Vorbis dev - Apr 2007 - Re: [ogg-dev] Ambisonics in Ogg Vorbis

Ian Malone <ibmalone@gmail.com> wrote:
> It depends what your aim is.  The mapping type
> in the vorbis setup header is meant for
> this[1],[2].  Of course a nonzero mapping type will
> cause a lot of players to give up, but so will
> including the XML stream.  I believe this is how
> is was intended multi-channel would be handled.
Thanks for the response, and for the
references.  Did you mean mapping type = 0
for multi-channel and 1 for Ambisonics?

What else is there to do in Vorbis other than
stating "1 = Ambisonics"?  ('Cause I think you
just did that.:-))

...
> Without knowing what you need the metadata to record
> (I assume it can be fairly strictly defined?) I'd say
> of the two metadata approaches going the Skeleton route
> is the easier task here.
So Ogg Skeleton it is.  For B-Format, the
metadata needed is just a flag saying "this is
B-Format" plus two integer numbers specifying
the horizontal and height orders.  A version
number would also be useful.  This can all
easily fit into key-value pairs.  I will post to
ogg-dev on this in the future, as that seems the
appropriate forum for Ogg Skeleton.

Thanks again,
Martin
-- 
Martin J Leese
E-mail: martin.leese@stanfordalumni.org
Web: http://members.tripod.com/martin_leese/

On 4/18/07, Martin Leese <martin.leese@stanfordalumni.org>
wrote:
> Ian Malone <ibmalone@gmail.com> wrote:
>
> > It depends what your aim is.  The mapping type
> > in the vorbis setup header is meant for
> > this[1],[2].  Of course a nonzero mapping type will
> > cause a lot of players to give up, but so will
> > including the XML stream.  I believe this is how
> > is was intended multi-channel would be handled.
>
> Thanks for the response, and for the
> references.  Did you mean mapping type = 0
> for multi-channel and 1 for Ambisonics?
In Vorbis?  Not much.  make sure the encoder knows what to do (eg, how
to tell it the file is ambisonic, and make sure it only uses lossless
couplings).

Players will need proper decode/playback support.

OK, it is officially time for me to set up an ambisonic playback rig here.

Monty