[PD] learning ambisonics - cartesian to polar patch?

[IOhannes m zmoelnig]

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On 2013-03-03 23:42, João Pais wrote:
> Hello,
> 
> I wanted to learn how to use ambisonics to use them in my patches.
> So far my attempts have failed, as I didn't find any documentation
> that gave me a good overview on the subjetc. Mainly, what I needed
> was a patch that allowed me to send in cartesian (x,y) coordinates
> of a room, and spacialize the sound in an ambisonic format. Does
> anyone have such a model that I could follow?

ambisonics works in spheric coordinates distance, azimuth and
elevation (that's *not* polar, which uses distance, azimuth, height)
spheric coordinates are given relative to the listener's position
(whereas cartesian coordinates are often given relative to some
abstract point of origin - which may coincide with the listener's
position or not).

so what you basically have to do is:
- - transform the (global) cartesian coordinate system to a
listener-local cartesian system, by subtracting the listener's
position from the sound-source position
- - transform the cartesian system to a spherical system. e.g. using
zexy's [cart2sph]
- - feed the spherical coordinates into an ambisonics encoder (usually
only the azimuth/elevation part, as distance is something not covered
by standard ambisonics)


fmasdr
IOhannes
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