Vorbis dev - Sep 2008 - Ambisonia proposal (was Re: vorbis-tools 1.3.0 BETA - Help testing.)

2008/9/25 e deleflie <edeleflie at gmail.com>:
> Hi Vorbis-dev,
>
Hi,
> I've been on this list for a couple of weeks, but its been quiet, so I
> dont know who is who.
>
> My name is Etienne Deleflie, I am the creator of www.ambisonia.com,
> and I am (together with the Ambisonic community) looking for a
> 'delivery format' for Ambisonic data.
>
> There has been a lot of discussion on the sursound list (and even more
> off-list) about how Ambisonics could be wrapped into Vorbis compressed
> streams. A group of around 10 of us have been putting together a
> 'proposal' (given our understanding of Vorbis) of how this could be
> done. The aim of this group is to have a coherent front in discussions
> with the vorbis-dev people ... to facilitate a reasonable and strong
> integration.
>
> Ambisonics is a fast growing field and we really need to cement a
> strong, open, future proof, Internet friendly delivery format... we
> feel Vorbis is a good fit.
>
> Would the Vorbis-dev team be amenable to considering our proposal?
Of course, and you can all be part of the vorbis-dev team by just
participating :-)

Please send a pointer to an archive of your discussions, as well as the
current form of the proposal. It would be useful if these were linked from
a page on wiki.xiph.org, which is where we usually develop new specifications.
When you've made a new page, please link it from:

http://wiki.xiph.org/index.php/Work_In_Progress

Also, there has been some recent work on channel mappings for OggPCM
(uncompressed PCM data in an Ogg container), which may be related:

http://wiki.xiph.org/index.php/Channel_mapping_examples

cheers,

Conrad.

thanks Conrad,

You can see an archive of the discussions here:
http://groups.google.com/group/ambisonics

There's also been many discussions on the Sursound list but they dont
publicise their archives.

The draft spec can be seen here:
http://docs.google.com/Doc?id=df4dtw69_3626qqq6st

Are you saying that I should create a page on the Xiph Wiki?
> Also, there has been some recent work on channel mappings for OggPCM
> (uncompressed PCM data in an Ogg container), which may be related:
>
> http://wiki.xiph.org/index.php/Channel_mapping_examples
It is indeed related. We are proposing a different ambisonic channel
scheme (not speaker mapping though) called N3D (different to the usual
FuMa scheme). The N3D scheme has a number of 'future proof'
advantages, including no extra header info required and support for
Higher Orders (up to 6th and beyond). It is also believed that the N3D
scheme is more compatible with Vorbis compression.

We were hoping to get some feedback from the vorbis-dev team and then
feed our draft spec back to the greater ambisonic community (i.e. post
it to sursound).

Etienne

On Thu, Sep 25, 2008 at 11:52 AM, Ivo Emanuel Gon?alves
<justivo at gmail.com> wrote:
> Now, the only thing to do is reach a consensus in how to do this.  I
> remember the top suggestions to be:
>
> 1) use Vorbis mapping 1 as opposed to default's 0
that is what the spec draft proposes. but one channel mapping type is
not enough for defining all combinations of horizontal and vertical
orders above 3rd order. for example 9 channels can be interpreted as
2/2 or 4/0 (2nd order horizonal 2nd order vertical or 4th order
horizontal without any vertical component).
> 2) use OggPCM channels
nobody has proposed any solution how this could be implemented / where
to put the needed metadata. keep in mind that most of the Ambisonics
guys (including me) are not familiar with all of the Ogg and Vorbis
specs.
> 3) do a specific Ambisonics stream with all the extra channels and let
> it be compatible with both audio formats (Vorbis and OggPCM)
could you explain this in more detail? i'm not sure what this exactly means.