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Re: Multichannel audio cards
I believe in order to do 3D audio over a loud speaker array, it is
possible to use both ambisonics and more modern discrete sound source
panning techniques on the same system ....
The trick is firstly to write a software library which does the correct
sound card handling routines ....
Issues include :
a] You have to sync all the sound cards, which should not be too difficult
a task as driver developers are starting to think about this, and for
example I believe the ALSA drivers are more then capable of multi
sound card syncing with the standard release.
b] Mixer ... signals have to be dynamicly mixed down to the speakers
... ambisonics (a simple 'pinv()' routine in octave/matlab
suffices or you can see for Jot's paper  for more modern
approaches). Using discrete source panning (my library  - pdf paper
there too) or (Pulki's VBAP  or the Lake DSP methods ).  and 
are similar and face the same problems/issues.
 "A Comparative Study of 3-D Audio Encoding and Rendering Techniques",
Jot JM., Larcher v., Pernaux JM., AES 16'th International Conference on
Spatial Sound Reproduction, 1999.
 mffm 3D Audio library : http://mffm3daudio.sourceforge.net
 "Creating Auditory Displays with Multiple Loudspeakers Using VBAP: A
Case Study with DIVA Project", Pulkki V., Lokki T., International
Conference on Auditory Display, Glasgow, England, 1998.
 "Optimal 3D Speaker Panning" Dickins G., Flax M. R., McKeag A.,
McGrath D., AES 16th International Conference on Spatial Sound
Reproduction. April 10-12, 1999
On 24 October 2001, Peter Lennox wrote:
> I would strongly suggest considering a 2nd-order ambisonic setup, especially
> if you have Matlab. Derby University in the uk have a programme: 'simulink'
> which runs under matlab and which allows configuration of ambisonic decoders
> on fast PC with multichannel soundcards.
> The benefit of this route is that ambisoncs supports periphonic
> (with-height) displays, but it is a kernel system and so is compatible with
> lower-orders of spatial encoding, so horizontal-only material is entirely
> compatible with it. It's very easy to put mono, stereo, 5.1, 7.1 , 1st-order
> ambisonics, and even binaural (though here the conversion is not perfect)
> into an ambisonic 2nd-orderdisplay, and this can be encoded in realtime with
> managable latency.
> I know they are at present experimenting with a new 32xspeaker periphonic
> setup for medium-to-large scale listening, running on a PC with 2x16ch
> soundcards (operated as a single device). I can find out the soundcard
> manufacturer if you wish
> ----- Original Message -----
> From: "Sanja Dupor" <106744.1511@COMPUSERVE.COM>
> To: <AUDITORY@LISTS.MCGILL.CA>
> Sent: 24 October 2001 08:16
> Subject: Multichannel audio cards
> Hi Regis,
> see EWS88MT Terratec card at www.terratec.net
> Nachricht geschrieben von Regis Rossi Alves Faria
> We are looking for suggestions on multichannel audio cards (models
> and/or brands) as well as multichannel softwares (to generate more than
> 2 stereo audio outputs, be it either 5.1 or n-independent
> channels/outputs) to drive a virtual 3D (audio) environment (i.e., n
> independent speakers set in a way to produce audio spacialization).
> The system is to synchronize with a similar virtual 3D visual
> environment, where objects can be visualized and heard.
> Those who can advise on this, or think could help if having more
> information, I would be grateful in contacting.
> Regis Rossi A. Faria
> Media Engineering Center
> LSI - University of Sao Paulo
For electronic musicians ...
Vector Bass : http://mffmvectorbass.sourceforge.net/
For developers ...
3D Audio Library : http://mffm3daudiolib.sourceforge.net/
Multimedia Time Code : http://mffmtimecode.sourceforge.net/