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.util;
034
035import java.util.ArrayList;
036import java.util.Arrays;
037import java.util.List;
038
039import org.openimaj.util.pair.IndependentPair;
040
041/**
042 *      Static utility methods that are related to music (more semantic
043 *      than audio utilities).
044 *      <p>     
045 *      For working with notes, see {@link WesternScaleNote}.
046 *
047 *      @author David Dupplaw (dpd@ecs.soton.ac.uk)
048 *      
049 *      @created 27 Nov 2011
050 */
051public class MusicUtils
052{
053        /**
054         *      Given a beats-per-minute rate, returns the number of milliseconds
055         *      in a single beat.
056         * 
057         *      @param bpm Beats per minute
058         *      @return Number of milliseconds per beat.
059         */
060        public static int millisPerBeat( final float bpm )
061        {
062                return (int)(60000f/bpm);
063        }
064        
065        /**
066         *      Parses the music notation from ABC files (without the header). Note number
067         *      -1 signifies a rest.
068         * 
069         *      @param abc The abc note string
070         *      @return An list of note numbers and lengths
071         */
072        public static List<IndependentPair<Integer,Double>> 
073                parseABCNotes( final String abc )
074        {
075                final List<IndependentPair<Integer, Double>> ret = 
076                                new ArrayList<IndependentPair<Integer,Double>>();
077                
078                // Start with middle-C and alter from there
079                int nn = 60;
080                int length = 1;
081                IndependentPair<Integer,Double> lastNote = null;
082                
083                for( int i = 0; i < abc.length(); i++ )
084                {
085                        char c = abc.charAt( i );
086                        
087                        switch( c )
088                        {
089                                case '_': nn -= 1; break;
090                                case '=': nn -= 0; break;
091                                case '^': nn += 1; break;
092                                case ',': nn -= 12; break;
093                                case '\'': nn += 12; break;
094                                case '/': 
095                                        if( lastNote != null )
096                                                lastNote.setSecondObject( lastNote.getSecondObject()/2d );
097                                        break;
098                                case '-':
099                                case 'z':
100                                        nn = -1; break;
101                                default: 
102                                break; 
103                        }
104                        
105                        if( Character.isDigit( c ) && lastNote != null )
106                                lastNote.setSecondObject( lastNote.getSecondObject() * (c-48) );
107                        
108                        // If it's a note name...
109                        if( Character.isLetter( c ) && "abcdefgABCDEFG".contains( ""+c ) )
110                        {
111                                // If it's lower case it's the upper octave
112                                if( Character.isLowerCase( c ) )
113                                        nn += 12;
114                                
115                                // Convert to upper case and get the note offset
116                                c = Character.toUpperCase( c );
117                                nn += Arrays.asList( WesternScaleNote.noteNames ).indexOf( ""+c );
118                                
119                                // Add it to the list
120                                ret.add( lastNote = new IndependentPair<Integer, Double>( nn, 
121                                                (double)length ) );
122                                
123                                // Reset our variables for the next note
124                                nn = 60;
125                                length = 1;
126                        }
127                        else
128                        if( nn == -1 )
129                                ret.add( new IndependentPair<Integer, Double>( -1, (double)length ) );
130                }
131                
132                return ret;
133        }
134}