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
thanks
alex
You can get an approximate brown noise by running a noise source through [fexpr~ if(abs($x+$y)>1.0,$y-$x,$x+$y)] (an integrator with +/- 1 bounds.
Scale your noise source by somewhere in the 0.05 to 0.001 range (I don't know the exact value). If you want a quasi-gaussian noise source, you can just add 6 to 12 or so independent [noise~]s together.
I'm sure there are more precise ways, but if you need something quickly....
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres porres@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
thanks
alex
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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.
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres porres@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
thanks
alex
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
"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@gmail.com wrote:
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.
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres < porres@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
thanks
alex
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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."
thanks
2015-11-14 17:17 GMT-02:00 Matt Barber brbrofsvl@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@gmail.com wrote:
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.
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres < porres@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
thanks
alex
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Here's a simple way to do reddish noise: low-pass filtered white noise. By making the low-pass cutoff infrasonic it sounds like red or brown noise. The gain needs to be adjusted as the cutoff changes..
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres porres@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
thanks
alex
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
[expr 50/$f1] can also be expressed as
[50 $1( | [/ ]
(just as a reminder that messages spread their atoms to many inlets. I think it is a beautiful feature of Pd)
Roman
On Sat, 2015-11-14 at 20:46 -0500, Martin Peach wrote:
Here's a simple way to do reddish noise: low-pass filtered white noise. By making the low-pass cutoff infrasonic it sounds like red or brown noise. The gain needs to be adjusted as the cutoff changes..
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres porres@gmail.com wrote: hi, wondering how to implement brown noise in Pd (vanilla or extended) - moreover, I'd like and if there's an external that does it.
same about grey noise thanks alex _______________________________________________ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
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Absolutely. Also don't forget about [swap] if you also eventually need to change the dividend, and/or the numbers arrive out of order.
| / [swap 50] | / [/ ]
On Sun, Nov 15, 2015 at 3:58 AM, Roman Haefeli reduzent@gmail.com wrote:
[expr 50/$f1] can also be expressed as
[50 $1( | [/ ]
(just as a reminder that messages spread their atoms to many inlets. I think it is a beautiful feature of Pd)
Roman
On Sat, 2015-11-14 at 20:46 -0500, Martin Peach wrote:
Here's a simple way to do reddish noise: low-pass filtered white noise. By making the low-pass cutoff infrasonic it sounds like red or brown noise. The gain needs to be adjusted as the cutoff changes..
Martin
On Fri, Nov 13, 2015 at 10:35 PM, Alexandre Torres Porres porres@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 thanks alex _______________________________________________ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
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