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.filters; 034 035import org.openimaj.audio.AudioStream; 036 037/** 038 * Applies a Hanning window on top of the audio signal. 039 * 040 * @see "http://cnx.org/content/m0505/latest/" 041 * @author David Dupplaw (dpd@ecs.soton.ac.uk) 042 * @created 31 Oct 2011 043 */ 044public class HanningAudioProcessor extends WeightedWindowedAudioProcessor 045{ 046 /** 047 * Default constructor for non chainable processing. 048 * @param sizeRequired Size of the window required 049 */ 050 public HanningAudioProcessor( final int sizeRequired ) 051 { 052 super( sizeRequired ); 053 } 054 055 /** 056 * Chainable constructor. Takes the audio stream and the size required. 057 * 058 * @param stream The audio stream to process 059 * @param sizeRequired The size of window required. 060 */ 061 public HanningAudioProcessor( final AudioStream stream, final int sizeRequired ) 062 { 063 super( stream, sizeRequired ); 064 } 065 066 /** 067 * Constructor that takes the size of the window and the number of samples 068 * overlap. 069 * 070 * @param nSamplesInWindow Samples in window 071 * @param nSamplesOverlap Samples in window overlap 072 */ 073 public HanningAudioProcessor( final int nSamplesInWindow, final int nSamplesOverlap ) 074 { 075 super( nSamplesInWindow, nSamplesOverlap ); 076 } 077 078 /** 079 * Chainable constructor that takes the size of the window and 080 * the number of samples overlap. 081 * 082 * @param as The chained audio stream 083 * @param nSamplesInWindow Samples in window 084 * @param nSamplesOverlap Samples in window overlap 085 */ 086 public HanningAudioProcessor( final AudioStream as, final int nSamplesInWindow, 087 final int nSamplesOverlap ) 088 { 089 super( as, nSamplesInWindow, nSamplesOverlap ); 090 } 091 092 /** 093 * Generate the cos table cache 094 * @param length The length of the window to generate (per channel) 095 * @param nc The number of channels for which to generate a weight table 096 */ 097 @Override 098 protected void generateWeightTableCache( final int length, final int nc ) 099 { 100 final int ns = length; 101 this.weightTable = new double[ length ]; 102 for( int n = 0; n < ns; n++ ) 103 for( int c = 0; c < nc; c++ ) 104 this.weightTable[n*nc+c] = 0.5*(1-Math.cos((2*Math.PI*n)/ns)); 105 } 106}