[PD] ambi_decode3 ... getting the speaker feeds

e deleflie edeleflie at gmail.com
Thu Jan 29 06:19:58 CET 2009

I think I've got this figured out. (but need help with matrices)

[ambi_decode3] spits out a matrix of numbers. Each line represents one
speaker, each column (in each line) is the factor to multiply the
appropriate component (or channel) of the incoming ambisonic signal.

If I am right then all I need to do is, for each row (i.e. speaker),
multiple each col value to the appropriate component of the ambisonic
signal ... then add them all up.... and that will be that particular
speaker's feed.

I've got 2 libs loaded iem_matrix and iemmatrix. iemmatrix seems to
have far more objects in it, but none of them have any help patches
(and many need the * replaced with 'mul'). (OSX PD Extended).

I'm not too familiar with the concept of matrices ... but this is what
I need to do:

Is there a matrix object that can have 9 inputs (i.e. second order 3D
ambisonic signal) .... and then have 16 outputs (being my speakers).
Then I pump in how each output is created by adding up the 9 imputs
which have been factored?

I can do this outside of matrices but its gonna be shitloads of objects.


On Wed, Jan 28, 2009 at 11:27 AM, e deleflie <edeleflie at gmail.com> wrote:
> Hi all,
> Wondering if anyone can help me with something that I am sure is
> obvious to those in the know.
> The IEM object [ambi_decode3] produces an ambisonic decoder matrix
> (i.e. a bunch of floats) ... how can I turn that (with a source sound)
> into speaker feeds?
> Would anyone have a sample patch?
> Etienne
> BTW: IOhannes, [ambi_decode2] [ambi_decode] [ambi_decode_cube] dont
> have help patches.

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