[vorbis] Ogg and Vorbis questions

[Beni Cherniavksy]

On 2002-01-19, volsung at asu.edu wrote:

> On Fri, 18 Jan 2002, Ross Vandegrift wrote:
>
> > Is this paragraph talking about multiple streams in a single Vorbis stream in an
> > Ogg, or is it talking about multiple Vorbis streams in a single Ogg?
> >
> > (If it's the former while the latter remains possible, OggVorbis is really
> > awesome ::-)
> >
> > And I can make an Ogg that has a Vorbis stream, and maybe a FLAC stream and
> > perhaps another FLAC stream in it, right?  (I'd look this up on the site, but I
> > can't seem to reach it...)
>
> I think you might be confused about some terms.  Here is a one way to think
> about it:
>
> * The Ogg file taken as a whole (either on disk or streaming through your
> network connection) is a _physical bitstream_.  In theory, a physical bistream
> can contain data corresponding to all sorts of media types.
>
> * The physical bitstream can be broken down into 1 or more _logical
> bitstreams_.  Each logical bitstream contains data of a particular format,
> like Vorbis, FLAC, Tarkin, etc.  Most Ogg file you run into are degenerate
> streams which contain exactly one logical bitstream containing Vorbis data.
>
> * Chaining refers to the property of Ogg files that two physical Ogg streams
> concatenated together is also a valid physical Ogg stream.  The interpretation
> of this is that the logical bitstreams in the second file are played after the
> logical bitstreams in the first file.  This is handy for streaming where you
> might output each file from your playlist, one after the other, in a
> continuous stream.
>
> But, yes, you can put two FLAC streams and a Vorbis stream into the same Ogg
> physical stream, each in their own logical bitstream.
>
But can you chain for example a stream containg only Ogg with a stream
containing only FLAC?  It can get more interesting: can you chain a stream
containg tarkin video (when it appears) with a stream containg Ogg MIDI?
I guess it depends on hte player capabilities and players are required to
play sequentially all chained streams that can understand.


-- 
Beni Cherniavsky <cben at tx.technion.ac.il>
                 (also scben at t2 in Technion)

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