Re: [PD] 8 channel circle panner, how?

[Dudley Brooks]

On 9/12/19 6:35 AM, Winfried Ritsch wrote:

Am Mittwoch, 11. September 2019, 01:01:01 CEST schrieb Dudley Brooks:
A quick question, of purely academic interest:
In theory, wouldn't it be possible to get 3D spatialization with just
four speakers arranged in, say, the corners of a tetrahedron, such as
one directly above and three in an equilateral triangle below the
listener's "horizon" (i.e. the plane of the listener's ears)?  I'm sure
that six speakers would be preferable -- maybe fewer "dead spots"?
But, strictly speaking, four could do it, right?
yes,

... done 1951 with pupitre d'espace, even with 3D-Soundcontroller, the
function of controlling a weigthed Amplification matrix like done in
Ambisonics, so you can use it as Ambisonics 1st order,.. ;-).

see https://books.google.at/books?
id=psKyCwAAQBAJ&pg=PA205&lpg=PA205&dq=pupitre+de+espace#v=onepage&q&f=false

mfg
  winfried

Thank you, Winfried!  I was sure it was possible.  Mathematically, four 
non-coplanar points allow you to define three axes which span 3D space.  
The tetrahedral placement I described gives you one speaker above your 
ears and three below, so that up and down are defined; one in front (and 
below) and two behind (and below), so that front and back are defined; 
and one left (and behind and below) and one right (and behind and 
below), so that right and left are defined.  Thus any (x,y,z) can be 
specified, and Ambisonics can translate any (x,y,z) into this speaker 
placement.

Perhaps there are "dead spots" because of the shape of the coverage of 
the individual speakers.  I don't know anything about that aspect of the 
problem.

-- Dudley

On 9/10/19 12:39 PM, Roman Haefeli wrote:
On Tue, 2019-09-10 at 14:43 -0300, Alexandre Torres Porres wrote:
Em ter, 10 de set de 2019 às 06:15, Roman Haefeli <reduz...@gmail.com

escreveu:
For true spatialization
what is "true spatialization"?
I mean true spatialization as opposed to simple panning. You asked for
a panner and you were given a panner. Then you said you were thinking
of a more sophisticated panner. And I said what you want might be
spatialization that not only emulates a sound source traveling along a
virtual circle, but that is able to emulate also every position in
between. Sounds to me like true spatialization. But I'm only guessing.
I can't read your mind, don't know what you really want. I can only
read you mails. Only apt has super-cow powers.

And why would else/pan4~ not be "truthful"?
Did I say it is not "truthful"? I'm sure it's a very true panner. It's
even 2D (it positions the sound source anywhere between the speakers,
not only on the outlines). Now, isn't that exactly what you want, but
only with four channels? I'm confused now.

- it sounds to me that is what you're aiming at
- use Ambisonics[1].
hmm, I don't really know, and here's a silly question. It seems to me
ambisonics tries to locate a sound source in a 3D sphere, but the
idea would actually be to pan the sound source in a 2D circle space.
It's a totally fine question. I'm not an expert either. Ambisonics is
able to render in 3D, but you can also do 2D (for instance, if you
place all speakers on the same plane). What I understand is special
about Ambisonics, is that you do not need to know beforehand for which
speaker setup you're making a recording or a rendering for. Only the
decoder needs to know the exact configuration of the speakers. This
allows for setups that are not a perfect circle or sphere.

So, can ambisonics help there or is it overcomplicated for that
matter? And how is it possible with 8 speakers to simulate a 3D
sphere?
Again, not an expert speaking here, but depending on your goals you
need that complexity. If your speaker setup is for some reason not a
perfect circle, or the positions are not evenly spaced, the image of
your virtual sound source(s) is distorted. If  you want to account for
that, it's probably easier to use Ambisonics than figuring out all the
calculations on your own. Do you care for a good reproduction of
spatial image? Do you need the flexibility that Ambisoncis gives you?
Do you want re-invent things each time the setup is different? Would
like to be able to switch between 2D and 3D with the same system? Do
you want your piece to be played "correctly" at some other venue that
is not the studio where you worked on your piece?

I'm not saying you want all that. I'm just thinking that the more you
deal with the stuff, the more those aspect are going to matter.

There seem to be Pd externals for this.
yeah, I know, just not sure if all the complicated encoding and
everything is indispensable and stuff
I don't know. I'm not sure if what you want is different from
[else/pan4~], but with 8 channels...

Roman

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