[ogg-dev] oggfile, skeleton and vorbis tools

Ian Malone ibmalone at gmail.com
Thu Mar 9 16:42:55 PST 2006

Conrad Parker wrote:
> On Tue, Mar 07, 2006 at 12:10:57PM -0500, Monty wrote:
>>On Wed, Mar 01, 2006 at 10:36:38PM +0000, Ian Malone wrote:
>>>I assume what this all means is there's no desire for any kind of stop-
>>>gap libvorbisfile that does the "vorbis out of any otherwise valid Ogg
>>>stream"[1], and that anything along these lines will wait until Oggfile.
>>Well, vorbis-only vorbisfile is what we're talking about.  What Sylvia
>>mentioned was that we need to decide what to do if there's more than
>>one concurrent Vorbis stream but we're still talking about the
>>Vorbis-only case.
>>>[1] The motivation for this would be to allow current players to play
>>>Annodexed Ogg Vorbis without noticing.
>>Yes, there are a few applications that boild down to that (eg, playing
>>only the audio from an A/V file in general).

> (afaik) Ian is working towards patching libvorbisfile to read the first
> vorbis logical bitstream in an Ogg file, eg. to allow playing just the
> audio from a theora+vorbis file.
> ie. libvorbisfile continues to handle vorbis only, the change in behaviour
> is that it would no longer fail on files which are not vorbis-only.

Pretty much, thanks for translating (although 'working towards' is a
rather strong phrase).  Yep, Vorbis out of A/V, Vorbis out of Annodexed
audio (I recently pointed someone looking to do bookmarking on an audio
stream at Annodex), Vorbis out of hypothetical Vorbis + metadata.
Barring logical impossibilities I can do the simple bit: extending
vorbisfile to pick out a vorbis stream from each link in a chain (but I
won't have a free weekend to look at it for at least a month).

Re-reading Monty's email: when you talk about vorbis-only vorbisfile and
the concurrent vorbis stream case do you mean vorbisfile will need to be
able to choose?  I'd been thinking (as above) about cases where there is
a Vorbis stream in with other stuff, the first two examples are
realities.  The obvious applications for multiple concurrent Vorbis
streams are the same as for DVD: multiple languages, commentaries,
scores (possibly needing mixing).  Deciding what to play needs
application involvement; how much should vorbisfile be able to do, and
how much should wait until oggfile (and how much should be left to media
players that understand all the complexities involved)?


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