[PD] brown/grey noise in pd
Alexandre Torres Porres
porres at gmail.com
Sat Nov 14 22:09:54 CET 2015
was looking for a substitute/parallel object to BrownNoise in Sc, which is
described just as "Generates noise whose spectrum falls off in power by 6
dB per octave."
Another one would be GreyNoise, described as "Generates noise which results
from flipping random bits in a word. This type of noise has a high RMS
level relative to its peak to peak level. The spectrum is emphasized
towards lower frequencies."
2015-11-14 17:17 GMT-02:00 Matt Barber <brbrofsvl at gmail.com>:
> "True" pink noise is likewise impossible: if it's equal energy per octave,
> then since there is no "lowest octave," any energy in any octave implies
> infinity at 0hz. The fexpr~ approach I gave accumulates, but imagines a
> "container" with "walls" at +/- 1.0 where whatever was doing the random
> walk "bounces" off the wall. It should have a color within auditory range
> similar to unrestricted integration. A lot depends on what you want to do
> with the noise (it's not necessarily an audio source).
> Convolution is a pretty good way to go. I've seen a number of filters that
> try to distribute phase randomly across the frequency magnitude curve. Also
> remember that the 6dB dropoff is with respect to log frequency, whereas FFT
> is linear in frequency.
> On Sat, Nov 14, 2015 at 1:35 PM, Martin Peach <chakekatzil at gmail.com>
>> There's [rojo~] in mrpeach, if by brown noise you mean red noise.
>> (brownian noise?)
>> [rojo~] tends to grow out of bounds, which is a problem with correlated
>> noise: if you want long term correlations you have to be ready for the
>> noise to get very loud. So in practice there is no red noise possible, it's
>> all high pass filtered.
>> To get any arbitrary shape of noise it can be done most efficiently by
>> convolving a frequency curve table with white noise. The table would have
>> the same length as the number of bins in the FFT.
>> On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres <
>> porres at gmail.com> wrote:
>>> hi, wondering how to implement brown noise in Pd (vanilla or extended) -
>>> moreover, I'd like and if there's an external that does it.
>>> same about grey noise
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