[vorbis-dev] Carrying non-audio data in an Ogg/Vorbis I stream

[Alejandro G. Belluscio]

Hello Tor-Einar,

Monday, October 28, 2002, 6:47:39 PM, you wrote:
TEJ> A problem I've encountered when splitting ogg files is, as you
TEJ> already mentioned, how to determine the content type of the
TEJ> logical stream. An Ogg file contains no information about what
TEJ> exactly its logical streams are carrying, and a demultiplexer has
TEJ> to "peek" into the streams and run a sort of try-and-error loop
TEJ> to determine the stream's content type.

TEJ> I am not familiar with other media APIs, but the Java Media
TEJ> Framework offers a plugin interface, where demultiplexing of
TEJ> streams and decoding of content is completely separated. This
TEJ> means that having an Ogg demultiplexer and an MPEG decoder would
TEJ> theoretically make the framework capable of playing back MPEG
TEJ> data carried by an Ogg stream, without the demultiplexer and
TEJ> decoder plugins being aware of eachother. Due to the lack og
TEJ> content description in the Ogg format, and the requirement in the
TEJ> JMF API that the demultiplexer must know the content type of it's
TEJ> resulting streams, it is not possible to implement a reasonable
TEJ> Ogg demultiplexer.
I'm not a programmer, but given what I've read in the specification,
and what it's been discused in the Theora Development list (you should
postthis question thera, BTW), that's not exactly true. The
demultiplexing is based on the serian number of the ogg logical
streams. If your question is how the demux find out which kind of data
is each stream, then you must talk with Monty (I know...) since they
are working right on that in the Theora Project. In other words, it's
specifically not spec at this time.

Regards,
Alejandro Belluscio

<p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.