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1 /* |
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2 * Copyright (c) 1998, 2002, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package javax.sound.midi; |
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27 |
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28 |
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29 /** |
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30 * A <code>VoiceStatus</code> object contains information about the current |
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31 * status of one of the voices produced by a {@link Synthesizer}. |
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32 * <p> |
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33 * MIDI synthesizers are generally capable of producing some maximum number of |
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34 * simultaneous notes, also referred to as voices. A voice is a stream |
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35 * of successive single notes, and the process of assigning incoming MIDI notes to |
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36 * specific voices is known as voice allocation. |
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37 * However, the voice-allocation algorithm and the contents of each voice are |
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38 * normally internal to a MIDI synthesizer and hidden from outside view. One can, of |
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39 * course, learn from MIDI messages which notes the synthesizer is playing, and |
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40 * one might be able deduce something about the assignment of notes to voices. |
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41 * But MIDI itself does not provide a means to report which notes a |
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42 * synthesizer has assigned to which voice, nor even to report how many voices |
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43 * the synthesizer is capable of synthesizing. |
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44 * <p> |
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45 * In Java Sound, however, a |
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46 * <code>Synthesizer</code> class can expose the contents of its voices through its |
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47 * {@link Synthesizer#getVoiceStatus() getVoiceStatus()} method. |
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48 * This behavior is recommended but optional; |
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49 * synthesizers that don't expose their voice allocation simply return a |
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50 * zero-length array. A <code>Synthesizer</code> that does report its voice status |
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51 * should maintain this information at |
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52 * all times for all of its voices, whether they are currently sounding or |
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53 * not. In other words, a given type of <code>Synthesizer</code> always has a fixed |
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54 * number of voices, equal to the maximum number of simultaneous notes it is |
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55 * capable of sounding. |
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56 * <p> |
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57 * <A NAME="description_of_active"></A> |
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58 * If the voice is not currently processing a MIDI note, it |
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59 * is considered inactive. A voice is inactive when it has |
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60 * been given no note-on commands, or when every note-on command received has |
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61 * been terminated by a corresponding note-off (or by an "all notes off" |
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62 * message). For example, this happens when a synthesizer capable of playing 16 |
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63 * simultaneous notes is told to play a four-note chord; only |
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64 * four voices are active in this case (assuming no earlier notes are still playing). |
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65 * Usually, a voice whose status is reported as active is producing audible sound, but this |
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66 * is not always true; it depends on the details of the instrument (that |
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67 * is, the synthesis algorithm) and how long the note has been going on. |
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68 * For example, a voice may be synthesizing the sound of a single hand-clap. Because |
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69 * this sound dies away so quickly, it may become inaudible before a note-off |
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70 * message is received. In such a situation, the voice is still considered active |
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71 * even though no sound is currently being produced. |
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72 * <p> |
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73 * Besides its active or inactive status, the <code>VoiceStatus</code> class |
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74 * provides fields that reveal the voice's current MIDI channel, bank and |
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75 * program number, MIDI note number, and MIDI volume. All of these can |
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76 * change during the course of a voice. While the voice is inactive, each |
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77 * of these fields has an unspecified value, so you should check the active |
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78 * field first. |
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79 * |
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80 * @see Synthesizer#getMaxPolyphony |
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81 * @see Synthesizer#getVoiceStatus |
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82 * |
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83 * @author David Rivas |
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84 * @author Kara Kytle |
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85 */ |
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86 |
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87 public class VoiceStatus { |
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88 |
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89 |
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90 /** |
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91 * Indicates whether the voice is currently processing a MIDI note. |
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92 * See the explanation of |
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93 * <A HREF="#description_of_active">active and inactive voices</A>. |
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94 */ |
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95 public boolean active = false; |
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96 |
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97 |
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98 /** |
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99 * The MIDI channel on which this voice is playing. The value is a |
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100 * zero-based channel number if the voice is active, or |
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101 * unspecified if the voice is inactive. |
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102 * |
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103 * @see MidiChannel |
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104 * @see #active |
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105 */ |
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106 public int channel = 0; |
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107 |
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108 |
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109 /** |
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110 * The bank number of the instrument that this voice is currently using. |
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111 * This is a number dictated by the MIDI bank-select message; it does not |
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112 * refer to a <code>SoundBank</code> object. |
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113 * The value ranges from 0 to 16383 if the voice is active, and is |
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114 * unspecified if the voice is inactive. |
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115 * @see Patch |
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116 * @see Soundbank |
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117 * @see #active |
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118 * @see MidiChannel#programChange(int, int) |
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119 */ |
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120 public int bank = 0; |
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121 |
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122 |
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123 /** |
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124 * The program number of the instrument that this voice is currently using. |
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125 * The value ranges from 0 to 127 if the voice is active, and is |
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126 * unspecified if the voice is inactive. |
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127 * |
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128 * @see MidiChannel#getProgram |
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129 * @see Patch |
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130 * @see #active |
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131 */ |
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132 public int program = 0; |
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133 |
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134 |
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135 /** |
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136 * The MIDI note that this voice is playing. The range for an active voice |
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137 * is from 0 to 127 in semitones, with 60 referring to Middle C. |
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138 * The value is unspecified if the voice is inactive. |
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139 * |
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140 * @see MidiChannel#noteOn |
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141 * @see #active |
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142 */ |
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143 public int note = 0; |
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144 |
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145 |
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146 /** |
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147 * The current MIDI volume level for the voice. |
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148 * The value ranges from 0 to 127 if the voice is active, and is |
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149 * unspecified if the voice is inactive. |
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150 * <p> |
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151 * Note that this value does not necessarily reflect |
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152 * the instantaneous level of the sound produced by this |
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153 * voice; that level is the result of many contributing |
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154 * factors, including the current instrument and the |
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155 * shape of the amplitude envelope it produces. |
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156 * |
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157 * @see #active |
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158 */ |
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159 public int volume = 0; |
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160 } |