Public Types | Public Member Functions | Public Attributes | List of all members
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...

Public Types

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...
 
using CoefficientsPtr = typename Coefficients< NumericType >::Ptr
 A typedef for a ref-counted pointer to the coefficients object. 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
 
Filteroperator= (const Filter &)=default
 
Filteroperator= (Filter &&)=default
 
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 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 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...
 

Detailed Description

template<typename SampleType>
class 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

Member Typedef Documentation

◆ NumericType

template<typename SampleType >
using 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)

◆ CoefficientsPtr

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

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

Constructor & Destructor Documentation

◆ Filter() [1/4]

template<typename SampleType >
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 >
dsp::IIR::Filter< SampleType >::Filter ( CoefficientsPtr  coefficientsToUse)

Creates a filter with a given set of coefficients.

◆ Filter() [3/4]

template<typename SampleType >
dsp::IIR::Filter< SampleType >::Filter ( const Filter< SampleType > &  )
default

◆ Filter() [4/4]

template<typename SampleType >
dsp::IIR::Filter< SampleType >::Filter ( Filter< SampleType > &&  )
default

Member Function Documentation

◆ operator=() [1/2]

template<typename SampleType >
Filter& dsp::IIR::Filter< SampleType >::operator= ( const Filter< SampleType > &  )
default

◆ operator=() [2/2]

template<typename SampleType >
Filter& dsp::IIR::Filter< SampleType >::operator= ( Filter< SampleType > &&  )
default

◆ reset() [1/2]

template<typename SampleType >
void dsp::IIR::Filter< SampleType >::reset ( )

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

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

◆ reset() [2/2]

template<typename SampleType >
void dsp::IIR::Filter< SampleType >::reset ( SampleType  resetToValue)

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

See also
reset

◆ prepare()

template<typename SampleType >
void dsp::IIR::Filter< SampleType >::prepare ( const ProcessSpec )
noexcept

Called before processing starts.

◆ process()

template<typename SampleType >
template<typename ProcessContext >
void dsp::IIR::Filter< SampleType >::process ( const ProcessContext &  context)
noexcept

Processes a block of samples.

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

◆ processSample()

template<typename SampleType >
SampleType JUCE_VECTOR_CALLTYPE 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.

◆ snapToZero()

template<typename SampleType >
void 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 dsp::IIR::Filter< SampleType >::process().

Member Data Documentation

◆ coefficients

template<typename SampleType >
CoefficientsPtr 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.

Referenced by dsp::IIR::Coefficients< NumericType >::getRawCoefficients().


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