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AvgSpecFlatness.java

00001 /*
00002  *  Copyright 2006-2007 Columbia University.
00003  *
00004  *  This file is part of MEAPsoft.
00005  *
00006  *  MEAPsoft is free software; you can redistribute it and/or modify
00007  *  it under the terms of the GNU General Public License version 2 as
00008  *  published by the Free Software Foundation.
00009  *
00010  *  MEAPsoft is distributed in the hope that it will be useful, but
00011  *  WITHOUT ANY WARRANTY; without even the implied warranty of
00012  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013  *  General Public License for more details.
00014  *
00015  *  You should have received a copy of the GNU General Public License
00016  *  along with MEAPsoft; if not, write to the Free Software
00017  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
00018  *  02110-1301 USA
00019  *
00020  *  See the file "COPYING" for the text of the license.
00021  */
00022 
00023 package com.meapsoft.featextractors;
00024 
00025 import com.meapsoft.STFT;
00026 
00034 public class AvgSpecFlatness extends FeatureExtractor 
00035 {
00036         
00037     public double[] features(STFT stft, long startFrame, int length) 
00038     {
00039         double[] curFrame;
00040         double[] avgSpecFlatness= new double[1];
00041         double num = 1;
00042         double den = Double.MIN_VALUE;
00043 
00044         avgSpecFlatness[0] = 0;
00045 
00046         for(int frame=0; frame<length; frame++) 
00047         {
00048             num = 0; den = 0;
00049             int nband = stft.getRows();
00050             curFrame = stft.getFrame(startFrame+frame);
00051             for(int band = 0; band < nband; band++) 
00052             {
00053                 // convert back to linear power
00054                 double p = Math.pow(10,curFrame[band]/10);
00055 
00056                 num += Math.log(p)/nband;
00057                 den += p/nband;
00058             }
00059             avgSpecFlatness[0] += Math.exp(num)/(den*length);
00060         }
00061         
00062         return avgSpecFlatness;
00063     }
00064 
00065         public String description()
00066         {
00067                 return "Provides a measure of the peakiness of the chunks average spectrum.";
00068         }
00069 }

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