dsp::IIR::Filter< SampleType > Class Template Reference
juce_dsp » processors

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
Filter & | operator= (const Filter &)=default
Filter & | operator= (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.

## 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.

## 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:

- juce_dsp/processors/juce_IIRFilter.h