[PD] 8 channel circle panner, how?

Patrice Colet colet.patrice at free.fr
Wed Sep 11 15:51:59 CEST 2019


Le 11/09/2019 à 00:26, Andrew Lyons a écrit :
> Sounds like you want spatialization on a plane through 8 speakers 
> positioned on a circle?
> So you need to convert any cartesian locations to polar coords first. 
> For an approximate 3D sound effect you really only need a function to 
> create distance (and Doppler?) effects, and then feed that output, and 
> the angle into the planner.
> The Doppler effects are the trickiest obviously. Last time I checked, 
> real time pitch shifting as a function of change in distance was best 
> done in the Fourier domain. Not sure how real time that is these days.
> Distance effects are just inverse square of distance (or 1/ d^1.5 
> according to some). Then add filters for high and low frequencies. 
> Constant power panning and variants popular and easy for speakers on a 
> circle.

  When soundwaves are propagating through a medium, there are several 
effects happening, like dispersion and reflexion, and they may travel at 
different speeds with same frequency following it's shear modulus (see 
https://en.m.wikipedia.org/wiki/Speed_of_sound). That's how ambisonic 
tools might be usefull...

Doppler effect is involved when the source of a sound and the listener 
are moving relative to each other.

> There's pseudo code in this book from memory: Dodge, Charles; Jerse, 
> Thomas A. 1997 Computer music : synthesis, composition,
> and performance. 2nd ed. New York : Schirmer Books ; London : Prentice
> Hall International.
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