166 lines
2.8 KiB
Racket
166 lines
2.8 KiB
Racket
#lang scribble/manual
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@(require (for-label racket))
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@title{RandSeed}
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Sets the synth's random generator seed.@section{related}
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Classes/RandID
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@section{categories}
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UGens>Generators>Stochastic, UGens>Random
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@section{description}
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When the trigger signal changes from nonpositive to positive, the synth's
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random generator seed is reset to the given value. All synths that use
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the same random number generator reproduce the same sequence of numbers
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again.
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See link::Classes/RandID:: UGen for setting the randgen id and
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link::Reference/randomSeed:: for the client side equivalent.
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@section{classmethods}
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@section{method}
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kr, ir
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@section{argument}
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trig
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The trigger. Trigger can be any signal. A trigger happens when
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the signal changes from non-positive to positive.
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@section{argument}
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seed
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The random seed.
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@section{Examples}
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@racketblock[
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// start a noise patch
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(
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{
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var noise, filterfreq;
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noise = WhiteNoise.ar(0.05 ! 2) + Dust2.ar(70 ! 2);
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filterfreq = LFNoise1.kr(3, 5500, 6000);
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Resonz.ar(noise * 5, filterfreq, 0.5) + (noise * 0.5)
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}.play;
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)
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// reset the seed at a variable rate
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(
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x = { arg seed=1956;
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RandSeed.kr(Impulse.kr(MouseX.kr(0.1, 100)), seed);
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}.play;
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)
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x.set(\seed, 2001);
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x.set(\seed, 1798);
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x.set(\seed, 1902);
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// above you can see that the sound of the LFNoise1 is not exactly reproduced (filter frequency)
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// this is due to interference between the internal phase of the noise ugen and the
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// seed setting rate.
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// a solution is to start a new synth:
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(
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SynthDef("pseudorandom", { arg out, sustain=1, seed=1967, id=0;
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var noise, filterfreq;
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RandID.ir(id);
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RandSeed.ir(1, seed);
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noise = WhiteNoise.ar(0.05 ! 2) + Dust2.ar(70 ! 2);
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filterfreq = LFNoise1.kr(3, 5500, 6000);
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Out.ar(out,
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Resonz.ar(noise * 5, filterfreq, 0.5) + (noise * 0.5)
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*
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Line.kr(1, 0, sustain, doneAction: Done.freeSelf)
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)
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}).add;
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)
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// the exact same sound is reproduced
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(
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fork {
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loop {
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Synth("pseudorandom");
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1.1.wait; // wait a bit longer than sustain, so sounds don't overlap
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}
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}
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)
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// changing the rand seed changes the sound:
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(
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fork {
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(1902..2005).do { |seed|
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seed.postln;
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3.do {
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Synth("pseudorandom", [\seed, seed]);
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1.1.wait;
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}
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}
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}
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)
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// cd skipper
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(
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fork {
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(1902..2005).do { |seed|
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seed.postln;
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rrand(4,10).do {
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Synth("pseudorandom", [\seed, seed, \sustain, 0.05]);
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0.06.wait;
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}
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}
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}
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)
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// if the sounds overlap, this does not work as expected anymore
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// sounds vary.
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(
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fork {
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loop {
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Synth("pseudorandom");
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0.8.wait; // instead of 1.1
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}
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}
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)
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// rand id can be used to restrict the resetting of the seed to each voice:
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(
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fork {
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var id=0;
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(1902..2005).do { |seed|
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seed.postln;
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3.do {
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Synth("pseudorandom", [\seed, seed, \id, id]);
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id = id + 1 % 16; // there is 16 different random generators
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0.8.wait;
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}
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}
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}
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)
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::
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]
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