import WebAudio from 'wavesurfer.js/src/webaudio.js'

public class | source

WebAudio

Extends:

util.Observer → WebAudio

Direct Subclass:

MediaElement

Indirect Subclass:

MediaElementWebAudio

WebAudio backend

Constructor Summary

Public Constructor
public	constructor(params: WavesurferParams) Construct the backend

Member Summary

Public Members
public	ac: * ac: Audio Context instance
public	analyser: * analyser: provides audio analysis information
public	audioContext: * audioContext: allows to process audio with WebAudio API
public	destroyed: boolean Boolean indicating if the backend was destroyed.
public	gainNode: * gainNode: allows to control audio volume
public	scriptNode: * scriptNode: allows processing audio

Method Summary

Public Methods
public	createAnalyserNode() Create analyser node to perform audio analysis
public	createScriptNode() Create ScriptProcessorNode to process audio
public	createVolumeNode() Create the gain node needed to control the playback volume.
public	destroy() This is called when wavesurfer is destroyed
public	destroyWebAudio() Destroy all references with WebAudio, disconnecting audio nodes and closing Audio Context
public	getAudioContext(): AudioContext Get the audio context used by this backend or create one
public	getCurrentTime(): number Returns the current time in seconds relative to the audio-clip's duration.
public	getDuration(): number Used by `wavesurfer.getDuration()`
public	getOfflineAudioContext(sampleRate: number): OfflineAudioContext Get the offline audio context used by this backend or create one
public	getPeaks(length: number, first: number, last: number): number[] \| Number<Array[]> Compute the max and min value of the waveform when broken into <length> subranges.
public	getPlaybackRate(): number Returns the current playback rate.
public	getPlayedPercents(): number Get the position from 0 to 1
public	getPlayedTime(): number Get the playback position in seconds
public	getVolume(): number Get the current volume
public	init() Initialise the backend, called in `wavesurfer.createBackend()`
public	isPaused(): boolean Used by `wavesurfer.isPlaying()` and `wavesurfer.playPause()`
public	load(buffer: Object) Loaded a decoded audio buffer
public	pause() Pauses the loaded audio.
public	play(start: number, end: number) Plays the loaded audio region.
public	seekTo(start: number, end: number): {start: number, end: number} Used by `wavesurfer.seekTo()`
public	setFilter(filters: ...AudioNode) Unpacked `setFilters()`
public	setFilters(filters: AudioNode[]) Insert custom Web Audio nodes into the graph
public	setLength(length: number) Set the rendered length (different from the length of the audio)
public	setPeaks(peaks: number[] \| Number<Array[]>, duration: number) Set pre-decoded peaks
public	setPlayEnd(end: number) Set a point in seconds for playback to stop at.	version 3.3.0
public	setPlaybackRate(value: number) Set the audio source playback rate.
public	setSinkId(deviceId: string): Promise Set the sink id for the media player
public	setVolume(value: number) Set the audio volume
public	supportsWebAudio(): boolean Does the browser support this backend

Public Constructors

public constructor(params: WavesurferParams) source

Construct the backend

Params:

Name	Type	Attribute	Description
params	WavesurferParams		Wavesurfer parameters

Public Members

public ac: * source

ac: Audio Context instance

public analyser: * source

analyser: provides audio analysis information

public audioContext: * source

audioContext: allows to process audio with WebAudio API

public destroyed: boolean source

Boolean indicating if the backend was destroyed.

public gainNode: * source

gainNode: allows to control audio volume

public scriptNode: * source

scriptNode: allows processing audio

Public Methods

public createAnalyserNode() source

Create analyser node to perform audio analysis

public createScriptNode() source

Create ScriptProcessorNode to process audio

public createVolumeNode() source

Create the gain node needed to control the playback volume.

public destroy() source

This is called when wavesurfer is destroyed

public destroyWebAudio() source

Destroy all references with WebAudio, disconnecting audio nodes and closing Audio Context

public getAudioContext(): AudioContext source

Get the audio context used by this backend or create one

Return:

AudioContext

Existing audio context, or creates a new one

public getCurrentTime(): number source

Returns the current time in seconds relative to the audio-clip's duration.

Return:

number

The current time in seconds

public getDuration(): number source

Used by wavesurfer.getDuration()

Return:

number

Duration of loaded buffer

public getOfflineAudioContext(sampleRate: number): OfflineAudioContext source

Get the offline audio context used by this backend or create one

Params:

Name	Type	Attribute	Description
sampleRate	number		The sample rate to use

Return:

OfflineAudioContext

Existing offline audio context, or creates a new one

public getPeaks(length: number, first: number, last: number): number[] | Number<Array[]> source

Compute the max and min value of the waveform when broken into <length> subranges.

Params:

Name	Type	Attribute	Description
length	number		How many subranges to break the waveform into.
first	number		First sample in the required range.
last	number		Last sample in the required range.

Return:

number[] | Number<Array[]>

Array of 2*<length> peaks or array of arrays of peaks consisting of (max, min) values for each subrange.

public getPlaybackRate(): number source

Returns the current playback rate. (0=no playback, 1=normal playback)

Return:

number

The current playback rate

public getPlayedPercents(): number source

Get the position from 0 to 1

Return:

number

Position

public getPlayedTime(): number source

Get the playback position in seconds

Return:

number

The playback position in seconds

public getVolume(): number source

Get the current volume

Return:

number

value A floating point value between 0 and 1.

public init() source

Initialise the backend, called in wavesurfer.createBackend()

public isPaused(): boolean source

Used by wavesurfer.isPlaying() and wavesurfer.playPause()

Return:

boolean

Whether or not this backend is currently paused

public load(buffer: Object) source

Loaded a decoded audio buffer

Params:

Name	Type	Attribute	Description
buffer	Object		Decoded audio buffer to load

public pause() source

Pauses the loaded audio.

public play(start: number, end: number) source

Plays the loaded audio region.

Params:

Name	Type	Attribute	Description
start	number		Start offset in seconds, relative to the beginning of a clip.
end	number		When to stop relative to the beginning of a clip.

public seekTo(start: number, end: number): {start: number, end: number} source

Used by wavesurfer.seekTo()

Params:

Name	Type	Attribute	Description
start	number		Position to start at in seconds
end	number		Position to end at in seconds

Return:

{start: number, end: number}

Object containing start and end positions

public setFilter(filters: ...AudioNode) source

Unpacked setFilters()

Params:

Name	Type	Attribute	Description
filters	...AudioNode		One or more filters to set

public setFilters(filters: AudioNode[]) source

Insert custom Web Audio nodes into the graph

Params:

Name	Type	Attribute	Description
filters	AudioNode[]		Packed filters array

Example:

const lowpass = wavesurfer.backend.ac.createBiquadFilter();
wavesurfer.backend.setFilter(lowpass);

public setLength(length: number) source

Set the rendered length (different from the length of the audio)

Params:

Name	Type	Attribute	Description
length	number		The rendered length

public setPeaks(peaks: number[] | Number<Array[]>, duration: number) source

Set pre-decoded peaks

Params:

Name	Type	Attribute	Description
peaks	number[] \| Number<Array[]>		Peaks data
duration	number	nullable: true	Explicit duration

public setPlayEnd(end: number) version 3.3.0 source

Set a point in seconds for playback to stop at.

Params:

Name	Type	Attribute	Description
end	number		Position to end at

public setPlaybackRate(value: number) source

Set the audio source playback rate.

Params:

Name	Type	Attribute	Description
value	number		The playback rate to use

public setSinkId(deviceId: string): Promise source

Set the sink id for the media player

Params:

Name	Type	Attribute	Description
deviceId	string		String value representing audio device id.

Return:

Promise

A Promise that resolves to undefined when there are no errors.

public setVolume(value: number) source

Set the audio volume

Params:

Name	Type	Attribute	Description
value	number		A floating point value between 0 and 1.

public supportsWebAudio(): boolean source

Does the browser support this backend

Return:

boolean

Whether or not this browser supports this backend