001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030/**
031 *
032 */
033package org.openimaj.audio.features;
034
035import java.util.Stack;
036
037import org.openimaj.audio.AudioStream;
038
039/**
040 *      Wrapper around the jAudio implementation of Spectral flux.
041 *
042 *      @author David Dupplaw (dpd@ecs.soton.ac.uk)
043 *  @created 23 May 2013
044 *      @version $Author$, $Revision$, $Date$
045 */
046public class SpectralFlux extends JAudioFeatureExtractor
047{
048        /** The mag spec processor */
049        private MagnitudeSpectrum magSpec = null;
050
051        /** The last n spectral flux values */
052        private final Stack<double[]> lastSpec = new Stack<double[]>();
053
054        /** The number of previous spectral flux to store */
055        private int numberToStore = 2;
056
057        /**
058         *      Default constructor
059         */
060        public SpectralFlux()
061        {
062                this.featureExtractor = new jAudioFeatureExtractor.AudioFeatures.SpectralFlux();
063                this.magSpec = new MagnitudeSpectrum();
064        }
065
066        /**
067         *      Constructor that's chainable.
068         *      @param as The stream to chain to
069         */
070        public SpectralFlux( final AudioStream as )
071        {
072                super( as );
073                this.featureExtractor = new jAudioFeatureExtractor.AudioFeatures.SpectralFlux();
074                this.magSpec = new MagnitudeSpectrum();
075        }
076
077        /**
078         *      {@inheritDoc}
079         *      @see org.openimaj.audio.features.JAudioFeatureExtractor#getExtraInputs(double[], double)
080         */
081        @Override
082        public double[][] getExtraInputs( final double[] samples, final double sampleRate )
083        {
084                // Calculate the mag spec for this sample array
085                final double[] ms = this.magSpec.process( samples, sampleRate );
086
087                double[] ms1 = null;
088                if( this.lastSpec.size() == this.numberToStore )
089                        ms1 = this.lastSpec.pop();
090                this.lastSpec.push( ms );
091
092//              System.out.println( Arrays.toString(ms) );
093//              System.out.println( Arrays.toString(ms1) );
094
095                // If we don't have 2 spectra, we return empty otherwise we return both.
096                return ms1 == null ? new double[][] {{0},{0}} : new double[][] {ms, ms1};
097        }
098
099        /**
100         *      Get the number of spectral flux values to store in the feature
101         *      @return the numberToStore The number to store
102         */
103        public int getNumberToStore()
104        {
105                return this.numberToStore;
106        }
107
108        /**
109         *      Set the number of spectral flux values to store in the feature
110         *      @param numberToStore The number of values to store
111         */
112        public void setNumberToStore( final int numberToStore )
113        {
114                this.numberToStore = numberToStore;
115        }
116}