sfxr.lua

Contents

• Functions
• Constants
• Class Sound
• Parameters
• Volume
• Envelope
• Frequency
• Change
• Duty
• Phaser
• Lowpass
• Highpass
• Vibrato
• Randomization
• Serialization

API

• sfxr

Module sfxr

A port of the sfxr sound effect synthesizer to pure Lua, designed to be used together with the awesome LÖVE game framework.

Functions

newSound (...)

Construct and return a new Sound instance.

Constants

VERSION	The module version (SemVer format)
WAVEFORM	Waveform constants
SAMPLERATE	Sampling rate constants (use the number values directly, these are just for lookup)
BITDEPTH	Bit depth constants (use the number values directly, these are just for lookup)
ENDIANNESS	Endianness constants

Class Sound

sfxr.Sound:__init ()	Initialize the Sound instance.
self.vibrato	A vibrato-like amplitude modulation effect SerializationVibrato
sfxr.Sound:resetParameters ()	Set all parameters to their default values.
sfxr.Sound:sanitizeParameters ()	Clamp all parameters within their sane ranges.
sfxr.Sound:generate ([rate=44100[, depth=0]])	Generate the sound and yield the sample data.
sfxr.Sound:getEnvelopeLimit ([rate=44100])	Get the maximum sample limit allowed by the current envelope.
sfxr.Sound:generateTable ([rate=44100[, depth=0[, tab]]])	Generate the sound into a table.
sfxr.Sound:generateString ([rate=44100[, depth=16[, endianness=0]]])	Generate the sound to a binary string.
sfxr.Sound:generateSoundData ([rate=44100[, depth=0[, sounddata]]])	Synthesize the sound to a LÖVE SoundData instance.

Parameters

self.supersampling	Number of supersampling passes to perform (default 8)
self.repeatspeed	Repeat speed: Times to repeat the frequency slide over the course of the envelope (default 0.0, min 0.0, max 1.0)
self.waveform	The base waveform (default SQUARE)

Volume

self.volume	The sound volume and gain all samples are multiplied with
self.volume.master	Master volume (default 0.5)
self.volume.sound	Additional gain (default 0.5)

Envelope

self.envelope	The ASD envelope that controls the sound amplitude (volume) over time
self.envelope.attack	Attack time: Time the sound takes to reach its peak amplitude (default 0.0, min 0.0, max 1.0)
self.envelope.sustain	Sustain time: Time the sound stays on its peak amplitude (default 0.0, min 0.0, max 1.0)
self.envelope.punch	Sustain punch: Amount by which the sound peak amplitude is increased at the start of the sustain time (default 0.0, min 0.0, max 1.0)
self.envelope.decay	Decay time: Time the sound takes to decay after its sustain time (default 0.0, min 0.0, max 1.0)

Frequency

self.frequency	The base and minimum frequencies of the tone generator and their slides
self.frequency.start	Start frequency: Base tone of the sound, before sliding (default 0.0, min 0.0, max 1.0)
self.frequency.min	Min frequency: Tone below which the sound will get cut off (default 0.0, min 0.0, max 1.0)
self.frequency.slide	Slide: Amount by which the frequency is increased or decreased over time (default 0.0, min -1.0, max 1.0)
self.frequency.dslide	Delta slide: Amount by which the slide is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Change

self.change	Changes the frequency mid-sound to create a characteristic "coin"-effect
self.change.amount	Change amount: Amount by which the frequency is changed mid-sound (default 0.0, min -1.0, max 1.0)
self.change.speed	Change speed: Time before the frequency change happens (default 0.0, min 0.0, max 1.0)

Duty

self.duty	The duty of the square waveform
self.duty.ratio	Square duty: Width of the square wave pulse cycle (doesn't affect other waveforms) (default 0.0, min 0.0, max 1.0)
self.duty.sweep	Duty sweep: Amount by which the square duty is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Phaser

self.phaser	A simple phaser effect
self.phaser.offset	Phaser offset: Amount by which the phaser signal is offset from the sound (default 0.0, min -1.0, max 1.0)
self.phaser.sweep	Phaser sweep: Amount by which the phaser offset is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Lowpass

self.lowpass	A lowpass filter effect
self.lowpass.cutoff	Lowpass filter cutoff: Lower bound for frequencies allowed to pass through this filter (default 0.0, min 0.0, max 1.0)
self.lowpass.sweep	Lowpass filter cutoff sweep: Amount by which the LP filter cutoff is increased or decreased over time (default 0.0, min -1.0, max 1.0)
self.lowpass.resonance	Lowpass filter resonance: Amount by which certain resonant frequencies near the cutoff are increased (default 0.0, min 0.0, max 1.0)

Highpass

self.highpass	A highpass filter effect
self.highpass.cutoff	Highpass filter cutoff: Upper bound for frequencies allowed to pass through this filter (default 0.0, min 0.0, max 1.0)
self.highpass.sweep	Highpass filter cutoff sweep: Amount by which the HP filter cutoff is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Vibrato

self.vibrato.depth	Vibrato depth: Amount of amplitude modulation (default 0.0, min 0.0, max 1.0)
self.vibrato.speed	Vibrato speed: Oscillation speed of the vibrato (default 0.0, min 0.0, max 1.0)
self.vibrato.delay	Vibrato delay: Unused and unimplemented (default 0.0, min 0.0, max 1.0)

Randomization

sfxr.Sound:randomize ([seed])	Randomize all sound parameters
sfxr.Sound:mutate ([amount=1][, seed], changefreq)	Mutate all sound parameters
sfxr.Sound:randomPickup ([seed])	Randomize all sound parameters to generate a "pick up" sound
sfxr.Sound:randomLaser ([seed])	Randomize all sound parameters to generate a laser sound
sfxr.Sound:randomExplosion ([seed])	Randomize all sound parameters to generate an explosion sound
sfxr.Sound:randomPowerup ([seed])	Randomize all sound parameters to generate a "power up" sound
sfxr.Sound:randomHit ([seed])	Randomize all sound parameters to generate a hit sound
sfxr.Sound:randomJump ([seed])	Randomize all sound parameters to generate a jump sound
sfxr.Sound:randomBlip ([seed])	Randomize all sound parameters to generate a "blip" sound

Serialization

sfxr.Sound:exportWAV (f[, rate=44100[, depth=0]])	Generate and export the audio data to a PCM WAVE file.
sfxr.Sound:save (f[, minify=true])	Save the sound parameters to a file as a Lua table
sfxr.Sound:load (f)	Load the sound parameters from a file containing a Lua table
sfxr.Sound:saveBinary (f)	Save the sound parameters to a file in the sfxr binary format (version 102)
sfxr.Sound:loadBinary (f)	Load the sound parameters from a file in the sfxr binary format (version 100-102)

Functions

newSound (...)

Construct and return a new Sound instance.

Parameters:

• ...

Returns:

Sound a Sound instance

Constants

VERSION

The module version (SemVer format)

WAVEFORM

Waveform constants

Fields:

• SQUARE square wave (= 0)
• SAW saw wave (= 1)
• SINE sine wave (= 2)
• NOISE white noise (= 3)

SAMPLERATE

Sampling rate constants (use the number values directly, these are just for lookup)

Fields:

• 22050 22.05 kHz (= 22050)
• 44100 44.1 kHz (= 44100)

BITDEPTH

Bit depth constants (use the number values directly, these are just for lookup)

Fields:

• 0 floating point bit depth, -1 to 1 (= 0)
• 8 unsigned 8 bit, 0x00 to 0xFF (= 8)
• 16 unsigned 16 bit, 0x0000 to 0xFFFF (= 16)

ENDIANNESS

Endianness constants

Fields:

• LITTLE little endian (= 0)
• BIG big endian (= 1)

Class Sound

sfxr.Sound:__init ()

Initialize the Sound instance. Called by the constructor.

self.vibrato

A vibrato-like amplitude modulation effect SerializationVibrato

sfxr.Sound:resetParameters ()

Set all parameters to their default values. Does not affect supersampling and volume. Called by the initializer.

sfxr.Sound:sanitizeParameters ()

Clamp all parameters within their sane ranges.

sfxr.Sound:generate ([rate=44100[, depth=0]])

Generate the sound and yield the sample data.

Parameters:

• rate SAMPLERATE the sampling rate (default 44100)
• depth BITDEPTH the bit depth (default 0)

Returns:

function() a generator that yields the next sample when called

Raises:

"invalid sampling rate: x", "invalid bit depth: x"

Usage:

 for s in sound:generate(44100, 0) do
   -- do something with s
 end

sfxr.Sound:getEnvelopeLimit ([rate=44100])

Get the maximum sample limit allowed by the current envelope. Does not take any other limits into account, so the returned count might be higher than samples actually generated. Still useful though.

Parameters:

• rate SAMPLERATE the sampling rate (default 44100)

Raises:

"invalid sampling rate: x", "invalid bit depth: x"

sfxr.Sound:generateTable ([rate=44100[, depth=0[, tab]]])

Generate the sound into a table.

Parameters:

• rate SAMPLERATE the sampling rate (default 44100)
• depth BITDEPTH the bit depth (default 0)
• tab {} the table to synthesize into (optional)

Returns:

1. {number,...} the table filled with sample data
2. int the number of written samples (== #tab)

Raises:

"invalid sampling rate: x", "invalid bit depth: x"

sfxr.Sound:generateString ([rate=44100[, depth=16[, endianness=0]]])

Generate the sound to a binary string.

Parameters:

• rate SAMPLERATE the sampling rate (default 44100)
• depth BITDEPTH the bit depth (may not be 0) (default 16)
• endianness ENDIANNESS the endianness (ignored when depth == 8) (default 0)

Returns:

1. string a binary string of sample data
2. int the number of written samples

Raises:

"invalid sampling rate: x", "invalid bit depth: x", "invalid endianness: x"

sfxr.Sound:generateSoundData ([rate=44100[, depth=0[, sounddata]]])

Synthesize the sound to a LÖVE SoundData instance.

Parameters:

• rate SAMPLERATE the sampling rate (default 44100)
• depth BITDEPTH the bit depth (default 0)
• sounddata love.sound.SoundData a SoundData instance (will be created if not passed) (optional)

Returns:

1. love.sound.SoundData a SoundData instance
2. int the number of written samples

Raises:

"invalid sampling rate: x", "invalid bit depth: x"

Parameters

self.supersampling

Number of supersampling passes to perform (default 8)

self.repeatspeed

Repeat speed: Times to repeat the frequency slide over the course of the envelope (default 0.0, min 0.0, max 1.0)

self.waveform

The base waveform (default SQUARE)

Volume

self.volume

The sound volume and gain all samples are multiplied with

self.volume.master

Master volume (default 0.5)

self.volume.sound

Additional gain (default 0.5)

Envelope

self.envelope

The ASD envelope that controls the sound amplitude (volume) over time

self.envelope.attack

Attack time: Time the sound takes to reach its peak amplitude (default 0.0, min 0.0, max 1.0)

self.envelope.sustain

Sustain time: Time the sound stays on its peak amplitude (default 0.0, min 0.0, max 1.0)

self.envelope.punch

Sustain punch: Amount by which the sound peak amplitude is increased at the start of the sustain time (default 0.0, min 0.0, max 1.0)

self.envelope.decay

Decay time: Time the sound takes to decay after its sustain time (default 0.0, min 0.0, max 1.0)

Frequency

self.frequency

The base and minimum frequencies of the tone generator and their slides

self.frequency.start

Start frequency: Base tone of the sound, before sliding (default 0.0, min 0.0, max 1.0)

self.frequency.min

Min frequency: Tone below which the sound will get cut off (default 0.0, min 0.0, max 1.0)

self.frequency.slide

Slide: Amount by which the frequency is increased or decreased over time (default 0.0, min -1.0, max 1.0)

self.frequency.dslide

Delta slide: Amount by which the slide is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Change

self.change

Changes the frequency mid-sound to create a characteristic "coin"-effect

self.change.amount

Change amount: Amount by which the frequency is changed mid-sound (default 0.0, min -1.0, max 1.0)

self.change.speed

Change speed: Time before the frequency change happens (default 0.0, min 0.0, max 1.0)

Duty

self.duty

The duty of the square waveform

self.duty.ratio

Square duty: Width of the square wave pulse cycle (doesn't affect other waveforms) (default 0.0, min 0.0, max 1.0)

self.duty.sweep

Duty sweep: Amount by which the square duty is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Phaser

self.phaser

A simple phaser effect

self.phaser.offset

Phaser offset: Amount by which the phaser signal is offset from the sound (default 0.0, min -1.0, max 1.0)

self.phaser.sweep

Phaser sweep: Amount by which the phaser offset is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Lowpass

self.lowpass

A lowpass filter effect

self.lowpass.cutoff

Lowpass filter cutoff: Lower bound for frequencies allowed to pass through this filter (default 0.0, min 0.0, max 1.0)

self.lowpass.sweep

Lowpass filter cutoff sweep: Amount by which the LP filter cutoff is increased or decreased over time (default 0.0, min -1.0, max 1.0)

self.lowpass.resonance

Lowpass filter resonance: Amount by which certain resonant frequencies near the cutoff are increased (default 0.0, min 0.0, max 1.0)

Highpass

self.highpass

A highpass filter effect

self.highpass.cutoff

Highpass filter cutoff: Upper bound for frequencies allowed to pass through this filter (default 0.0, min 0.0, max 1.0)

self.highpass.sweep

Highpass filter cutoff sweep: Amount by which the HP filter cutoff is increased or decreased over time (default 0.0, min -1.0, max 1.0)

Vibrato

self.vibrato.depth

Vibrato depth: Amount of amplitude modulation (default 0.0, min 0.0, max 1.0)

self.vibrato.speed

Vibrato speed: Oscillation speed of the vibrato (default 0.0, min 0.0, max 1.0)

self.vibrato.delay

Vibrato delay: Unused and unimplemented (default 0.0, min 0.0, max 1.0)

Randomization

sfxr.Sound:randomize ([seed])

Randomize all sound parameters

Parameters:

• seed number a random seed (optional)

sfxr.Sound:mutate ([amount=1][, seed], changefreq)

Mutate all sound parameters

Parameters:

• amount number by how much to mutate the parameters (default 1)
• seed number a random seed (optional)
• changefreq bool whether to change the frequency parameters

sfxr.Sound:randomPickup ([seed])

Randomize all sound parameters to generate a "pick up" sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomLaser ([seed])

Randomize all sound parameters to generate a laser sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomExplosion ([seed])

Randomize all sound parameters to generate an explosion sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomPowerup ([seed])

Randomize all sound parameters to generate a "power up" sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomHit ([seed])

Randomize all sound parameters to generate a hit sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomJump ([seed])

Randomize all sound parameters to generate a jump sound

Parameters:

• seed number a random seed (optional)

sfxr.Sound:randomBlip ([seed])

Randomize all sound parameters to generate a "blip" sound

Parameters:

• seed number a random seed (optional)

Serialization

sfxr.Sound:exportWAV (f[, rate=44100[, depth=0]])

Generate and export the audio data to a PCM WAVE file.

Parameters:

• f string, file or love.filesystem.File a path or file in wb-mode (passed files will not be closed)
• rate SAMPLERATE the sampling rate (default 44100)
• depth BITDEPTH the bit depth (default 0)

Raises:

"invalid sampling rate: x", "invalid bit depth: x"

sfxr.Sound:save (f[, minify=true])

Save the sound parameters to a file as a Lua table

Parameters:

• f string, file or love.filesystem.File a path or file in w-mode (passed files will not be closed)
• minify bool whether to minify the output or not (default true)

sfxr.Sound:load (f)

Load the sound parameters from a file containing a Lua table

Parameters:

• f string, file or love.filesystem.File a path or file in r-mode (passed files will not be closed)

Raises:

"incompatible version: x.x.x"

sfxr.Sound:saveBinary (f)

Save the sound parameters to a file in the sfxr binary format (version 102)

Parameters:

• f string, file or love.filesystem.File a path or file in wb-mode (passed files will not be closed)

sfxr.Sound:loadBinary (f)

Load the sound parameters from a file in the sfxr binary format (version 100-102)

Parameters:

• f string, file or love.filesystem.File a path or file in rb-mode (passed files will not be closed)

Raises:

"incompatible version: x", "unexpected file length"