filters

package
v0.0.0-...-486f928 Latest Latest
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 Go to latest Published: Apr 14, 2022 License: MIT Imports: 6 Imported by: 0

Documentation

Overview

Filters take samples as an input and produce samples as an output.

Index

Constants

View Source 
const MaxInt int = (1<<bits.UintSize)/2 - 1

Variables

This section is empty.

Functions

func BandPassConvolution 

func BandPassConvolution(sampleRate, lowest, highest float64, order int) []float64

Order should be odd.

func Delay 

func Delay(s, factor, feedback float64, ring *ring.Ring) float64

func HighPassConvolution 

func HighPassConvolution(sampleRate, cutoff float64, order int) []float64

Order should be odd.

func LowPassConvolution 

func LowPassConvolution(sampleRate, cutoff float64, order int) []float64

Order should be odd.

Types

type BandPassConvolutionFilter 

type BandPassConvolutionFilter struct {
	// The lowest frequency to be included, in Hz.
	Lowest float64

	// The Highest frequency to be included, in Hz.
	Highest float64

	// The order of the filter. Should be odd.
	// The order can't be changed once set without resetting the convolution
	// filter.
	Order int

	// The underlying SimpleConvolutionFilter used.
	ConvolutionFilter *SimpleConvolutionFilter
}

A FIR band pass filter.

func NewBandPassConvolutionFilter 

func NewBandPassConvolutionFilter(lowest, highest float64, order int) *BandPassConvolutionFilter

func (*BandPassConvolutionFilter) Filter 

func (f *BandPassConvolutionFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type BaseFilter 

type BaseFilter struct {
	FilterFunc func(cfg *audio.AudioConfig, samples []float64) []float64
}

func (*BaseFilter) Filter 

func (f *BaseFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type DelayFilter 

type DelayFilter struct {
	LeftTime      float64
	LeftFactor    float64
	LeftFeedback  float64
	LeftDelayed   *ring.Ring
	RightTime     float64
	RightFactor   float64
	RightFeedback float64
	RightDelayed  *ring.Ring
}

func NewDelayFilter 

func NewDelayFilter(time, factor, feedback float64) *DelayFilter

func (*DelayFilter) Filter 

func (f *DelayFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type DistortionFilter 

type DistortionFilter struct {
	Level float64
}

func NewDistortionFilter 

func NewDistortionFilter(level float64) *DistortionFilter

func (*DistortionFilter) Filter 

func (f *DistortionFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type Equalizer 

type Equalizer struct {
	Bands  int
	Values []float64
}

func NewEqualizer 

func NewEqualizer(bands int, values []float64) *Equalizer

type Filter 

type Filter interface {
	Filter(cfg *audio.AudioConfig, samples []float64) []float64
}

func AverageFilter 

func AverageFilter(filters ...Filter) Filter

func ComposedFilter 

func ComposedFilter(f1 Filter, f2 Filter) Filter

func MustNewSimpleConvolutionFilterFromWav 

func MustNewSimpleConvolutionFilterFromWav(wav string) Filter

func NewBaseFilter 

func NewBaseFilter(f func(cfg *audio.AudioConfig, samples []float64) []float64) Filter

func NewSimpleConvolutionFilterFromWav 

func NewSimpleConvolutionFilterFromWav(wav string) (Filter, error)

func SumFilter 

func SumFilter(filters ...Filter) Filter

type FlangerFilter 

type FlangerFilter struct {
	Time    float64
	Factor  float64
	LFORate float64

	LeftDelayed  []float64
	RightDelayed []float64
	Phase        int
}

func NewFlangerFilter 

func NewFlangerFilter(time, factor, rate float64) *FlangerFilter

func (*FlangerFilter) Filter 

func (f *FlangerFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type HighPassConvolutionFilter 

type HighPassConvolutionFilter struct {
	// The cutoff frequency, in Hz.
	Cutoff float64

	// The order of the filter. Should be odd.
	// The order can't be changed once set without resetting the convolution
	// filter.
	Order int

	// The underlying SimpleConvolutionFilter used.
	ConvolutionFilter *SimpleConvolutionFilter
}

A FIR high pass filter.

func NewHighPassConvolutionFilter 

func NewHighPassConvolutionFilter(cutoff float64, order int) *HighPassConvolutionFilter

func (*HighPassConvolutionFilter) Filter 

func (f *HighPassConvolutionFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type LowPassConvolutionFilter 

type LowPassConvolutionFilter struct {
	Cutoff float64

	// The order of the filter. Should be odd.
	// The order can't be changed once set without resetting the convolution
	// filter.
	Order int

	// The underlying SimpleConvolutionFilter used.
	ConvolutionFilter *SimpleConvolutionFilter
}

func NewLowPassConvolutionFilter 

func NewLowPassConvolutionFilter(cutoff float64, order int) *LowPassConvolutionFilter

func (*LowPassConvolutionFilter) Filter 

func (f *LowPassConvolutionFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type LowPassFilter 

type LowPassFilter struct {
	Cutoff        float64
	PreviousLeft  float64
	PreviousRight float64
}

Cutoff frequency = Alpha / ((1 - Alpha) * 2 * Pi * dt Alpha = 2Pi * dt * Cutoff / (2Pi * dt * Cutoff + 1)

func NewLowPassFilter 

func NewLowPassFilter(cutoff float64) *LowPassFilter

func (*LowPassFilter) Filter 

func (f *LowPassFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type OverdriveFilter 

type OverdriveFilter struct {
	Factor float64
}

func NewOverdriveFilter 

func NewOverdriveFilter(factor float64) *OverdriveFilter

func (*OverdriveFilter) Filter 

func (f *OverdriveFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type SimpleConvolutionFilter 

type SimpleConvolutionFilter struct {
	Coefficients   []float64
	LeftDelayLine  *ring.Ring
	RightDelayLine *ring.Ring
}

The simple convolution filter is efficient when the number of coefficients is small (on my desktop: <300), and works by multiplying the coefficients with the values in the delay line.

This filter should be appropriate for implementing low pass, high pass, band pass and band stop filters.

func NewSimpleConvolutionFilter 

func NewSimpleConvolutionFilter(coefficients []float64) *SimpleConvolutionFilter

func (*SimpleConvolutionFilter) Filter 

func (s *SimpleConvolutionFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

type TremeloFilter 

type TremeloFilter struct {
	Rate   float64
	Factor float64
	Phase  float64
}

func NewTremeloFilter 

func NewTremeloFilter(rate, factor float64) *TremeloFilter

func (*TremeloFilter) Filter 

func (f *TremeloFilter) Filter(cfg *audio.AudioConfig, samples []float64) []float64

Source Files

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