The FX-Functions module contains specialized audio DSP C++ functions that are inlcuded with and documented in Will Pirkle's new plugin programming book. These objects are described with even more documentation in this book and are free to use in your projects, commercial or personal. More...

Functions
bool	checkFloatUnderflow (double &value)
	Perform underflow check; returns true if we did underflow (user may not care)

double	doLinearInterpolation (double x1, double x2, double y1, double y2, double x)
	performs linear interpolation of x distance between two (x,y) points; returns interpolated value

double	doLinearInterpolation (double y1, double y2, double fractional_X)
	performs linear interpolation of fractional x distance between two adjacent (x,y) points; returns interpolated value

double	doLagrangeInterpolation (double x, double y, int n, double xbar)
	implements n-order Lagrange Interpolation

void	boundValue (double &value, double minValue, double maxValue)
	Bound a value to min and max limits.

double	doUnipolarModulationFromMin (double unipolarModulatorValue, double minValue, double maxValue)
	Perform unipolar modulation from a min value up to a max value using a unipolar modulator value.

double	doUnipolarModulationFromMax (double unipolarModulatorValue, double minValue, double maxValue)
	Perform unipolar modulation from a max value down to a min value using a unipolar modulator value.

double	doBipolarModulation (double bipolarModulatorValue, double minValue, double maxValue)
	Perform bipolar modulation about a center that his halfway between the min and max values.

double	unipolarToBipolar (double value)
	calculates the bipolar [-1.0, +1.0] value FROM a unipolar [0.0, +1.0] value

double	bipolarToUnipolar (double value)
	calculates the unipolar [0.0, +1.0] value FROM a bipolar [-1.0, +1.0] value

double	raw2dB (double raw)
	calculates dB for given input

double	dB2Raw (double dB)
	converts dB to raw value

double	peakGainFor_Q (double Q)
	calculates the peak magnitude for a given Q

double	dBPeakGainFor_Q (double Q)
	calculates the peak magnitude in dB for a given Q

double	doWhiteNoise ()
	calculates a random value between -1.0 and +1.0

double	sgn (double xn)
	calculates sgn( ) of input

double	calcWSGain (double xn, double saturation, double asymmetry)
	calculates gain of a waveshaper

double	atanWaveShaper (double xn, double saturation)
	calculates arctangent waveshaper

double	tanhWaveShaper (double xn, double saturation)
	calculates hyptan waveshaper

double	softClipWaveShaper (double xn, double saturation)
	calculates hyptan waveshaper

double	fuzzExp1WaveShaper (double xn, double saturation, double asymmetry)
	calculates fuzz exp1 waveshaper

double	getMagResponse (double theta, double a0, double a1, double a2, double b1, double b2)
	returns the magnitude resonse of a 2nd order H(z) transfer function

ComplexNumber	complexMultiply (ComplexNumber c1, ComplexNumber c2)
	returns the complex product of two complex numbers

void	calcEdgeFrequencies (double fc, double Q, double &f_Low, double &f_High)
	calculagte low and high edge frequencies of BPF or BSF

int	findEdgeTargetBin (double testFreq, double bin1Freq)
	find bin for target frequency

bool	getTransitionBandData (double testFreq, double bin1Freq, unsigned int relax_Bins, TransitionBandData &transitionData)
	get bin data for a filter's transitino band (see FX book for details)

bool	calculateBrickwallMagArray (BrickwallMagData &magData)
	calculate an arra of magnitude points from brickwall specifications

bool	calculateAnalogMagArray (AnalogMagData &magData)
	calculate an arra of magnitude points from analog filter specifications

void	freqSample (int N, double A[], double h[], int symm)
	calcuate the IR for an array of magnitude points using the frequency sampling method. NOTE: very old function that is all over the internet.

double	getMagnitude (double re, double im)
	calculates magnitude of a complex numb er

double	getPhase (double re, double im)
	calculates phase of a complex numb er

double	principalArg (double phaseIn)
	calculates proncipal argument of a phase value; this is the wrapped value on the range of [-pi, +pi]

bool	resample (double input, double output, uint32_t inLength, uint32_t outLength, interpolation interpType=interpolation::kLinear, double scalar=1.0, double *outWindow=nullptr)
	function that resamples an input array of length N into an output array of length M. You can set the interpolation type (linear or lagrange) and you can supply an optional window array that the resampled array will be processed through.

std::unique_ptr< double[]>	makeWindow (unsigned int windowLength, unsigned int hopSize, windowType window, double &gainCorrectionValue)
	creates a new std::unique_ptr<double[]> array for a given window lenght and type.

unsigned int	countForRatio (rateConversionRatio ratio)
	returns the up or downsample ratio as a numeric value

double *	getFilterIRTable (unsigned int FIRLength, rateConversionRatio ratio, unsigned int sampleRate)
	returns the up or downsample ratio as a numeric value

double **	decomposeFilter (double *filterIR, unsigned int FIRLength, unsigned int ratio)
	performs a polyphase decomposition on a big FIR into a set of sub-band FIRs

SpeakerArrangement	Steinberg::Vst::ASPiK::getSupportedSpeakerArrangement (uint32_t index)
	implements n-order Lagrange Interpolation

uint32_t	Steinberg::Vst::ASPiK::getChannelFormatForSpkrArrangement (SpeakerArrangement arr)
	implements n-order Lagrange Interpolation

Detailed Description

The FX-Functions module contains specialized audio DSP C++ functions that are inlcuded with and documented in Will Pirkle's new plugin programming book. These objects are described with even more documentation in this book and are free to use in your projects, commercial or personal.

Download them from https://www.willpirkle.com/Downloads/fxobjects.zip and then you may drop them into your ASPiK's PluginObject folder and import them into your Visual Studio or XCode projects (you need to do this manually for several reasons, one involving FFTW and that is why it is not a direct part of the SDK). These objects are 100% free for you to use in your commercial or non-commercial plugins. See the ASPiK licensing agreement for details.

Function Documentation

◆ atanWaveShaper()

double atanWaveShaper	(	double	xn,
		double	saturation
	)

inline

calculates arctangent waveshaper

@atanWaveShaper

Parameters

xn	- the input value
saturation	- the saturation control

Returns: the waveshaped output value

◆ bipolarToUnipolar()

double bipolarToUnipolar ( double value )

inline

calculates the unipolar [0.0, +1.0] value FROM a bipolar [-1.0, +1.0] value

@bipolarToUnipolar

Parameters

value - value to convert

Returns: the unipolar value

◆ boundValue()

void boundValue	(	double &	value,
		double	minValue,
		double	maxValue
	)

inline

Bound a value to min and max limits.

@boundValue

Parameters

value	- value to bound
minValue	- lower bound limit
maxValue	- upper bound limit

◆ calcEdgeFrequencies()

void calcEdgeFrequencies	(	double	fc,
		double	Q,
		double &	f_Low,
		double &	f_High
	)

inline

calculagte low and high edge frequencies of BPF or BSF

@calcEdgeFrequencies

Parameters

fc	- the center frequency of the BPF or BSF
Q	- the Q (fc/BW) of the filter
f_Low	- the returned low edge frequency
f_High	- the returned high edge frequency

◆ calculateAnalogMagArray()

bool calculateAnalogMagArray ( AnalogMagData & magData )

inline

calculate an arra of magnitude points from analog filter specifications

@calculateAnalogMagArray

Parameters

magData - the the target magnitude data

Returns: true if data was filled, false otherwise

◆ calculateBrickwallMagArray()

bool calculateBrickwallMagArray ( BrickwallMagData & magData )

inline

calculate an arra of magnitude points from brickwall specifications

@calculateBrickwallMagArray

Parameters

magData - the the target magnitude data

Returns: true if data was filled, false otherwise

◆ calcWSGain()

double calcWSGain	(	double	xn,
		double	saturation,
		double	asymmetry
	)

inline

calculates gain of a waveshaper

@calcWSGain

Parameters

xn	- the input value
saturation	- the saturation control
asymmetry	- the degree of asymmetry

Returns: gain value

◆ checkFloatUnderflow()

bool checkFloatUnderflow ( double & value )

inline

Perform underflow check; returns true if we did underflow (user may not care)

@checkFloatUnderflow

Parameters

value - the value to check for underflow

Returns: true if overflowed, false otherwise

◆ complexMultiply()

ComplexNumber complexMultiply	(	ComplexNumber	c1,
		ComplexNumber	c2
	)

inline

returns the complex product of two complex numbers

@complexMultiply

Parameters

c1,c2 - complex numbers to multiply

Returns: the complex product of c1 and c2

◆ countForRatio()

unsigned int countForRatio ( rateConversionRatio ratio )

inline

returns the up or downsample ratio as a numeric value

@countForRatio

Parameters

ratio - enum class ratio value

Returns: the up or downsample ratio as a numeric value

◆ dB2Raw()

double dB2Raw ( double dB )

inline

converts dB to raw value

@dBTo_Raw

Parameters

dB	- value to convert to raw

Returns: the raw value

◆ dBPeakGainFor_Q()

double dBPeakGainFor_Q ( double Q )

inline

calculates the peak magnitude in dB for a given Q

@dBPeakGainFor_Q

Parameters

Q	- the Q value

Returns: the peak gain in dB

◆ decomposeFilter()

double ** decomposeFilter	(	double *	filterIR,
		unsigned int	FIRLength,
		unsigned int	ratio
	)

inline

performs a polyphase decomposition on a big FIR into a set of sub-band FIRs

@decomposeFilter

Parameters

filterIR	- pointer to filter IR array
FIRLength	- lenght of IR array
ratio	- up or down sampling ratio

Returns: a pointer an arry of buffer pointers to the decomposed mini-filters

◆ doBipolarModulation()

double doBipolarModulation	(	double	bipolarModulatorValue,
		double	minValue,
		double	maxValue
	)

inline

Perform bipolar modulation about a center that his halfway between the min and max values.

@doBipolarModulation

Parameters

bipolarModulatorValue	- modulation value on range [-1.0, +1.0]
minValue	- lower modulation limit
maxValue	- upper modulation limit

Returns: the modulated value

◆ doLagrangeInterpolation()

double doLagrangeInterpolation	(	double *	x,
		double *	y,
		int	n,
		double	xbar
	)

inline

implements n-order Lagrange Interpolation

@doLagrangeInterpolation

Parameters

x	- Pointer to an array containing the x-coordinates of the input values
y	- Pointer to an array containing the y-coordinates of the input values
n	- the order of the interpolator, this is also the length of the x,y input arrays
xbar	- The x-coorinates whose y-value we want to interpolate

Returns: the interpolated value

◆ doLinearInterpolation() [1/2]

double doLinearInterpolation	(	double	x1,
		double	x2,
		double	y1,
		double	y2,
		double	x
	)

inline

performs linear interpolation of x distance between two (x,y) points; returns interpolated value

@doLinearInterpolation

Parameters

x1	- the x coordinate of the first point
x2	- the x coordinate of the second point
y1	- the y coordinate of the first point
y2	- the 2 coordinate of the second point
x	- the interpolation location

Returns: the interpolated value or y1 if the x coordinates are unusable

◆ doLinearInterpolation() [2/2]

double doLinearInterpolation	(	double	y1,
		double	y2,
		double	fractional_X
	)

inline

performs linear interpolation of fractional x distance between two adjacent (x,y) points; returns interpolated value

@doLinearInterpolation

Parameters

y1	- the y coordinate of the first point
y2	- the 2 coordinate of the second point
x	- the interpolation location as a fractional distance between x1 and x2 (which are not needed)

Returns: the interpolated value or y2 if the interpolation is outside the x interval

◆ doUnipolarModulationFromMax()

double doUnipolarModulationFromMax	(	double	unipolarModulatorValue,
		double	minValue,
		double	maxValue
	)

inline

Perform unipolar modulation from a max value down to a min value using a unipolar modulator value.

@doUnipolarModulationFromMax

Parameters

unipolarModulatorValue	- modulation value on range [0.0, +1.0]
minValue	- lower modulation limit
maxValue	- upper modulation limit

Returns: the modulated value

◆ doUnipolarModulationFromMin()

double doUnipolarModulationFromMin	(	double	unipolarModulatorValue,
		double	minValue,
		double	maxValue
	)

inline

Perform unipolar modulation from a min value up to a max value using a unipolar modulator value.

@doUnipolarModulationFromMin

Parameters

unipolarModulatorValue	- modulation value on range [0.0, +1.0]
minValue	- lower modulation limit
maxValue	- upper modulation limit

Returns: the modulated value

◆ doWhiteNoise()

double doWhiteNoise ( )

inline

calculates a random value between -1.0 and +1.0

@doWhiteNoise

Returns: the random value on the range [-1.0, +1.0]

◆ findEdgeTargetBin()

int findEdgeTargetBin	(	double	testFreq,
		double	bin1Freq
	)

inline

find bin for target frequency

@findEdgeTargetBin

Parameters

testFreq	- the target frequency
bin1Freq	- the frequency of bin 1

Returns: the index of the target bin

◆ freqSample()

void freqSample	(	int	N,
		double	A[],
		double	h[],
		int	symm
	)

inline

calcuate the IR for an array of magnitude points using the frequency sampling method. NOTE: very old function that is all over the internet.

@freqSample

Parameters

N	- Number of filter coefficients
A[]	- Sample points of desired response [N/2]
symmetry	- Symmetry of desired filter
h[]	- the output array of impulse response

◆ fuzzExp1WaveShaper()

double fuzzExp1WaveShaper	(	double	xn,
		double	saturation,
		double	asymmetry
	)

inline

calculates fuzz exp1 waveshaper

@fuzzExp1WaveShaper

Parameters

xn	- the input value
saturation	- the saturation control

Returns: the waveshaped output value

◆ getChannelFormatForSpkrArrangement()

uint32_t Steinberg::Vst::ASPiK::getChannelFormatForSpkrArrangement ( SpeakerArrangement arr )

implements n-order Lagrange Interpolation

@getChannelFormatForSpkrArrangement

Parameters

SpeakerArrangement the VST speaker arrangement

Returns: the ASPiK channel I/O combination enum

◆ getFilterIRTable()

double * getFilterIRTable	(	unsigned int	FIRLength,
		rateConversionRatio	ratio,
		unsigned int	sampleRate
	)

inline

returns the up or downsample ratio as a numeric value

@getFilterIRTable

Parameters

FIRLength	- lenght of FIR
ratio	- the conversinon ratio
sampleRate	- the sample rate

Returns: a pointer to the appropriate FIR coefficient table in filters.h or nullptr if not found

◆ getMagnitude()

double getMagnitude	(	double	re,
		double	im
	)

inline

calculates magnitude of a complex numb er

@getMagnitude

Parameters

re	- complex number real part
im	- complex number imaginary part

Returns: the magnitude value

◆ getMagResponse()

double getMagResponse	(	double	theta,
		double	a0,
		double	a1,
		double	a2,
		double	b1,
		double	b2
	)

inline

returns the magnitude resonse of a 2nd order H(z) transfer function

@getMagResponse

Parameters

theta	- the angular frequency to apply
a0,a1,a2,b1,b2	- the transfer function coefficients

Returns: the magnigtude response of the transfer function at w = theta

◆ getPhase()

double getPhase	(	double	re,
		double	im
	)

inline

calculates phase of a complex numb er

@getPhase

Parameters

re	- complex number real part
im	- complex number imaginary part

Returns: the phase value

◆ getSupportedSpeakerArrangement()

SpeakerArrangement Steinberg::Vst::ASPiK::getSupportedSpeakerArrangement ( uint32_t index )

implements n-order Lagrange Interpolation

@getSupportedSpeakerArrangement

Parameters

index index of channel I/O struct

Returns: the VST SpeakerArrangement version of ASPiK channel I/O combi

◆ getTransitionBandData()

bool getTransitionBandData	(	double	testFreq,
		double	bin1Freq,
		unsigned int	relax_Bins,
		TransitionBandData &	transitionData
	)

inline

get bin data for a filter's transitino band (see FX book for details)

@getTransitionBandData

Parameters

testFreq	- the target frequency
bin1Freq	- the frequency of bin 1
relax_Bins	- numebr of bins to relax the filter specification
transitionData	- the output parameter containing the data

Returns: true if data was filled, false otherwise

◆ makeWindow()

std::unique_ptr< double[]> makeWindow	(	unsigned int	windowLength,
		unsigned int	hopSize,
		windowType	window,
		double &	gainCorrectionValue
	)

inline

creates a new std::unique_ptr<double[]> array for a given window lenght and type.

@makeWindow

Parameters

windowLength	- length of window array (does NOT need to be power of 2)
hopSize	- hopSize for vococerf applications, may set to 0 for non vocoder use
gainCorrectionValue	- return variable that contains the window gain correction value

◆ peakGainFor_Q()

double peakGainFor_Q ( double Q )

inline

calculates the peak magnitude for a given Q

@peakGainFor_Q

Parameters

Q	- the Q value

Returns: the peak gain (not in dB)

◆ principalArg()

double principalArg ( double phaseIn )

inline

calculates proncipal argument of a phase value; this is the wrapped value on the range of [-pi, +pi]

@principalArg

Parameters

phaseIn - value to convert

Returns: the phase value on the range of [-pi, +pi]

◆ raw2dB()

double raw2dB ( double raw )

inline

calculates dB for given input

@rawTo_dB

Parameters

raw	- value to convert to dB

Returns: the dB value

◆ resample()

bool resample	(	double *	input,
		double *	output,
		uint32_t	inLength,
		uint32_t	outLength,
		interpolation	interpType = `interpolation::kLinear`,
		double	scalar = `1.0`,
		double *	outWindow = `nullptr`
	)

inline

function that resamples an input array of length N into an output array of length M. You can set the interpolation type (linear or lagrange) and you can supply an optional window array that the resampled array will be processed through.

@resample

Parameters

input	- input array
output	- output array
inLength	- length N of input buffer
outLength	- length M of output buffer
interpType	- linear or lagrange interpolation
scalar	- output scaling value (optional)
outWindow	- output windowing buffer (optional)

Returns: true if resampling was sucessful

◆ sgn()

double sgn ( double xn )

inline

calculates sgn( ) of input

@sgn

Parameters

xn	- the input value

Returns: -1 if xn is negative or +1 if xn is 0 or greater

◆ softClipWaveShaper()

double softClipWaveShaper	(	double	xn,
		double	saturation
	)

inline

calculates hyptan waveshaper

@softClipWaveShaper

Parameters

xn	- the input value
saturation	- the saturation control

Returns: the waveshaped output value

◆ tanhWaveShaper()

double tanhWaveShaper	(	double	xn,
		double	saturation
	)

inline

calculates hyptan waveshaper

@tanhWaveShaper

Parameters

xn	- the input value
saturation	- the saturation control

Returns: the waveshaped output value

◆ unipolarToBipolar()

double unipolarToBipolar ( double value )

inline

calculates the bipolar [-1.0, +1.0] value FROM a unipolar [0.0, +1.0] value

@unipolarToBipolar

Parameters

value - value to convert

Returns: the bipolar value