jm.music.tools.Prob Maven / Gradle / Ivy
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/*
* Prob.java 18th February 2003
*
* Copyright (C) 2003 Adam Kirby
*
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
package jm.music.tools;
import jm.music.data.Note;
import java.util.Random;
/**
* A utility class for generating random pitches, durations, etc in a gaussian
* distribution.
*
* @author Adam Kirby
* @version $Revision: 1.1.1.1 $, $Date: 2009/05/30 07:56:50 $
*/
public final class Prob {
private static final Random RNG = new Random();
/**
* The Prob class provides static methods and is not meant to be
* instansiated.
*/
private Prob() {
}
/**
* Returns random pitches dispersed by a gaussian distribution around
* the mean specified. Around 68% of the pitches returned will be no
* greater than the mean plus the standard deviation specified and no
* less than the mean minus the standard deviation. Around 95% of
* pitches will be within twice this range.
*
* @param meanPitch the pitch that should be most commonly returned
* by this method.
* @param stdDeviation the standard deviation measured in semitones.
*/
public static final int gaussianPitch(final int meanPitch,
final int stdDeviation) {
long nextPitch;
do {
nextPitch = Math.round(
(RNG.nextGaussian() * stdDeviation) + meanPitch);
} while (nextPitch < Note.MIN_PITCH
|| nextPitch > Note.MAX_PITCH);
return (int) nextPitch;
}
/**
* Returns a random frequency dispersed by a gaussian distribution
* around the mean specified. Around 68% of the frequencies returned
* will be no greater than the mean plus the standard deviation
* specified and no less than the mean minus the standard deviation.
* Around 95% of frequencies will be within twice this range.
*
* @param meanFrequency values returned should average this frequency
* @param stdDeviation the standard deviation. See method comment
*/
public static final double gaussianFrequency(
final double meanFrequency, final double stdDeviation) {
double nextFrequency;
do {
nextFrequency = (RNG.nextGaussian() * stdDeviation)
+ meanFrequency;
} while (nextFrequency < Note.MIN_FREQUENCY);
return nextFrequency;
}
/**
* Returns random rhythm values dispersed by a gaussian distribution
* around the mean specified. Only rhythm values which are multiples
* of the granularity RV will be returned. Thus if you
* specify a granularity of JMC.CROTCHET quavers and dotted crotchets
* will not be returned.
* Around 68% of the rhythm values returned will be no greater than
* the mean plus the standard deviation specified and no less than the
* mean minus the standard deviation. Around 95% of rhythm values will
* be within twice this range.
*
* @param meanRV the average rhythm value returned
* @param stdDev an rhythm interval defining the standard
* deviation.
* @param granularity a rhythm value representing the minimum sort of
* value returned here. If you only want quavers
* and multiples of quavers, use JMC.QUAVER.
*/
public static final double gaussianRhythmValue(final double meanRV,
final double stdDev,
final double granularity) {
double nextRV;
do {
nextRV = (RNG.nextGaussian() * stdDev) + meanRV;
nextRV /= granularity;
nextRV = (double) Math.round(nextRV);
nextRV *= granularity;
} while (nextRV < Note.MIN_RHYTHM_VALUE
|| nextRV > Note.MAX_RHYTHM_VALUE);
return nextRV;
}
/**
* Returns random dynamics dispersed by a gaussian distribution around
* the mean specified. Around 68% of the dynamics returned will be no
* greater than the mean plus the standard deviation specified and no
* less than the mean minus the standard deviation. Around 95% of
* dynamics will be within twice this range. Dynamic values in jMusic
* are the same as MIDI, values between 1 (softest) and 127 (loudest).
*
* @param meanDynamic the dynamic that should be most commonly
* returned by this method.
* @param stdDeviation the standard deviation. See method comment.
*/
public static final int gaussianDynamic(final int meanDynamic,
final int stdDeviation) {
long nextDynamic;
do {
nextDynamic = Math.round(
(RNG.nextGaussian() * stdDeviation) + meanDynamic);
} while (nextDynamic < Note.MIN_DYNAMIC
|| nextDynamic > Note.MAX_DYNAMIC);
return (int) nextDynamic;
}
/**
* Returns random pans dispersed by a gaussian distribution around
* the mean specified. This method limits values returned between the
* range of 0.0 and 1.0. There is another method which allows you to
* specify a different max value for arrangments beyond stereo.
*
* Around 68% of the pans returned will be no greater than the mean
* plus the standard deviation specified and no less than the mean
* minus the standard deviation. Around 95% of pans will be within
* twice this range.
*
* @param meanPan the pan that should be most commonly
* returned by this method.
* @param stdDeviation the standard deviation. See method comment.
*/
public static final double gaussianPan(final double meanPan,
final double stdDeviation) {
return gaussianPan(meanPan, stdDeviation, 1.0);
}
/**
* Returns random pans dispersed by a gaussian distribution around
* the mean specified. This method limits values returned between the
* range of 0.0 and maxPan. This method is useful if
* output from more than two speakers is required.
*
* Around 68% of the pans returned will be no greater than the mean
* plus the standard deviation specified and no less than the mean
* minus the standard deviation. Around 95% of pans will be within
* twice this range.
*
* @param meanPan the pan that should be most commonly
* returned by this method.
* @param stdDeviation the standard deviation. See method comment.
*/
public static final double gaussianPan(final double meanPan,
final double stdDeviation,
double maxPan) {
maxPan = (maxPan >= 0.0) ? maxPan : 0.0;
long nextPan;
do {
nextPan = Math.round((RNG.nextGaussian() * stdDeviation)
+ meanPan);
} while (nextPan < Note.MIN_PAN || nextPan > maxPan);
return (int) nextPan;
}
}