FX Class: Echo

Interactive example

Overview

This simple Echo effect is based on delaying a signal over time. Listeners perceive an audible repetition of a signal after some duration of time.

Implementation example

The wet property is the volume of each repeat and the the dry property is the volume of the original sound. Both values can be set between 0.0 and 1.0, **or** the setMix() method can be used instead to balance between the two.

The decay property controls the tail or trail of the echo which can be set between 0 and 1. The user also has access to the bpm property (beats per minute) of the echo (between 40 and 250) and the beats property which controls the delay in beats (between 0.03125 and 2).

One instance allocates around 770 kb memory.

Usage example without the optional FX processing chain:

class SuperpoweredEchoStageProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    onReady() {
        this.echo = new this.Superpowered.Echo(
            this.samplerate, // the samplerate
            96000 // The maximumSamplerate, the same in this case
        );
        this.effect.enabled = true;
    }

    // Runs before the node is destroyed.
    // Clean up memory and objects here (such as free allocated linear memory or destruct Superpowered objects).
    onDestruct() {
        this.echo.destruct();
    }

    // Messages are received from the main scope through this method.
    onMessageFromMainScope(message) {
        if (typeof(message.dry) != 'undefined') this.echo.dry = message.dry;
        if (typeof(message.wet) != 'undefined') this.echo.wet = message.wet;
        if (typeof(message.bpm) != 'undefined') this.echo.bpm = message.bpm;
        if (typeof(message.decay) != 'undefined') this.echo.decay = message.decay;
        if (typeof(message.beats) != 'undefined') this.echo.beats = message.beats;
        if (typeof(message.enabled) != 'undefined') this.echo.enabled = Boolean(message.enabled);
    }

    // THe mai process block of the DSP
    processAudio(inputBuffer, outputBuffer, buffersize, parameters) {
        // Ensure the samplerate is in sync on every audio processing callback
        this.echo.samplerate = this.samplerate;

        // Render the output buffers
        if (!this.echo.process(inputBuffer.pointer, outputBuffer.pointer, buffersize)) {
            for (let n = 0; n < buffersize * 2 ; n++) outputBuffer.array[n] = inputBuffer.array[n];
        }
    }
}

Or, to use with an optional effect FX added to the wet signal:

class SuperpoweredEchoStageProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    onReady() {
        this.echo = new this.Superpowered.Echo(
            this.samplerate,
            96000
        );
        this.filter = new this.Superpowered.Filter(
            this.Superpowered.Filter.Resonant_Lowpass,
            this.samplerate
        );
        this.echo.enabled = true;
        this.filter.frequency = 4000;
        this.filter.enabled = true;
    }

    // Runs before the node is destroyed.
    // Clean up memory and objects here (such as free allocated linear memory or destruct Superpowered objects).
    onDestruct() {
        this.echo.destruct();
        this.filter.destruct();
    }

    // messages are received from the main scope through this method.
    onMessageFromMainScope(message) {
        if (typeof(message.dry) != 'undefined') this.echo.dry = message.dry;
        if (typeof(message.wet) != 'undefined') this.echo.wet = message.wet;
        if (typeof(message.bpm) != 'undefined') this.echo.bpm = message.bpm;
        if (typeof(message.decay) != 'undefined') this.echo.decay = message.decay;
        if (typeof(message.beats) != 'undefined') this.echo.beats = message.beats;
        if (typeof(message.enabled) != 'undefined') this.echo.enabled = Boolean(message.enabled);
        if (typeof(message.frequency) != 'undefined') this.filter.frequency = Number(message.frequency);
    }

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

        // Render the output buffers
        if (!this.echo.processWithFx(inputBuffer.pointer, outputBuffer.pointer, buffersize, this.filter)) {
            for (let n = 0; n < buffersize * 2 ; n++) outputBuffer.array[n] = inputBuffer.array[n];
        }
    }
}

To setup without the optional FX processing chain

#include "SuperpoweredEcho.h"

void initEchoEffect() {
    const unsigned int sampleRate = 44100;
    echo = new Superpowered::Echo(sampleRate);
}

void configureEchoEffect() {
    echo->dry = 0.5;
    echo->wet = 42;
    echo->bpm = 170;
    echo->decay = 0.5;
    echo->beats = 0.5;

    echo->enabled = true;
}

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

    // Render the output buffers
    bool outputChanged = echo->process(interleavedInput, interleavedOutput, numberOfFrames);
    ...
}

Or, to use with the optional FX processing chain

#include "SuperpoweredEcho.h"

void initEchoEffect() {
    const unsigned int sampleRate = 44100;
    const unsigned int maximumSampleRate = 96000;
    echo = new Superpowered::Echo(sampleRate, maximumSampleRate);
    filter = new Superpowered::Filter(Superpowered::Filter::Resonant_Lowpass, sampleRate);
}

void configureEchoEffect() {
    echo->dry = 0.5;
    echo->wet = 42;
    echo->bpm = 170;
    echo->decay = 0.5;
    echo->beats = 0.5;

    echo->enabled = true;

    filter->frequency - 4000;
    filter->enabled = true;
}

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

    // Render the output buffers
    bool outputChanged = echo->processWithFx(interleavedInput, interleavedOutput, numberOfFrames, filter);
    ...
}

The optional FX processing is demonstrated below:

Properties

beats

PROPERTY

Delay between the echo sounds in beats. 0.03125 to 2.

Type	Min	Max	Default
Number	0.03125	2	0.5

beats

PROPERTY

Delay between the echo sounds in beats. 0.03125 to 2.

Type	Min	Max	Default
float	0.03125	2	0.5

bpm

PROPERTY

Beats per minute, the base tempo of the echo.

Type	Min	Max	Default
Number	40	250	128

bpm

PROPERTY

Beats per minute, the base tempo of the echo.

Type	Min	Max	Default
float	40	250	128

decay

PROPERTY

Decay factor of the echo sounds.

Type	Min	Max	Default
Number	0	0.99	0.5

decay

PROPERTY

Decay factor of the echo sounds.

Type	Min	Max	Default
float	0	0.99	0.5

dry

PROPERTY

Dry signal mix.

Type	Min	Max	Default
Number	0	1	1

dry

PROPERTY

Dry signal mix.

Type	Min	Max	Default
float	0	1	1

wet

PROPERTY

Wet signal mix.

Type	Min	Max	Default
Number	0	1	0.5

wet

PROPERTY

Wet signal mix.

Type	Min	Max	Default
float	0	1	0.5

Inherited from FX Class

enabled

PROPERTY

Turns the effect on/off. The actual switch will happen on the next process() call for smooth, audio-artifact free operation.

Type	Min	Max	Default
Boolean			false

enabled

PROPERTY

Turns the effect on/off. The actual switch will happen on the next process() call for smooth, audio-artifact free operation.

Type	Min	Max	Default
bool			false

samplerate

PROPERTY

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

Type	Min	Max	Default
Number

samplerate

PROPERTY

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

Type	Min	Max	Default
unsigned int

Methods

constructor
METHOD
Creates an instance of the Echo class.
Parameters
Name Type Description
samplerate Number The initial sample rate in Hz.
maximumSamplerate Number Maximum sample rate (affects memory usage, the lower the smaller).
Returns
Type Description
Superpowered.Echo The constructed instance.
constructor
METHOD
Creates an instance of the Echo class.
Parameters
Name Type Default Description
samplerate unsigned int The initial sample rate in Hz.
maximumSamplerate unsigned int 96000 Maximum sample rate (affects memory usage, the lower the smaller).
Returns
Type Description
Superpowered::Echo The constructed instance.

Name	Type	Description
samplerate	`Number`	The initial sample rate in Hz.
maximumSamplerate	`Number`	Maximum sample rate (affects memory usage, the lower the smaller).

Type	Description
`Superpowered.Echo`	The constructed instance.

Name	Type	Default	Description
samplerate	`unsigned int`		The initial sample rate in Hz.
maximumSamplerate	`unsigned int`	96000	Maximum sample rate (affects memory usage, the lower the smaller).

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

processWithFx

METHOD

Processes/renders the audio. Always call it in the audio processing callback, regardless if the effect is enabled or not for smooth, audio-artifact free operation. It's never blocking for real-time usage. You can change all properties and call setMix() on any thread, concurrently with process().

Parameters

Name	Type	Description
input	`Number (pointer in Linear Memory)`	32-bit interleaved stereo input.
output	`Number (pointer in Linear Memory)`	32-bit interleaved stereo output.
numberOfFrames	`Number`	Number of frames to process. Recommendations for best performance: multiply of 4, minimum 64.
fx	`Superpowered.FX object`	A Superpowered FX class instance, such as a Filter. fx->process() will be used to pass audio from input to the internal buffer, "coloring" the echo sounds.

Returns

Type	Description
`Boolean`	If process() returns with true, the contents of output are replaced with the audio output. If process() returns with false, it indicates silence. The contents of output are not changed in this case (not overwritten with zeros).

processWithFx

METHOD

Parameters

Name	Type	Description
input	`float *`	32-bit interleaved stereo input.
output	`float *`	32-bit interleaved stereo output.
numberOfFrames	`unsigned int`	Number of frames to process. Recommendations for best performance: multiply of 4, minimum 64.
fx	`Superpowered::FX *`	A Superpowered FX class instance, such as a Filter. fx->process() will be used to pass audio from input to the internal buffer, "coloring" the echo sounds.

Returns

Type	Description
`bool`	If process() returns with true, the contents of output are replaced with the audio output. If process() returns with false, it indicates silence. The contents of output are not changed in this case (not overwritten with zeros).

setMix
METHOD
Sets dry and wet simultaneously with a good balance between them. Wet always equals to mix, but dry changes with a curve.
Parameters
Name Type Description
mix Number Mix value >= 0 and <= 1.
Returns
None
setMix
METHOD
Sets dry and wet simultaneously with a good balance between them. Wet always equals to mix, but dry changes with a curve.
Parameters
Name Type Default Description
mix float Mix value >= 0 and <= 1.
Returns
None

Name	Type	Description
mix	`Number`	Mix value >= 0 and <= 1.

Name	Type	Default	Description
mix	`float`		Mix value >= 0 and <= 1.

Inherited from FX Class

destruct
METHOD
Destructor to free Linear Memory.
Parameters
None
Returns
None

process

METHOD

Parameters

Name	Type	Description
input	`Number (pointer in Linear Memory)`	32-bit interleaved stereo input.
output	`Number (pointer in Linear Memory)`	32-bit interleaved stereo output.
numberOfFrames	`Number`	Number of frames to process. Recommendations for best performance: multiply of 4, minimum 64.

Returns

Type	Description
`Boolean`	If process() returns with true, the contents of output are replaced with the audio output. If process() returns with false, it indicates silence. The contents of output are not changed in this case (not overwritten with zeros).

process

METHOD

Processes/renders the audio. Always call it in the audio processing callback, regardless if the effect is enabled or not for smooth, audio-artifact free operation. It's never blocking for real-time usage. You can change all effect properties on any thread, concurrently with process().

Parameters

Name	Type	Description
input	`float *`	32-bit interleaved stereo input.
output	`float *`	32-bit interleaved stereo output.
numberOfFrames	`unsigned int`	Number of frames to process. Recommendations for best performance: multiply of 4, minimum 64.

Returns

Type	Description
`bool`	If process() returns with true, the contents of output are replaced with the audio output. If process() returns with false, it indicates silence. The contents of output are not changed in this case (not overwritten with zeros).

FX Class: Echo

Interactive example

Overview

Implementation example

Properties

beats

beats

bpm

bpm

decay

decay

dry

dry

wet

wet

enabled

enabled

samplerate

samplerate

Methods

constructor

constructor

processWithFx

processWithFx

setMix

setMix

destruct

process

process