VST 3 Interfaces  VST 3.7
SDK for developing VST plug-in
IAudioProcessor Class Referenceabstract

Audio processing interface: Vst::IAudioProcessor. More...

#include <ivstaudioprocessor.h>

+ Inheritance diagram for IAudioProcessor:

Public Member Functions

virtual tresult setBusArrangements (SpeakerArrangement *inputs, int32 numIns, SpeakerArrangement *outputs, int32 numOuts)=0
 Try to set (host => plug-in) a wanted arrangement for inputs and outputs. More...
 
virtual tresult getBusArrangement (BusDirection dir, int32 index, SpeakerArrangement &arr)=0
 Gets the bus arrangement for a given direction (input/output) and index. More...
 
virtual tresult canProcessSampleSize (int32 symbolicSampleSize)=0
 Asks if a given sample size is supported see SymbolicSampleSizes. More...
 
virtual uint32 getLatencySamples ()=0
 Gets the current Latency in samples. More...
 
virtual tresult setupProcessing (ProcessSetup &setup)=0
 Called in disable state (setActive not called with true) before setProcessing is called and processing will begin. More...
 
virtual tresult setProcessing (TBool state)=0
 Informs the plug-in about the processing state. More...
 
virtual tresult process (ProcessData &data)=0
 The Process call, where all information (parameter changes, event, audio buffer) are passed. More...
 
virtual uint32 getTailSamples ()=0
 Gets tail size in samples. More...
 
- Public Member Functions inherited from FUnknown
virtual tresult queryInterface (const TUID _iid, void **obj)=0
 
virtual uint32 addRef ()=0
 
virtual uint32 release ()=0
 

Static Public Attributes

static const FUID iid
 
- Static Public Attributes inherited from FUnknown
static const FUID iid
 

Detailed Description

Audio processing interface: Vst::IAudioProcessor.

  • [plug imp]
  • [extends IComponent]
  • [released: 3.0.0]
  • [mandatory]

This interface must always be supported by audio processing plug-ins.

Member Function Documentation

◆ setBusArrangements()

virtual tresult setBusArrangements ( SpeakerArrangement inputs,
int32  numIns,
SpeakerArrangement outputs,
int32  numOuts 
)
pure virtual

Try to set (host => plug-in) a wanted arrangement for inputs and outputs.

The host should always deliver the same number of input and output busses than the plug-in needs (see IComponent::getBusCount). The plug-in has 3 possibilities to react on this setBusArrangements call:

  1. The plug-in accepts these arrangements, then it should modify, if needed, its busses to match these new arrangements (later on asked by the host with IComponent::getBusInfo () or IAudioProcessor::getBusArrangement ()) and then should return kResultTrue.
  2. The plug-in does not accept or support these requested arrangements for all inputs/outputs or just for some or only one bus, but the plug-in can try to adapt its current arrangements according to the requested ones (requested arrangements for kMain busses should be handled with more priority than the ones for kAux busses), then it should modify its busses arrangements and should return kResultFalse.
  3. Same than the point 2 above the plug-in does not support these requested arrangements but the plug-in cannot find corresponding arrangements, the plug-in could keep its current arrangement or fall back to a default arrangement by modifying its busses arrangements and should return kResultFalse.
    Parameters
    inputspointer to an array of /ref SpeakerArrangement
    numInsnumber of /ref SpeakerArrangement in inputs array
    outputspointer to an array of /ref SpeakerArrangement
    numOutsnumber of /ref SpeakerArrangement in outputs array Returns kResultTrue when Arrangements is supported and is the current one, else returns kResultFalse.

Implemented in AudioEffect, and SingleComponentEffect.

◆ getBusArrangement()

virtual tresult getBusArrangement ( BusDirection  dir,
int32  index,
SpeakerArrangement arr 
)
pure virtual

Gets the bus arrangement for a given direction (input/output) and index.

Note: IComponent::getBusInfo () and IAudioProcessor::getBusArrangement () should be always return the same information about the busses arrangements.

Implemented in AudioEffect, and SingleComponentEffect.

◆ canProcessSampleSize()

virtual tresult canProcessSampleSize ( int32  symbolicSampleSize)
pure virtual

Asks if a given sample size is supported see SymbolicSampleSizes.

Implemented in AudioEffect, and SingleComponentEffect.

◆ getLatencySamples()

virtual uint32 getLatencySamples ( )
pure virtual

Gets the current Latency in samples.

The returned value defines the group delay or the latency of the plug-in. For example, if the plug-in internally needs to look in advance (like compressors) 512 samples then this plug-in should report 512 as latency. If during the use of the plug-in this latency change, the plug-in has to inform the host by using IComponentHandler::restartComponent (kLatencyChanged), this could lead to audio playback interruption because the host has to recompute its internal mixer delay compensation. Note that for player live recording this latency should be zero or small.

Implemented in AudioEffect, and SingleComponentEffect.

◆ setupProcessing()

virtual tresult setupProcessing ( ProcessSetup setup)
pure virtual

Called in disable state (setActive not called with true) before setProcessing is called and processing will begin.

Implemented in AudioEffect, and SingleComponentEffect.

◆ setProcessing()

virtual tresult setProcessing ( TBool  state)
pure virtual

Informs the plug-in about the processing state.

This will be called before any process calls start with true and after with false. Note that setProcessing (false) may be called after setProcessing (true) without any process calls. Note this function could be called in the UI or in Processing Thread, thats why the plug-in should only light operation (no memory allocation or big setup reconfiguration), this could be used to reset some buffers (like Delay line or Reverb). The host has to be sure that it is called only when the plug-in is enable (setActive (true) was called).

Implemented in AudioEffect, and SingleComponentEffect.

◆ process()

virtual tresult process ( ProcessData data)
pure virtual

The Process call, where all information (parameter changes, event, audio buffer) are passed.

Implemented in AudioEffect, and SingleComponentEffect.

◆ getTailSamples()

virtual uint32 getTailSamples ( )
pure virtual

Gets tail size in samples.

For example, if the plug-in is a Reverb plug-in and it knows that the maximum length of the Reverb is 2sec, then it has to return in getTailSamples() (in VST2 it was getGetTailSize ()): 2*sampleRate. This information could be used by host for offline processing, process optimization and downmix (avoiding signal cut (clicks)). It should return:

  • kNoTail when no tail
  • x * sampleRate when x Sec tail.
  • kInfiniteTail when infinite tail.

Implemented in AudioEffect, and SingleComponentEffect.

Member Data Documentation

◆ iid

const FUID iid
static
Empty

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