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/*
* Copyright 1997 Phil Burk, Mobileer Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jsyn.unitgen;
import com.jsyn.util.PseudoRandom;
/**
* RedNoise unit. This unit interpolates straight line segments between pseudo-random numbers to
* produce "red" noise. It is a grittier alternative to the white generator WhiteNoise. It is also
* useful as a slowly changing random control generator for natural sounds. Frequency port controls
* the number of times per second that a new random number is chosen.
*
* @author (C) 1997 Phil Burk, SoftSynth.com
* @see WhiteNoise
*/
public class RedNoise extends UnitOscillator {
private PseudoRandom randomNum;
protected double prevNoise, currNoise;
/* Define Unit Ports used by connect() and set(). */
public RedNoise() {
super();
randomNum = new PseudoRandom();
}
@Override
public void generate(int start, int limit) {
double[] amplitudes = amplitude.getValues();
double[] frequencies = frequency.getValues();
double[] outputs = output.getValues();
double currPhase = phase.getValue();
double phaseIncrement, currOutput;
double framePeriod = getFramePeriod();
for (int i = start; i < limit; i++) {
// compute phase
phaseIncrement = frequencies[i] * framePeriod;
// verify that phase is within minimums and is not negative
if (phaseIncrement < 0.0) {
phaseIncrement = 0.0 - phaseIncrement;
}
if (phaseIncrement > 1.0) {
phaseIncrement = 1.0;
}
currPhase += phaseIncrement;
// calculate new random whenever phase passes 1.0
if (currPhase > 1.0) {
prevNoise = currNoise;
currNoise = randomNum.nextRandomDouble();
// reset phase for interpolation
currPhase -= 1.0;
}
// interpolate current
currOutput = prevNoise + (currPhase * (currNoise - prevNoise));
outputs[i] = currOutput * amplitudes[i];
}
// store new phase
phase.setValue(currPhase);
}
}
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