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

[Tor-Einar Jarnbjo]

Mandag, 28 oktober 2002, skrev du:

>>> 1 - Chaining a logical bistream at the end. If this is the way 
>>> to go, two questions arise to begin with:
>>
>>Probably not the way to go.
>
>Ok...
>
>>> 4 - Can I possibly just concatenate a completely separate Ogg 
>>> at the end of the first one? This seems to violate the 
>>> constraints of an Ogg/Vorbis I stream though.
>>
>>Sure. Multiple Ogg files can be chained by 'cat'.
>>This is perfectly legal (and gapless).

But isn't concatenating separate ogg files exactly the same as chaining 
logical bit streams?

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

I am not familiar with other media APIs, but the Java Media Framework 
offers a plugin interface, where demultiplexing of streams and decoding 
of content is completely separated. This means that having an Ogg 
demultiplexer and an MPEG decoder would theoretically make the framework 
capable of playing back MPEG data carried by an Ogg stream, without 
the demultiplexer and decoder plugins being aware of eachother. Due 
to the lack og content description in the Ogg format, and the requirement 
in the JMF API that the demultiplexer must know the content type 
of it's resulting streams, it is not possible to implement a reasonable 
Ogg demultiplexer.

Tor

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