Source Class: Generator

Interactive example

Single Generator demo

Superpowered WebAssembly Audio SDK v2.6.1

Overview

The Generator creates audio in various waveform shapes. Generators can be chained together to make complex audio sources that power synths, but are also useful as a tool for diagnostics. We're using a Superpowered Generator in our oscillator input stage you might have seen through the other audio effects examples on this site.

The Superpowered Generator supports 7 different shapes, these are stored as constants under the Generator namespace:

Superpowered.Generator.Sine       // sine
Superpowered.Generator.Triangle   // triangle
Superpowered.Generator.Sawtooth   // sawtooth
Superpowered.Generator.PWM        // pulse wave with adjustable width
Superpowered.Generator.PinkNoise  // pink noise
Superpowered.Generator.WhiteNoise // white noise
Superpowered.Generator.SyncMaster // generates no sound, but sync data to use with generateSyncMaster

Superpowered::Generator::Sine       // sine
Superpowered::Generator::Triangle   // triangle
Superpowered::Generator::Sawtooth   // sawtooth
Superpowered::Generator::PWM        // pulse wave with adjustable width
Superpowered::Generator::PinkNoise  // pink noise
Superpowered::Generator::WhiteNoise // white noise
Superpowered::Generator::SyncMaster // generates no sound, but sync data to use with generateSyncMaster

Implementation example

Let's start of with the most simple application of a Generator, a simple sine tone oscillator. We set the initial frequency and point to our output buffer in the generate method call. Notice also that this class does not have a process method.

class SuperpoweredSingleGeneratorStageProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // runs after the constructor
    onReady() {
        this.generator = new this.Superpowered.Generator(
            this.samplerate,                      // The initial sample rate in Hz.
            this.Superpowered.Generator.Sine // The initial shape.
        );
        this.generator.frequency = 440;

        // Create an empty buffer o store the ouput of the mono generator. 2048 is the largest buffer size we'll need to deal with
        this.genOutputBuffer = new this.Superpowered.Float32Buffer(2048);
    }

    onDestruct() {
        this.generator.destruct();
    }

    // messages are received from the main scope through this method.
    onMessageFromMainScope(message) {
        if (typeof message.frequency !== 'undefined') this.generator.frequency = message.frequency;
    }

    processAudio(inputBuffer, outputBuffer, buffersize, parameters) {
        // Ensure the samplerate is in sync on every audio processing callback
        this.generator.samplerate = this.samplerate;

        // Generate the output buffers
        this.generator.generate(
            this.genOutputBuffer.pointer, // output, // Pointer to floating point numbers. 32-bit MONO output.
            buffersize   // number of samples to generate
        );

        // We now need to convert the mono signal from the generator into he interleaved stereo format that the parent audio context requires.
        this.Superpowered.Interleave(
            this.genOutputBuffer.pointer, // left mono input
            this.genOutputBuffer.pointer, // right mono input
            outputBuffer.pointer, // stereo output - this is what is routed to the AudioWorkletProcessor output
            buffersize // number of frames
        );
    }
}

#include "SuperpoweredGenerator.h"

void initGeneratorSource() {
    generator = new Superpowered::Generator(48000. Superpowered::Generator::Sine);
    generator->frequency = 440;
}

void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames, unsigned int samplerate) {
    // Ensure the samplerate is in sync on every audio processing callback
    generator->samplerate = samplerate;

    // Generate the output buffers
    generator->generate(interleavedOutput, numberOfFrames);
}

Multiple voices

We can create multiple Oscillators and sum the results together.

class SuperpoweredMultipleGeneratorStageProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // runs after the constructor
    onReady() {
        this.generator1 = new this.Superpowered.Generator(
            this.samplerate,                      // The initial sample rate in Hz.
            this.Superpowered.Generator.Sine // The initial shape.
        );
        this.generator2 = new this.Superpowered.Generator(
            this.samplerate,                      // The initial sample rate in Hz.
            this.Superpowered.Generator.Sine // The initial shape.
        );

        this.gen1OutputBuffer = new this.Superpowered.Float32Buffer(2048); // A floating point number is 4 bytes, therefore we allocate length * 4 bytes of memory.
        this.gen2OutputBuffer = new this.Superpowered.Float32Buffer(2048);

        // An empty buffer to hold the summed generators
        this.summedMonoOutputBuffer = new this.Superpowered.Float32Buffer(2048);

        this.generator1.frequency = 440;
        this.generator2.frequency = 880;
    }

    onDestruct() {
        this.generator1.destruct();
        this.generator2.destruct();
    }

    // messages are received from the main scope (AudioEngine in this case) through this method.
    onMessageFromMainScope(message) {
        if (typeof message.frequency1 !== 'undefined') this.generator1.frequency = message.frequency1;
        if (typeof message.pulsewidth1 !== 'undefined') this.generator1.pulsewidth = message.pulsewidth1;
        if (typeof message.shape1 !== 'undefined') this.generator1.shape = this.Superpowered.Generator[message.shape1];
        if (typeof message.frequency2 !== 'undefined') this.generator2.frequency = message.frequency2;
        if (typeof message.pulsewidth2 !== 'undefined') this.generator2.pulsewidth = message.pulsewidth2;
        if (typeof message.shape2 !== 'undefined') this.generator2.shape = this.Superpowered.Generator[message.shape2];
    }

    processAudio(inputBuffer, outputBuffer, buffersize, parameters) {
        // Ensure the samplerate is in sync on every audio processing callback
        this.generator1.samplerate = this.samplerate;
        this.generator2.samplerate = this.samplerate;


        this.generator1.generate(
            this.gen1Pointer.pointer, // output, // Pointer to floating point numbers. 32-bit MONO output.
            buffersize   // we multiple this by two because .generate returns a mono signal whereas the outputBuffer is interleaved stereo.
        );

        this.generator2.generate(
            this.gen2Pointer.pointer, // output, // Pointer to floating point numbers. 32-bit MONO output.
            buffersize // we multiple this by two because .generate returns a mono signal whereas the outputBuffer is interleaved stereo.
        );

        this.Superpowered.Add2(
            this.gen1Pointer.pointer,   // Pointer to floating point numbers. Mono input for left channel.
            this.gen2Pointer.pointer,  // Pointer to floating point numbers. Mono input for right channel.
            this.monoSumPointer.pointer, // Pointer to floating point numbers. Stereo interleaved output.
            buffersize  // The number of frames to process.
        );

        // We now need to convert the mono signal from the generator into he interleaved stereo format that the parent audio context requires.
        this.Superpowered.Interleave(
            this.monoSumPointer.pointer, // left mono input
            this.monoSumPointer.pointer, // right mono input
            outputBuffer.pointer, // stereo output - this is what is routed to the AudioWorkletProcessor output
            buffersize // number of frames
        );
}

#include "SuperpoweredGenerator.h"

void initGeneratorSources() {
    generator1 = new Superpowered::Generator(48000. Superpowered::Generator::Sine);
    generator2 = new Superpowered::Generator(48000. Superpowered::Generator::Sine);
    generator1->frequency = 440;
    generator2->frequency = 880;
}

void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames, unsigned int samplerate) {
    // Ensure the samplerate is in sync on every audio processing callback
    generator1->samplerate = samplerate;
    generator2->samplerate = samplerate

    // Create two buffers to store the output of the two generators before summing
    float gen1OutputBuffer[numberOfFrames];
    float gen2OutputBuffer[numberOfFrames];
    float monoSumBuffer[numberOfFrames];

    // Generate the output buffers
    generator1->generate(gen1OutputBuffer, numberOfFrames);
    generator2->generate(gen2OutputBuffer, numberOfFrames);

    Superpowered->Add2(
        gen1OutputBuffer,  // Pointer to floating point numbers.
        gen2OutputBuffer,  // Pointer to floating point numbers.
        monoSumBuffer, // Pointer to floating point numbers.
        numberOfFrames  // The number of frames to process.
    );

    Superpowered->Interleave(
        monoSumBuffer,   // Pointer to floating point numbers. Mono input for left channel.
        monoSumBuffer,  // Pointer to floating point numbers. Mono input for right channel.
        interleavedOutput, // Pointer to floating point numbers. Stereo interleaved output.
        buffersize    // The number of frames to process.
    );
}

Here's how multiple oscillators sound:

Multiple Generators demo

100%

Superpowered WebAssembly Audio SDK v2.6.1

FM synthesis

We can use the Superpowered synthesizer to create frequency modulated outputs from our Generators. For a guide on Frequency modulation, see the Wikipedia page.

class SuperpoweredFmGeneratorStageProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // Runs after the constructor
    onReady() {
        this.carrier = new this.Superpowered.Generator(
            this.samplerate,                      // The initial sample rate in Hz.
            this.Superpowered.Generator.Sine // The initial shape.
        );
        this.modulator = new this.Superpowered.Generator(
            this.samplerate,                      // The initial sample rate in Hz.
            this.Superpowered.Generator.Sine // The initial shape.
        );

        this.carrierBuffer = new this.Superpowered.Float32Buffer(2048); // A floating point number is 4 bytes, therefore we allocate length * 4 bytes of memory.
        this.modulatorBuffer = new this.Superpowered.Float32Buffer(2048);
        this.carrier.frequency = 440
        this.modulator.frequency = 1.5;
        this.modDepth = 250;
    }

    onDestruct() {
        this.carrier.destruct();
        this.modulator.destruct();
    }

    // Messages are received from the main scope (AudioEngine in this case) through this method.
    onMessageFromMainScope(message) {
        if (typeof message.frequency1 !== 'undefined') this.carrier.frequency = Number(message.frequency1) ;
        if (typeof message.pulsewidth1 !== 'undefined') this.carrier.pulsewidth = Number(message.pulsewidth1);
        if (typeof message.shape1 !== 'undefined') this.carrier.shape = this.Superpowered.Generator[message.shape1];
        if (typeof message.frequency2 !== 'undefined') this.modulator.frequency = Number(message.frequency2);
        if (typeof message.modDepth !== 'undefined') this.modDepth = Number(message.modDepth);
        if (typeof message.shape2 !== 'undefined') this.modulator.shape = this.Superpowered.Generator[message.shape2];
    }

    processAudio(inputBuffer, outputBuffer, buffersize, parameters) {

        // Generate the modulator output first
        this.modulator.generate(
            this.modulatorBuffer.pointer, // output, // Pointer to floating point numbers. 32-bit MONO output.
            buffersize   // we multiple this by two because .generate returns a mono signal whereas the outputBuffer is interleaved stereo.
        );

        // Use the modulator output as the FM source of the carrier.
        this.carrier.generateFM(
            this.carrierBuffer.pointer, // output, // Pointer to floating point numbers. 32-bit MONO output.
            buffersize,   // we multiple this by two because .generate returns a mono signal whereas the outputBuffer is interleaved stereo.
            this.modulatorBuffer.pointer, // The Modulator source,
            this.modDepth
        );

        this.Superpowered.Interleave(
            this.carrierBuffer.pointer,   // Pointer to floating point numbers. Mono input for left channel.
            this.carrierBuffer.pointer,  // Pointer to floating point numbers. Mono input for right channel.
            outputBuffer.pointer, // Pointer to floating point numbers. Stereo interleaved output.
            buffersize    // The number of frames to process.
        );
    }
}

#include "SuperpoweredGenerator.h"

void initGeneratorSources() {
    carrier = new Superpowered::Generator(48000. Superpowered::Generator::Sine);
    modulator = new Superpowered::Generator(48000. Superpowered::Generator::Sine);
    carrier->frequency = 440;
    modulator->frequency = 880;
    modDeph = 250;
}

void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames, unsigned int samplerate) {

    // Create two buffers to store the output of the two generators before summing
    float carrierBuffer[numberOfFrames];
    float modulatorBuffer[numberOfFrames];

    // Ensure the samplerate is in sync on every audio processing callback
    carrier->samplerate = samplerate;
    modulator->samplerate = samplerate

    // Generate the modulator output first
    modulator->generate(modulatorBuffer, numberOfFrames);

    // Use the modulator output as the FM source of the carrier.
    carrier->generateFM(carrierBuffer, numberOfFrames, modulatorBuffer, modDepth);

    // Interleave the left and right channels for the output pointer
    Superpowered->Interleave(
        carrierBuffer,
        carrierBuffer,
        interleavedOutput,
        numberOfFrames
    );
}

Here's how FM synthesis sounds:

FM Synthesis Generators demo

100%

Superpowered WebAssembly Audio SDK v2.6.1

Shapes

Superpowered.Generator.GeneratorShape

CONSTANTS

Superpowered generator shapes.

Value	Description
Sine	sine wave
Triangle	triangle wave
Sawtooth	sawtooth wave
PWM	pulse wave with adjustable width
PinkNoise	pink noise
WhiteNoise	white noise
SyncMaster	generates no sound, but sync data to use with generateSyncMaster

Superpowered::Generator::GeneratorShape

CONSTANTS

Superpowered generator shapes.

Value	Description
Sine	sine wave
Triangle	triangle wave
Sawtooth	sawtooth wave
PWM	pulse wave with adjustable width
PinkNoise	pink noise
WhiteNoise	white noise
SyncMaster	generates no sound, but sync data to use with generateSyncMaster

Properties

frequency

PROPERTY

Frequency of generator output in Hz.

Type	Min	Max	Default
Number	0.0001	sample rate / 2	440

frequency

PROPERTY

Frequency of generator output in Hz.

Type	Min	Max	Default
float	0.0001	sample rate / 2	440

pulsewidth

PROPERTY

Pulse Width for PWM shape. 0.5 results in a square wave.

Type	Min	Max	Default
Number	0.0001	0.9999	0.5

pulsewidth

PROPERTY

Pulse Width for PWM shape. 0.5 results in a square wave.

Type	Min	Max	Default
float	0.0001	0.9999	0.5

samplerate

PROPERTY

The sample rate of the audio context inHz, you must update if it changes.

Type	Min	Max	Default
Number

samplerate

PROPERTY

The sample rate of the audio context inHz, you must update if it changes.

Type	Min	Max	Default
unsigned int

shape

PROPERTY

Waveform shape of generator.

Type	Min	Max	Default
Number

shape

PROPERTY

Waveform shape of generator.

Type	Min	Max	Default
Superpowered::Generator::shape

Methods

constructor
METHOD
Creates a Generator instance.
Parameters
Name Type Description
samplerate Number The initial sample rate in Hz.
GeneratorShape Generator.GeneratorShape The initial shape.
Returns
Type Description
Superpowered.Superpowered::Generator The constructed instance.
constructor
METHOD
Creates a Generator instance.
Parameters
Name Type Default Description
samplerate unsigned int The initial sample rate in Hz.
GeneratorShape Generator::GeneratorShape The initial shape.
Returns
Type Description
Superpowered::Superpowered::Generator The constructed instance.
generate
METHOD
Generates (outputs) audio. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.
Parameters
Name Type Description
output Number (pointer in Linear Memory) 32-bit MONO output
numberOfSamples Number Number of samples to produce.
Returns
None
generate
METHOD
Generates (outputs) audio. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.
Parameters
Name Type Default Description
output float * 32-bit MONO output
numberOfSamples unsigned int Number of samples to produce.
Returns
None

Name	Type	Description
samplerate	`Number`	The initial sample rate in Hz.
GeneratorShape	`Generator.GeneratorShape`	The initial shape.

Type	Description
`Superpowered.Superpowered::Generator`	The constructed instance.

Name	Type	Default	Description
samplerate	`unsigned int`		The initial sample rate in Hz.
GeneratorShape	`Generator::GeneratorShape`		The initial shape.

Type	Description
`Superpowered::Superpowered::Generator`	The constructed instance.

generateAndCreateSync

METHOD

Generates audio for an oscillator that also serves as synchronization source for another oscillator. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.

Parameters

Name	Type	Description
output	`Number (pointer in Linear Memory)`	32-bit MONO output
syncdata	`Number (pointer in Linear Memory)`	A buffer to receive hard sync information for syncing oscillators. Should be numberOfSamples + 1 floats big minimum.
numberOfSamples	`Number`	Number of samples to produce.

Returns

None

generateAndCreateSync

METHOD

Parameters

Name	Type	Description
output	`float *`	32-bit MONO output
syncdata	`float *`	A buffer to receive hard sync information for syncing oscillators. Should be numberOfSamples + 1 floats big minimum.
numberOfSamples	`unsigned int`	Number of samples to produce.

Returns

None

generateFM

METHOD

Generates (outputs) audio for a frequency modulated (FM) oscillator. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.

Parameters

Name	Type	Description
output	`Number (pointer in Linear Memory)`	32-bit MONO output
numberOfSamples	`Number`	Number of samples to produce.
fmsource	`Number (pointer in Linear Memory)`	Source for FM modulation containing numberOfSamples samples, usually from a previous call to generate().
fmdepth	`Number`	Frequency modulation depth. 0 means no modulation, 1000 is a reasonable upper limit.

Returns

None

generateFM

METHOD

Generates (outputs) audio for a frequency modulated (FM) oscillator. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.

Parameters

Name	Type	Description
output	`float *`	32-bit MONO output
numberOfSamples	`unsigned int`	Number of samples to produce.
fmsource	`float *`	Source for FM modulation containing numberOfSamples samples, usually from a previous call to generate().
fmdepth	`float`	Frequency modulation depth. 0 means no modulation, 1000 is a reasonable upper limit.

Returns

None

generateSynchronized

METHOD

Generates audio for an oscillator that is hard-synced to another oscillator. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.

Parameters

Name	Type	Description
output	`Number (pointer in Linear Memory)`	32-bit MONO output
syncdata	`Number (pointer in Linear Memory)`	A buffer to receive hard sync information for syncing oscillators. Should be numberOfSamples + 1 floats big minimum.
numberOfSamples	`Number`	Number of samples to produce.

Returns

None

generateSynchronized

METHOD

Generates audio for an oscillator that is hard-synced to another oscillator. It's never blocking for real-time usage. You can change all properties on any thread, concurrently with this function.

Parameters

Name	Type	Description
output	`float *`	32-bit MONO output
syncdata	`float *`	A buffer to receive hard sync information for syncing oscillators. Should be numberOfSamples + 1 floats big minimum.
numberOfSamples	`unsigned int`	Number of samples to produce.

Returns

None

reset
METHOD
Start oscillator with given phase angle. In a synthesizer, this should be called whenever a voice starts.
Parameters
Name Type Description
phase Number Start phase of the oscillator between 0.0 (0 degree) and 1.0 (180 degrees).
Returns
None
reset
METHOD
Start oscillator with given phase angle. In a synthesizer, this should be called whenever a voice starts.
Parameters
Name Type Default Description
phase float Start phase of the oscillator between 0.0 (0 degree) and 1.0 (180 degrees).
Returns
None

Source Class: Generator

Interactive example

Overview

Implementation example

Multiple voices

FM synthesis

Shapes

Superpowered.Generator.GeneratorShape

Superpowered::Generator::GeneratorShape

Properties

frequency

frequency

pulsewidth

pulsewidth

samplerate

samplerate

shape

shape

Methods

constructor

constructor

generate

generate

generateAndCreateSync

generateAndCreateSync

generateFM

generateFM

generateSynchronized

generateSynchronized

reset

reset