124 lines
3 KiB
Racket
124 lines
3 KiB
Racket
#lang scribble/manual
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@(require (for-label racket))
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@title{Ringz}
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Ringing filter.@section{related}
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Classes/Formlet, Classes/RHPF, Classes/RLPF, Classes/Resonz
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@section{categories}
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UGens>Filters>Linear
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@section{description}
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This is the same as link::Classes/Resonz:: , except that it is a constant skirt gain filter, meaning that the peak gain depends on the value of Q. Also, instead of the
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resonance parameter in Resonz, the bandwidth is specified in a 60dB ring decay time. One Ringz is equivalent to one component of the
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link::Classes/Klank:: UGen.
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@section{classmethods}
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@section{method}
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ar, kr
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@section{argument}
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in
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The input signal.
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@section{argument}
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freq
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Resonant frequency in Hertz.
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@section{argument}
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decaytime
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The 60 dB decay time of the filter.
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@section{argument}
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mul
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Output will be multiplied by this value.
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@section{argument}
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add
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This value will be added to the output.
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@section{Examples}
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@racketblock[
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{ Ringz.ar(Dust.ar(3, 0.3), 2000, 2) }.play
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{ Ringz.ar(WhiteNoise.ar(0.005), 2000, 0.5) }.play
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// modulate frequency
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{ Ringz.ar(WhiteNoise.ar(0.005), XLine.kr(100,3000,10), 0.5) }.play
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{ Ringz.ar(Impulse.ar(6, 0, 0.3), XLine.kr(100,3000,10), 0.5) }.play
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// modulate ring time
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{ Ringz.ar(Impulse.ar(6, 0, 0.3), 2000, XLine.kr(4, 0.04, 8)) }.play
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// modulate ring time opposite direction
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{ Ringz.ar(Impulse.ar(6, 0, 0.3), 2000, XLine.kr(0.04, 4, 8)) }.play
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(
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{
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var exciter;
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exciter = WhiteNoise.ar(0.001);
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Mix.arFill(10, {
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Ringz.ar(exciter,
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XLine.kr(exprand(100.0,5000.0), exprand(100.0,5000.0), 20),
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0.5)
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})
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}.play
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)
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::
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]
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@section{Section}
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Interaction with sample rate
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Ringz (and UGens that are based on it: link::Classes/Klank::, link::Classes/DynKlank:: and link::Classes/Formlet::) are "sample-rate independent" with respect to emphasis::impulses:: at the input. That is, given single-sample impulses, the output signal at different sample rates should be the same frequency and amplitude.
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This design has a side effect: If the input is not made of impulses, the output amplitude is proportional to the sample rate.
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@racketblock[
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(
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a = {
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// rectangular pulse exciter (deterministic input)
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var exc = EnvGen.ar(Env([1, 1, 0], [0.01, 0], \lin)),
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sig = Ringz.ar(exc, 440, decaytime: 0.2),
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rms = sqrt(Integrator.ar(sig.squared) * (0.2 / SampleRate.ir)),
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end = DetectSilence.ar(sig, doneAction: 2);
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rms.poll(end);
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Silent.ar(1)
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}.play;
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)
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::
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At 44.1 kHz, this prints a RMS amplitude of 1.0758. At 88.2 kHz, the amplitude doubles.
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Modal synthesis (simulating the vibrating modes of a struck surface) feeds a short, decaying burst of noise into Ringz-style resonators. This is a common use case that emphasis::is:: subject to this amplitude effect.
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If you will need the results to be compatible at different sample rates, make sure to scale the volume appropriately: if ]
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@racketblock[sig:: is the Ringz, Klank or Formlet signal, use ]
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@racketblock[sig * (originalSampleRate / SampleRate.ir):: and substitute the right value in place of ]
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@racketblock[originalSampleRate::.
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]
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