1 /*
2 * Copyright (c) 1998, 2002, Oracle and/or its affiliates. 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
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7 * published by the Free Software Foundation. Oracle designates this
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9 * by Oracle 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 *
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
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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 }