krotos::Filter Class Reference

Filter an audio signal. More...

#include <Filter.h>

Public Types
enum class	Mode {   LPF12 , LPF24 , HPF12 , HPF24 ,   BPF12 , BPF24 }

Public Member Functions
	Filter ()
	~Filter ()=default
void	prepareToPlay (double sampleRate, int)
void	reset () noexcept
float	processSample (float inputValue, int channelToUse) noexcept
void	setMode (Mode newMode) noexcept
void	setCutoff (float newCutoff) noexcept
void	setResonance (float newResonance) noexcept
void	setDrive (float newDrive) noexcept

Private Member Functions
void	setSampleRate (float newValue) noexcept
void	setNumChannels (int newValue)

Private Attributes
std::vector< std::array< float, numStates > >	state
std::array< float, numStates >	A
float	cutoffFreqHz {1.0f}
float	cutoffFreqScaler
float	cutoffTransformValue
float	resonance {0.0f}
float	scaledResonanceValue
float	drive
float	drive2
float	gain
float	gain2
float	comp
dsp::LookupTableTransform< float >	saturationLUT {[](float x) { return std::tanh(x); }, -5.0f, 5.0f, 128}
Mode	mode {Mode::LPF12}
DryWet	m_mix
const int	NUM_CHANNELS_MAX {2}

Static Private Attributes
static constexpr size_t	numStates = 5

Detailed Description

Filter an audio signal.

This class is a basic filter implementation derived from the juce::dsp::LadderFilter class. The code was copied from JUCE in order to remove the smoothers and provide better integration with the Kwidget system, which already handles parameter smoothing.

This class can also be used to add other types of filtering, such as the formant filter present in krotos_modules_2.

TODO: Add formant filtering capability.

Member Enumeration Documentation

Mode

enum class krotos::Filter::Mode

strong

Enumerator
LPF12
LPF24
HPF12
HPF24
BPF12
BPF24

Constructor & Destructor Documentation

Filter()

krotos::Filter::Filter ( )

inline

Constructs a filter object. Call prepareToPlay() before using it!

~Filter()

krotos::Filter::~Filter ( )

default

Member Function Documentation

prepareToPlay()

void krotos::Filter::prepareToPlay ( double sampleRate, int  )

inline

Call this function to prepare the filter for processing, or whenever the sample rate and block size change.

processSample()

float krotos::Filter::processSample ( float inputValue, int channelToUse )

inlinenoexcept

Process a single sample through a particular channel.

reset()

void krotos::Filter::reset ( )

inlinenoexcept

Resets the internal state variables of the filter.

setCutoff()

void krotos::Filter::setCutoff ( float newCutoff )

inlinenoexcept

Sets the cutoff frequency of the filter.

Parameters

newCutoff

cutoff frequency in Hz

setDrive()

void krotos::Filter::setDrive ( float newDrive )

inlinenoexcept

Sets the amount of saturation in the filter.

Parameters

newDrive

saturation amount; it can be any number greater than or equal to one. Higher values result in more distortion.

setMode()

void krotos::Filter::setMode ( Mode newMode )

inlinenoexcept

Sets filter mode.

setNumChannels()

void krotos::Filter::setNumChannels ( int newValue )

inlineprivate

setResonance()

void krotos::Filter::setResonance ( float newResonance )

inlinenoexcept

Sets the resonance of the filter.

Parameters

newResonance

a value between 0 and 1; higher values increase the resonance and can result in self oscillation!

setSampleRate()

void krotos::Filter::setSampleRate ( float newValue )

inlineprivatenoexcept

Member Data Documentation

A

std::array<float, numStates> krotos::Filter::A

private

comp

float krotos::Filter::comp

private

cutoffFreqHz

float krotos::Filter::cutoffFreqHz {1.0f}

private

cutoffFreqScaler

float krotos::Filter::cutoffFreqScaler

private

cutoffTransformValue

float krotos::Filter::cutoffTransformValue

private

drive

float krotos::Filter::drive

private

drive2

float krotos::Filter::drive2

private

gain

float krotos::Filter::gain

private

gain2

float krotos::Filter::gain2

private

m_mix

DryWet krotos::Filter::m_mix

private

mode

Mode krotos::Filter::mode {Mode::LPF12}

private

NUM_CHANNELS_MAX

const int krotos::Filter::NUM_CHANNELS_MAX {2}

private

numStates

size_t krotos::Filter::numStates = 5

staticconstexprprivate

resonance

float krotos::Filter::resonance {0.0f}

private

saturationLUT

dsp::LookupTableTransform<float> krotos::Filter::saturationLUT {[](float x) { return std::tanh(x); }, -5.0f, 5.0f, 128}

private

scaledResonanceValue

float krotos::Filter::scaledResonanceValue

private

state

std::vector<std::array<float, numStates> > krotos::Filter::state

private

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

• krotos_dsp/processors/filter/Filter.h