Clipper

Interactive example

Overview

Hard knee clipping with 0 latency. This effect will reduce the amplitude of the audio signal above the threshold level, and prevents going over the maximum level. The thresholdDb property can be set between `-100` and `0`. Anything below this value will be unchanged, and above will be attenuated. The maximumDb property is the maximum level between -48 and 48 decibels.

The clipper doesn't allocate any internal buffers and needs just a few bytes of memory.

Implementation example

The clipper expects both an input and output buffer. The process() method should be called on every loop of the audio processing block.

class SuperpoweredClipperProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // Called when the AudioWorklet is ready to start processing audio
    onReady() {
        this.clipper = new this.Superpowered.Clipper();
    }

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

    // The shape of the message we pass from our main thread is up to you
    onMessageFromMainScope(message) {
        // Here is an example of how to apply changes to the Three Band EQ instance
        if (typeof message.thresholdDb !== 'undefined') this.clipper.thresholdDb = message.thresholdDb;
        if (typeof message.maximumDb !== 'undefined') this.clipper.maximumDb = message.maximumDb;
    }

    // This is the process loop which is passed pointers to buffers
    // from the WebAudio API (inputBuffer and outputBuffer), with the buffersize (128 samples when running as a native AudioWorklet)
    processAudio(inputBuffer, outputBuffer, buffersize) {
        this.clipper.process(inputBuffer.pointer, outputBuffer.pointer, buffersize);
    }
}

#include "SuperpoweredClipper.h"

void initClipperEffect() {
    clipper = new Superpowered::Clipper();
    clipper->thresholdDb = -6;
    clipper->maximumDb = 0;
}

void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames, unsigned int samplerate) {
    // Render the output buffers
    clipper->process(interleavedInput, interleavedOutput, numberOfFrames);
}

Properties

Number

float

Number

float

Methods

• constructor

  METHOD

  Creates an instance of the Clipper class.

  Parameters

  None

  Returns

  Type	Description
  Superpowered.Clipper	The constructed instance.

• constructor

  METHOD

  Creates an instance of the Clipper class.

  Parameters

  None

  Returns

  Type	Description
  Superpowered::Clipper	The constructed instance.

• destruct

  METHOD

  Destructor to free Linear Memory.

  Parameters

  None

  Returns

  None

• process

  METHOD

  Processes the audio. It's never blocking for real-time usage. You can change all properties 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. Should be 4 minimum and exactly divisible with 4.

  Returns

  None

• process

  METHOD

  Processes the audio. It's never blocking for real-time usage. You can change all 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. Should be 4 minimum and exactly divisible with 4.

  Returns

  None