/**
* @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
*/
package org.vocvark.AudioFeatures;
import org.vocvark.DataTypes.FeatureDefinition;
/**
* A variation on spectral flux that is based upon peaks instead of bins. Given
* two sets of peaks, calculate the correlation between adjacent peaks. This
* should use proper peak tracking, but for now tracks peaks by matching peaks
* from the bottom up. Unmatched peaks are discarded. This feature 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.
*
* @author Daniel McEnnis
*/
public class HarmonicSpectralFlux extends FeatureExtractorBaseImpl {
/**
* Basic constructor that sets dependencies, definition, and offsets.
*/
public HarmonicSpectralFlux() {
String name = "Partial Based Spectral Flux";
String description = "Cacluate the correlation bettween adjacent frames based peaks instead of spectral bins. Peak tracking is primitive - whe the number of bins changes, the bottom bins are matched sequentially and the extra unmatched bins are ignored.";
definition = new FeatureDefinition(name, description, true, 1);
dependencies = new String[]{"Peak Detection", "Peak Detection"};
offsets = new int[]{0, -1};
}
/**
* Extract the peak based spectral flux 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).
* @see FeatureExtractorBaseImpl#extractFeature(double[], double, double[][])
*/
public double[] extractFeature(double[] samples, double sampling_rate,
double[][] other_feature_values) {
double[] result = new double[1];
double[] old = other_feature_values[1];
double[] now = other_feature_values[0];
double x, y, xy, x2, y2;
x = y = xy = x2 = y2 = 0.0;
int peakCount = Math.min(old.length, now.length);
for (int i = 0; i < peakCount; ++i) {
x += old[i];
y += now[i];
xy += old[i] * now[i];
x2 = old[i] * old[i];
y2 = now[i] * now[i];
}
double top = xy - (x * y) / peakCount;
double bottom = Math.sqrt(Math.abs((x2 - ((x * x) / peakCount))
* (y2 - ((y * y) / peakCount))));
result[0] = top / bottom;
return result;
}
/**
* Proviede a complete copy of this feature. Used to implement the prottype
* pattern
*/
public Object clone() {
return new HarmonicSpectralFlux();
}
}