Re: Spherical harmonics for room acoustic modelling

Actually I implemented a basic beam tree that used the material properties
to estimate reverb in closed environments. The beam tree was too large for
detailed outdoor environments, but I suppose if you have a decent mesh
reduction algorithm you could scale it down, I just never had the time to
finish this work.

Cheers,
-Ken Noland

On Sun, Jul 18, 2010 at 11:03 AM, Jon Watte <[email protected]> wrote:

>
>  I'd have doubts you'd get good enough response time on CPU alone
>
>
>
> Actually, the CPU can give you excellent response times if you're using a
> convolution based solution. DJBFFT is a very high performance, unencumbered
> convolution implementation, and it takes a minimal amount of CPU for a
> single sound stream. The problem comes when you want to combine delay lines
> to do overlap-add long convolution (or use the variable-window-size that's
> allegedly still patented by Lake DSP). It starts adding up! The GPU might be
> good at larger convolutions, but it has higher latency than the CPU.
>
> I'm not sure Spherical Harmonics is the right solution. Sound reflection is
> a function of frequency mapping to absorption and directional spread. And
> whereas the eye is only sensitive to three separate frequencies, the ear is
> sensitive to thousands... And in SH based PRT, you often collapse the
> direction-dependent response into a single term, and filter the three
> frequencies using a separate RGB "diffuse reflectance" texture. If you
> applied the same to sound, you'd probably get a better than nothing, but you
> might only get good enough that the problems start to become obvious :-)
> (Bass, Mid and Treble, with a fixed reflectance function)
>
> Sincerely,
>
> jw
>
>
> --
> Americans might object: there is no way we would sacrifice our living
> standards for the benefit of people in the rest of the world. Nevertheless,
> whether we get there willingly or not, we shall soon have lower consumption
> rates, because our present rates are unsustainable.
>
>
>
> On Sat, Jul 17, 2010 at 2:23 PM, Oscar Forth <
> [email protected]> wrote:
>
>> OK maybe not spherical harmonic based but gives the same sorta results
>> and, therefore, just as interesting :)
>>
>>
>
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