J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2002 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.sound.midi; |
| 27 | |
| 28 | |
| 29 | /** |
| 30 | * A <code>VoiceStatus</code> object contains information about the current |
| 31 | * status of one of the voices produced by a {@link Synthesizer}. |
| 32 | * <p> |
| 33 | * MIDI synthesizers are generally capable of producing some maximum number of |
| 34 | * simultaneous notes, also referred to as voices. A voice is a stream |
| 35 | * of successive single notes, and the process of assigning incoming MIDI notes to |
| 36 | * specific voices is known as voice allocation. |
| 37 | * However, the voice-allocation algorithm and the contents of each voice are |
| 38 | * normally internal to a MIDI synthesizer and hidden from outside view. One can, of |
| 39 | * course, learn from MIDI messages which notes the synthesizer is playing, and |
| 40 | * one might be able deduce something about the assignment of notes to voices. |
| 41 | * But MIDI itself does not provide a means to report which notes a |
| 42 | * synthesizer has assigned to which voice, nor even to report how many voices |
| 43 | * the synthesizer is capable of synthesizing. |
| 44 | * <p> |
| 45 | * In Java Sound, however, a |
| 46 | * <code>Synthesizer</code> class can expose the contents of its voices through its |
| 47 | * {@link Synthesizer#getVoiceStatus() getVoiceStatus()} method. |
| 48 | * This behavior is recommended but optional; |
| 49 | * synthesizers that don't expose their voice allocation simply return a |
| 50 | * zero-length array. A <code>Synthesizer</code> that does report its voice status |
| 51 | * should maintain this information at |
| 52 | * all times for all of its voices, whether they are currently sounding or |
| 53 | * not. In other words, a given type of <code>Synthesizer</code> always has a fixed |
| 54 | * number of voices, equal to the maximum number of simultaneous notes it is |
| 55 | * capable of sounding. |
| 56 | * <p> |
| 57 | * <A NAME="description_of_active"></A> |
| 58 | * If the voice is not currently processing a MIDI note, it |
| 59 | * is considered inactive. A voice is inactive when it has |
| 60 | * been given no note-on commands, or when every note-on command received has |
| 61 | * been terminated by a corresponding note-off (or by an "all notes off" |
| 62 | * message). For example, this happens when a synthesizer capable of playing 16 |
| 63 | * simultaneous notes is told to play a four-note chord; only |
| 64 | * four voices are active in this case (assuming no earlier notes are still playing). |
| 65 | * Usually, a voice whose status is reported as active is producing audible sound, but this |
| 66 | * is not always true; it depends on the details of the instrument (that |
| 67 | * is, the synthesis algorithm) and how long the note has been going on. |
| 68 | * For example, a voice may be synthesizing the sound of a single hand-clap. Because |
| 69 | * this sound dies away so quickly, it may become inaudible before a note-off |
| 70 | * message is received. In such a situation, the voice is still considered active |
| 71 | * even though no sound is currently being produced. |
| 72 | * <p> |
| 73 | * Besides its active or inactive status, the <code>VoiceStatus</code> class |
| 74 | * provides fields that reveal the voice's current MIDI channel, bank and |
| 75 | * program number, MIDI note number, and MIDI volume. All of these can |
| 76 | * change during the course of a voice. While the voice is inactive, each |
| 77 | * of these fields has an unspecified value, so you should check the active |
| 78 | * field first. |
| 79 | * |
| 80 | * @see Synthesizer#getMaxPolyphony |
| 81 | * @see Synthesizer#getVoiceStatus |
| 82 | * |
| 83 | * @author David Rivas |
| 84 | * @author Kara Kytle |
| 85 | */ |
| 86 | |
| 87 | public class VoiceStatus { |
| 88 | |
| 89 | |
| 90 | /** |
| 91 | * Indicates whether the voice is currently processing a MIDI note. |
| 92 | * See the explanation of |
| 93 | * <A HREF="#description_of_active">active and inactive voices</A>. |
| 94 | */ |
| 95 | public boolean active = false; |
| 96 | |
| 97 | |
| 98 | /** |
| 99 | * The MIDI channel on which this voice is playing. The value is a |
| 100 | * zero-based channel number if the voice is active, or |
| 101 | * unspecified if the voice is inactive. |
| 102 | * |
| 103 | * @see MidiChannel |
| 104 | * @see #active |
| 105 | */ |
| 106 | public int channel = 0; |
| 107 | |
| 108 | |
| 109 | /** |
| 110 | * The bank number of the instrument that this voice is currently using. |
| 111 | * This is a number dictated by the MIDI bank-select message; it does not |
| 112 | * refer to a <code>SoundBank</code> object. |
| 113 | * The value ranges from 0 to 16383 if the voice is active, and is |
| 114 | * unspecified if the voice is inactive. |
| 115 | * @see Patch |
| 116 | * @see Soundbank |
| 117 | * @see #active |
| 118 | * @see MidiChannel#programChange(int, int) |
| 119 | */ |
| 120 | public int bank = 0; |
| 121 | |
| 122 | |
| 123 | /** |
| 124 | * The program number of the instrument that this voice is currently using. |
| 125 | * The value ranges from 0 to 127 if the voice is active, and is |
| 126 | * unspecified if the voice is inactive. |
| 127 | * |
| 128 | * @see MidiChannel#getProgram |
| 129 | * @see Patch |
| 130 | * @see #active |
| 131 | */ |
| 132 | public int program = 0; |
| 133 | |
| 134 | |
| 135 | /** |
| 136 | * The MIDI note that this voice is playing. The range for an active voice |
| 137 | * is from 0 to 127 in semitones, with 60 referring to Middle C. |
| 138 | * The value is unspecified if the voice is inactive. |
| 139 | * |
| 140 | * @see MidiChannel#noteOn |
| 141 | * @see #active |
| 142 | */ |
| 143 | public int note = 0; |
| 144 | |
| 145 | |
| 146 | /** |
| 147 | * The current MIDI volume level for the voice. |
| 148 | * The value ranges from 0 to 127 if the voice is active, and is |
| 149 | * unspecified if the voice is inactive. |
| 150 | * <p> |
| 151 | * Note that this value does not necessarily reflect |
| 152 | * the instantaneous level of the sound produced by this |
| 153 | * voice; that level is the result of many contributing |
| 154 | * factors, including the current instrument and the |
| 155 | * shape of the amplitude envelope it produces. |
| 156 | * |
| 157 | * @see #active |
| 158 | */ |
| 159 | public int volume = 0; |
| 160 | } |