Base class for audio processing filters or plugins. More...

Inheritance diagram for AudioProcessor:

Classes
struct	AudioBusArrangement
	Represents a set of input and output buses for an AudioProcessor. More...

struct	AudioProcessorBus
	Describes the layout and properties of an audio bus. More...

Public Types
enum	ProcessingPrecision { singlePrecision, doublePrecision }

enum	WrapperType { wrapperType_Undefined = 0, wrapperType_VST, wrapperType_VST3, wrapperType_AudioUnit, wrapperType_AudioUnitv3, wrapperType_RTAS, wrapperType_AAX, wrapperType_Standalone }
	Flags to indicate the type of plugin context in which a processor is being used. More...

Public Member Functions
virtual	~AudioProcessor ()
	Destructor. More...

virtual const String	getName () const =0
	Returns the name of this processor. More...

virtual void	prepareToPlay (double sampleRate, int maximumExpectedSamplesPerBlock)=0
	Called before playback starts, to let the filter prepare itself. More...

virtual void	releaseResources ()=0
	Called after playback has stopped, to let the filter free up any resources it no longer needs. More...

virtual void	processBlock (AudioBuffer< float > &buffer, MidiBuffer &midiMessages)=0
	Renders the next block. More...

virtual void	processBlock (AudioBuffer< double > &buffer, MidiBuffer &midiMessages)
	Renders the next block. More...

virtual void	processBlockBypassed (AudioBuffer< float > &buffer, MidiBuffer &midiMessages)
	Renders the next block when the processor is being bypassed. More...

virtual void	processBlockBypassed (AudioBuffer< double > &buffer, MidiBuffer &midiMessages)
	Renders the next block when the processor is being bypassed. More...

virtual bool	setPreferredBusArrangement (bool isInputBus, int busIndex, const AudioChannelSet &preferredSet)
	Called by the host, this attempts to change the plugin's channel layout on a particular bus. More...

virtual bool	supportsDoublePrecisionProcessing () const
	Returns true if the Audio processor supports double precision floating point processing. More...

ProcessingPrecision	getProcessingPrecision () const noexcept
	Returns the precision-mode of the processor. More...

bool	isUsingDoublePrecision () const noexcept
	Returns true if the current precision is set to doublePrecision. More...

void	setProcessingPrecision (ProcessingPrecision precision) noexcept
	Changes the processing precision of the receiver. More...

AudioPlayHead *	getPlayHead () const noexcept
	Returns the current AudioPlayHead object that should be used to find out the state and position of the playhead. More...

int	getTotalNumInputChannels () const noexcept
	Returns the total number of input channels. More...

int	getTotalNumOutputChannels () const noexcept
	Returns the total number of output channels. More...

int	getMainBusNumInputChannels () const noexcept
	Returns the number of input channels on the main bus. More...

int	getMainBusNumOutputChannels () const noexcept
	Returns the number of output channels on the main bus. More...

double	getSampleRate () const noexcept
	Returns the current sample rate. More...

int	getBlockSize () const noexcept
	Returns the current typical block size that is being used. More...

int	getLatencySamples () const noexcept
	This returns the number of samples delay that the filter imposes on the audio passing through it. More...

void	setLatencySamples (int newLatency)
	The filter should call this to set the number of samples delay that it introduces. More...

virtual double	getTailLengthSeconds () const =0
	Returns the length of the filter's tail, in seconds. More...

virtual bool	acceptsMidi () const =0
	Returns true if the processor wants midi messages. More...

virtual bool	producesMidi () const =0
	Returns true if the processor produces midi messages. More...

virtual bool	supportsMPE () const
	Returns true if the processor supports MPE. More...

const CriticalSection &	getCallbackLock () const noexcept
	This returns a critical section that will automatically be locked while the host is calling the processBlock() method. More...

void	suspendProcessing (bool shouldBeSuspended)
	Enables and disables the processing callback. More...

bool	isSuspended () const noexcept
	Returns true if processing is currently suspended. More...

virtual void	reset ()
	A plugin can override this to be told when it should reset any playing voices. More...

bool	isNonRealtime () const noexcept
	Returns true if the processor is being run in an offline mode for rendering. More...

virtual void	setNonRealtime (bool isNonRealtime) noexcept
	Called by the host to tell this processor whether it's being used in a non-realtime capacity for offline rendering or bouncing. More...

virtual AudioProcessorEditor *	createEditor ()=0
	Creates the filter's UI. More...

virtual bool	hasEditor () const =0
	Your filter must override this and return true if it can create an editor component. More...

AudioProcessorEditor *	getActiveEditor () const noexcept
	Returns the active editor, if there is one. More...

AudioProcessorEditor *	createEditorIfNeeded ()
	Returns the active editor, or if there isn't one, it will create one. More...

virtual int	getNumParameters ()
	This must return the correct value immediately after the object has been created, and mustn't change the number of parameters later. More...

virtual const String	getParameterName (int parameterIndex)
	Returns the name of a particular parameter. More...

virtual float	getParameter (int parameterIndex)
	Called by the host to find out the value of one of the filter's parameters. More...

virtual String	getParameterName (int parameterIndex, int maximumStringLength)
	Returns the name of a parameter as a text string with a preferred maximum length. More...

virtual const String	getParameterText (int parameterIndex)
	Returns the value of a parameter as a text string. More...

virtual String	getParameterText (int parameterIndex, int maximumStringLength)
	Returns the value of a parameter as a text string with a preferred maximum length. More...

virtual int	getParameterNumSteps (int parameterIndex)
	Returns the number of discrete steps that this parameter can represent. More...

virtual float	getParameterDefaultValue (int parameterIndex)
	Returns the default value for the parameter. More...

virtual String	getParameterLabel (int index) const
	Some plugin types may be able to return a label string for a parameter's units. More...

virtual bool	isParameterOrientationInverted (int index) const
	This can be overridden to tell the host that particular parameters operate in the reverse direction. More...

virtual void	setParameter (int parameterIndex, float newValue)
	The host will call this method to change the value of one of the filter's parameters. More...

void	setParameterNotifyingHost (int parameterIndex, float newValue)
	Your filter can call this when it needs to change one of its parameters. More...

virtual bool	isParameterAutomatable (int parameterIndex) const
	Returns true if the host can automate this parameter. More...

virtual bool	isMetaParameter (int parameterIndex) const
	Should return true if this parameter is a "meta" parameter. More...

void	beginParameterChangeGesture (int parameterIndex)
	Sends a signal to the host to tell it that the user is about to start changing this parameter. More...

void	endParameterChangeGesture (int parameterIndex)
	Tells the host that the user has finished changing this parameter. More...

void	updateHostDisplay ()
	The filter can call this when something (apart from a parameter value) has changed. More...

void	addParameter (AudioProcessorParameter *)
	Adds a parameter to the list. More...

const OwnedArray< AudioProcessorParameter > &	getParameters () const noexcept
	Returns the current list of parameters. More...

virtual int	getNumPrograms ()=0
	Returns the number of preset programs the filter supports. More...

virtual int	getCurrentProgram ()=0
	Returns the number of the currently active program. More...

virtual void	setCurrentProgram (int index)=0
	Called by the host to change the current program. More...

virtual const String	getProgramName (int index)=0
	Must return the name of a given program. More...

virtual void	changeProgramName (int index, const String &newName)=0
	Called by the host to rename a program. More...

virtual void	getStateInformation (juce::MemoryBlock &destData)=0
	The host will call this method when it wants to save the filter's internal state. More...

virtual void	getCurrentProgramStateInformation (juce::MemoryBlock &destData)
	The host will call this method if it wants to save the state of just the filter's current program. More...

virtual void	setStateInformation (const void *data, int sizeInBytes)=0
	This must restore the filter's state from a block of data previously created using getStateInformation(). More...

virtual void	setCurrentProgramStateInformation (const void *data, int sizeInBytes)
	The host will call this method if it wants to restore the state of just the filter's current program. More...

virtual void	numChannelsChanged ()
	This method is called when the number of input or output channels is changed. More...

virtual void	addListener (AudioProcessorListener *newListener)
	Adds a listener that will be called when an aspect of this processor changes. More...

virtual void	removeListener (AudioProcessorListener *listenerToRemove)
	Removes a previously added listener. More...

virtual void	setPlayHead (AudioPlayHead *newPlayHead)
	Tells the processor to use this playhead object. More...

void	setPlayConfigDetails (int numIns, int numOuts, double sampleRate, int blockSize)
	This is called by the processor to specify its details before being played. More...

void	setRateAndBufferSizeDetails (double sampleRate, int blockSize) noexcept
	This is called by the processor to specify its details before being played. More...

void	editorBeingDeleted (AudioProcessorEditor *) noexcept
	Not for public use - this is called before deleting an editor component. More...

Static Public Member Functions
static int	getDefaultNumParameterSteps () noexcept
	Returns the default number of steps for a parameter. More...

static void	copyXmlToBinary (const XmlElement &xml, juce::MemoryBlock &destData)
	Helper function that just converts an xml element into a binary blob. More...

static XmlElement *	getXmlFromBinary (const void *data, int sizeInBytes)
	Retrieves an XML element that was stored as binary with the copyXmlToBinary() method. More...

static void JUCE_CALLTYPE	setTypeOfNextNewPlugin (WrapperType)

Public Attributes
AudioBusArrangement	busArrangement
	The processor's bus arrangement. More...

WrapperType	wrapperType
	When loaded by a plugin wrapper, this flag will be set to indicate the type of plugin within which the processor is running. More...

Protected Member Functions
	AudioProcessor ()
	Constructor. More...

void	sendParamChangeMessageToListeners (int parameterIndex, float newValue)

Protected Attributes
AudioPlayHead *	playHead

Detailed Description

Base class for audio processing filters or plugins.

This is intended to act as a base class of audio filter that is general enough to be wrapped as a VST, AU, RTAS, etc, or used internally.

It is also used by the plugin hosting code as the wrapper around an instance of a loaded plugin.

Derive your filter class from this base class, and if you're building a plugin, you should implement a global function called createPluginFilter() which creates and returns a new instance of your subclass.

Member Enumeration Documentation

enum AudioProcessor::ProcessingPrecision

Enumerator
singlePrecision
doublePrecision

enum AudioProcessor::WrapperType

Flags to indicate the type of plugin context in which a processor is being used.

Enumerator
wrapperType_Undefined
wrapperType_VST
wrapperType_VST3
wrapperType_AudioUnit
wrapperType_AudioUnitv3
wrapperType_RTAS
wrapperType_AAX
wrapperType_Standalone

Constructor & Destructor Documentation

AudioProcessor::AudioProcessor ( )

protected

Constructor.

virtual AudioProcessor::~AudioProcessor ( )

virtual

Destructor.

Member Function Documentation

virtual const String AudioProcessor::getName ( ) const

pure virtual

Returns the name of this processor.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::prepareToPlay	(	double	sampleRate,
		int	maximumExpectedSamplesPerBlock
	)

pure virtual

Called before playback starts, to let the filter prepare itself.

The sample rate is the target sample rate, and will remain constant until playback stops.

You can call getTotalNumInputChannels and getTotalNumOutputChannels or query the busArrangement member variable to find out the number of channels your processBlock callback must process.

The maximumExpectedSamplesPerBlock value is a strong hint about the maximum number of samples that will be provided in each block. You may want to use this value to resize internal buffers. You should program defensively in case a buggy host exceeds this value. The actual block sizes that the host uses may be different each time the callback happens: completely variable block sizes can be expected from some hosts.

See also: busArrangement, getTotalNumInputChannels, getTotalNumOutputChannels

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::releaseResources ( )

pure virtual

Called after playback has stopped, to let the filter free up any resources it no longer needs.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::processBlock	(	AudioBuffer< float > &	buffer,
		MidiBuffer &	midiMessages
	)

pure virtual

Renders the next block.

When this method is called, the buffer contains a number of channels which is at least as great as the maximum number of input and output channels that this filter is using. It will be filled with the filter's input data and should be replaced with the filter's output.

So for example if your filter has a total of 2 input channels and 4 output channels, then the buffer will contain 4 channels, the first two being filled with the input data. Your filter should read these, do its processing, and replace the contents of all 4 channels with its output.

Or if your filter has a total of 5 inputs and 2 outputs, the buffer will have 5 channels, all filled with data, and your filter should overwrite the first 2 of these with its output. But be VERY careful not to write anything to the last 3 channels, as these might be mapped to memory that the host assumes is read-only!

If your plug-in has more than one input or output buses then the buffer passed to the processBlock methods will contain a bundle of all channels of each bus. Use AudioBusArrangement::getBusBuffer to obtain an audio buffer for a particular bus.

Note that if you have more outputs than inputs, then only those channels that correspond to an input channel are guaranteed to contain sensible data - e.g. in the case of 2 inputs and 4 outputs, the first two channels contain the input, but the last two channels may contain garbage, so you should be careful not to let this pass through without being overwritten or cleared.

Also note that the buffer may have more channels than are strictly necessary, but you should only read/write from the ones that your filter is supposed to be using.

The number of samples in these buffers is NOT guaranteed to be the same for every callback, and may be more or less than the estimated value given to prepareToPlay(). Your code must be able to cope with variable-sized blocks, or you're going to get clicks and crashes!

Also note that some hosts will occasionally decide to pass a buffer containing zero samples, so make sure that your algorithm can deal with that!

If the filter is receiving a midi input, then the midiMessages array will be filled with the midi messages for this block. Each message's timestamp will indicate the message's time, as a number of samples from the start of the block.

Any messages left in the midi buffer when this method has finished are assumed to be the filter's midi output. This means that your filter should be careful to clear any incoming messages from the array if it doesn't want them to be passed-on.

Be very careful about what you do in this callback - it's going to be called by the audio thread, so any kind of interaction with the UI is absolutely out of the question. If you change a parameter in here and need to tell your UI to update itself, the best way is probably to inherit from a ChangeBroadcaster, let the UI components register as listeners, and then call sendChangeMessage() inside the processBlock() method to send out an asynchronous message. You could also use the AsyncUpdater class in a similar way.

See also: AudioBusArrangement::getBusBuffer

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::processBlock	(	AudioBuffer< double > &	buffer,
		MidiBuffer &	midiMessages
	)

virtual

Renders the next block.

When this method is called, the buffer contains a number of channels which is at least as great as the maximum number of input and output channels that this filter is using. It will be filled with the filter's input data and should be replaced with the filter's output.

So for example if your filter has a combined total of 2 input channels and 4 output channels, then the buffer will contain 4 channels, the first two being filled with the input data. Your filter should read these, do its processing, and replace the contents of all 4 channels with its output.

Or if your filter has 5 inputs and 2 outputs, the buffer will have 5 channels, all filled with data, and your filter should overwrite the first 2 of these with its output. But be VERY careful not to write anything to the last 3 channels, as these might be mapped to memory that the host assumes is read-only!

If your plug-in has more than one input or output buses then the buffer passed to the processBlock methods will contain a bundle of all channels of each bus. Use AudioBusArrangement::getBusBuffer to obtain a audio buffer for a particular bus.

Note that if you have more outputs than inputs, then only those channels that correspond to an input channel are guaranteed to contain sensible data - e.g. in the case of 2 inputs and 4 outputs, the first two channels contain the input, but the last two channels may contain garbage, so you should be careful not to let this pass through without being overwritten or cleared.

Also note that the buffer may have more channels than are strictly necessary, but you should only read/write from the ones that your filter is supposed to be using.

If your plugin uses buses, then you should use AudioBusArrangement::getBusBuffer() or AudioBusArrangement::getChannelIndexInProcessBlockBuffer() to find out which of the input and output channels correspond to which of the buses.

The number of samples in these buffers is NOT guaranteed to be the same for every callback, and may be more or less than the estimated value given to prepareToPlay(). Your code must be able to cope with variable-sized blocks, or you're going to get clicks and crashes!

Also note that some hosts will occasionally decide to pass a buffer containing zero samples, so make sure that your algorithm can deal with that!

If the filter is receiving a midi input, then the midiMessages array will be filled with the midi messages for this block. Each message's timestamp will indicate the message's time, as a number of samples from the start of the block.

Any messages left in the midi buffer when this method has finished are assumed to be the filter's midi output. This means that your filter should be careful to clear any incoming messages from the array if it doesn't want them to be passed-on.

Be very careful about what you do in this callback - it's going to be called by the audio thread, so any kind of interaction with the UI is absolutely out of the question. If you change a parameter in here and need to tell your UI to update itself, the best way is probably to inherit from a ChangeBroadcaster, let the UI components register as listeners, and then call sendChangeMessage() inside the processBlock() method to send out an asynchronous message. You could also use the AsyncUpdater class in a similar way.

See also: AudioBusArrangement::getBusBuffer

Reimplemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

virtual void AudioProcessor::processBlockBypassed	(	AudioBuffer< float > &	buffer,
		MidiBuffer &	midiMessages
	)

virtual

Renders the next block when the processor is being bypassed.

The default implementation of this method will pass-through any incoming audio, but you may override this method e.g. to add latency compensation to the data to match the processor's latency characteristics. This will avoid situations where bypassing will shift the signal forward in time, possibly creating pre-echo effects and odd timings. Another use for this method would be to cross-fade or morph between the wet (not bypassed) and dry (bypassed) signals.

virtual void AudioProcessor::processBlockBypassed	(	AudioBuffer< double > &	buffer,
		MidiBuffer &	midiMessages
	)

virtual

Renders the next block when the processor is being bypassed.

The default implementation of this method will pass-through any incoming audio, but you may override this method e.g. to add latency compensation to the data to match the processor's latency characteristics. This will avoid situations where bypassing will shift the signal forward in time, possibly creating pre-echo effects and odd timings. Another use for this method would be to cross-fade or morph between the wet (not bypassed) and dry (bypassed) signals.

virtual bool AudioProcessor::setPreferredBusArrangement	(	bool	isInputBus,
		int	busIndex,
		const AudioChannelSet &	preferredSet
	)

virtual

Called by the host, this attempts to change the plugin's channel layout on a particular bus.

The base class implementation will perform some basic sanity-checking and then apply the changes to the processor's busArrangement value. You may override it and return false if you want to make your plugin smarter about refusing certain layouts that you don't want to support. Your plug-in may also respond to this call by changing the channel layout of other buses, for example, if your plug-in requires the same number of input and output channels.

For most basic plug-ins, which do not require side-chains, aux buses or detailed audio channel layout information, it is easier to specify the acceptable channel configurations via the "PlugIn Channel Configurations" field in the Projucer. In this case, you should not override this method.

If, on the other hand, you decide to override this method then you need to make sure that "PlugIn Channel Configurations" field in the Projucer is empty.

Note, that you must not do any heavy allocations or calculations in this callback as it may be called several hundred times during initialization. If you require any layout specific allocations then defer these to prepareToPlay callback.

Returns: false if there is no way for the processor to support the given format on the specified bus.

See also: prepareToPlay, busArrangement, AudioBusArrangement::getBusBuffer, getTotalNumInputChannels, getTotalNumOutputChannels

Referenced by StandalonePluginHolder::createPlugin(), PluginBusUtilities::enableAllBuses(), PluginBusUtilities::findMaxNumberOfChannelsForBus(), AudioUnitHelpers::getAUChannelInfo(), PluginBusUtilities::getDefaultLayoutForChannelNumAndBus(), and PluginBusUtilities::restoreBusArrangement().

virtual bool AudioProcessor::supportsDoublePrecisionProcessing ( ) const

virtual

Returns true if the Audio processor supports double precision floating point processing.

The default implementation will always return false. If you return true here then you must override the double precision versions of processBlock. Additionally, you must call getProcessingPrecision() in your prepareToPlay method to determine the precision with which you need to allocate your internal buffers.

See also: getProcessingPrecision, setProcessingPrecision

Reimplemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

ProcessingPrecision AudioProcessor::getProcessingPrecision ( ) const

noexcept

Returns the precision-mode of the processor.

Depending on the result of this method you MUST call the corresponding version of processBlock. The default processing precision is single precision.

See also: setProcessingPrecision, supportsDoublePrecisionProcessing

bool AudioProcessor::isUsingDoublePrecision ( ) const

noexcept

Returns true if the current precision is set to doublePrecision.

void AudioProcessor::setProcessingPrecision ( ProcessingPrecision precision )

noexcept

Changes the processing precision of the receiver.

A client of the AudioProcessor calls this function to indicate which version of processBlock (single or double precision) it intends to call. The client MUST call this function before calling the prepareToPlay method so that the receiver can do any necessary allocations in the prepareToPlay() method. An implementation of prepareToPlay() should call getProcessingPrecision() to determine with which precision it should allocate it's internal buffers.

Note that setting the processing precision to double floating point precision on a receiver which does not support double precision processing (i.e. supportsDoublePrecisionProcessing() returns false) will result in an assertion.

See also: getProcessingPrecision, supportsDoublePrecisionProcessing

AudioPlayHead* AudioProcessor::getPlayHead ( ) const

noexcept

Returns the current AudioPlayHead object that should be used to find out the state and position of the playhead.

You can ONLY call this from your processBlock() method! Calling it at other times will produce undefined behaviour, as the host may not have any context in which a time would make sense, and some hosts will almost certainly have multithreading issues if it's not called on the audio thread.

The AudioPlayHead object that is returned can be used to get the details about the time of the start of the block currently being processed. But do not store this pointer or use it outside of the current audio callback, because the host may delete or re-use it.

If the host can't or won't provide any time info, this will return nullptr.

int AudioProcessor::getTotalNumInputChannels ( ) const

noexcept

Returns the total number of input channels.

This method will return the total number of input channels by accumulating the number of channels on each input bus. The number of channels of the buffer passed to your processBlock callback will be equivalent to either getTotalNumInputChannels or getTotalNumOutputChannels - which ever is greater.

Note that getTotalNumInputChannels is equivalent to getMainBusNumInputChannels if your processor does not have any sidechains or aux buses.

References AudioProcessor::AudioBusArrangement::getTotalNumInputChannels().

Referenced by StandalonePluginHolder::reloadAudioDeviceState(), and StandalonePluginHolder::showAudioSettingsDialog().

int AudioProcessor::getTotalNumOutputChannels ( ) const

noexcept

Returns the total number of output channels.

This method will return the total number of output channels by accumulating the number of channels on each output bus. The number of channels of the buffer passed to your processBlock callback will be equivalent to either getTotalNumInputChannels or getTotalNumOutputChannels - which ever is greater.

Note that getTotalNumOutputChannels is equivalent to getMainBusNumOutputChannels if your processor does not have any sidechains or aux buses.

References AudioProcessor::AudioBusArrangement::getTotalNumOutputChannels().

Referenced by StandalonePluginHolder::reloadAudioDeviceState(), and StandalonePluginHolder::showAudioSettingsDialog().

int AudioProcessor::getMainBusNumInputChannels ( ) const

noexcept

Returns the number of input channels on the main bus.

int AudioProcessor::getMainBusNumOutputChannels ( ) const

noexcept

Returns the number of output channels on the main bus.

double AudioProcessor::getSampleRate ( ) const

noexcept

Returns the current sample rate.

This can be called from your processBlock() method - it's not guaranteed to be valid at any other time, and may return 0 if it's unknown.

int AudioProcessor::getBlockSize ( ) const

noexcept

Returns the current typical block size that is being used.

This can be called from your processBlock() method - it's not guaranteed to be valid at any other time.

Remember it's not the ONLY block size that may be used when calling processBlock, it's just the normal one. The actual block sizes used may be larger or smaller than this, and will vary between successive calls.

int AudioProcessor::getLatencySamples ( ) const

noexcept

This returns the number of samples delay that the filter imposes on the audio passing through it.

The host will call this to find the latency - the filter itself should set this value by calling setLatencySamples() as soon as it can during its initialisation.

void AudioProcessor::setLatencySamples ( int newLatency )

The filter should call this to set the number of samples delay that it introduces.

The filter should call this as soon as it can during initialisation, and can call it later if the value changes.

virtual double AudioProcessor::getTailLengthSeconds ( ) const

pure virtual

Returns the length of the filter's tail, in seconds.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual bool AudioProcessor::acceptsMidi ( ) const

pure virtual

Returns true if the processor wants midi messages.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual bool AudioProcessor::producesMidi ( ) const

pure virtual

Returns true if the processor produces midi messages.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual bool AudioProcessor::supportsMPE ( ) const

virtual

Returns true if the processor supports MPE.

const CriticalSection& AudioProcessor::getCallbackLock ( ) const

noexcept

This returns a critical section that will automatically be locked while the host is calling the processBlock() method.

Use it from your UI or other threads to lock access to variables that are used by the process callback, but obviously be careful not to keep it locked for too long, because that could cause stuttering playback. If you need to do something that'll take a long time and need the processing to stop while it happens, use the suspendProcessing() method instead.

See also: suspendProcessing

void AudioProcessor::suspendProcessing ( bool shouldBeSuspended )

Enables and disables the processing callback.

If you need to do something time-consuming on a thread and would like to make sure the audio processing callback doesn't happen until you've finished, use this to disable the callback and re-enable it again afterwards.

E.g.

void loadNewPatch()
{
    suspendProcessing (true);
    ..do something that takes ages..
    suspendProcessing (false);
}

If the host tries to make an audio callback while processing is suspended, the filter will return an empty buffer, but won't block the audio thread like it would do if you use the getCallbackLock() critical section to synchronise access.

Any code that calls processBlock() should call isSuspended() before doing so, and if the processor is suspended, it should avoid the call and emit silence or whatever is appropriate.

See also: getCallbackLock

bool AudioProcessor::isSuspended ( ) const

noexcept

Returns true if processing is currently suspended.

See also: suspendProcessing

virtual void AudioProcessor::reset ( )

virtual

A plugin can override this to be told when it should reset any playing voices.

The default implementation does nothing, but a host may call this to tell the plugin that it should stop any tails or sounds that have been left running.

Reimplemented in AudioProcessorGraph.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

bool AudioProcessor::isNonRealtime ( ) const

noexcept

Returns true if the processor is being run in an offline mode for rendering.

If the processor is being run live on realtime signals, this returns false. If the mode is unknown, this will assume it's realtime and return false.

This value may be unreliable until the prepareToPlay() method has been called, and could change each time prepareToPlay() is called.

See also: setNonRealtime()

virtual void AudioProcessor::setNonRealtime ( bool isNonRealtime )

virtualnoexcept

Called by the host to tell this processor whether it's being used in a non-realtime capacity for offline rendering or bouncing.

Reimplemented in AudioProcessorGraph.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual AudioProcessorEditor* AudioProcessor::createEditor ( )

pure virtual

Creates the filter's UI.

This can return nullptr if you want a UI-less filter, in which case the host may create a generic UI that lets the user twiddle the parameters directly.

If you do want to pass back a component, the component should be created and set to the correct size before returning it. If you implement this method, you must also implement the hasEditor() method and make it return true.

Remember not to do anything silly like allowing your filter to keep a pointer to the component that gets created - it could be deleted later without any warning, which would make your pointer into a dangler. Use the getActiveEditor() method instead.

The correct way to handle the connection between an editor component and its filter is to use something like a ChangeBroadcaster so that the editor can register itself as a listener, and be told when a change occurs. This lets them safely unregister themselves when they are deleted.

Here are a few things to bear in mind when writing an editor:

Initially there won't be an editor, until the user opens one, or they might not open one at all. Your filter mustn't rely on it being there.
An editor object may be deleted and a replacement one created again at any time.
It's safe to assume that an editor will be deleted before its filter.

See also: hasEditor

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual bool AudioProcessor::hasEditor ( ) const

pure virtual

Your filter must override this and return true if it can create an editor component.

See also: createEditor

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

AudioProcessorEditor* AudioProcessor::getActiveEditor ( ) const

noexcept

Returns the active editor, if there is one.

Bear in mind this can return nullptr, even if an editor has previously been opened.

AudioProcessorEditor* AudioProcessor::createEditorIfNeeded ( )

Returns the active editor, or if there isn't one, it will create one.

This may call createEditor() internally to create the component.

virtual int AudioProcessor::getNumParameters ( )

virtual

This must return the correct value immediately after the object has been created, and mustn't change the number of parameters later.

NOTE! This method will eventually be deprecated! It's recommended that you use the AudioProcessorParameter class instead to manage your parameters.

virtual const String AudioProcessor::getParameterName ( int parameterIndex )

virtual

Returns the name of a particular parameter.

NOTE! This method will eventually be deprecated! It's recommended that you use the AudioProcessorParameter class instead to manage your parameters.

virtual float AudioProcessor::getParameter ( int parameterIndex )

virtual

Called by the host to find out the value of one of the filter's parameters.

The host will expect the value returned to be between 0 and 1.0.

This could be called quite frequently, so try to make your code efficient. It's also likely to be called by non-UI threads, so the code in here should be thread-aware.

NOTE! This method will eventually be deprecated! It's recommended that you use the AudioProcessorParameter class instead to manage your parameters.

virtual String AudioProcessor::getParameterName	(	int	parameterIndex,
		int	maximumStringLength
	)

virtual

Returns the name of a parameter as a text string with a preferred maximum length.

If you want to provide customised short versions of your parameter names that will look better in constrained spaces (e.g. the displays on hardware controller devices or mixing desks) then you should implement this method. If you don't override it, the default implementation will call getParameterText(int), and truncate the result.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getName() instead.

virtual const String AudioProcessor::getParameterText ( int parameterIndex )

virtual

Returns the value of a parameter as a text string.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getText() instead.

virtual String AudioProcessor::getParameterText	(	int	parameterIndex,
		int	maximumStringLength
	)

virtual

Returns the value of a parameter as a text string with a preferred maximum length.

If you want to provide customised short versions of your parameter values that will look better in constrained spaces (e.g. the displays on hardware controller devices or mixing desks) then you should implement this method. If you don't override it, the default implementation will call getParameterText(int), and truncate the result.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getText() instead.

virtual int AudioProcessor::getParameterNumSteps ( int parameterIndex )

virtual

Returns the number of discrete steps that this parameter can represent.

The default return value if you don't implement this method is AudioProcessor::getDefaultNumParameterSteps(). If your parameter is boolean, then you may want to make this return 2. The value that is returned may or may not be used, depending on the host.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getNumSteps() instead.

static int AudioProcessor::getDefaultNumParameterSteps ( )

staticnoexcept

Returns the default number of steps for a parameter.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getNumSteps() instead.

See also: getParameterNumSteps

virtual float AudioProcessor::getParameterDefaultValue ( int parameterIndex )

virtual

Returns the default value for the parameter.

By default, this just returns 0. The value that is returned may or may not be used, depending on the host.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getDefaultValue() instead.

virtual String AudioProcessor::getParameterLabel ( int index ) const

virtual

Some plugin types may be able to return a label string for a parameter's units.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::getLabel() instead.

virtual bool AudioProcessor::isParameterOrientationInverted ( int index ) const

virtual

This can be overridden to tell the host that particular parameters operate in the reverse direction.

(Not all plugin formats or hosts will actually use this information).

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::isOrientationInverted() instead.

virtual void AudioProcessor::setParameter	(	int	parameterIndex,
		float	newValue
	)

virtual

The host will call this method to change the value of one of the filter's parameters.

The host may call this at any time, including during the audio processing callback, so the filter has to process this very fast and avoid blocking.

If you want to set the value of a parameter internally, e.g. from your editor component, then don't call this directly - instead, use the setParameterNotifyingHost() method, which will also send a message to the host telling it about the change. If the message isn't sent, the host won't be able to automate your parameters properly.

The value passed will be between 0 and 1.0.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::setValue() instead.

void AudioProcessor::setParameterNotifyingHost	(	int	parameterIndex,
		float	newValue
	)

Your filter can call this when it needs to change one of its parameters.

This could happen when the editor or some other internal operation changes a parameter. This method will call the setParameter() method to change the value, and will then send a message to the host telling it about the change.

Note that to make sure the host correctly handles automation, you should call the beginParameterChangeGesture() and endParameterChangeGesture() methods to tell the host when the user has started and stopped changing the parameter.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::setValueNotifyingHost() instead.

virtual bool AudioProcessor::isParameterAutomatable ( int parameterIndex ) const

virtual

Returns true if the host can automate this parameter.

By default, this returns true for all parameters.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::isAutomatable() instead.

virtual bool AudioProcessor::isMetaParameter ( int parameterIndex ) const

virtual

Should return true if this parameter is a "meta" parameter.

A meta-parameter is a parameter that changes other params. It is used by some hosts (e.g. AudioUnit hosts). By default this returns false.

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::isMetaParameter() instead.

void AudioProcessor::beginParameterChangeGesture ( int parameterIndex )

Sends a signal to the host to tell it that the user is about to start changing this parameter.

This allows the host to know when a parameter is actively being held by the user, and it may use this information to help it record automation.

If you call this, it must be matched by a later call to endParameterChangeGesture().

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::beginChangeGesture() instead.

void AudioProcessor::endParameterChangeGesture ( int parameterIndex )

Tells the host that the user has finished changing this parameter.

This allows the host to know when a parameter is actively being held by the user, and it may use this information to help it record automation.

A call to this method must follow a call to beginParameterChangeGesture().

NOTE! This method will eventually be deprecated! It's recommended that you use AudioProcessorParameter::endChangeGesture() instead.

void AudioProcessor::updateHostDisplay ( )

The filter can call this when something (apart from a parameter value) has changed.

It sends a hint to the host that something like the program, number of parameters, etc, has changed, and that it should update itself.

void AudioProcessor::addParameter ( AudioProcessorParameter * )

Adds a parameter to the list.

The parameter object will be managed and deleted automatically by the list when no longer needed.

const OwnedArray<AudioProcessorParameter>& AudioProcessor::getParameters ( ) const

noexcept

Returns the current list of parameters.

virtual int AudioProcessor::getNumPrograms ( )

pure virtual

Returns the number of preset programs the filter supports.

The value returned must be valid as soon as this object is created, and must not change over its lifetime.

This value shouldn't be less than 1.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual int AudioProcessor::getCurrentProgram ( )

pure virtual

Returns the number of the currently active program.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::setCurrentProgram ( int index )

pure virtual

Called by the host to change the current program.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual const String AudioProcessor::getProgramName ( int index )

pure virtual

Must return the name of a given program.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::changeProgramName	(	int	index,
		const String &	newName
	)

pure virtual

Called by the host to rename a program.

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

virtual void AudioProcessor::getStateInformation ( juce::MemoryBlock & destData )

pure virtual

The host will call this method when it wants to save the filter's internal state.

This must copy any info about the filter's state into the block of memory provided, so that the host can store this and later restore it using setStateInformation().

Note that there's also a getCurrentProgramStateInformation() method, which only stores the current program, not the state of the entire filter.

See also the helper function copyXmlToBinary() for storing settings as XML.

See also: getCurrentProgramStateInformation

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by StandalonePluginHolder::askUserToSaveState(), AudioProcessorGraph::changeProgramName(), AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph(), and StandalonePluginHolder::savePluginState().

virtual void AudioProcessor::getCurrentProgramStateInformation ( juce::MemoryBlock & destData )

virtual

The host will call this method if it wants to save the state of just the filter's current program.

Unlike getStateInformation, this should only return the current program's state.

Not all hosts support this, and if you don't implement it, the base class method just calls getStateInformation() instead. If you do implement it, be sure to also implement getCurrentProgramStateInformation.

See also: getStateInformation, setCurrentProgramStateInformation

virtual void AudioProcessor::setStateInformation	(	const void *	data,
		int	sizeInBytes
	)

pure virtual

This must restore the filter's state from a block of data previously created using getStateInformation().

Note that there's also a setCurrentProgramStateInformation() method, which tries to restore just the current program, not the state of the entire filter.

See also the helper function getXmlFromBinary() for loading settings as XML.

See also: setCurrentProgramStateInformation

Implemented in AudioProcessorGraph, and AudioProcessorGraph::AudioGraphIOProcessor.

Referenced by StandalonePluginHolder::askUserToLoadState(), AudioProcessorGraph::changeProgramName(), AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph(), and StandalonePluginHolder::reloadPluginState().

virtual void AudioProcessor::setCurrentProgramStateInformation	(	const void *	data,
		int	sizeInBytes
	)

virtual

The host will call this method if it wants to restore the state of just the filter's current program.

Not all hosts support this, and if you don't implement it, the base class method just calls setStateInformation() instead. If you do implement it, be sure to also implement getCurrentProgramStateInformation.

See also: setStateInformation, getCurrentProgramStateInformation

virtual void AudioProcessor::numChannelsChanged ( )

virtual

This method is called when the number of input or output channels is changed.

virtual void AudioProcessor::addListener ( AudioProcessorListener * newListener )

virtual

Adds a listener that will be called when an aspect of this processor changes.

virtual void AudioProcessor::removeListener ( AudioProcessorListener * listenerToRemove )

virtual

Removes a previously added listener.

virtual void AudioProcessor::setPlayHead ( AudioPlayHead * newPlayHead )

virtual

Tells the processor to use this playhead object.

The processor will not take ownership of the object, so the caller must delete it when it is no longer being used.

Reimplemented in AudioProcessorGraph.

Referenced by AudioProcessorGraph::AudioGraphIOProcessor::getParentGraph().

void AudioProcessor::setPlayConfigDetails	(	int	numIns,
		int	numOuts,
		double	sampleRate,
		int	blockSize
	)

This is called by the processor to specify its details before being played.

Use this version of the function if you are not interested in any sidechain and/or aux buses and do not care about the layout of channels. Otherwise use setRateAndBufferSizeDetails.

void AudioProcessor::setRateAndBufferSizeDetails	(	double	sampleRate,
		int	blockSize
	)

noexcept

This is called by the processor to specify its details before being played.

You should call this function after having informed the processor about the channel and bus layouts via setPreferredBusArrangement.

See also: setPreferredBusArrangement

Referenced by StandalonePluginHolder::createPlugin().

void AudioProcessor::editorBeingDeleted ( AudioProcessorEditor * )

noexcept

Not for public use - this is called before deleting an editor component.

static void AudioProcessor::copyXmlToBinary	(	const XmlElement &	xml,
		juce::MemoryBlock &	destData
	)

static

Helper function that just converts an xml element into a binary blob.

Use this in your filter's getStateInformation() method if you want to store its state as xml.

Then use getXmlFromBinary() to reverse this operation and retrieve the XML from a binary blob.

static XmlElement* AudioProcessor::getXmlFromBinary	(	const void *	data,
		int	sizeInBytes
	)

static

Retrieves an XML element that was stored as binary with the copyXmlToBinary() method.

This might return nullptr if the data's unsuitable or corrupted. Otherwise it will return an XmlElement object that the caller must delete when no longer needed.

static void JUCE_CALLTYPE AudioProcessor::setTypeOfNextNewPlugin ( WrapperType )

static

Referenced by StandalonePluginHolder::createPlugin().

void AudioProcessor::sendParamChangeMessageToListeners	(	int	parameterIndex,
		float	newValue
	)

protected

Member Data Documentation

AudioBusArrangement AudioProcessor::busArrangement

The processor's bus arrangement.

Your plugin can modify this either

in the plugin's constructor
in the setPreferredBusArrangement() callback Changing it at other times can result in undefined behaviour.

The host will negotiate with the plugin over its bus configuration by making calls to setPreferredBusArrangement().

See also: setPreferredBusArrangement

Referenced by StandalonePluginHolder::createPlugin(), AudioUnitHelpers::getAUChannelInfo(), and PluginBusUtilities::getFilterBus().

WrapperType AudioProcessor::wrapperType

When loaded by a plugin wrapper, this flag will be set to indicate the type of plugin within which the processor is running.

AudioPlayHead* AudioProcessor::playHead

protected

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

juce_AudioProcessor.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

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Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

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