openshot-audio
0.1.7
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#include <juce_audio_processors.h>
Public Types | |
enum | WrapperType { wrapperType_Undefined = 0, wrapperType_VST, wrapperType_VST3, wrapperType_AudioUnit, wrapperType_RTAS, wrapperType_AAX, wrapperType_Standalone } |
Static Public Member Functions | |
static int | getDefaultNumParameterSteps () noexcept |
static void | copyXmlToBinary (const XmlElement &xml, juce::MemoryBlock &destData) |
static XmlElement * | getXmlFromBinary (const void *data, int sizeInBytes) |
static void JUCE_CALLTYPE | setTypeOfNextNewPlugin (WrapperType) |
Public Attributes | |
WrapperType | wrapperType |
Protected Member Functions | |
AudioProcessor () | |
void | sendParamChangeMessageToListeners (int parameterIndex, float newValue) |
Protected Attributes | |
AudioPlayHead * | playHead |
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.
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protected |
Constructor.
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virtual |
Destructor.
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pure virtual |
Returns true if the processor wants midi messages.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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virtual |
Adds a listener that will be called when an aspect of this processor changes.
void AudioProcessor::addParameter | ( | AudioProcessorParameter * | p | ) |
Adds a parameter to the list. The parameter object will be managed and deleted automatically by the list when no longer needed.
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.
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pure virtual |
Called by the host to rename a program.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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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:
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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.
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noexcept |
Not for public use - this is called before deleting an editor component.
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.
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inlinenoexcept |
Returns the active editor, if there is one. Bear in mind this can return nullptr, even if an editor has previously been opened.
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inlinenoexcept |
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.
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inlinenoexcept |
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.
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pure virtual |
Returns the number of the currently active program.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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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.
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pure virtual |
Returns the name of one of the processor's input channels.
The processor might not supply very useful names for channels, and this might be something like "1", "2", "left", "right", etc.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
Returns a string containing a whitespace-separated list of speaker types corresponding to each input channel. For example in a 5.1 arrangement, the string may be "L R C Lfe Ls Rs" If the speaker arrangement is unknown, the returned string will be empty.
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inlinenoexcept |
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.
Returns the name of this processor.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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inlinenoexcept |
Returns the number of input channels that the host will be sending the filter.
If writing a plugin, your configuration macros should specify the number of channels that your filter would prefer to have, and this method lets you know how many the host is actually using.
Note that this method is only valid during or after the prepareToPlay() method call. Until that point, the number of channels will be unknown.
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inlinenoexcept |
Returns the number of output channels that the host will be sending the filter.
If writing a plugin, your configuration macros should specify the number of channels that your filter would prefer to have, and this method lets you know how many the host is actually using.
Note that this method is only valid during or after the prepareToPlay() method call. Until that point, the number of channels will be unknown.
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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.
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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 juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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pure virtual |
Returns the name of one of the processor's output channels.
The processor might not supply very useful names for channels, and this might be something like "1", "2", "left", "right", etc.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
Returns a string containing a whitespace-separated list of speaker types corresponding to each output channel. For example in a 5.1 arrangement, the string may be "L R C Lfe Ls Rs" If the speaker arrangement is unknown, the returned string will be empty.
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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.
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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.
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.
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.
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.
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.
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noexcept |
Returns the current list of parameters.
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.
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.
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inlinenoexcept |
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.
Must return the name of a given program.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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inlinenoexcept |
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.
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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.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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pure virtual |
Returns the length of the filter's tail, in seconds.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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pure virtual |
Your filter must override this and return true if it can create an editor component.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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pure virtual |
Returns true if the specified channel is part of a stereo pair with its neighbour.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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inlinenoexcept |
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.
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pure virtual |
Returns true if the specified channel is part of a stereo pair with its neighbour.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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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.
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inlinenoexcept |
Returns true if processing is currently suspended.
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virtual |
This method is called when the number of input or output channels is changed.
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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.
The estimatedSamplesPerBlock value is a HINT about the typical number of samples that will be processed for each callback, but isn't any kind of guarantee. The actual block sizes that the host uses may be different each time the callback happens, and may be more or less than this value.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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 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!
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!
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.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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pure virtual |
Returns true if the processor produces midi messages.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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pure virtual |
Called after playback has stopped, to let the filter free up any resources it no longer needs.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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Removes a previously added listener.
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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 juce::AudioProcessorGraph.
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protected |
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pure virtual |
Called by the host to change the current program.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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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.
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.
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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 juce::AudioProcessorGraph.
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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.
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noexcept |
This is called by the processor to specify its details before being played.
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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 juce::AudioProcessorGraph.
Not for public use - this is called to initialise the processor before playing.
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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.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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static |
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pure virtual |
Returns true if a silent input always produces a silent output.
Implemented in juce::AudioProcessorGraph, and juce::AudioProcessorGraph::AudioGraphIOProcessor.
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.
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.
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.
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protected |
WrapperType juce::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.