synthesizer

Documentation

Overview

wavetable implementation

Index

• func ADSR(maxamp, duration, attacktime, decaytime, sus, releasetime, controlrate float64, ...) float64
• func Balance(signal, comparator, delay []float64, frequency, samplerate float64) []float64
• func FourierTable(nharms int, amps []float64, length int, phase float64) []float64
• func Highpass(fs []float64, freq, delay, sr float64) []float64
• func Len(g *Gtable) int
• func Lowpass(fs []float64, freq, delay, sr float64) []float64
• func NoteToFrequency(note string, octave int) float64
• func ParseNoteToFrequency(note string) (float64, error)
• func SawTable(nharms, length int) []float64
• func SquareTable(nharms, length int) []float64
• func TriangleTable(nharms, length int) []float64
• type EqualTemperedNote
• type Gtable
  • func NewGtable(data []float64) *Gtable
  • func NewSineTable(length int) *Gtable
  • func NewTriangleTable(length int, nharmonics int) (*Gtable, error)
• type LookupOscillator
  • func NewLookupOscillator(sr int, t *Gtable, phase float64) (*LookupOscillator, error)
  • func (l *LookupOscillator) BatchInterpolateTick(freq float64, nframes int) []float64
  • func (l *LookupOscillator) BatchTruncateTick(freq float64, nframes int) []float64
  • func (l *LookupOscillator) InterpolateTick(freq float64) float64
  • func (l *LookupOscillator) TruncateTick(freq float64) float64
• type Oscillator
  • func NewOscillator(sr int, shape Shape) (*Oscillator, error)
  • func NewPhaseOscillator(sr int, phase float64, shape Shape) (*Oscillator, error)
  • func (o *Oscillator) Tick(freq float64) float64
• type Shape

Functions

func ADSR

func ADSR(maxamp, duration, attacktime, decaytime, sus, releasetime, controlrate float64, currentframe int) float64

ADSR creates an attack -> decay -> sustain -> release envelope time durations are passes as seconds. returns the value + the current time

func Balance

func Balance(signal, comparator, delay []float64, frequency, samplerate float64) []float64

Balance a signal (rescale output signal)

func FourierTable

func FourierTable(nharms int, amps []float64, length int, phase float64) []float64

FourierTable constructs a lookup table based on fourier addition with 'nharmns' harmonics If amps is provided, scales the harmonics by the provided amp

func Highpass

func Highpass(fs []float64, freq, delay, sr float64) []float64

Highpass applies a high-pass filter to the frames. Does not modify the input signal

func Len

func Len(g *Gtable) int

Len returns the length of the data segment without the guard point

func Lowpass

func Lowpass(fs []float64, freq, delay, sr float64) []float64

Lowpass applies a low-pass filter to the frames Does not modify the input signal

func NoteToFrequency

func NoteToFrequency(note string, octave int) float64

NoteToFrequency turns a given note & octave into a frequency using Equal-Tempered tuning with reference pitch = A440

func ParseNoteToFrequency

func ParseNoteToFrequency(note string) (float64, error)

ParseNoteToFrequency tries to parse a string representation of a note+octave (e.g C#4) and will return a float64 frequency value using 'NoteToFrequency'

func SawTable

func SawTable(nharms, length int) []float64

SawTable creates a sawtooth wavetable using Fourier addition

func SquareTable

func SquareTable(nharms, length int) []float64

SquareTable uses fourier addition to create a square waveform

func TriangleTable

func TriangleTable(nharms, length int) []float64

TriangleTable uses fourier addition to create a triangle waveform

Types

type EqualTemperedNote

type EqualTemperedNote float64

EqualTemperedNote

const (
	C0  EqualTemperedNote = 16.35
	C0S EqualTemperedNote = 17.32
	D0  EqualTemperedNote = 18.35
	D0S EqualTemperedNote = 19.45
	E0  EqualTemperedNote = 20.60
	F0  EqualTemperedNote = 21.83
	F0S EqualTemperedNote = 23.12
	G0  EqualTemperedNote = 24.50
	G0S EqualTemperedNote = 25.96
	A0  EqualTemperedNote = 27.50
	A0S EqualTemperedNote = 29.14
	B0  EqualTemperedNote = 30.87
	C1  EqualTemperedNote = 32.70
	C1S EqualTemperedNote = 34.65
	D1  EqualTemperedNote = 36.71
	D1S EqualTemperedNote = 38.89
	E1  EqualTemperedNote = 41.20
	F1  EqualTemperedNote = 43.65
	F1S EqualTemperedNote = 46.25
	G1  EqualTemperedNote = 49.00
	G1S EqualTemperedNote = 51.91
	A1  EqualTemperedNote = 55.00
	A1S EqualTemperedNote = 58.27
	B1  EqualTemperedNote = 61.74
	C2  EqualTemperedNote = 65.41
	C2S EqualTemperedNote = 69.30
	D2  EqualTemperedNote = 73.42
	D2S EqualTemperedNote = 77.78
	E2  EqualTemperedNote = 82.41
	F2  EqualTemperedNote = 87.31
	F2S EqualTemperedNote = 92.50
	G2  EqualTemperedNote = 98.00
	G2S EqualTemperedNote = 103.83
	A2  EqualTemperedNote = 110.00
	A2S EqualTemperedNote = 116.54
	B2  EqualTemperedNote = 123.47
	C3  EqualTemperedNote = 130.81
	C3S EqualTemperedNote = 138.59
	D3  EqualTemperedNote = 146.83
	D3S EqualTemperedNote = 155.56
	E3  EqualTemperedNote = 164.81
	F3  EqualTemperedNote = 174.61
	F3S EqualTemperedNote = 185.00
	G3  EqualTemperedNote = 196.00
	G3S EqualTemperedNote = 207.65
	A3  EqualTemperedNote = 220.00
	A3S EqualTemperedNote = 233.08
	B3  EqualTemperedNote = 246.94
	C4  EqualTemperedNote = 261.63
	C4S EqualTemperedNote = 277.18
	D4  EqualTemperedNote = 293.66
	D4S EqualTemperedNote = 311.13
	E4  EqualTemperedNote = 329.63
	F4  EqualTemperedNote = 349.23
	F4S EqualTemperedNote = 369.99
	G4  EqualTemperedNote = 392.00
	G4S EqualTemperedNote = 415.30
	A4  EqualTemperedNote = 440.00
	A4S EqualTemperedNote = 466.16
	B4  EqualTemperedNote = 493.88
	C5  EqualTemperedNote = 523.25
	C5S EqualTemperedNote = 554.37
	D5  EqualTemperedNote = 587.33
	D5S EqualTemperedNote = 622.25
	E5  EqualTemperedNote = 659.25
	F5  EqualTemperedNote = 698.46
	F5S EqualTemperedNote = 739.99
	G5  EqualTemperedNote = 783.99
	G5S EqualTemperedNote = 830.61
	A5  EqualTemperedNote = 880.00
	A5S EqualTemperedNote = 932.33
	B5  EqualTemperedNote = 987.77
	C6  EqualTemperedNote = 1046.50
	C6S EqualTemperedNote = 1108.73
	D6  EqualTemperedNote = 1174.66
	D6S EqualTemperedNote = 1244.51
	E6  EqualTemperedNote = 1318.51
	F6  EqualTemperedNote = 1396.91
	F6S EqualTemperedNote = 1479.98
	G6  EqualTemperedNote = 1567.98
	G6S EqualTemperedNote = 1661.22
	A6  EqualTemperedNote = 1760.00
	A6S EqualTemperedNote = 1864.66
	B6  EqualTemperedNote = 1975.53
	C7  EqualTemperedNote = 2093.00
	C7S EqualTemperedNote = 2217.46
	D7  EqualTemperedNote = 2349.32
	D7S EqualTemperedNote = 2489.02
	E7  EqualTemperedNote = 2636.02
	F7  EqualTemperedNote = 2793.83
	F7S EqualTemperedNote = 2959.96
	G7  EqualTemperedNote = 3135.96
	G7S EqualTemperedNote = 3322.44
	A7  EqualTemperedNote = 3520.00
	A7S EqualTemperedNote = 3729.31
	B7  EqualTemperedNote = 3951.07
	C8  EqualTemperedNote = 4186.01
	C8S EqualTemperedNote = 4434.92
	D8  EqualTemperedNote = 4698.63
	D8S EqualTemperedNote = 4978.03
	E8  EqualTemperedNote = 5274.04
	F8  EqualTemperedNote = 5587.65
	F8S EqualTemperedNote = 5919.91
	G8  EqualTemperedNote = 6271.93
	G8S EqualTemperedNote = 6644.88
	A8  EqualTemperedNote = 7040.00
	A8S EqualTemperedNote = 7458.62
	B8  EqualTemperedNote = 7902.13
)

These constants represent the frequncies for the equal-tempered scale tuned to A4 = 440Hz

type Gtable

type Gtable struct {
	// contains filtered or unexported fields
}

Gtable is a Guard-table for oscillator lookup

func NewGtable

func NewGtable(data []float64) *Gtable

func NewSineTable

func NewSineTable(length int) *Gtable

NewSineTable returns a lookup table populated for sine-wave generation.

func NewTriangleTable

func NewTriangleTable(length int, nharmonics int) (*Gtable, error)

NewTriangleTable generates a lookup table for a triangle wave of the specified length and with the requested number of harmonics.

type LookupOscillator

type LookupOscillator struct {
	Oscillator
	Table      *Gtable
	SizeOverSr float64 // convenience variable for calculations
}

LookupOscillator is an oscillator that's more gentle on your CPU By performing a table lookup to generate the required waveform..

func NewLookupOscillator

func NewLookupOscillator(sr int, t *Gtable, phase float64) (*LookupOscillator, error)

NewLookupOscillator creates a new oscillator which performs a table-lookup to generate the required waveform

func (*LookupOscillator) BatchInterpolateTick

func (l *LookupOscillator) BatchInterpolateTick(freq float64, nframes int) []float64

BatchInterpolateTick performs a lookup for N frames, and interpolates the value if the requested index does not appear in the table.

func (*LookupOscillator) BatchTruncateTick

func (l *LookupOscillator) BatchTruncateTick(freq float64, nframes int) []float64

BatchTruncateTick returns a slice of samples from the oscillator of the requested length

func (*LookupOscillator) InterpolateTick

func (l *LookupOscillator) InterpolateTick(freq float64) float64

InterpolateTick performs a lookup but interpolates the value if the requested index does not appear in the table.

func (*LookupOscillator) TruncateTick

func (l *LookupOscillator) TruncateTick(freq float64) float64

TruncateTick performs a lookup and truncates the value index down (if the index for lookup = 10.5, return index 10)

type Oscillator

type Oscillator struct {
	// contains filtered or unexported fields
}

Oscillator represents a wave-oscillator where each tick is calculated in the moment.

func NewOscillator

func NewOscillator(sr int, shape Shape) (*Oscillator, error)

NewOscillator set to a given sample rate

func NewPhaseOscillator

func NewPhaseOscillator(sr int, phase float64, shape Shape) (*Oscillator, error)

NewPhaseOscillator creates a new oscillator where the initial phase is offset by a given phase

func (*Oscillator) Tick

func (o *Oscillator) Tick(freq float64) float64

Tick generates the next value of the oscillator waveform at a given frequency in Hz

type Shape

type Shape int

Shape for defining the different possible waveform shapes for use with the Oscillator

const (
	SINE Shape = iota
	SQUARE
	DOWNWARD_SAWTOOTH
	UPWARD_SAWTOOTH
	TRIANGLE
)

Shapes for which we can generate waveforms