[PD] Stereo simulation of multichannel audio [ot?]

Nicholas Mariette nicholas.mariette at limsi.fr
Mon Jul 20 15:45:17 CEST 2009

Hi Joao,

It sounds like you need a stereo auralization of various multichannel  
diffusion pieces.

One option is to make a binaural down-mix of the multichannel  
material, although that has the restriction of only sounding good on  
headphones. This would still leave a decision on where to place sound  
sources, and how to do the auralization (i.e. how to do the room  
simulation, etc).

For stereo speaker playback, there is not really a canonical  
solution.  Again though, you could do an auralization of the intended  
diffusion to an intermediate format like ambisonics, then do a stereo  
decode.  This will not leave as much of a spatial impression as a  
binaural mix, but it will be more portable to different listening  

Either way there are still various (essentially aesthetic/artistic)  
decisions to make about the specification of the auralization.

So you might find that the best results for generalised playback  
(headphone or speakers), is just to make aesthetic decisions and do a  
multichannel downmix.

At any rate, if you want to explore ambisonic and/or binaural down- 
mixes, the IEM tools for doing this are all in Pd extended.

For more info on the binaural stuff, you can try the patches and  
publications here:

The patches are windows only, but they can be reconstituted from the  
IEM objects available for other platforms inside Pd Extended (or SVN).


Nicholas Mariette

Audio and Acoustics group
LIMSI-CNRS, Orsay, France
nicholas.mariette at limsi.fr

On Jul 20, 2009, at 3:30 PM, João Pais wrote:

> Hi,
> my laptop trio Endphase (http://www.endphase.net/) is going to work  
> out
> our archived recordings, so that we get decent stereo versions to  
> spread
> around. Since many of them are multichannel (from 4 to 8) in different
> setups (not necessarily only 2d around the audience), we'll be  
> searching
> for efficient ways to try to "convert" the original audio to stereo.  
> That
> is, having a good as possible compromise between both situations,  
> knowing
> that a 100% simulation is impossible.
> This is a field that I don't know that well, and we're still in the
> beginning of the work. Does anyone has any suggestions to which  
> approaches
> are best? Ambisonics, phase inversion, hrtf, home medicine? Are any of
> these also available through Pd? (it would be nice to mix/spacialize  
> the
> materials in Pd)
> Thanks,
> João Pais
> -- 
> Friedenstr. 58
> 10249 Berlin (Deutschland)
> Tel +49 30 42020091 | Mob +49 162 6843570
> jmmmpais at googlemail.com | skype: jmmmpjmmmp
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