[theora-dev] Theora streaming

Arc arc at indymedia.org
Thu Feb 27 12:08:10 PST 2003

On Thu, Feb 27, 2003 at 09:00:30PM +0100, Guenter Bartsch wrote:
> > In Ogg Theora you have a Theora and Vorbis bitstream
> what about having more than one audio stream in the bitstream (e.g.
> multiple sound tracks) ? Some ogg (so-called ogm) files feature that
> even today. 

Of course you could have more than one concurrent Vorbis bitstream, but
it would be up to the players to decide how to deal with them.  As I
remember, in my tests, most players just ignore them.  Chained
bitstreams, that being end-to-end, have always been legal and is exactly
the format that you receive Icecast2 streams in.

> > their BOS packets
> > for each stream are one after another, the EOS for each are one after
> > another, and at that point the file can either end or a new set of
> > bistreams can begin.
> you mean that all streams have to end at that point - what happens if
> one stream continues and another one ends - is this just illegal?

Sorry, actually, yes they can end at any order or at any time.
According to the RFC which was recently produced a new bitstream cannot
begin until all older ones have ended and all concurrent streams must
have their BOS packets together.

When I spoke with Monty he said this was for software simplicity and
wasn't nessesarily a long-term requirement.  It has to do with having
the players needing to look up which codec to use, etc, and it was
easier to have it in this "gather the list of codecs I need to load"
state only when it wasn't activly playing them.  Of course, this isn't
much of a restriction, since you can work around it pretty easily.

Need to start a new stream? Toss out a EOS for the old streams followed
immediatly by a BOS for the same streams plus the new one.

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