Re: Multichannel audio cards (Matt Flax )

Subject: Re: Multichannel audio cards
From:    Matt Flax  <flatmax(at)CSE.UNSW.EDU.AU>
Date:    Wed, 24 Oct 2001 22:00:14 +1000

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 [1] for more modern approaches). Using discrete source panning (my library [2] - pdf paper there too) or (Pulki's VBAP [3] or the Lake DSP methods [4]). [3] and [4] are similar and face the same problems/issues. [1] "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. [2] mffm 3D Audio library : [3] "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. [4] "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 > regards, > ppl > ----- Original Message ----- > From: "Sanja Dupor" <106744.1511(at)COMPUSERVE.COM> > To: <AUDITORY(at)LISTS.MCGILL.CA> > Sent: 24 October 2001 08:16 > Subject: Multichannel audio cards > > > Hi Regis, > see EWS88MT Terratec card at > Zlatan > > > 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 > Brazil > regis(at) > < -- Matt For electronic musicians ... Vector Bass : For developers ... 3D Audio Library : Multimedia Time Code :

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