Will these changes result in any different audio output for csd's that use
bformenc/dec in the usual 2-, 4- and 8-speaker setups?

If so, will it result in a "truer" spatial image and clearer positioning?

Art Hunkins

----- Original Message ----- 
From: "jpff" 
To: 
Sent: Thursday, July 05, 2007 6:09 AM
Subject: [Cs-dev] Ambisonic opcodes


> A small group of us has been looking at these opcodes and perceived
> short-comings.  As a result I am committing to the CVS a revised
> system.  The major changes are:
>
> 1: The gain parameters in bformenc are optional, and default to 1
>
> 2: If the isetup parameter of bformdec is negative (this is the
> parameter that says where the speakers are) then it uses the
> Malham/Furze "controlled opposites" coefficients rather than the
> spherical harmonics form.
>
> For some more information the page
>     http://www.muse.demon.co.uk/ref/speakers.html
>
> Known problems with this include the 5.1 format is still bad, but we
> may be able to improve that. The argument checking in bformenc is less
> good as the optional arguments are in a sense always there.  I can
> think of nasty hacks to reinstate but probably will not.
>
> I would like to move to a freer speaker setup system, but so far am
> lost in the maths.
>
> I have not changed the documentation yet as I want to see if this is
> an acceptable hack.
>
> ==John ffitch
>
>
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The changes are directly compatible with the 5.06 code -- exactly the
same coefficients.  If you use the negative setup values you will get
a different decode (allegedly better), and here is a new setup,
numbers 6 that give 5.1 in a better way.

I am unable to test any of this as I only have a stereo system here.

==John ffitch

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