A Base class for filter based effects including methods for simple high, low and band pass filtering. More...

#include <AudioEffectsSuite.h>

Inheritance diagram for FilterEffectBase:

Public Member Functions
	FilterEffectBase ()

	FilterEffectBase (FilterEffectBase &copy)=default

	~FilterEffectBase ()=default

virtual bool	active ()
	determines if the effect is active

virtual effectsuite_t	applyFilter (effectsuite_t sampVal)

virtual AudioEffect *	clone ()=0

effectsuite_t	envelope (effectsuite_t sample)

int	id ()
	Allows to identify an effect.

virtual effect_t	process (effect_t inputSample) override
	see applyFilter

virtual effectsuite_t	processDouble (effectsuite_t inputSample) override
	Main process block for applying audio effect.

virtual void	setActive (bool value)
	sets the effect active/inactive

bool	setChebyICoefficients (effectsuite_t cutFreq, bool shelfType, effectsuite_t ripple)

void	setId (int id)
	Allows to identify an effect.

Protected Member Functions
void	allocateBufferMemory ()

bool	changeChebyICoefficients (effectsuite_t cutFreq, bool shelfType, effectsuite_t ripple, int poles)

void	clearMemory ()

int16_t	clip (int32_t in, int16_t clipLimit=32767, int16_t resultLimit=32767)
	generic clipping method

void	copyParent (AudioEffect *copy)

void	incBufferIndex ()

effectsuite_t	rms (effectsuite_t sample)

bool	setSimpleLpf (int order)

Protected Attributes
bool	active_flag = true

int	bufferIndex = 0

int	filterOrder = 0

effectsuite_t *	firBuffer = 0

effectsuite_t *	firCoefficients = 0

effectsuite_t *	firTemp = 0

int	id_value = -1

effectsuite_t *	iirBuffer = 0

effectsuite_t *	iirCoefficients = 0

effectsuite_t *	iirTemp = 0

effectsuite_t *	rmsBuffer = new effectsuite_t[rmsWindowSize]

int	rmsBufferIndex = 0

const int	rmsWindowSize = 128

int	samplingRate = 0

Detailed Description

A Base class for filter based effects including methods for simple high, low and band pass filtering.

See also: FilterEffectBase

Author: Matthew Hamilton

Copyright: MIT License

Constructor & Destructor Documentation

◆ FilterEffectBase() [1/2]

FilterEffectBase ( )

inline

Constructor.

◆ FilterEffectBase() [2/2]

FilterEffectBase ( FilterEffectBase & copy )

default

◆ ~FilterEffectBase()

~FilterEffectBase ( )

default

Destructor.

Member Function Documentation

◆ active()

virtual bool active ( )

inlinevirtualinherited

determines if the effect is active

◆ allocateBufferMemory()

void allocateBufferMemory ( )

inlineprotected

will allocate memory to a buffer given the current filter order and set all values == 0.00

◆ applyFilter()

virtual effectsuite_t applyFilter ( effectsuite_t sampVal )

inlinevirtual

with the current filter coefficients this method filters a sample then stores it the sample Buffer and increments the index

Parameters

sampVal is the sample to be processed

Returns: filtered audio sample

◆ changeChebyICoefficients()

bool changeChebyICoefficients	(	effectsuite_t	cutFreq,
		bool	shelfType,
		effectsuite_t	ripple,
		int	poles
	)

inlineprotected

set firCoefficients and iirCoefficients for required chebyshev type I filter sampleBuffer memory is also set @params cutFreq normalised cutoff frequency (0 < x < .5) @params shelfType bool filter shelf type, false = low pass, true = high pass @params ripple percentage ripple (<.2929) @params poles number of poles

Returns: boolean false on error and true on success

◆ clearMemory()

void clearMemory ( )

inlineprotected

checks internal memory storage of filter coeffcients and deletes if required

◆ clip()

int16_t clip	(	int32_t	in,
		int16_t	clipLimit = `32767`,
		int16_t	resultLimit = `32767`
	)

inlineprotectedinherited

generic clipping method

◆ clone()

virtual AudioEffect * clone ( )

pure virtualinherited

Implemented in SimpleLPF, Boost, Distortion, Fuzz, Tremolo, Delay, ADSRGain, PitchShift, Compressor, SimpleChorus, FilteredDelay, SimpleDelay, SimpleFlanger, STKChorus, STKEcho, STKFreeVerb, STKChowningReverb, STKNReverb, STKPerryReverb, STKLentPitShift, and STKPitShift.

◆ copyParent()

void copyParent ( AudioEffect * copy )

inlineprotectedinherited

◆ envelope()

effectsuite_t envelope ( effectsuite_t sample )

inline

detect the envelop of an incoming signal

Parameters

sample the incoming signal sample value

Returns: returns envelope dection signal sample value

◆ id()

int id ( )

inlineinherited

Allows to identify an effect.

◆ incBufferIndex()

void incBufferIndex ( )

inlineprotected

increment the buffer index and wrap it to the filter order

◆ process()

virtual effect_t process ( effect_t inputSample )

inlineoverridevirtual

see applyFilter

Reimplemented from EffectSuiteBase.

Reimplemented in FilteredDelay.

◆ processDouble()

virtual effectsuite_t processDouble ( effectsuite_t inputSample )

inlineoverridevirtual

Main process block for applying audio effect.

Parameters

inputSample The input audio sample for the effect to be applied to

Returns: an audio sample as a effectsuite_t with effect applied

Implements EffectSuiteBase.

Reimplemented in SimpleChorus, FilteredDelay, and EnvelopeFilter.

◆ rms()

effectsuite_t rms ( effectsuite_t sample )

inlineprotected

root mean square of signal over a specific sample window

◆ setActive()

virtual void setActive ( bool value )

inlinevirtualinherited

sets the effect active/inactive

◆ setChebyICoefficients()

bool setChebyICoefficients	(	effectsuite_t	cutFreq,
		bool	shelfType,
		effectsuite_t	ripple
	)

inline

changes the current Chebyshev type 1 coefficients without altering the filter order. This allows for use in an audio process thread as it avoids dynamic allocation of memory. Filter sample and coefficient buffers are unaltered for initialising a chebyshev type 1 filter

See also: setChebyICoefficients @params cutFreq normalised cutoff frequency (0 < x < .5) @params shelfType bool Filters shelf type, false = low pass, true = high pass @params ripple percentage ripple (<.2929)

Returns: boolean false on error and true on success

◆ setId()

void setId ( int id )

inlineinherited

Allows to identify an effect.

◆ setSimpleLpf()

bool setSimpleLpf ( int order )

inlineprotected

a simple normalised fir low pass filter @params order number of delay coefficients

Member Data Documentation

◆ active_flag

bool active_flag = true

protectedinherited

◆ bufferIndex

int bufferIndex = 0

protected

current buffer index

◆ filterOrder

int filterOrder = 0

protected

order of delay filter including the zero delay coefficients

◆ firBuffer

effectsuite_t* firBuffer = 0

protected

buffer to hold forward delay sample data

◆ firCoefficients

effectsuite_t* firCoefficients = 0

protected

Numerator coefficients in delay filter firCoefficients[0] z^0 coeffcieint firCoefficients[1] z^-1 coefficient

◆ firTemp

effectsuite_t* firTemp = 0

protected

hold temporary values for fir coeffcient buffer

◆ id_value

int id_value = -1

protectedinherited

◆ iirBuffer

effectsuite_t* iirBuffer = 0

protected

buffer to hold backward delay sample data

◆ iirCoefficients

effectsuite_t* iirCoefficients = 0

protected

Denomiator coefficients in delay filter

See also: firCoefficients

◆ iirTemp

effectsuite_t* iirTemp = 0

protected

hold temporary values for iir coeffcient buffer

◆ rmsBuffer

effectsuite_t* rmsBuffer = new effectsuite_t[rmsWindowSize]

protected

RMS window buffer

◆ rmsBufferIndex

int rmsBufferIndex = 0

protected

current write index of rmsBuffer

◆ rmsWindowSize

const int rmsWindowSize = 128

protected

window size in samples of rms window

◆ samplingRate

int samplingRate = 0

protected

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

src/AudioTools/AudioLibs/AudioEffectsSuite.h

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ FilterEffectBase() [1/2]

◆ FilterEffectBase() [2/2]

◆ ~FilterEffectBase()

Member Function Documentation

◆ active()

◆ allocateBufferMemory()

◆ applyFilter()

◆ changeChebyICoefficients()

◆ clearMemory()

◆ clip()

◆ clone()

◆ copyParent()

◆ envelope()

◆ id()

◆ incBufferIndex()

◆ process()

◆ processDouble()

◆ rms()

◆ setActive()

◆ setChebyICoefficients()

◆ setId()

◆ setSimpleLpf()

Member Data Documentation

◆ active_flag

◆ bufferIndex

◆ filterOrder

◆ firBuffer

◆ firCoefficients

◆ firTemp

◆ id_value

◆ iirBuffer

◆ iirCoefficients

◆ iirTemp

◆ rmsBuffer

◆ rmsBufferIndex

◆ rmsWindowSize

◆ samplingRate