[PD] Colored (fractal, 1/f^a) noise generator for PD

[alberto.zin at poste.it]

Hi ~Kyle,

>But is the algorithm only supposed to generate 1/2 of the
>hfa array?
>I "doodled" in it, just to play with the convolution, and
>now the
>agorithm is only writing to the first 512 locations of the
>array.  Is
>it a bug?

It is wanted to be like that; actually in the original algo
there are arrays (of noise and hfa coeff) of 2n elements: n
values are filled, the other are padded with zeros.    
Then real fft is done on the first n and convolution on 2n
elements.. so mine is an adaptation of this. When I looked 
at the spectrum (in audacity) the noise seems to behave
fine; my concern is the strange sensation
in hearing the noise, like a small "feedback" even on a
single channel of output for high alpha..

Alberto
 


On 8/19/06, alberto.zin at poste.it <alberto.zin at poste.it> wrote:
> Hi,
>
> attached is an abstraction for generation of "colored" noise
> (http://en.wikipedia.org/wiki/Colors_of_noise) using a
> relatively new method (by J.N. Kasdin, 1995) that uses
> frequency domain multiplication. White, pink, brown noise
> (and intermediate flavors) can be obtained by varying
> a single parameter (the slope of the spectrum in a linear
> log(PSD)-log(f) plot).
> I searched a bit in the archives and it seems to me that in
> for noise generation in PD we actually have noise~ (uniform
> white noise), pink~ (from zexy and cyclone) and a variety of
> filters, but no direct generation of 1/f^a noise (am I
> right?).
>
> Inside the archive there is a short readme, look at it
> first. To me the patch sounds a little "tubby", let me know
> if you have the same feeling.
>
> Any comment, suggestion for improvements is welcome.
>
> The abstraction lives in
> http://www.puredata.org/Members/AlbertoZ
>
> All the best,
>
> Alberto Zin
>
>
>
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