[matroska-devel] 1. Vorbis and other Xiph codecs in matroska 2. Codec muxing description for every format ( recommendation ) to put on our website ?

ChristianHJW christian.hj.wiesner at web.de
Sun Jan 19 20:08:52 CET 2003



Hi,

i know this is a hot thing to talk about right now, but with matroska alpha
date coming closer and closer, and spyder working on the Ogg transmuxer i
thought it was necessary to raise the point.

Suiryc gave me some very good idea how it should be done, and i guess he
discussed with spyder also ( hopefully ). Generally speaking, simply all the
data packets from the Ogg container pages should be taken and put into
matroska, without any major changes. As i understood from suiryc some Vorbis
packets are data only, while others are tagged as holding specific info
about the stream type, etc. In any case, the Vorbis decoder knows how to
handle them and all it expects is to receive the packets same way as if they
were stored in an Ogg container before.


The discussion, although not very complicated because Vorbis doesnt leave
you with many options here, lead me to another idea :

In order to avoid incompatibilities between matroska files generated from
different programs and developers, wouldnt it make sense to add a kind of
'recommendation' to our homepage for every codec/compression format, so
developers can read how to mux the data from each codec into matroska
preferably ?

Especially protected formats like Dolby AC3/AAC for sure need a kind of
'special treatment' here, as we have to make sure the demuxed streams can be
decoded in external ( maybe Dshow based ) decoders, as for sure we as the
matroska team can not make specific AC3 decoder plugins based on UCI, for
the very well known licensing problems we had to fear. Maybe formats like
AC3/AAC should not have a 'native' track typ at all to avoid these problems,
but be only used in Dshow compatibility mode, using UUID/GUID to identify ?

In my idea the developers could go to the matroska homepage and look up how
exactly a MPEG2/1 video stream was to be handled when being muxed into a
matroska file, bearing in mind how complicated the structure of MPEG files
is ( remember Alex' comments about the different layers of it, what layers
to copy/read/trash ).

What you think ?

Christian

http://matroska.org



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