On Fri, Jul 18, 2008 at 12:52:20PM -0400, Art Hunkins wrote:

> If there are significantly better and truer ambisonic opcodes to be had, I 
> for one would be happy to redo my recent compositions to take advantage of 
> them. For one thing, Victor's "kludge" of stereo ambisonics (granted, a most 
> effective one) would hopefully no longer be required.
> 
> Can someone advise as to what sonic improvement results from the revisions?

The new opcodes implement the same decoders as the existing ones:

    layout     orders             
-------------------------
    stereo     1
    square     1
    5.1        1,2
    octagon    1,2,3
    cube       1

but this time they are correctly implemented. There were
several serious errors in the earlier ones, some of them
making part of the code as good as useless.

All the decoders are single-band (i.e. frequency independent)
'in phase' AKA 'controlled opposites' ones. They are not
optimal (this would require dual band, the option to select
max rV and max rE, and near-field compensation), but are
robust in the sense that they will work even if your setup
is not ideal. They are meant as 'entry level' decoders.

The original encoder opcode had several gain factors wrong,
and these errors were repeated in the decoders (and they
would *not* cancel out).

The new version provides nothing new, just a correctly
working version of basic ambisonics functions that does
not require the composer to compensate for the errors
in the opcode (which is probably what has happened a lot
before).

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

O tu, che porte, correndo si ?
E guerra e morte !




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