Class: Waveform

Overview

Provides waveform data in 150 points/sec resolution (each number will represent 6.666 milliseconds regardless of the sample rate).

Implementation example

class SuperpoweredClipperProcessor extends SuperpoweredWebAudio.AudioWorkletProcessor {

    // Called when the AudioWorklet is ready to start processing audio
    onReady() {
        this.waveform = new this.Superpowered.Waveform(
            48000, // The sample rate of the audio input.
            60     // The length in seconds of the audio input. It will not be able to process more audio than this. You can change this value in the process() method.
        );
    }

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

    calculateAndSendWaveformData() {
        //First instruct the waveform instance to run its calculations internally. processAudio should not run when this is called!
        this.waveform.makeResult();

        // Then get the peakWaveform data
        // returns a Superpowered.Uint8Buffer. 150 points/sec waveform data displaying the peak volume. Uint8Array. Each byte represents one "pixel".
        const wasmResult = waveform.getPeakWaveform();

        // Result is backed by WebAssembly Linear Memory that can not be passed to another scope (thread).
        // Let's clone it into "result".
        const result = new Uint8Array();
        result.set(wasmResult.array);

        // Then send this back to the main scope from from this AudioWorklet scope
        this.sendMessageToMainScope({
            waveformData: result
        });
    }

    onMessageFromMainScope(message) {
        // handle an incoming instruction from the main thread to generate data
        // We're using sendMessageTOAudioScope({requestWaveformData: true}) here, but you decide the object shape.
        // We trigger this to be sent from the main scope on a window.requestAnimationFrame loop for example.
        if (typeof message.requestWaveformData) this.calculateAndSendWaveformData();
    }

    processAudio(inputBuffer, outputBuffer, buffersize) {
        this.waveform.process(
            inputBuffer.pointer,
            buffersize,
            -1
        );
    }
}

#include "SuperpoweredWaveform.h"

void initWaveformAnalyzer() {
    waveform = new Superpowered::Waveform(
        48000, // The sample rate of the audio input.
        60     // The length in seconds of the audio input. It will not be able to process more audio than this. You can change this value in the process() method.
    );
}

unsigned char *getWaveformPeakResult(int *size) {
    //First instruct the waveform instance to run its calculations internally. processAudio should not run when this is called!
    waveform->makeResult();
    *size = waveform->waveformSize;
    return waveform->getPeakWaveform(); // Each byte represents one "pixel".
}


void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames) {
    waveform->process(
        interleavedInput, // Pointer to floating point numbers. 32-bit interleaved stereo input.
        numberOfFrames,   // Number of frames to process.
        -1     // If the audio input length may change, set this to the current length. Use -1 otherwise. If this value is not -1, this method can NOT be used in a real-time audio thread.
    );
}

Properties

waveformSize

PROPERTY

The number of bytes in the peak waveform.

Type	Min	Max	Default
Number

waveformSize

PROPERTY

The number of bytes in the peak waveform.

Type	Min	Max	Default
int

Methods

constructor

METHOD

Creates a Waveform instance.

Parameters

Name	Type	Description
samplerate	`Number`	The sample rate of the audio input.
lengthSeconds	`Number`	The length in seconds of the audio input. It will not be able to process more audio than this. You can change this value in the process() method.

Returns

Type	Description
`Superpowered.Waveform`	The constructed instance.

constructor

METHOD

Creates a Waveform instance.

Parameters

Name	Type	Default	Description
samplerate	`unsigned int`		The sample rate of the audio input.
lengthSeconds	`int`		The length in seconds of the audio input. It will not be able to process more audio than this. You can change this value in the process() method.

Returns

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

destruct
METHOD
Destructor to free Linear Memory.
Parameters
None
Returns
None
getPeakWaveform
METHOD
Returns with 150 points/sec waveform data displaying the peak volume. Each number is an unsigned byte (8-bits), representing one "pixel". Available after calling makeResults().
Parameters
Name Type Description
takeOwnership Boolean If true, you take ownership on the data, so don't forget to free() the memory to prevent memory leaks.
Returns
Type Description
Superpowered.Uint8Buffer 150 points/sec waveform data
getPeakWaveform
METHOD
Returns with 150 points/sec waveform data displaying the peak volume. Each number is an unsigned byte (8-bits), representing one "pixel". Available after calling makeResults().
Parameters
Name Type Default Description
takeOwnership bool If true, you take ownership on the data, so don't forget to free() the memory to prevent memory leaks.
Returns
Type Description
unsigned char * 150 points/sec waveform data
makeResult
METHOD
Makes the result from the collected data. This method should NOT be used in a real-time audio thread.
Parameters
None
Returns
None
makeResult
METHOD
Makes the result from the collected data. This method should NOT be used in a real-time audio thread.
Parameters
None
Returns
None

Name	Type	Description
takeOwnership	`Boolean`	If true, you take ownership on the data, so don't forget to free() the memory to prevent memory leaks.

Type	Description
`Superpowered.Uint8Buffer`	150 points/sec waveform data

Name	Type	Default	Description
takeOwnership	`bool`		If true, you take ownership on the data, so don't forget to free() the memory to prevent memory leaks.

Type	Description
`unsigned char *`	150 points/sec waveform data

process

METHOD

Processes some audio. This method can be used in a real-time audio thread if lengthSeconds is -1.

Parameters

Name	Type	Description
input	`Number (pointer in Linear Memory)`	32-bit interleaved stereo input.
numberOfFrames	`Number`	Number of frames to process.
lengthSeconds	`Number`	If the audio input length may change, set this to the current length. Use -1 otherwise. If this value is not -1, this method can NOT be used in a real-time audio thread.

Returns

None

process

METHOD

Processes some audio. This method can be used in a real-time audio thread if lengthSeconds is -1.

Parameters

Name	Type	Default	Description
input	`float *`		32-bit interleaved stereo input.
numberOfFrames	`unsigned int`		Number of frames to process.
lengthSeconds	`int`	-1	If the audio input length may change, set this to the current length. Use -1 otherwise. If this value is not -1, this method can NOT be used in a real-time audio thread.

Returns

None