[PD] Cubemixer with hdsp and 8 lodspeakers?

[IOhannes m zmoelnig]

Roman Haefeli wrote:
> hi rodrigo
> 
> afaik, the number of speakers for an ambisonic installation doesn't
> matter, since you first compute an ambisonic sound in the B-Format,
> which has always 4 channels, iirc. once you have the b-format computed,

yawn...who still uses the b-format nowadays? b-format is just a very
small subset of ambisonics (otoh, when you are stick to 8 channels
b-format will be the best you get...)


> you can use it for several configurations of loudspeakers, but you'll
> have to measure the position of each loudspeaker and then compute the
> signal for each speaker accordingly.
> 
> i don't know the cubemixer of iem, but the website
> (http://iem.at/projekte/acoustic/awt/abcde/project_view) says:
> 
> "Dabei wird nach dem ambisonic-Prinzip eine mehrkanalige
> lautsprecherunabhängige Repräsentation eines periphonen Schallfeldes
> generiert (Encodierung), und diese anschließend über ein bestimmtes
> Lautsprechersetting (Hemisphere) wiedergegeben (Decodierung)."
> 
> for me it sounds that you can use the cubemixer to compute ambisoncics
> b-format (encoding). so you could do the decoding afterwards for your
> special configuration, which has 8 instead of 16 speakers.

yes, that is what ambisonics is all about.

basically you should have a look at the decoder~ on the DSP-side. iirc,
somewhere it should read in a matrix (or something similar) of
loudspeaker positions: adapt that to your needs.

additionally you will also have to reduce the ambisonics order to 1st
order only (which is b-format) since the number of loudspeakers must be
>= the number of ambisonic channels which are (n+1)² (with n being the
order)


hopefully i'll have more time to answer your question better next week.


mfg.asd.r
IOhannes