Manages the state of some audio and midi i/o devices. More...

Inheritance diagram for AudioDeviceManager:

Classes
struct	AudioDeviceSetup
	This structure holds a set of properties describing the current audio setup. More...

Public Member Functions
	AudioDeviceManager ()
	Creates a default AudioDeviceManager. More...

	~AudioDeviceManager ()
	Destructor. More...

String	initialise (int numInputChannelsNeeded, int numOutputChannelsNeeded, const XmlElement savedState, bool selectDefaultDeviceOnFailure, const String &preferredDefaultDeviceName=String(), const AudioDeviceSetup preferredSetupOptions=nullptr)
	Opens a set of audio devices ready for use. More...

String	initialiseWithDefaultDevices (int numInputChannelsNeeded, int numOutputChannelsNeeded)
	Resets everything to a default device setup, clearing any stored settings. More...

XmlElement *	createStateXml () const
	Returns some XML representing the current state of the manager. More...

void	getAudioDeviceSetup (AudioDeviceSetup &result)
	Returns the current device properties that are in use. More...

String	setAudioDeviceSetup (const AudioDeviceSetup &newSetup, bool treatAsChosenDevice)
	Changes the current device or its settings. More...

AudioIODevice *	getCurrentAudioDevice () const noexcept
	Returns the currently-active audio device. More...

String	getCurrentAudioDeviceType () const
	Returns the type of audio device currently in use. More...

AudioIODeviceType *	getCurrentDeviceTypeObject () const
	Returns the currently active audio device type object. More...

void	setCurrentAudioDeviceType (const String &type, bool treatAsChosenDevice)
	Changes the class of audio device being used. More...

void	closeAudioDevice ()
	Closes the currently-open device. More...

void	restartLastAudioDevice ()
	Tries to reload the last audio device that was running. More...

void	addAudioCallback (AudioIODeviceCallback *newCallback)
	Registers an audio callback to be used. More...

void	removeAudioCallback (AudioIODeviceCallback *callback)
	Deregisters a previously added callback. More...

double	getCpuUsage () const
	Returns the average proportion of available CPU being spent inside the audio callbacks. More...

void	setMidiInputEnabled (const String &midiInputDeviceName, bool enabled)
	Enables or disables a midi input device. More...

bool	isMidiInputEnabled (const String &midiInputDeviceName) const
	Returns true if a given midi input device is being used. More...

void	addMidiInputCallback (const String &midiInputDeviceName, MidiInputCallback *callback)
	Registers a listener for callbacks when midi events arrive from a midi input. More...

void	removeMidiInputCallback (const String &midiInputDeviceName, MidiInputCallback *callback)
	Removes a listener that was previously registered with addMidiInputCallback(). More...

void	setDefaultMidiOutput (const String &deviceName)
	Sets a midi output device to use as the default. More...

const String &	getDefaultMidiOutputName () const noexcept
	Returns the name of the default midi output. More...

MidiOutput *	getDefaultMidiOutput () const noexcept
	Returns the current default midi output device. More...

const OwnedArray< AudioIODeviceType > &	getAvailableDeviceTypes ()
	Returns a list of the types of device supported. More...

virtual void	createAudioDeviceTypes (OwnedArray< AudioIODeviceType > &types)
	Creates a list of available types. More...

void	addAudioDeviceType (AudioIODeviceType *newDeviceType)
	Adds a new device type to the list of types. More...

void	playTestSound ()
	Plays a beep through the current audio device. More...

void	playSound (const File &file)
	Plays a sound from a file. More...

void	playSound (const void *resourceData, size_t resourceSize)
	Convenient method to play sound from a JUCE resource. More...

void	playSound (AudioFormatReader *buffer, bool deleteWhenFinished=false)
	Plays the sound from an audio format reader. More...

void	playSound (PositionableAudioSource *audioSource, bool deleteWhenFinished=false)
	Plays the sound from a positionable audio source. More...

void	playSound (AudioSampleBuffer *buffer, bool deleteWhenFinished=false, bool playOnAllOutputChannels=false)
	Plays the sound from an audio sample buffer. More...

void	enableInputLevelMeasurement (bool enableMeasurement)
	Turns on level-measuring. More...

double	getCurrentInputLevel () const
	Returns the current input level. More...

CriticalSection &	getAudioCallbackLock () noexcept
	Returns the a lock that can be used to synchronise access to the audio callback. More...

CriticalSection &	getMidiCallbackLock () noexcept
	Returns the a lock that can be used to synchronise access to the midi callback. More...

Public Member Functions inherited from ChangeBroadcaster
	ChangeBroadcaster () noexcept
	Creates an ChangeBroadcaster. More...

virtual	~ChangeBroadcaster ()
	Destructor. More...

void	addChangeListener (ChangeListener *listener)
	Registers a listener to receive change callbacks from this broadcaster. More...

void	removeChangeListener (ChangeListener *listener)
	Unregisters a listener from the list. More...

void	removeAllChangeListeners ()
	Removes all listeners from the list. More...

void	sendChangeMessage ()
	Causes an asynchronous change message to be sent to all the registered listeners. More...

void	sendSynchronousChangeMessage ()
	Sends a synchronous change message to all the registered listeners. More...

void	dispatchPendingMessages ()
	If a change message has been sent but not yet dispatched, this will call sendSynchronousChangeMessage() to make the callback immediately. More...

Detailed Description

Manages the state of some audio and midi i/o devices.

This class keeps tracks of a currently-selected audio device, through with which it continuously streams data from an audio callback, as well as one or more midi inputs.

The idea is that your application will create one global instance of this object, and let it take care of creating and deleting specific types of audio devices internally. So when the device is changed, your callbacks will just keep running without having to worry about this.

The manager can save and reload all of its device settings as XML, which makes it very easy for you to save and reload the audio setup of your application.

And to make it easy to let the user change its settings, there's a component to do just that - the AudioDeviceSelectorComponent class, which contains a set of device selection/sample-rate/latency controls.

To use an AudioDeviceManager, create one, and use initialise() to set it up. Then call addAudioCallback() to register your audio callback with it, and use that to process your audio data.

The manager also acts as a handy hub for incoming midi messages, allowing a listener to register for messages from either a specific midi device, or from whatever the current default midi input device is. The listener then doesn't have to worry about re-registering with different midi devices if they are changed or deleted.

And yet another neat trick is that amount of CPU time being used is measured and available with the getCpuUsage() method.

The AudioDeviceManager is a ChangeBroadcaster, and will send a change message to listeners whenever one of its settings is changed.

See also: AudioDeviceSelectorComponent, AudioIODevice, AudioIODeviceType

Constructor & Destructor Documentation

AudioDeviceManager::AudioDeviceManager ( )

Creates a default AudioDeviceManager.

Initially no audio device will be selected. You should call the initialise() method and register an audio callback with setAudioCallback() before it'll be able to actually make any noise.

AudioDeviceManager::~AudioDeviceManager ( )

Destructor.

Member Function Documentation

String AudioDeviceManager::initialise	(	int	numInputChannelsNeeded,
		int	numOutputChannelsNeeded,
		const XmlElement *	savedState,
		bool	selectDefaultDeviceOnFailure,
		const String &	preferredDefaultDeviceName = `String()`,
		const AudioDeviceSetup *	preferredSetupOptions = `nullptr`
	)

Opens a set of audio devices ready for use.

This will attempt to open either a default audio device, or one that was previously saved as XML.

Parameters

numInputChannelsNeeded	the maximum number of input channels your app would like to use (the actual number of channels opened may be less than the number requested)
numOutputChannelsNeeded	the maximum number of output channels your app would like to use (the actual number of channels opened may be less than the number requested)
savedState	either a previously-saved state that was produced by createStateXml(), or nullptr if you want the manager to choose the best device to open.
selectDefaultDeviceOnFailure	if true, then if the device specified in the XML fails to open, then a default device will be used instead. If false, then on failure, no device is opened.
preferredDefaultDeviceName	if this is not empty, and there's a device with this name, then that will be used as the default device (assuming that there wasn't one specified in the XML). The string can actually be a simple wildcard, containing "*" and "?" characters
preferredSetupOptions	if this is non-null, the structure will be used as the set of preferred settings when opening the device. If you use this parameter, the preferredDefaultDeviceName field will be ignored

Returns: an error message if anything went wrong, or an empty string if it worked ok.

Referenced by StandalonePluginHolder::reloadAudioDeviceState().

String AudioDeviceManager::initialiseWithDefaultDevices	(	int	numInputChannelsNeeded,
		int	numOutputChannelsNeeded
	)

Resets everything to a default device setup, clearing any stored settings.

XmlElement* AudioDeviceManager::createStateXml ( ) const

Returns some XML representing the current state of the manager.

This stores the current device, its samplerate, block size, etc, and can be restored later with initialise().

Note that this can return a null pointer if no settings have been explicitly changed (i.e. if the device manager has just been left in its default state).

Referenced by StandalonePluginHolder::saveAudioDeviceState().

void AudioDeviceManager::getAudioDeviceSetup ( AudioDeviceSetup & result )

Returns the current device properties that are in use.

See also: setAudioDeviceSetup

String AudioDeviceManager::setAudioDeviceSetup	(	const AudioDeviceSetup &	newSetup,
		bool	treatAsChosenDevice
	)

Changes the current device or its settings.

If you want to change a device property, like the current sample rate or block size, you can call getAudioDeviceSetup() to retrieve the current settings, then tweak the appropriate fields in the AudioDeviceSetup structure, and pass it back into this method to apply the new settings.

Parameters

newSetup the settings that you'd like to use

treatAsChosenDevice if this is true and if the device opens correctly, these new settings will be taken as having been explicitly chosen by the user, and the next time createStateXml() is called, these settings will be returned. If it's false, then the device is treated as a temporary or default device, and a call to createStateXml() will return either the last settings that were made with treatAsChosenDevice as true, or the last XML settings that were passed into initialise().

Returns: an error message if anything went wrong, or an empty string if it worked ok.

See also: getAudioDeviceSetup

AudioIODevice* AudioDeviceManager::getCurrentAudioDevice ( ) const

noexcept

Returns the currently-active audio device.

String AudioDeviceManager::getCurrentAudioDeviceType ( ) const

Returns the type of audio device currently in use.

See also: setCurrentAudioDeviceType

AudioIODeviceType* AudioDeviceManager::getCurrentDeviceTypeObject ( ) const

Returns the currently active audio device type object.

Don't keep a copy of this pointer - it's owned by the device manager and could change at any time.

void AudioDeviceManager::setCurrentAudioDeviceType	(	const String &	type,
		bool	treatAsChosenDevice
	)

Changes the class of audio device being used.

This switches between, e.g. ASIO and DirectSound. On the Mac you probably won't ever call this because there's only one type: CoreAudio.

For a list of types, see getAvailableDeviceTypes().

void AudioDeviceManager::closeAudioDevice ( )

Closes the currently-open device.

You can call restartLastAudioDevice() later to reopen it in the same state that it was just in.

void AudioDeviceManager::restartLastAudioDevice ( )

Tries to reload the last audio device that was running.

Note that this only reloads the last device that was running before closeAudioDevice() was called - it doesn't reload any kind of saved-state, and can only be called after a device has been opened with SetAudioDevice().

If a device is already open, this call will do nothing.

void AudioDeviceManager::addAudioCallback ( AudioIODeviceCallback * newCallback )

Registers an audio callback to be used.

The manager will redirect callbacks from whatever audio device is currently in use to all registered callback objects. If more than one callback is active, they will all be given the same input data, and their outputs will be summed.

If necessary, this method will invoke audioDeviceAboutToStart() on the callback object before returning.

To remove a callback, use removeAudioCallback().

void AudioDeviceManager::removeAudioCallback ( AudioIODeviceCallback * callback )

Deregisters a previously added callback.

If necessary, this method will invoke audioDeviceStopped() on the callback object before returning.

See also: addAudioCallback

double AudioDeviceManager::getCpuUsage ( ) const

Returns the average proportion of available CPU being spent inside the audio callbacks.

Returns: A value between 0 and 1.0 to indicate the approximate proportion of CPU time spent in the callbacks.

void AudioDeviceManager::setMidiInputEnabled	(	const String &	midiInputDeviceName,
		bool	enabled
	)

Enables or disables a midi input device.

The list of devices can be obtained with the MidiInput::getDevices() method.

Any incoming messages from enabled input devices will be forwarded on to all the listeners that have been registered with the addMidiInputCallback() method. They can either register for messages from a particular device, or from just the "default" midi input.

Routing the midi input via an AudioDeviceManager means that when a listener registers for the default midi input, this default device can be changed by the manager without the listeners having to know about it or re-register.

It also means that a listener can stay registered for a midi input that is disabled or not present, so that when the input is re-enabled, the listener will start receiving messages again.

See also: addMidiInputCallback, isMidiInputEnabled

bool AudioDeviceManager::isMidiInputEnabled ( const String & midiInputDeviceName ) const

Returns true if a given midi input device is being used.

See also: setMidiInputEnabled

void AudioDeviceManager::addMidiInputCallback	(	const String &	midiInputDeviceName,
		MidiInputCallback *	callback
	)

Registers a listener for callbacks when midi events arrive from a midi input.

The device name can be empty to indicate that it wants to receive all incoming events from all the enabled MIDI inputs. Or it can be the name of one of the MIDI input devices if it just wants the events from that device. (see MidiInput::getDevices() for the list of device names).

Only devices which are enabled (see the setMidiInputEnabled() method) will have their events forwarded on to listeners.

void AudioDeviceManager::removeMidiInputCallback	(	const String &	midiInputDeviceName,
		MidiInputCallback *	callback
	)

Removes a listener that was previously registered with addMidiInputCallback().

void AudioDeviceManager::setDefaultMidiOutput ( const String & deviceName )

Sets a midi output device to use as the default.

The list of devices can be obtained with the MidiOutput::getDevices() method.

The specified device will be opened automatically and can be retrieved with the getDefaultMidiOutput() method.

Pass in an empty string to deselect all devices. For the default device, you can use MidiOutput::getDevices() [MidiOutput::getDefaultDeviceIndex()].

See also: getDefaultMidiOutput, getDefaultMidiOutputName

const String& AudioDeviceManager::getDefaultMidiOutputName ( ) const

noexcept

Returns the name of the default midi output.

See also: setDefaultMidiOutput, getDefaultMidiOutput

MidiOutput* AudioDeviceManager::getDefaultMidiOutput ( ) const

noexcept

Returns the current default midi output device.

If no device has been selected, or the device can't be opened, this will return nullptr.

See also: getDefaultMidiOutputName

const OwnedArray<AudioIODeviceType>& AudioDeviceManager::getAvailableDeviceTypes ( )

Returns a list of the types of device supported.

virtual void AudioDeviceManager::createAudioDeviceTypes ( OwnedArray< AudioIODeviceType > & types )

virtual

Creates a list of available types.

This will add a set of new AudioIODeviceType objects to the specified list, to represent each available types of device.

You can override this if your app needs to do something specific, like avoid using DirectSound devices, etc.

void AudioDeviceManager::addAudioDeviceType ( AudioIODeviceType * newDeviceType )

Adds a new device type to the list of types.

The manager will take ownership of the object that is passed-in.

void AudioDeviceManager::playTestSound ( )

Plays a beep through the current audio device.

This is here to allow the audio setup UI panels to easily include a "test" button so that the user can check where the audio is coming from.

void AudioDeviceManager::playSound ( const File & file )

Plays a sound from a file.

void AudioDeviceManager::playSound	(	const void *	resourceData,
		size_t	resourceSize
	)

Convenient method to play sound from a JUCE resource.

void AudioDeviceManager::playSound	(	AudioFormatReader *	buffer,
		bool	deleteWhenFinished = `false`
	)

Plays the sound from an audio format reader.

If deleteWhenFinished is true then the format reader will be automatically deleted once the sound has finished playing.

void AudioDeviceManager::playSound	(	PositionableAudioSource *	audioSource,
		bool	deleteWhenFinished = `false`
	)

Plays the sound from a positionable audio source.

This will output the sound coming from a positionable audio source. This gives you slightly more control over the sound playback compared to the other playSound methods. For example, if you would like to stop the sound prematurely you can call this method with a TransportAudioSource and then call audioSource->stop. Note that, you must call audioSource->start to start the playback, if your audioSource is a TransportAudioSource.

The audio device manager will not hold any references to this audio source once the audio source has stopped playing for any reason, for example when the sound has finished playing or when you have called audioSource->stop. Therefore, calling audioSource->start() on a finished audioSource will not restart the sound again. If this is desired simply call playSound with the same audioSource again.

Parameters

audioSource	the audio source to play
deleteWhenFinished	If this is true then the audio source will be deleted once the device manager has finished playing.

void AudioDeviceManager::playSound	(	AudioSampleBuffer *	buffer,
		bool	deleteWhenFinished = `false`,
		bool	playOnAllOutputChannels = `false`
	)

Plays the sound from an audio sample buffer.

This will output the sound contained in an audio sample buffer. If deleteWhenFinished is true then the audio sample buffer will be automatically deleted once the sound has finished playing.

If playOnAllOutputChannels is true, then if there are more output channels than buffer channels, then the ones that are available will be re-used on multiple outputs so that something is sent to all output channels. If it is false, then the buffer will just be played on the first output channels.

void AudioDeviceManager::enableInputLevelMeasurement ( bool enableMeasurement )

Turns on level-measuring.

When enabled, the device manager will measure the peak input level across all channels, and you can get this level by calling getCurrentInputLevel().

This is mainly intended for audio setup UI panels to use to create a mic level display, so that the user can check that they've selected the right device.

A simple filter is used to make the level decay smoothly, but this is only intended for giving rough feedback, and not for any kind of accurate measurement.

double AudioDeviceManager::getCurrentInputLevel ( ) const

Returns the current input level.

To use this, you must first enable it by calling enableInputLevelMeasurement(). See enableInputLevelMeasurement() for more info.

CriticalSection& AudioDeviceManager::getAudioCallbackLock ( )

noexcept

Returns the a lock that can be used to synchronise access to the audio callback.

Obviously while this is locked, you're blocking the audio thread from running, so it must only be used for very brief periods when absolutely necessary.

CriticalSection& AudioDeviceManager::getMidiCallbackLock ( )

noexcept

Returns the a lock that can be used to synchronise access to the midi callback.

Obviously while this is locked, you're blocking the midi system from running, so it must only be used for very brief periods when absolutely necessary.

The documentation for this class was generated from the following file:

juce_AudioDeviceManager.h

Classes

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation