Simple Chorus effect with a single delay voice and mono output Chorus is effective between 15 and 20 miliseconds delay of original audio. Requires the sample rate when initialising. More...

#include <AudioEffectsSuite.h>

Inheritance diagram for SimpleChorus:

Public Member Functions
	SimpleChorus (int extSampleRate=44100)

	SimpleChorus (SimpleChorus &copy)=default

	~SimpleChorus ()=default

virtual bool	active ()
	determines if the effect is active

virtual effectsuite_t	applyFilter (effectsuite_t sampVal)

void	clipWave (effectsuite_t amp)

SimpleChorus *	clone () override

effectsuite_t	envelope (effectsuite_t sample)

int	id ()
	Allows to identify an effect.

bool	isNoise ()

void	printInterpTable ()

virtual effect_t	process (effect_t inputSample) override
	see applyFilter

virtual effectsuite_t	processDouble (effectsuite_t inputSample) override

effectsuite_t	readNoise ()

effectsuite_t	readTable (effectsuite_t freq)

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

void	setBase (effectsuite_t baseAmount)

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

void	setDC ()

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

bool	setInterpTable ()

void	setNoise ()

void	setOffSine ()

void	setRamp ()

void	setSawtooth ()

void	setSine ()

void	setSquare ()

void	setSwing (effectsuite_t swingAmount)

void	setTriangle ()

void	setupChorus (effectsuite_t extSampleRate)

void	setupDelayEffectBase (const int bufferSizeSamples)

void	setupModulationBaseClass (effectsuite_t extSampRate)
	setup the class with a given sample rate. Basically reperforming the constructor

Public Attributes
int	sampleRate

effectsuite_t	tableIndex = 0

effectsuite_t	timeStep

effectsuite_t *	waveTable

Protected Member Functions
void	allocateBufferMemory ()

bool	allocateMemory ()

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	delaySample (effectsuite_t inputSample)

effectsuite_t	getInterpolatedOut (effectsuite_t bufferIndex)

effectsuite_t	getInterpOut (effectsuite_t bufferIndex)

effectsuite_t	getModSignal ()

effectsuite_t	getSplineOut (effectsuite_t bufferIndex, int freq)

void	incBufferIndex ()

void	incDelayBuffReadIndex (effectsuite_t indexInc)

void	incDelayBuffWriteIndex ()

effectsuite_t	rms (effectsuite_t sample)

bool	setDelayBuffer (int bufferSizeSamples)

void	setDelayBuffReadIndex (effectsuite_t index)

void	setRandLfo ()

bool	setSimpleLpf (int order)

void	storeSample (effectsuite_t inputSample)

Static Protected Member Functions
static effectsuite_t **	setInterpolationTable ()

Protected Attributes
bool	active_flag = true

effectsuite_t	base

int	bufferIndex = 0

effectsuite_t	currentDelayReadIndex = 0

int	currentDelayWriteIndex = 0

effectsuite_t *	delayBuffer = 0

int	delayTimeSamples = 44100

bool	error

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	interpTable [order][res]

bool	is_noise = false

int	maxDelayBufferSize = 441000

effectsuite_t	modMax = .5

effectsuite_t	modMin = .5

effectsuite_t	modNorm = 1 / (modMax - modMin)

const effectsuite_t	readSpeed = ((readNoise() + 1) * .5) * .0005

effectsuite_t *	rmsBuffer = new effectsuite_t[rmsWindowSize]

int	rmsBufferIndex = 0

const int	rmsWindowSize = 128

int	samplingRate = 0

effectsuite_t	swing

Static Protected Attributes
static const int	interpOrder = 4

static const int	interpResolution = 1000

static const int	order = 4

static const int	res = 100

Detailed Description

Simple Chorus effect with a single delay voice and mono output Chorus is effective between 15 and 20 miliseconds delay of original audio. Requires the sample rate when initialising.

Author: Matthew Hamilton

Copyright: MIT License

Constructor & Destructor Documentation

◆ SimpleChorus() [1/2]

SimpleChorus ( int extSampleRate = 44100 )

inline

Constructor: initialises the effect parameters Since the class inherits DelayEffectBase it must set a delay buffer size when initialisi.

◆ SimpleChorus() [2/2]

SimpleChorus ( SimpleChorus & copy )

default

◆ ~SimpleChorus()

~SimpleChorus ( )

default

Member Function Documentation

◆ active()

virtual bool active ( )

inlinevirtualinherited

determines if the effect is active

◆ allocateBufferMemory()

void allocateBufferMemory ( )

inlineprotectedinherited

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

◆ allocateMemory()

bool allocateMemory ( )

inlineprotectedinherited

allocate memory to internal wave table based on sample rate

Returns: returns true on success or false on failure

◆ applyFilter()

virtual effectsuite_t applyFilter ( effectsuite_t sampVal )

inlinevirtualinherited

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
	)

inlineprotectedinherited

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 ( )

inlineprotectedinherited

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

◆ clipWave()

void clipWave ( effectsuite_t amp )

inlineinherited

clip wave table values with a tanh function. Effect change with a variable amp to control intensity.

Parameters

amp	amount to multiply signal before being fed through a tanh function

◆ clone()

SimpleChorus * clone ( )

inlineoverridevirtual

Implements AudioEffect.

◆ copyParent()

void copyParent ( AudioEffect * copy )

inlineprotectedinherited

◆ delaySample()

void delaySample ( effectsuite_t inputSample )

inlineprotectedinherited

store input sample into the delay buffer and increment currentDelayWriteIndex for tracking when to loop back to start of buffer

Parameters

inputSample sample to be stored for delay (effectsuite_t)

◆ envelope()

effectsuite_t envelope ( effectsuite_t sample )

inlineinherited

detect the envelop of an incoming signal

Parameters

sample the incoming signal sample value

Returns: returns envelope dection signal sample value

◆ getInterpolatedOut()

effectsuite_t getInterpolatedOut ( effectsuite_t bufferIndex )

inlineprotectedinherited

get the value of the requested buffer index by interpolating other points

Parameters

bufferIndex The required buffer index

Returns: interpolated output

◆ getInterpOut()

effectsuite_t getInterpOut ( effectsuite_t bufferIndex )

inlineprotectedinherited

get the interpolated output of the waveTable from the given buffer index

Parameters

bufferIndex buffer index as effectsuite_t

Returns: returns interpolated value from surrounding wavtable indices

◆ getModSignal()

effectsuite_t getModSignal ( )

inlineprotected

modulation signal scaling equation: ((n - modMin)*modNorm*swing) + base modulates a random white noise signal by lowpass filtering then scaling to a range between 15 to 25 miliseconds of delay.

◆ getSplineOut()

effectsuite_t getSplineOut	(	effectsuite_t	bufferIndex,
		int	freq
	)

inlineprotectedinherited

get a cubic spline interpolated out from the wave table

Derived from code by Alec Wright at repository: https://github.com/Alec-Wright/Chorus

Authors: Matthew Hamilton, Alec Wright

Parameters

bufferIndex	the required buffer index
freq	(speed) that the table is being read through

Returns: returns interpolated value as effectsuite_t

◆ id()

int id ( )

inlineinherited

Allows to identify an effect.

◆ incBufferIndex()

void incBufferIndex ( )

inlineprotectedinherited

increment the buffer index and wrap it to the filter order

◆ incDelayBuffReadIndex()

void incDelayBuffReadIndex ( effectsuite_t indexInc )

inlineprotectedinherited

Increments the currentDelayBufferReadIndex by indexInc

Parameters

indexInc The amount to increment the delay buffer index

◆ incDelayBuffWriteIndex()

void incDelayBuffWriteIndex ( )

inlineprotectedinherited

Increments the currentDelayWriteBufferIndex by 1

◆ isNoise()

bool isNoise ( )

inlineinherited

◆ printInterpTable()

void printInterpTable ( )

inlineinherited

◆ process()

virtual effect_t process ( effect_t inputSample )

inlineoverridevirtualinherited

see applyFilter

Reimplemented from EffectSuiteBase.

Reimplemented in FilteredDelay.

◆ processDouble()

virtual effectsuite_t processDouble ( effectsuite_t inputSample )

inlineoverridevirtual

apply chorus effect to audio sample

Parameters

inputSample input audio sample

Returns: processed audio sample

Reimplemented from FilterEffectBase.

◆ readNoise()

effectsuite_t readNoise ( )

inlineinherited

reads out white noise

Returns: random number between -1 and 1

◆ readTable()

effectsuite_t readTable ( effectsuite_t freq )

inlineinherited

Read through values in waveTable as a given frequency

Parameters

freq	read speed in Hz: essentially the number of samples jumped between reads

Returns: value from table as effectsuite_t

◆ rms()

effectsuite_t rms ( effectsuite_t sample )

inlineprotectedinherited

root mean square of signal over a specific sample window

◆ setActive()

virtual void setActive ( bool value )

inlinevirtualinherited

sets the effect active/inactive

◆ setBase()

void setBase ( effectsuite_t baseAmount )

inline

sets the 'base' of the chorus: the minimum delay in the signal.

Parameters

baseAmount <baseAmount description#>

◆ setChebyICoefficients()

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

inlineinherited

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

◆ setDC()

void setDC ( )

inlineinherited

sets wavetable to DC one

◆ setDelayBuffer()

bool setDelayBuffer ( int bufferSizeSamples )

inlineprotectedinherited

Allocates memory for delay buffer and initialises all elements to 0

Parameters

bufferSizeSamples the size of delay buffer to be used

Returns: false and error description if there's a problem, or sets the internal delay buffer and returns true

◆ setDelayBuffReadIndex()

void setDelayBuffReadIndex ( effectsuite_t index )

inlineprotectedinherited

sets the currentDelayBufferReadIndex by indexInc (Currently no wrapping)

Parameters

index the read index index required

◆ setId()

void setId ( int id )

inlineinherited

Allows to identify an effect.

◆ setInterpolationTable()

static effectsuite_t ** setInterpolationTable ( )

inlinestaticprotectedinherited

Sets the internal lagrange interpolation table. Ideally it should be shared amongst all

Returns: false and an error description if there's a problem, or sets the interpolation lookup table and returns true

◆ setInterpTable()

bool setInterpTable ( )

inlineinherited

populates the internal interpolation table

Returns: return tru on success, else false

◆ setNoise()

void setNoise ( )

inlineinherited

◆ setOffSine()

void setOffSine ( )

inlineinherited

sets wavetable to one period of a sine wave oscillating between 0 and 1

◆ setRamp()

void setRamp ( )

inlineinherited

set wave table to be a ramp from 0 to 1

◆ setRandLfo()

void setRandLfo ( )

inlineprotected

◆ setSawtooth()

void setSawtooth ( )

inlineinherited

sets wavetable to one period of a sawtooth wave

◆ setSimpleLpf()

bool setSimpleLpf ( int order )

inlineprotectedinherited

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

◆ setSine()

void setSine ( )

inlineinherited

sets wavetable to one period of a sine wave oscillating between -1 and 1

◆ setSquare()

void setSquare ( )

inlineinherited

sets wavetable to one period of a square wave

◆ setSwing()

void setSwing ( effectsuite_t swingAmount )

inline

set the 'swing' of the chorus: The amount intensity of vibrato in the delay signal

Parameters

swingAmount <swingAmount description#>

◆ setTriangle()

void setTriangle ( )

inlineinherited

sets wavetable to one period of a triangle wave

◆ setupChorus()

void setupChorus ( effectsuite_t extSampleRate )

inline

set parameters and internal sample rate

Parameters

extSampleRate external sample rate

◆ setupDelayEffectBase()

void setupDelayEffectBase ( const int bufferSizeSamples )

inlineinherited

<Description#>

Parameters

bufferSizeSamples <bufferSizeSamples description#>

◆ setupModulationBaseClass()

void setupModulationBaseClass ( effectsuite_t extSampRate )

inlineinherited

setup the class with a given sample rate. Basically reperforming the constructor

Parameters

extSampRate External sample rate

◆ storeSample()

void storeSample ( effectsuite_t inputSample )

inlineprotectedinherited

store input sample into the delay buffer

Parameters

inputSample sample to be stored for delay (effectsuite_t)

Member Data Documentation

◆ active_flag

bool active_flag = true

protectedinherited

◆ base

effectsuite_t base

protected

minimum delay in samples. Typically 10 milliseconds

◆ bufferIndex

int bufferIndex = 0

protectedinherited

current buffer index

◆ currentDelayReadIndex

effectsuite_t currentDelayReadIndex = 0

protectedinherited

◆ currentDelayWriteIndex

int currentDelayWriteIndex = 0

protectedinherited

◆ delayBuffer

effectsuite_t* delayBuffer = 0

protectedinherited

buffer to stored audio buffer for delay effects

◆ delayTimeSamples

int delayTimeSamples = 44100

protectedinherited

the delay time of signal in samples

◆ error

bool error

protectedinherited

internal class error boolean

◆ filterOrder

int filterOrder = 0

protectedinherited

order of delay filter including the zero delay coefficients

◆ firBuffer

effectsuite_t* firBuffer = 0

protectedinherited

buffer to hold forward delay sample data

◆ firCoefficients

effectsuite_t* firCoefficients = 0

protectedinherited

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

◆ firTemp

effectsuite_t* firTemp = 0

protectedinherited

hold temporary values for fir coeffcient buffer

◆ id_value

int id_value = -1

protectedinherited

◆ iirBuffer

effectsuite_t* iirBuffer = 0

protectedinherited

buffer to hold backward delay sample data

◆ iirCoefficients

effectsuite_t* iirCoefficients = 0

protectedinherited

Denomiator coefficients in delay filter

See also: firCoefficients

◆ iirTemp

effectsuite_t* iirTemp = 0

protectedinherited

hold temporary values for iir coeffcient buffer

◆ interpOrder

const int interpOrder = 4

staticprotectedinherited

◆ interpResolution

const int interpResolution = 1000

staticprotectedinherited

◆ interpTable

effectsuite_t interpTable[order][res]

protectedinherited

◆ is_noise

bool is_noise = false

protectedinherited

◆ maxDelayBufferSize

int maxDelayBufferSize = 441000

protectedinherited

Maximum number of samples that can be stored in delayBuffer

◆ modMax

effectsuite_t modMax = .5

protected

the maximum value of the lowpassed random modulation signal

◆ modMin

effectsuite_t modMin = .5

protected

the minimum value of the lowpassed random modulation signal

◆ modNorm

effectsuite_t modNorm = 1 / (modMax - modMin)

protected

the normalising factor of the random delay signal

◆ order

const int order = 4

staticprotectedinherited

◆ readSpeed

const effectsuite_t readSpeed = ((readNoise() + 1) * .5) * .0005

protected

◆ res

const int res = 100

staticprotectedinherited

◆ rmsBuffer

effectsuite_t* rmsBuffer = new effectsuite_t[rmsWindowSize]

protectedinherited

RMS window buffer

◆ rmsBufferIndex

int rmsBufferIndex = 0

protectedinherited

current write index of rmsBuffer

◆ rmsWindowSize

const int rmsWindowSize = 128

protectedinherited

window size in samples of rms window

◆ sampleRate

int sampleRate

inherited

Internal Sample Rate

◆ samplingRate

int samplingRate = 0

protectedinherited

◆ swing

effectsuite_t swing

protected

swing range of delayed audio index in samples typical maximum swing would be 15 milliseconds (i.e. 0.015*sampleRate)

◆ tableIndex

effectsuite_t tableIndex = 0

inherited

current table read index

◆ timeStep

effectsuite_t timeStep

inherited

time between samples: 1/sampRate

◆ waveTable

effectsuite_t* waveTable

inherited

store modulation signal as

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

src/AudioTools/AudioLibs/AudioEffectsSuite.h

Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ SimpleChorus() [1/2]

◆ SimpleChorus() [2/2]

◆ ~SimpleChorus()

Member Function Documentation

◆ active()

◆ allocateBufferMemory()

◆ allocateMemory()

◆ applyFilter()

◆ changeChebyICoefficients()

◆ clearMemory()

◆ clip()

◆ clipWave()

◆ clone()

◆ copyParent()

◆ delaySample()

◆ envelope()

◆ getInterpolatedOut()

◆ getInterpOut()

◆ getModSignal()

◆ getSplineOut()

◆ id()

◆ incBufferIndex()

◆ incDelayBuffReadIndex()

◆ incDelayBuffWriteIndex()

◆ isNoise()

◆ printInterpTable()

◆ process()

◆ processDouble()

◆ readNoise()

◆ readTable()

◆ rms()

◆ setActive()

◆ setBase()

◆ setChebyICoefficients()

◆ setDC()

◆ setDelayBuffer()

◆ setDelayBuffReadIndex()

◆ setId()

◆ setInterpolationTable()

◆ setInterpTable()

◆ setNoise()

◆ setOffSine()

◆ setRamp()

◆ setRandLfo()

◆ setSawtooth()

◆ setSimpleLpf()

◆ setSine()

◆ setSquare()

◆ setSwing()

◆ setTriangle()

◆ setupChorus()

◆ setupDelayEffectBase()

◆ setupModulationBaseClass()

◆ storeSample()

Member Data Documentation

◆ active_flag

◆ base

◆ bufferIndex

◆ currentDelayReadIndex

◆ currentDelayWriteIndex

◆ delayBuffer

◆ delayTimeSamples

◆ error

◆ filterOrder

◆ firBuffer

◆ firCoefficients

◆ firTemp

◆ id_value

◆ iirBuffer

◆ iirCoefficients

◆ iirTemp

◆ interpOrder