AudioContext()
The AudioContext()
constructor creates a new AudioContext
object which represents an audio-processing graph, built from audio modules linked together, each represented by an AudioNode
.
Syntax
new AudioContext(); new AudioContext(options);
Parameters
-
options
Optional -
An object used to configure the context. See below for available properties.
Options
latencyHint
-
The type of playback that the context will be used for, as a predefined string (
"balanced"
,"interactive"
or"playback"
) or a double-precision floating-point value indicating the preferred maximum latency of the context in seconds. The user agent may or may not choose to meet this request; check the value ofAudioContext.baseLatency
to determine the true latency after creating the context.-
"balanced"
: The browser balances audio output latency and power consumption when selecting a latency value. -
"interactive"
(default value): The audio is involved in interactive elements, such as responding to user actions or needing to coincide with visual cues such as a video or game action. The browser selects the lowest possible latency that doesn't cause glitches in the audio. This is likely to require increased power consumption. -
"playback"
: The browser selects a latency that will maximize playback time by minimizing power consumption at the expense of latency. Useful for non-interactive playback, such as playing music.
-
sampleRate
-
Indicates the sample rate to use for the new context. The value must be a floating-point value indicating the sample rate, in samples per second, for which to configure the new context; additionally, the value must be one which is supported by
AudioBuffer.sampleRate
. The value is typically be between 8,000 Hz and 96,000 Hz; the default will vary depending on the output device, but the sample rate 44,100 Hz is the most common. If thesampleRate
property is not included in the options, or the options are not specified when creating the audio context, the new context's output device's preferred sample rate is used by default.
Return value
The newly constructed AudioContext
instance.
Exceptions
-
NotSupportedError
DOMException
-
Thrown if the specified
sampleRate
isn't supported by the context.
Usage notes
The specification doesn't go into a lot of detail about things like how many audio contexts a user agent should support, or minimum or maximum latency requirements (if any), so these details can vary from browser to browser. Be sure to check the values if they matter to you.
In particular, the specification doesn't indicate a maximum or minimum number of audio contexts that must be able to be open at the same time, so this is left up to the browser implementations to decide.
Google Chrome
Per-tab audio context limitation in Chrome
Prior to version 66 Google Chrome only supported up to six audio contexts per tab at a time.
Non-standard exceptions in Chrome
If the value of the latencyHint
property isn't valid, Chrome throws a TypeError
exception with the message "The provided value '...' is not a valid enum value of type AudioContextLatencyCategory".
Example
This example creates a new AudioContext
for interactive audio (optimizing for latency) and a sample rate of 44.1kHz.
var AudioContext = window.AudioContext || window.webkitAudioContext; var audioCtx = new AudioContext({ latencyHint: 'interactive', sampleRate: 44100, });
Specifications
Specification |
---|
Web Audio API # dom-audiocontext-audiocontext |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
AudioContext |
35
["Before Chrome 66, each tab is limited to 6 audio contexts in Chrome; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, Chrome throws a TypeError exception. See Non-standard exceptions in Chrome for details."]14-57
|
12 |
25 |
No |
22
["Before Opera 53, each tab is limited to 6 audio contexts in Opera; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, Opera throws a TypeError exception. See Non-standard exceptions in Chrome for details."]15-44
|
14.1
6
|
37
["Before WebView 66, each tab is limited to 6 audio contexts in WebView; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, WebView throws a TypeError exception. See Non-standard exceptions in Chrome for details."]≤37-57
|
35
["Before Chrome 66, each tab is limited to 6 audio contexts in Chrome; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, Chrome throws a TypeError exception. See Non-standard exceptions in Chrome for details."]18-57
|
25 |
22
["Before Opera Android 47, each tab is limited to 6 audio contexts in Opera; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, Opera throws a TypeError exception. See Non-standard exceptions in Chrome for details."]14-43
|
14.5
6
|
3.0
["Before Samsung Internet 9.0, each tab is limited to 6 audio contexts in Samsung Internet; attempting to create more will throw a
DOMException . For details see Per-tab audio context limitation in Chrome.", "If latencyHint isn't valid, Samsung Internet throws a TypeError exception. See Non-standard exceptions in Chrome for details."]1.0-7.0
|
options_latencyHint_parameter |
60 |
79 |
61 |
No |
47 |
No
See bug 214258.
|
60 |
60 |
61 |
44 |
No
See bug 214258.
|
8.0 |
options_sampleRate_parameter |
74 |
79 |
61 |
No |
62 |
14.1 |
74 |
74 |
61 |
53 |
14.5 |
11.0 |
See also
-
new OfflineAudioContext()
constructor
© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/AudioContext