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1: /* MidiFileWriter.java -- Write MIDI files. 2: Copyright (C) 2006 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package gnu.javax.sound.midi.file; 39: 40: import java.io.File; 41: import java.io.FileInputStream; 42: import java.io.FileOutputStream; 43: import java.io.IOException; 44: import java.io.InputStream; 45: import java.io.OutputStream; 46: 47: import javax.sound.midi.MetaMessage; 48: import javax.sound.midi.MidiEvent; 49: import javax.sound.midi.Sequence; 50: import javax.sound.midi.Track; 51: 52: /** 53: * A MIDI file writer. 54: * 55: * This code writes MIDI file types 0 and 1. 56: * 57: * There are many decent documents on the web describing the MIDI file 58: * format. I didn't bother looking for the official document. If it 59: * exists, I'm not even sure if it is freely available. We should 60: * update this comment if we find out anything helpful here. 61: * 62: * @author Anthony Green (green@redhat.com) 63: * 64: */ 65: public class MidiFileWriter 66: extends javax.sound.midi.spi.MidiFileWriter 67: { 68: /* Return an array indicating which midi file types are supported. 69: * @see javax.sound.midi.spi.MidiFileWriter#getMidiFileTypes() 70: */ 71: public int[] getMidiFileTypes() 72: { 73: return new int[]{0, 1}; 74: } 75: 76: /* Return an array indicating which midi file types are supported 77: * for a given Sequence. 78: * @see javax.sound.midi.spi.MidiFileWriter#getMidiFileTypes(javax.sound.midi.Sequence) 79: */ 80: public int[] getMidiFileTypes(Sequence sequence) 81: { 82: if (sequence.getTracks().length == 1) 83: return new int[]{0}; 84: else 85: return new int[]{1}; 86: } 87: 88: /* Write a sequence to an output stream in standard midi format. 89: * @see javax.sound.midi.spi.MidiFileWriter#write(javax.sound.midi.Sequence, int, java.io.OutputStream) 90: */ 91: public int write(Sequence in, int fileType, OutputStream out) 92: throws IOException 93: { 94: MidiDataOutputStream dos = new MidiDataOutputStream (out); 95: Track[] tracks = in.getTracks(); 96: dos.writeInt(0x4d546864); // MThd 97: dos.writeInt(6); 98: dos.writeShort(fileType); 99: dos.writeShort(tracks.length); 100: float divisionType = in.getDivisionType(); 101: int resolution = in.getResolution(); 102: // FIXME: division computation is incomplete. 103: int division = 0; 104: if (divisionType == Sequence.PPQ) 105: division = resolution & 0x7fff; 106: dos.writeShort(division); 107: int length = 14; 108: for (int i = 0; i < tracks.length; i++) 109: length += writeTrack(tracks[i], dos); 110: return length; 111: } 112: 113: /** 114: * Compute the length of a track as it will be written to the 115: * output stream. 116: * 117: * @param track the track to measure 118: * @param dos a MidiDataOutputStream used for helper method 119: * @return the length of the track 120: */ 121: private int computeTrackLength(Track track, MidiDataOutputStream dos) 122: { 123: int count = 0, length = 0, i = 0, eventCount = track.size(); 124: long ptick = 0; 125: while (i < eventCount) 126: { 127: MidiEvent me = track.get(i); 128: long tick = me.getTick(); 129: length += dos.variableLengthIntLength((int) (tick - ptick)); 130: ptick = tick; 131: length += me.getMessage().getLength(); 132: i++; 133: } 134: return length; 135: } 136: 137: /** 138: * Write a track to an output stream. 139: * 140: * @param track the track to write 141: * @param dos a MidiDataOutputStream to write to 142: * @return the number of bytes written 143: */ 144: private int writeTrack(Track track, MidiDataOutputStream dos) 145: throws IOException 146: { 147: int i = 0, elength = track.size(), trackLength; 148: MidiEvent pme = null; 149: dos.writeInt(0x4d54726b); // "MTrk" 150: trackLength = computeTrackLength(track, dos); 151: dos.writeInt(trackLength); 152: while (i < elength) 153: { 154: MidiEvent me = track.get(i); 155: int dtime = 0; 156: if (pme != null) 157: dtime = (int) (me.getTick() - pme.getTick()); 158: dos.writeVariableLengthInt(dtime); 159: // FIXME: use running status byte 160: byte msg[] = me.getMessage().getMessage(); 161: dos.write(msg); 162: pme = me; 163: i++; 164: } 165: 166: // We're done if the last event was an End of Track meta message. 167: if (pme != null && (pme.getMessage() instanceof MetaMessage)) 168: { 169: MetaMessage mm = (MetaMessage) pme.getMessage(); 170: if (mm.getType() == 0x2f) // End of Track message 171: return trackLength + 8; 172: } 173: 174: // Write End of Track meta message 175: dos.writeVariableLengthInt(0); // Delta time of 0 176: dos.writeByte(0xff); // Meta Message 177: dos.writeByte(0x2f); // End of Track message 178: dos.writeVariableLengthInt(0); // Length of 0 179: 180: return trackLength + 8 + 4; 181: } 182: 183: /* Write a Sequence to a file. 184: * @see javax.sound.midi.spi.MidiFileWriter#write(javax.sound.midi.Sequence, int, java.io.File) 185: */ 186: public int write(Sequence in, int fileType, File out) throws IOException 187: { 188: OutputStream os = new FileOutputStream(out); 189: try 190: { 191: return write(in, fileType, os); 192: } 193: finally 194: { 195: os.close(); 196: } 197: } 198: 199: }