org.deepsymmetry.beatlink

Class BeatFinder

java.lang.Object

org.deepsymmetry.beatlink.LifecycleParticipant

org.deepsymmetry.beatlink.BeatFinder

public class BeatFinder
extends LifecycleParticipant

Watches for devices to report new beats by broadcasting beat packets on port 50001, and passes them on to registered listeners. When players are actively playing music, they send beat packets at the start of each beat which, in addition to announcing the start of the beat, provide information about where the beat falls within a measure of music (assuming that the track was properly configured in rekordbox, and is in 4/4 time), the current BPM of the track being played, and the current player pitch adjustment, from which the actual effective BPM can be calculated.

When players are stopped, they do not send beat packets, but the mixer continues sending them at the last BPM reported by the master player, so it acts as the most reliable synchronization source. The mixer does not make any effort to keep its notion of measures (down beats) consistent with any player, however. So systems which want to stay in sync with measures as well as beats will want to use the VirtualCdj to maintain awareness of which player is the master player.

This class also receives special sync and on-air control messages which are sent to the same port as beat packets. If the VirtualCdj is sending status packets, it needs to be notified about these so it can properly update its sync and on-air state if the mixer tells it to, so it will ensure the BeatFinder is running whenever it is sending status updates.

Author:

James Elliott

Field Summary

Fields

Modifier and Type	Field and Description
static int	BEAT_PORT The port to which devices broadcast beat messages.

Method Summary

Modifier and Type	Method and Description
void	addBeatListener(BeatListener listener) Adds the specified beat listener to receive beat announcements when DJ Link devices broadcast them on the network.
void	addFaderStartListener(FaderStartListener listener) Adds the specified fader start listener to receive fader start commands when the mixer broadcasts them on the network.
void	addMasterHandoffListener(MasterHandoffListener listener) Adds the specified master handoff listener to receive tempo master handoff commands when DJ Link devices send them to Beat Link.
void	addOnAirListener(OnAirListener listener) Adds the specified on-air listener to receive channel on-air updates when the mixer broadcasts them on the network.
void	addSyncListener(SyncListener listener) Adds the specified sync command listener to receive sync commands when DJ Link devices send them to Beat Link.
Set<BeatListener>	getBeatListeners() Get the set of beat listeners that are currently registered.
Set<FaderStartListener>	getFaderStartListeners() Get the set of fader start listeners that are currently registered.
static BeatFinder	getInstance() Get the singleton instance of this class.
Set<MasterHandoffListener>	getMasterHandoffListeners() Get the set of master handoff command listeners that are currently registered.
Set<OnAirListener>	getOnAirListeners() Get the set of on-air listeners that are currently registered.
Set<SyncListener>	getSyncListeners() Get the set of sync command listeners that are currently registered.
boolean	isRunning() Check whether we are presently listening for beat packets.
void	removeBeatListener(BeatListener listener) Removes the specified beat listener so that it no longer receives beat announcements when DJ Link devices broadcast them to the network.
void	removeFaderStartListener(FaderStartListener listener) Removes the specified fader start listener so that it no longer receives fader start commands when the mixer broadcasts them to the network.
void	removeMasterHandoffListener(MasterHandoffListener listener) Removes the specified master handoff listener so that it no longer receives tempo master handoff commands when DJ Link devices send them to Beat Link.
void	removeOnAirListener(OnAirListener listener) Removes the specified on-air listener so that it no longer receives channel on-air updates when the mixer broadcasts them to the network.
void	removeSyncListener(SyncListener listener) Removes the specified sync listener so that it no longer receives sync commands when DJ Link devices send them to Beat Link.
void	start() Start listening for beat announcements and sync commands.
void	stop() Stop listening for beats.
String	toString()

Methods inherited from class org.deepsymmetry.beatlink.LifecycleParticipant

addLifecycleListener, deliverLifecycleAnnouncement, ensureRunning, getLifecycleListeners, removeLifecycleListener

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

BEAT_PORT

public static final int BEAT_PORT

The port to which devices broadcast beat messages.

See Also:

Constant Field Values

Method Detail

isRunning

public boolean isRunning()

Check whether we are presently listening for beat packets.

Specified by:

isRunning in class LifecycleParticipant

Returns:

true if our socket is open and monitoring for DJ Link beat packets on the network

start

public void start()
           throws SocketException

Start listening for beat announcements and sync commands. If already listening, has no effect.

Throws:

SocketException - if the socket to listen on port 50001 cannot be created

stop

public void stop()

Stop listening for beats.

addBeatListener

public void addBeatListener(BeatListener listener)

Adds the specified beat listener to receive beat announcements when DJ Link devices broadcast them on the network. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

To reduce latency, beat announcements are delivered to listeners directly on the thread that is receiving them them from the network, so if you want to interact with user interface objects in listener methods, you need to use javax.swing.SwingUtilities.invokeLater(Runnable) to do so on the Event Dispatch Thread. Even if you are not interacting with user interface objects, any code in the listener method must finish quickly, or it will add latency for other listeners, and beat announcements will back up. If you want to perform lengthy processing of any sort, do so on another thread.

Parameters:

listener - the beat listener to add

removeBeatListener

public void removeBeatListener(BeatListener listener)

Removes the specified beat listener so that it no longer receives beat announcements when DJ Link devices broadcast them to the network. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the beat listener to remove

getBeatListeners

public Set<BeatListener> getBeatListeners()

Get the set of beat listeners that are currently registered.

Returns:

the currently registered beat listeners

addSyncListener

public void addSyncListener(SyncListener listener)

Adds the specified sync command listener to receive sync commands when DJ Link devices send them to Beat Link. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

To reduce latency, sync commands are delivered to listeners directly on the thread that is receiving them them from the network, so if you want to interact with user interface objects in listener methods, you need to use javax.swing.SwingUtilities.invokeLater(Runnable) to do so on the Event Dispatch Thread. Even if you are not interacting with user interface objects, any code in the listener method must finish quickly, or it will add latency for other listeners, and beat announcements will back up. If you want to perform lengthy processing of any sort, do so on another thread.

Parameters:

listener - the sync listener to add

removeSyncListener

public void removeSyncListener(SyncListener listener)

Removes the specified sync listener so that it no longer receives sync commands when DJ Link devices send them to Beat Link. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the sync listener to remove

getSyncListeners

public Set<SyncListener> getSyncListeners()

Get the set of sync command listeners that are currently registered.

Returns:

the currently registered sync listeners

addMasterHandoffListener

public void addMasterHandoffListener(MasterHandoffListener listener)

Adds the specified master handoff listener to receive tempo master handoff commands when DJ Link devices send them to Beat Link. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

To reduce latency, handoff commands are delivered to listeners directly on the thread that is receiving them them from the network, so if you want to interact with user interface objects in listener methods, you need to use javax.swing.SwingUtilities.invokeLater(Runnable) to do so on the Event Dispatch Thread. Even if you are not interacting with user interface objects, any code in the listener method must finish quickly, or it will add latency for other listeners, and beat announcements will back up. If you want to perform lengthy processing of any sort, do so on another thread.

Parameters:

listener - the tempo master handoff listener to add

removeMasterHandoffListener

public void removeMasterHandoffListener(MasterHandoffListener listener)

Removes the specified master handoff listener so that it no longer receives tempo master handoff commands when DJ Link devices send them to Beat Link. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the tempo master handoff listener to remove

getMasterHandoffListeners

public Set<MasterHandoffListener> getMasterHandoffListeners()

Get the set of master handoff command listeners that are currently registered.

Returns:

the currently registered tempo master handoff command listeners

addOnAirListener

public void addOnAirListener(OnAirListener listener)

Adds the specified on-air listener to receive channel on-air updates when the mixer broadcasts them on the network. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

To reduce latency, on-air updates are delivered to listeners directly on the thread that is receiving them them from the network, so if you want to interact with user interface objects in listener methods, you need to use javax.swing.SwingUtilities.invokeLater(Runnable) to do so on the Event Dispatch Thread. Even if you are not interacting with user interface objects, any code in the listener method must finish quickly, or it will add latency for other listeners, and beat announcements will back up. If you want to perform lengthy processing of any sort, do so on another thread.

Parameters:

listener - the on-air listener to add

removeOnAirListener

public void removeOnAirListener(OnAirListener listener)

Removes the specified on-air listener so that it no longer receives channel on-air updates when the mixer broadcasts them to the network. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the on-air listener to remove

getOnAirListeners

public Set<OnAirListener> getOnAirListeners()

Get the set of on-air listeners that are currently registered.

Returns:

the currently registered on-air listeners

addFaderStartListener

public void addFaderStartListener(FaderStartListener listener)

Adds the specified fader start listener to receive fader start commands when the mixer broadcasts them on the network. If listener is null or already present in the list of registered listeners, no exception is thrown and no action is performed.

To reduce latency, fader start commands are delivered to listeners directly on the thread that is receiving them them from the network, so if you want to interact with user interface objects in listener methods, you need to use javax.swing.SwingUtilities.invokeLater(Runnable) to do so on the Event Dispatch Thread. Even if you are not interacting with user interface objects, any code in the listener method must finish quickly, or it will add latency for other listeners, and beat announcements will back up. If you want to perform lengthy processing of any sort, do so on another thread.

Parameters:

listener - the fader start listener to add

removeFaderStartListener

public void removeFaderStartListener(FaderStartListener listener)

Removes the specified fader start listener so that it no longer receives fader start commands when the mixer broadcasts them to the network. If listener is null or not present in the list of registered listeners, no exception is thrown and no action is performed.

Parameters:

listener - the fader start listener to remove

getFaderStartListeners

public Set<FaderStartListener> getFaderStartListeners()

Get the set of fader start listeners that are currently registered.

Returns:

the currently registered fader start listeners

getInstance

public static BeatFinder getInstance()

Get the singleton instance of this class.

Returns:

the only instance of this class which exists.

toString

public String toString()

Overrides:

toString in class Object