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

[jose manuel berenguer]

hello.

i can't explain this feedback. perhaps it is due to some iteration  
when reading some table. anyway, there is a problem in the  
abstraction : noise~, as you say, is not a gaussian noise source. it  
is a uniform white noise source.

to have a gaussian noise source in pd, i suspect a pd external should  
be writen.  Karl-L. Noell and  Helmut  Weber  wrote a library that  
implements the Marsaglia uniform random numbers generator. Inside,  
there is a routine to generate gaussian numbers. I used it to write  
some externals for maxmsp. the sources, that are public, could be  
easily adapted to pd ...

http://www.sonoscop.net/jmb/pub/gaussmt~.zip  (gaussian number  
generator using mersenne twister uniform random number generator)
http://www.sonoscop.net/jmb/pub/gaussm~.zip (gaussian number  
generator using tt80 uniform  random number generator)
http://www.sonoscop.net/jmb/pub/gaussr250.zip (gaussian number  
generator using r250 uniform  radom number generator)
http://www.sonoscop.net/jmb/pub/gauss~.sit (gaussian number generator  
using Marsaglia uniform random number generator)
http://www.sonoscop.net/jmb/pub/rojo~.zip (red noise generator  using  
Marsaglia uniform random number generator )
http://www.sonoscop.net/jmb/pub/ruidist.zip (red noise, 1/f^alpha  
noise, random  number generator and statistical distributions)
http://www.sonoscop.net/jmb/pub/ruidos~.zip (marsaglia, tt80 and  
mersenne twister uniform random number generators)

jmb



El 20/08/2006, a las 11:37, alberto..zin@@poste..it escribió:

> 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
>>
>>
>>
>> _______________________________________________
>> PD-list at iem.at mailing list
>> UNSUBSCRIBE and account-management ->
> http://lists.puredata.info/listinfo/pd-list
>>
>>
>>
>>
>
>
> --
>
> http://theradioproject.com
> http://perhapsidid.blogspot.com
>
> (((())))(()()((((((((()())))()(((((((())()()())())))
> (())))))(()))))))))))))(((((((((((()()))))))))((())))
> ))(((((((((((())))())))))))))))))))__________
> _____())))))(((((((((((((()))))))))))_______
> ((((((())))))))))))((((((((000)))oOOOOOO
>
>
>
> _______________________________________________
> PD-list at iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/ 
> listinfo/pd-list

jose manuel berenguer
jmbeal at telefonica.net  +34932857046 +34696538403. http:// 
www.sonoscop.net/jmb/
jmberenguer at sonoscop.net +34933064128. http://www.sonoscop.net/
caos->sonoscop. cccb. montalegre, 5. 08001 barcelona
spain


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20060820/e42bfe75/attachment.htm>