FX Class: Flanger

Interactive example

Overview

The flanger creates an aggressive “jet” like sound. It operates by mixing two identical audio signals together, with one of the signals playing at a slighter different and changing speed.

Similar to other effects the wet and depth properties allow controlling of the effect with values ranging from 0 to 1. The lfoBeats property is the length in beats between the “lowest and “highest” jet sound, from 0.25 (fastest) up to 128 (slowest).

The “jet” effect doesn't change the stereo sound stage, but using the additional stereo property it can sound wider.

The integrated Superpowered Clipper prevents overdrive. It can be fine-tuned using the clipperThresholdDb and clipperMaximumDb properties.

One instance allocates around 80 kb memory.

Implementation example

The flanger is is an FX class, it expects both an input and output buffer. The process() function should be called on every loop of the audio processing block.

class SuperpoweredFlangerProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // Called when the AudioWorklet is ready to start processing audio
    onReady() {
        this.flanger = new this.Superpowered.Flanger(
            this.samplerate, // The initial sample rate in Hz.
        );

        this.flanger.enabled = true;
        this.flanger.frequency = 22500;
        this.eflangerfect.bits = 8;
    }

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

    // messages are received from the main scope through this method.
    onMessageFromMainScope(message) {
        if (typeof message.wet !== 'undefined') this.flanger.wet = message.wet;
        if (typeof message.depth !== 'undefined') this.flanger.depth = message.depth;
        if (typeof message.lfoBeats !== 'undefined') this.flanger.lfoBeats = message.lfoBeats;
        if (typeof message.bpm !== 'undefined') this.flanger.bpm = message.bpm;
        if (typeof message.clipperThresholdDb !== 'undefined') this.flanger.clipperThresholdDb = message.clipperThresholdDb;
        if (typeof message.clipperMaximumDb !== 'undefined') this.flanger.clipperMaximumDb = message.clipperMaximumDb;

        if (typeof message.stereo !== 'undefined') this.flanger.stereo = Boolean(message.stereo);
        if (typeof message.enabled !== 'undefined') this.flanger.enabled = Boolean(message.enabled);
    }


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

        // Render the output buffers, forward input if process returns false (no output changes)
        if (!this.flanger.process(inputBuffer.pointer, outputBuffer.pointer, buffersize)) {
            for (let n = 0; n < buffersize * 2 ; n++) outputBuffer.array[n] = inputBuffer.array[n];
        }
    }
}

#include "SuperpoweredFlanger.h"

void initFlangerEffect() {
    const unsigned int sampleRate = 44100;
    flanger = new Superpowered::Flanger(sampleRate);
    flanger->enabled = true;
}

void configureFlangerEffect() {
    flanger->bpm = 140;
    flanger->lfoBeats = 1;
    flanger->wet = 0.5;

}

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

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

Properties

Number

float

Number

float

Number

float

Number

float

Number

float

Boolean

bool

Number

float

Boolean

bool

Number

unsigned int

Methods

• constructor

  METHOD

  Creates an instance of the Flanger class.

  Parameters

  Name	Type	Description
  samplerate	Number	The initial sample rate in Hz.

  Returns

  Type	Description
  Superpowered.Flanger	The constructed instance.

• constructor

  METHOD

  Creates an instance of the Flanger class.

  Parameters

  Name	Type	Default	Description
  samplerate	unsigned int		The initial sample rate in Hz.

  Returns

  Type	Description
  Superpowered::Flanger	The constructed instance.

• getDepthMs

  METHOD

  Returns with the current depth, 0.3 to 8.0 (0.3 ms to 8 ms).

  Parameters

  None

  Returns

  Type	Description
  Number	Current depth in milliseconds.

• getDepthMs

  METHOD

  Returns with the current depth, 0.3 to 8.0 (0.3 ms to 8 ms).

  Parameters

  None

  Returns

  Type	Description
  float	Current depth in milliseconds.

• destruct

  METHOD

  Destructor to free Linear Memory.

  Parameters

  None

  Returns

  None

• 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.

  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	Default	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).