[vorbis-dev] Metadata streams

Martin C. Martin martin at metahuman.org
Thu Apr 12 06:30:46 PDT 2001

On Wed, 11 Apr 2001 rillian at telus.net wrote:

> What sorts of metadata applications are you interested in? I've tried to 
> collect what requirements I can, but most people don't have much to 
> say...

Our project is making a mod for Unreal Tournament to take out the
shooting and turn it into a 3D virtual nightclub.  Think of it as chat
with live audio, dancing, powerups, etc.  Or think of it as a social MUD
with a 3D intefafce and music.

The dancing will be similar to Dance Dance Revolution, Parappa the
Rapper, Space Channel 5, etc.  Basically, you need to press certain
buttons on the beats of the music.  So, we need to know where the bars
begin and end.  Extracting that from music is an unsolved problem (in
general), so it'll have to be extracted before hand, with a user's help,
and stored in the file.  We'll also need to know which parts are chorus,
verse, and bridges without a beat.

In addition, we might add some sort of lighting information, controls
for a scripted band, special effects, a stage show, etc.  Since the
types of info may evolve, it needs to all be backward compatible, and
there could potentially be a large number of very-low-datarate "streams"

Our plan is to have two logical streams, one for the vorbis data, one
for everything else.  In the "everything else" stream, the first four
bytes of every packet will be a "type" field.  That way, we don't need a
separate stream_state for every type (a hastle), and we only need to
incur one page header for all the extra info combined, not every
individual type.

Is that the best way now?  Will that still be the best way in Vorbis


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