javax.sound.midi
Interface Sequencer

All Superinterfaces:

MidiDevice

public interface Sequencer

extends MidiDevice

A hardware or software device that plays back a MIDI sequence is known as a sequencer. A MIDI sequence contains lists of time-stamped MIDI data, such as might be read from a standard MIDI file. Most sequencers also provide functions for creating and editing sequences.

The Sequencer interface includes methods for the following basic MIDI sequencer operations:

• obtaining a sequence from MIDI file data
• starting and stopping playback
• moving to an arbitrary position in the sequence
• changing the tempo (speed) of playback
• synchronizing playback to an internal clock or to received MIDI messages
• controlling the timing of another device

In addition, the following operations are supported, either directly, or indirectly through objects that the Sequencer has access to:

• editing the data by adding or deleting individual MIDI events or entire tracks
• muting or soloing individual tracks in the sequence
• notifying listener objects about any meta-events or control-change events encountered while playing back the sequence.

See Also:

Sequencer.SyncMode, addMetaEventListener(javax.sound.midi.MetaEventListener), ControllerEventListener, Receiver, Transmitter, MidiDevice

Nested Class Summary

static class

Sequencer.SyncMode A SyncMode object represents one of the ways in which a MIDI sequencer's notion of time can be synchronized with a master or slave device.

Nested classes inherited from class javax.sound.midi.MidiDevice

MidiDevice.Info

Method Summary

int[]	addControllerEventListener(ControllerEventListener listener, int[] controllers) Registers a controller event listener to receive notification whenever the sequencer processes a control-change event of the requested type or types.
boolean	addMetaEventListener(MetaEventListener listener) Registers a meta-event listener to receive notification whenever a meta-event is encountered in the sequence and processed by the sequencer.
Sequencer.SyncMode	getMasterSyncMode() Obtains the current master synchronization mode for this sequencer.
Sequencer.SyncMode[]	getMasterSyncModes() Obtains the set of master synchronization modes supported by this sequencer.
long	getMicrosecondLength() Obtains the length of the current sequence, expressed in microseconds.
long	getMicrosecondPosition() Obtains the current position in the sequence, expressed in microseconds.
Sequence	getSequence() Obtains the sequence on which the Sequencer is currently operating.
Sequencer.SyncMode	getSlaveSyncMode() Obtains the current slave synchronization mode for this sequencer.
Sequencer.SyncMode[]	getSlaveSyncModes() Obtains the set of slave synchronization modes supported by the sequencer.
float	getTempoFactor() Returns the current tempo factor for the sequencer.
float	getTempoInBPM() Obtains the current tempo, expressed in beats per minute.
float	getTempoInMPQ() Obtains the current tempo, expressed in microseconds per quarter note.
long	getTickLength() Obtains the length of the current sequence, expressed in MIDI ticks.
long	getTickPosition() Obtains the current position in the sequence, expressed in MIDI ticks.
boolean	getTrackMute(int track) Obtains the current mute state for a track.
boolean	getTrackSolo(int track) Obtains the current solo state for a track.
boolean	isRecording() Indicates whether the Sequencer is currently recording.
boolean	isRunning() Indicates whether the Sequencer is currently running.
void	recordDisable(Track track) Disables recording to the specified track.
void	recordEnable(Track track, int channel) Prepares the specified track for recording events received on a particular channel.
int[]	removeControllerEventListener(ControllerEventListener listener, int[] controllers) Removes a controller event listener's interest in one or more types of controller event.
void	removeMetaEventListener(MetaEventListener listener) Removes the specified meta-event listener from this sequencer's list of registered listeners, if in fact the listener is registered.
void	setMasterSyncMode(Sequencer.SyncMode sync) Sets the source of timing information used by this sequencer.
void	setMicrosecondPosition(long microseconds) Sets the current position in the sequence, expressed in microseconds
void	setSequence(InputStream stream) Sets the current sequence on which the sequencer operates.
void	setSequence(Sequence sequence) Sets the current sequence on which the sequencer operates.
void	setSlaveSyncMode(Sequencer.SyncMode sync) Sets the slave synchronization mode for the sequencer.
void	setTempoFactor(float factor) Scales the sequencer's actual playback tempo by the factor provided.
void	setTempoInBPM(float bpm) Sets the tempo in beats per minute.
void	setTempoInMPQ(float mpq) Sets the tempo in microseconds per quarter note.
void	setTickPosition(long tick) Sets the current sequencer position in MIDI ticks
void	setTrackMute(int track, boolean mute) Sets the mute state for a track.
void	setTrackSolo(int track, boolean solo) Sets the solo state for a track.
void	start() Starts playback of the MIDI data in the currently loaded sequence.
void	startRecording() Starts recording and playback of MIDI data.
void	stop() Stops recording, if active, and playback of the currently loaded sequence, if any.
void	stopRecording() Stops recording, if active.

Methods inherited from interface javax.sound.midi.MidiDevice

close, getDeviceInfo, getMaxReceivers, getMaxTransmitters, getReceiver, getTransmitter, isOpen, open

Method Detail

setSequence

public void setSequence(Sequence sequence)
                 throws InvalidMidiDataException

Sets the current sequence on which the sequencer operates.

Parameters:

sequence - the sequence to be loaded.

Throws:

InvalidMidiDataException - if the sequence contains invalid MIDI data, or is not supported.

setSequence

public void setSequence(InputStream stream)
                 throws IOException,
                        InvalidMidiDataException

Sets the current sequence on which the sequencer operates. The stream must point to MIDI file data.

Parameters:

stream - stream containing MIDI file data.

Throws:

IOException - if an I/O exception occurs during reading of the stream.

InvalidMidiDataException - if invalid data is encountered in the stream, or the stream is not supported.

getSequence

public Sequence getSequence()

Obtains the sequence on which the Sequencer is currently operating.

Returns:

the current sequence, or null if no sequence is currently set.

start

public void start()

Starts playback of the MIDI data in the currently loaded sequence.

See Also:

start(), stop()

stop

public void stop()

Stops recording, if active, and playback of the currently loaded sequence, if any.

See Also:

start(), isRunning()

isRunning

public boolean isRunning()

Indicates whether the Sequencer is currently running. The default is false. The Sequencer starts running when either start() or startRecording() is called. isRunning then returns true until playback of the sequence completes or stop() is called.

Returns:

true if the Sequencer is running, otherwise false

startRecording

public void startRecording()

Starts recording and playback of MIDI data. Data is recorded to all enabled tracks, on the channel(s) for which they were enabled. Recording begins at the current position of the sequencer. Any events already in the track are overwritten for the duration of the recording session. Events from the currently loaded sequence, if any, are delivered to the sequencer's MIDI OUT receiver(s) along with messages received during recording.

Note that tracks are not by default enabled for recording. In order to record MIDI data, at least one track must be specifically enabled for recording.

See Also:

startRecording(), recordEnable(javax.sound.midi.Track, int), recordDisable(javax.sound.midi.Track)

stopRecording

public void stopRecording()

Stops recording, if active. Playback of the current sequence continues.

See Also:

startRecording(), isRecording()

isRecording

public boolean isRecording()

Indicates whether the Sequencer is currently recording. The default is false. The Sequencer begins recording when startRecording() is called, and then returns true until stop() or stopRecording() is called.

Returns:

true if the Sequencer is recording, otherwise false

recordEnable

public void recordEnable(Track track,
                         int channel)

Prepares the specified track for recording events received on a particular channel. Once enabled, a track will receive events when recording is active.

Parameters:

track - the track to which events will be recorded

channel - the channel on which events will be received. If -1 is specified for the channel value, the track will receive data from all channels.

Throws:

IllegalArgumentException - thrown if the track is not part of the current sequence.

recordDisable

public void recordDisable(Track track)

Disables recording to the specified track. Events will no longer be recorded into this track.

Parameters:

track - the track to disable for recording, or null to disable recording for all tracks.

getTempoInBPM

public float getTempoInBPM()

Obtains the current tempo, expressed in beats per minute. The actual tempo of playback is the product of the returned value and the tempo factor.

Returns:

the current tempo in beats per minute

See Also:

getTempoFactor(), setTempoInBPM(float), getTempoInMPQ()

setTempoInBPM

public void setTempoInBPM(float bpm)

Sets the tempo in beats per minute. The actual tempo of playback is the product of the specified value and the tempo factor.

Parameters:

bpm - desired new tempo in beats per minute

See Also:

getTempoFactor(), setTempoInMPQ(float), getTempoInBPM()

getTempoInMPQ

public float getTempoInMPQ()

Obtains the current tempo, expressed in microseconds per quarter note. The actual tempo of playback is the product of the returned value and the tempo factor.

Returns:

the current tempo in microseconds per quarter note

See Also:

getTempoFactor(), setTempoInMPQ(float), getTempoInBPM()

setTempoInMPQ

public void setTempoInMPQ(float mpq)

Sets the tempo in microseconds per quarter note. The actual tempo of playback is the product of the specified value and the tempo factor.

Parameters:

mpq - desired new tempo in microseconds per quarter note.

See Also:

getTempoFactor(), setTempoInBPM(float), getTempoInMPQ()

setTempoFactor

public void setTempoFactor(float factor)

Scales the sequencer's actual playback tempo by the factor provided. The default is 1.0. A value of 1.0 represents the natural rate (the tempo specified in the sequence), 2.0 means twice as fast, etc. The tempo factor does not affect the values returned by getTempoInMPQ() and getTempoInBPM(). Those values indicate the tempo prior to scaling.

Note that the tempo factor cannot be adjusted when external synchronization is used. In that situation, setTempoFactor always sets the tempo factor to 1.0.

Parameters:

factor - the requested tempo scalar

See Also:

getTempoFactor()

getTempoFactor

public float getTempoFactor()

Returns the current tempo factor for the sequencer. The default is 1.0.

Returns:

tempo factor.

See Also:

setTempoFactor(float)

getTickLength

public long getTickLength()

Obtains the length of the current sequence, expressed in MIDI ticks.

Returns:

length of the sequence in ticks

getTickPosition

public long getTickPosition()

Obtains the current position in the sequence, expressed in MIDI ticks. (The duration of a tick in seconds is determined both by the tempo and by the timing resolution stored in the Sequence.)

Returns:

current tick

See Also:

setTickPosition(long)

setTickPosition

public void setTickPosition(long tick)

Sets the current sequencer position in MIDI ticks

Parameters:

tick - the desired tick position

See Also:

getTickPosition()

getMicrosecondLength

public long getMicrosecondLength()

Obtains the length of the current sequence, expressed in microseconds.

Returns:

length of the sequence in microseconds

getMicrosecondPosition

public long getMicrosecondPosition()

Obtains the current position in the sequence, expressed in microseconds.

Specified by:

getMicrosecondPosition in interface MidiDevice

Returns:

the current position in microseconds

See Also:

setMicrosecondPosition(long)

setMicrosecondPosition

public void setMicrosecondPosition(long microseconds)

Sets the current position in the sequence, expressed in microseconds

Parameters:

microseconds - desired position in microseconds

See Also:

getMicrosecondPosition()

setMasterSyncMode

public void setMasterSyncMode(Sequencer.SyncMode sync)

Sets the source of timing information used by this sequencer. The sequencer synchronizes to the master, which is the internal clock, MIDI clock, or MIDI time code, depending on the value of sync. The sync argument must be one of the supported modes, as returned by getMasterSyncModes().

Parameters:

sync - the desired master synchronization mode

See Also:

Sequencer.SyncMode.INTERNAL_CLOCK, Sequencer.SyncMode.MIDI_SYNC, Sequencer.SyncMode.MIDI_TIME_CODE, getMasterSyncMode()

getMasterSyncMode

public Sequencer.SyncMode getMasterSyncMode()

Obtains the current master synchronization mode for this sequencer.

Returns:

the current master synchronization mode

See Also:

setMasterSyncMode(Sequencer.SyncMode), getMasterSyncModes()

getMasterSyncModes

public Sequencer.SyncMode[] getMasterSyncModes()

Obtains the set of master synchronization modes supported by this sequencer.

Returns:

the available master synchronization modes

See Also:

Sequencer.SyncMode.INTERNAL_CLOCK, Sequencer.SyncMode.MIDI_SYNC, Sequencer.SyncMode.MIDI_TIME_CODE, getMasterSyncMode(), setMasterSyncMode(Sequencer.SyncMode)

setSlaveSyncMode

public void setSlaveSyncMode(Sequencer.SyncMode sync)

Sets the slave synchronization mode for the sequencer. This indicates the type of timing information sent by the sequencer to its receiver. The sync argument must be one of the supported modes, as returned by getSlaveSyncModes().

Parameters:

sync - the desired slave synchronization mode

See Also:

Sequencer.SyncMode.MIDI_SYNC, Sequencer.SyncMode.MIDI_TIME_CODE, Sequencer.SyncMode.NO_SYNC, getSlaveSyncModes()

getSlaveSyncMode

public Sequencer.SyncMode getSlaveSyncMode()

Obtains the current slave synchronization mode for this sequencer.

Returns:

the current slave synchronization mode

See Also:

setSlaveSyncMode(Sequencer.SyncMode), getSlaveSyncModes()

getSlaveSyncModes

public Sequencer.SyncMode[] getSlaveSyncModes()

Obtains the set of slave synchronization modes supported by the sequencer.

Returns:

the available slave synchronization modes

See Also:

Sequencer.SyncMode.MIDI_SYNC, Sequencer.SyncMode.MIDI_TIME_CODE, Sequencer.SyncMode.NO_SYNC

setTrackMute

public void setTrackMute(int track,
                         boolean mute)

Sets the mute state for a track. This method may fail for a number of reasons. For example, the track number specified may not be valid for the current sequence, or the sequencer may not support this functionality. An application which needs to verify whether this operation succeeded should follow this call with a call to getTrackMute(int).

Parameters:

track - the track number. Tracks in the current sequence are numbered from 0 to the number of tracks in the sequence minus 1.

mute - the new mute state for the track. true implies the track should be muted, false implies the track should be unmuted.

See Also:

getSequence()

getTrackMute

public boolean getTrackMute(int track)

Obtains the current mute state for a track. The default mute state for all tracks which have not been muted is false. In any case where the specified track has not been muted, this method should return false. This applies if the sequencer does not support muting of tracks, and if the specified track index is not valid.

Parameters:

track - the track number. Tracks in the current sequence are numbered from 0 to the number of tracks in the sequence minus 1.

Returns:

true if muted, false if not.

setTrackSolo

public void setTrackSolo(int track,
                         boolean solo)

Sets the solo state for a track. If solo is true only this track and other solo'd tracks will sound. If solo is false then only other solo'd tracks will sound, unless no tracks are solo'd in which case all un-muted tracks will sound.

This method may fail for a number of reasons. For example, the track number specified may not be valid for the current sequence, or the sequencer may not support this functionality. An application which needs to verify whether this operation succeeded should follow this call with a call to getTrackSolo(int).

Parameters:

track - the track number. Tracks in the current sequence are numbered from 0 to the number of tracks in the sequence minus 1.

solo - the new solo state for the track. true implies the track should be solo'd, false implies the track should not be solo'd.

See Also:

getSequence()

getTrackSolo

public boolean getTrackSolo(int track)

Obtains the current solo state for a track. The default mute state for all tracks which have not been solo'd is false. In any case where the specified track has not been solo'd, this method should return false. This applies if the sequencer does not support soloing of tracks, and if the specified track index is not valid.

Parameters:

track - the track number. Tracks in the current sequence are numbered from 0 to the number of tracks in the sequence minus 1.

Returns:

true if solo'd, false if not.

addMetaEventListener

public boolean addMetaEventListener(MetaEventListener listener)

Registers a meta-event listener to receive notification whenever a meta-event is encountered in the sequence and processed by the sequencer. This method can fail if, for instance,this class of sequencer does not support meta-event notification.

Parameters:

listener - listener to add

Returns:

true if the listener was successfully added, otherwise false

See Also:

removeMetaEventListener(javax.sound.midi.MetaEventListener), MetaEventListener, MetaMessage

removeMetaEventListener

public void removeMetaEventListener(MetaEventListener listener)

Removes the specified meta-event listener from this sequencer's list of registered listeners, if in fact the listener is registered.

Parameters:

listener - the meta-event listener to remove

See Also:

addMetaEventListener(javax.sound.midi.MetaEventListener)

addControllerEventListener

public int[] addControllerEventListener(ControllerEventListener listener,
                                        int[] controllers)

Registers a controller event listener to receive notification whenever the sequencer processes a control-change event of the requested type or types. The types are specified by the controllers argument, which should contain an array of MIDI controller numbers. (Each number should be between 0 and 127, inclusive. See the MIDI 1.0 Specification for the numbers that correspond to various types of controllers.)

The returned array contains the MIDI controller numbers for which the listener will now receive events. Some sequencers might not support controller event notification, in which case the array has a length of 0. Other sequencers might support notification for some controllers but not all. This method may be invoked repeatedly. Each time, the returned array indicates all the controllers that the listener will be notified about, not only the controllers requested in that particular invocation.

Parameters:

listener - the controller event listener to add to the list of registered listeners

controllers - the MIDI controller numbers for which change notification is requested

Returns:

the numbers of all the MIDI controllers whose changes will now be reported to the specified listener

See Also:

removeControllerEventListener(javax.sound.midi.ControllerEventListener, int[]), ControllerEventListener

removeControllerEventListener

public int[] removeControllerEventListener(ControllerEventListener listener,
                                           int[] controllers)

Removes a controller event listener's interest in one or more types of controller event. The controllers argument is an array of MIDI numbers corresponding to the controllers for which the listener should no longer receive change notifications. To completely remove this listener from the list of registered listeners, pass in null for controllers. The returned array contains the MIDI controller numbers for which the listener will now receive events. The array has a length of 0 if the listener will not receive change notifications for any controllers.

Parameters:

listener - old listener

controllers - the MIDI controller numbers for which change notification should be cancelled, or null to cancel for all controllers

Returns:

the numbers of all the MIDI controllers whose changes will now be reported to the specified listener

See Also:

addControllerEventListener(javax.sound.midi.ControllerEventListener, int[])