codec specific data ( similar to ESDS atom in MPEG4 ) for WebM / Matroska

[nimesh.c...@accenture.com]

I’m trying to integrate Matroska / WebM support in Android Froyo. I need to initialize “decoder specific information”,  similar to the one found in ESDS atom in mpeg4 file format . Where do I get that chunk of data in in an MKV file ? is it in

CodecPrivate

3

[63][A2]

-

-

-

-

b

*

*

*

Private data only known to the codec.

?

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[Philip Jägenstedt]

VP8 has no private data, everything you need to set up the encoder is in
the first keyframe, at least that's the answer I got when I asked the same
question some time ago.

--
Philip Jägenstedt
Core Developer
Opera Software

[nimesh.c...@accenture.com]

Thanks Philip... this email might look out of place but I'm trying to integrate Matroska support ( and hence WebM also ) in Android FroYo , which may contain an m4v elementary stream... any idea?

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[Steve Lhomme]

In fact Vorbis has a huge CodecPrivate that is needed for the decoder initialization. So you indeed need to use these data from CodecPrivate for Vorbis.

You can find more information on codecs here [1] and especially in Haali's PDF [2]

http://www.matroska.org/technical/specs/codecid/index.html

http://haali.su/mkv/codecs.pdf

[nimesh.c...@accenture.com]

So does CodecPrivate contain the ES_Descriptor as mentioned in ISO/IEC 14496-1 ?

 

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[Steve Lhomme]

I don't have that ISO document, so I can't tell you. I doubt Vorbis is covered in any ISO specs though.

[nimesh.c...@accenture.com]

Yup ur right… there’s a bug in Android multimedia Framework which assumes presence of an Elementary stream descriptor while initializing the m4v decoder… I’ll report that bug..