[Ffmpeg-devel] Native ogg demuxer

matthieu castet castet.matthieu
Tue Apr 12 22:39:13 CEST 2005


Hi,

M?ns Rullg?rd wrote:
> matthieu castet <castet.matthieu at free.fr> writes:
> 
> 
>>Hi M?ns,
>>
>>M?ns Rullg?rd wrote:
>>
>>>matthieu castet <castet.matthieu at free.fr> writes:
>>>
>>>
>>>>What's the point of doing external sub-plugin that use global
>>>>variable instead of static variable and if conditions ?
>>>
>>>Cleaner design, IMHO.
>>>
>>
>>Yes but you could have all the sub-plugin in the same file and make it
>>static. This is more or less what do liboggz
> 
> 
> I fail to see a significant difference.
> 
> 
You couldn't use global var with the same name in the user application 
and there will be lot's of file for off in libavformat.


$cat t.c
int vorbis_codec;
int main () {
         ogg_init();
}
$gcc t.c /home/mat/appli/matroska/ffmpeg/libavformat/libavformat.a 
/home/mat/appli/matroska/ffmpeg/libavcodec/libavcodec.a -lm
/usr/bin/ld: AVERTISSEMENT: taille du symbole ? vorbis_codec ? a chang? 
de 4 dans /tmp/cc4kdoJN.o ? 20 dans 
/home/mat/appli/matroska/ffmpeg/libavformat/libavformat.a(oggparsevorbis.o)



>>>>Also now the parsing of the extrada (comments, codec init, ...) is
>>>>done twice : once in the demuxer, once in the decoder.
>>>
>>>The codec does not, and should not, touch the comment section.
>>>
>>
>>Actually if you look theora implementation it read and skip and the comment.
>>So you sugest to not put the comment in the codec extradata (2nd header
>>in vorbis and theora) ?
> 
> 
> Libvorbis requires the comment section, but doesn't actually use it
> for anything.  (Yes, we all know it's stupid.)
> 
> 
We could set an empty one (u32(0) u32(0) u1(1)).
Yes that's really stupid


Matthieu

PS : I attach a patch to support theora format.
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