> > >
> > >and then after you duplicated that code in every muxer, you will have to
> > >add code to every corresponding demuxer to undo it otherwise you cannot
> > >copy a stream between 2 containers witout reencoding ...
> > >
> > >simply putting the (de)packaging code into the 2 or 3 xiph codecs is much
> > >easier ...
> > >
> > In that case shouldn't there be a function in libtheora to concatenate
> > all of the "extradata" packets together in a container-insensitive
> > way?
> yes, there certainly should be. unfortunately the xiph people, in
> their infinite wisdom, are outwardly hostile to container-insensitive
> things and want to make their codecs as painful as possible to use
> with non-ogg containers.
> btw, is there a reason you want to use theora so much? it's not a good
> codec at all..
I have two reasons.
1) I want to show some support for a patent-free video codec.
2) Theora was quite good in a few basic tests I ran here. Compared
against ffmpeg's "mpeg4" codec at 400kbit CBR, theora was clearly
better. Compared against ffmpeg's "h264" (libx264), there was no
clear winner (part of the problem was that I couldn't get h264 to
stick to CBR).
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