package org.vocvark.AudioFeatures;
import org.vocvark.DataTypes.FeatureDefinition;
/**
* @author Daniel McEnnis
*
* This file is part of Solo695.
*
* Solo695 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.
*
* Solo695 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 MusicalBlackboard; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* A variation on spectral centroid that is based upon peaks instead of bins.
* Given a set of peaks, calculate the peak index that corresponds to 50% of
* the energy in the window. Is based upon Stephan McAdams Spectral Centroid in
* (McAdams 1999).
* <p/>
* McAdams, S. 1999. Perspectives on the contribution of timbre to musical
* structure. <i>Computer Music Journal</i>. 23(3):85-102.
*/
public class HarmonicSpectralCentroid extends FeatureExtractorBaseImpl {
/**
* Basic constructor that sets dependencies, definition, and offsets.
*/
public HarmonicSpectralCentroid() {
String name = "Partial Based Spectral Centroid";
String description = "Spectral Centroid calculated based on the center of mass of partials instead of center of mass of bins.";
definition = new FeatureDefinition(name, description, true, 1);
dependencies = new String[]{"Peak Detection"};
offsets = new int[]{0};
}
/**
* Extract the peak based spectral centroid from the window.
*
* @param samples The samples to extract the feature from.
* @param sampling_rate The sampling rate that the samples are encoded with.
* @param other_feature_values The values of other features that are needed to calculate this
* value. The order and offsets of these features must be the
* same as those returned by this class's getDependencies and
* getDependencyOffsets methods respectively. The first indice
* indicates the feature/window and the second indicates the
* value.
* @return The extracted feature value(s).
* @throws Exception Throws an informative exception if the feature cannot be
* calculated.
* @see FeatureExtractorBaseImpl#extractFeature(double[],
* double, double[][])
*/
public double[] extractFeature(double[] samples, double sampling_rate,
double[][] other_feature_values) {
double[] result = new double[1];
double[] peaks = other_feature_values[0];
double total = 0.0;
double weightedTotal = 0.0;
for (int i = 0; i < peaks.length; ++i) {
weightedTotal += i / 2 * peaks[i];
total += peaks[i];
}
result[0] = weightedTotal / total;
return result;
}
/**
* Proviede a complete copy of this feature. Used to implement the prottype
* pattern
*/
public Object clone() {
return new HarmonicSpectralCentroid();
}
}