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package javax.sound.midi;
/**
* A <code>VoiceStatus</code> object contains information about the current
* status of one of the voices produced by a {@link Synthesizer}.
* <p>
* MIDI synthesizers are generally capable of producing some maximum number of
* simultaneous notes, also referred to as voices. A voice is a stream
* of successive single notes, and the process of assigning incoming MIDI notes to
* specific voices is known as voice allocation.
* However, the voice-allocation algorithm and the contents of each voice are
* normally internal to a MIDI synthesizer and hidden from outside view. One can, of
* course, learn from MIDI messages which notes the synthesizer is playing, and
* one might be able deduce something about the assignment of notes to voices.
* But MIDI itself does not provide a means to report which notes a
* synthesizer has assigned to which voice, nor even to report how many voices
* the synthesizer is capable of synthesizing.
* <p>
* In Java Sound, however, a
* <code>Synthesizer</code> class can expose the contents of its voices through its
* {@link Synthesizer#getVoiceStatus() getVoiceStatus()} method.
* This behavior is recommended but optional;
* synthesizers that don't expose their voice allocation simply return a
* zero-length array. A <code>Synthesizer</code> that does report its voice status
* should maintain this information at
* all times for all of its voices, whether they are currently sounding or
* not. In other words, a given type of <code>Synthesizer</code> always has a fixed
* number of voices, equal to the maximum number of simultaneous notes it is
* capable of sounding.
* <p>
* <A NAME="description_of_active"></A>
* If the voice is not currently processing a MIDI note, it
* is considered inactive. A voice is inactive when it has
* been given no note-on commands, or when every note-on command received has
* been terminated by a corresponding note-off (or by an "all notes off"
* message). For example, this happens when a synthesizer capable of playing 16
* simultaneous notes is told to play a four-note chord; only
* four voices are active in this case (assuming no earlier notes are still playing).
* Usually, a voice whose status is reported as active is producing audible sound, but this
* is not always true; it depends on the details of the instrument (that
* is, the synthesis algorithm) and how long the note has been going on.
* For example, a voice may be synthesizing the sound of a single hand-clap. Because
* this sound dies away so quickly, it may become inaudible before a note-off
* message is received. In such a situation, the voice is still considered active
* even though no sound is currently being produced.
* <p>
* Besides its active or inactive status, the <code>VoiceStatus</code> class
* provides fields that reveal the voice's current MIDI channel, bank and
* program number, MIDI note number, and MIDI volume. All of these can
* change during the course of a voice. While the voice is inactive, each
* of these fields has an unspecified value, so you should check the active
* field first.
*
* @see Synthesizer#getMaxPolyphony
* @see Synthesizer#getVoiceStatus
*
* @author David Rivas
* @author Kara Kytle
*/
public class VoiceStatus {
/**
* Indicates whether the voice is currently processing a MIDI note.
* See the explanation of
* <A HREF="#description_of_active">active and inactive voices</A>.
*/
public boolean active = false;
/**
* The MIDI channel on which this voice is playing. The value is a
* zero-based channel number if the voice is active, or
* unspecified if the voice is inactive.
*
* @see MidiChannel
* @see #active
*/
public int channel = 0;
/**
* The bank number of the instrument that this voice is currently using.
* This is a number dictated by the MIDI bank-select message; it does not
* refer to a <code>SoundBank</code> object.
* The value ranges from 0 to 16383 if the voice is active, and is
* unspecified if the voice is inactive.
* @see Patch
* @see Soundbank
* @see #active
* @see MidiChannel#programChange(int, int)
*/
public int bank = 0;
/**
* The program number of the instrument that this voice is currently using.
* The value ranges from 0 to 127 if the voice is active, and is
* unspecified if the voice is inactive.
*
* @see MidiChannel#getProgram
* @see Patch
* @see #active
*/
public int program = 0;
/**
* The MIDI note that this voice is playing. The range for an active voice
* is from 0 to 127 in semitones, with 60 referring to Middle C.
* The value is unspecified if the voice is inactive.
*
* @see MidiChannel#noteOn
* @see #active
*/
public int note = 0;
/**
* The current MIDI volume level for the voice.
* The value ranges from 0 to 127 if the voice is active, and is
* unspecified if the voice is inactive.
* <p>
* Note that this value does not necessarily reflect
* the instantaneous level of the sound produced by this
* voice; that level is the result of many contributing
* factors, including the current instrument and the
* shape of the amplitude envelope it produces.
*
* @see #active
*/
public int volume = 0;
}