[Ffmpeg-devel] Native ogg demuxer

matthieu castet castet.matthieu
Tue Apr 12 22:46:34 CEST 2005


matthieu castet wrote:
> 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.
> 
correct patch

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