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.SampleChunk; 036import org.openimaj.audio.processor.AudioProcessor; 037 038/** 039 * Uses a {@link MusicalNoteFilterBank} to determine the power output of 040 * the notes of a western scale over the frame. It calculates the power 041 * difference between successive frames to determine whether a new note 042 * has been detected. 043 * 044 * @author David Dupplaw <dpd@ecs.soton.ac.uk> 045 * @created 22 May 2012 046 * @version $Author$, $Revision$, $Date$ 047 */ 048public class MusicalNoteOnsetDetector extends AudioProcessor 049{ 050 /** The filter bank to use */ 051 private final MusicalNoteFilterBank filterBank = new MusicalNoteFilterBank( 60, 72, null ); 052 053 /** The previous calculated output power */ 054 private double previousPower = 0; 055 056 /** Whether an onset was detected during the last process */ 057 private boolean onsetDetected = false; 058 059 /** The threshold over which onset is detected */ 060 private final double threshold = 100; 061 062 /** 063 * {@inheritDoc} 064 * @see org.openimaj.audio.processor.AudioProcessor#process(org.openimaj.audio.SampleChunk) 065 */ 066 @Override 067 public SampleChunk process( final SampleChunk sample ) throws Exception 068 { 069 this.filterBank.process( sample ); 070 final double p = this.filterBank.getOutputPower(); 071 072 final double delta = Math.abs( this.previousPower - p ); 073 074 if( delta > this.threshold ) 075 this.onsetDetected = true; 076 077 this.previousPower = p; 078 079 return sample; 080 } 081 082 /** 083 * Returns whether an onset was detected during the last processing cycle. 084 * @return TRUE if an onset was detected during the last processing cycle; 085 * FALSE otherwise. 086 */ 087 public boolean hasOnsetBeenDetected() 088 { 089 return this.onsetDetected; 090 } 091}