juce::dsp::IIR::Filter< SampleType > Class Template Reference

A processing class that can perform IIR filtering on an audio signal, using the Transposed Direct Form II digital structure. More...

#include <juce_IIRFilter.h>

Collaboration diagram for juce::dsp::IIR::Filter< SampleType >:

Public Types
using	CoefficientsPtr = typename Coefficients< NumericType >::Ptr
	A typedef for a ref-counted pointer to the coefficients object. More...
using	NumericType = typename SampleTypeHelpers::ElementType< SampleType >::Type
	The NumericType is the underlying primitive type used by the SampleType (which could be either a primitive or vector) More...

Public Member Functions
	Filter ()
	Creates a filter. More...
	Filter (CoefficientsPtr coefficientsToUse)
	Creates a filter with a given set of coefficients. More...
	Filter (const Filter &)=default
	Filter (Filter &&)=default
Filter &	operator= (const Filter &)=default
Filter &	operator= (Filter &&)=default
void	prepare (const ProcessSpec &) noexcept
	Called before processing starts. More...
template<typename ProcessContext >
void	process (const ProcessContext &context) noexcept
	Processes a block of samples. More...
SampleType JUCE_VECTOR_CALLTYPE	processSample (SampleType sample) noexcept
	Processes a single sample, without any locking. More...
void	reset ()
	Resets the filter's processing pipeline, ready to start a new stream of data. More...
void	reset (SampleType resetToValue)
	Resets the filter's processing pipeline to a specific value. More...
void	snapToZero () noexcept
	Ensure that the state variables are rounded to zero if the state variables are denormals. More...

Public Attributes
CoefficientsPtr	coefficients
	The coefficients of the IIR filter. More...

Private Member Functions
void	check ()
template<typename ProcessContext , bool isBypassed>
void	processInternal (const ProcessContext &context) noexcept
	Processes a block of samples. More...

Private Attributes
HeapBlock< SampleType >	memory
size_t	order = 0
SampleType *	state = nullptr

Detailed Description

template<typename SampleType>
class juce::dsp::IIR::Filter< SampleType >

A processing class that can perform IIR filtering on an audio signal, using the Transposed Direct Form II digital structure.

If you need a lowpass, bandpass or highpass filter with fast modulation of its cutoff frequency, you might use the class StateVariableFilter instead, which is designed to prevent artefacts at parameter changes, instead of the class Filter.

See also

Filter::Coefficients, FilterAudioSource, StateVariableFilter

@tags{DSP}

Member Typedef Documentation

CoefficientsPtr

template<typename SampleType >

using juce::dsp::IIR::Filter< SampleType >::CoefficientsPtr = typename Coefficients<NumericType>::Ptr

A typedef for a ref-counted pointer to the coefficients object.

NumericType

template<typename SampleType >

using juce::dsp::IIR::Filter< SampleType >::NumericType = typename SampleTypeHelpers::ElementType<SampleType>::Type

The NumericType is the underlying primitive type used by the SampleType (which could be either a primitive or vector)

Constructor & Destructor Documentation

Filter() [1/4]

template<typename SampleType >

juce::dsp::IIR::Filter< SampleType >::Filter

(

)

Creates a filter.

Initially the filter is inactive, so will have no effect on samples that you process with it. You can modify the coefficients member to turn it into the type of filter needed.

Filter() [2/4]

template<typename SampleType >

juce::dsp::IIR::Filter< SampleType >::Filter

(

CoefficientsPtr

coefficientsToUse

)

Creates a filter with a given set of coefficients.

Filter() [3/4]

template<typename SampleType >

juce::dsp::IIR::Filter< SampleType >::Filter ( const Filter< SampleType > &  )

default

Filter() [4/4]

template<typename SampleType >

juce::dsp::IIR::Filter< SampleType >::Filter ( Filter< SampleType > &&  )

default

Member Function Documentation

check()

template<typename SampleType >

void juce::dsp::IIR::Filter< SampleType >::check ( )

private

operator=() [1/2]

template<typename SampleType >

Filter& juce::dsp::IIR::Filter< SampleType >::operator= ( const Filter< SampleType > &  )

default

operator=() [2/2]

template<typename SampleType >

Filter& juce::dsp::IIR::Filter< SampleType >::operator= ( Filter< SampleType > &&  )

default

prepare()

template<typename SampleType >

void juce::dsp::IIR::Filter< SampleType >::prepare ( const ProcessSpec &  )

noexcept

Called before processing starts.

process()

template<typename SampleType >

template<typename ProcessContext >

void juce::dsp::IIR::Filter< SampleType >::process ( const ProcessContext &  context )

inlinenoexcept

Processes a block of samples.

References juce::dsp::IIR::Filter< SampleType >::snapToZero().

processInternal()

template<typename SampleType >

template<typename ProcessContext , bool isBypassed>

void juce::dsp::IIR::Filter< SampleType >::processInternal ( const ProcessContext &  context )

privatenoexcept

Processes a block of samples.

processSample()

template<typename SampleType >

SampleType JUCE_VECTOR_CALLTYPE juce::dsp::IIR::Filter< SampleType >::processSample ( SampleType  sample )

noexcept

Processes a single sample, without any locking.

Use this if you need processing of a single value.

Moreover, you might need the function snapToZero after a few calls to avoid potential denormalisation issues.

reset() [1/2]

template<typename SampleType >

void juce::dsp::IIR::Filter< SampleType >::reset ( )

inline

Resets the filter's processing pipeline, ready to start a new stream of data.

Note that this clears the processing state, but the type of filter and its coefficients aren't changed.

References juce::dsp::IIR::Filter< SampleType >::reset().

Referenced by juce::dsp::IIR::Filter< SampleType >::reset().

reset() [2/2]

template<typename SampleType >

void juce::dsp::IIR::Filter< SampleType >::reset

(

SampleType

resetToValue

)

Resets the filter's processing pipeline to a specific value.

See also

reset

snapToZero()

template<typename SampleType >

void juce::dsp::IIR::Filter< SampleType >::snapToZero ( )

noexcept

Ensure that the state variables are rounded to zero if the state variables are denormals.

This is only needed if you are doing sample by sample processing.

Referenced by juce::dsp::IIR::Filter< SampleType >::process().

Member Data Documentation

coefficients

template<typename SampleType >

CoefficientsPtr juce::dsp::IIR::Filter< SampleType >::coefficients

The coefficients of the IIR filter.

It's up to the caller to ensure that these coefficients are modified in a thread-safe way.

If you change the order of the coefficients then you must call reset after modifying them.

memory

template<typename SampleType >

HeapBlock<SampleType> juce::dsp::IIR::Filter< SampleType >::memory

private

order

template<typename SampleType >

size_t juce::dsp::IIR::Filter< SampleType >::order = 0

private

state

template<typename SampleType >

SampleType* juce::dsp::IIR::Filter< SampleType >::state = nullptr

private

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

• juce_dsp/processors/juce_IIRFilter.h