Web/API/AudioBuffer

The AudioBuffer interface represents a short audio asset residing in memory, created from an audio file using the AudioContext.decodeAudioData() method, or from raw data using AudioContext.createBuffer(). Once put into an AudioBuffer, the audio can then be played by being passed into an AudioBufferSourceNode.

Objects of these types are designed to hold small audio snippets, typically less than 45 s. For longer sounds, objects implementing the MediaElementAudioSourceNode are more suitable. The buffer contains data in the following format: non-interleaved IEEE754 32-bit linear PCM with a nominal range between -1 and +1, that is, 32bits floating point buffer, with each samples between -1.0 and 1.0. If the AudioBuffer has multiple channels, they are stored in separate buffer.

Constructor

AudioBuffer(): Creates and returns a new AudioBuffer object instance.

Properties

AudioBuffer.sampleRate Read only: Returns a float representing the sample rate, in samples per second, of the PCM data stored in the buffer.
AudioBuffer.length Read only: Returns an integer representing the length, in sample-frames, of the PCM data stored in the buffer.
AudioBuffer.duration Read only: Returns a double representing the duration, in seconds, of the PCM data stored in the buffer.
AudioBuffer.numberOfChannels Read only: Returns an integer representing the number of discrete audio channels described by the PCM data stored in the buffer.

Methods

AudioBuffer.getChannelData(): Returns a Float32Array containing the PCM data associated with the channel, defined by the channel parameter (with 0 representing the first channel).
AudioBuffer.copyFromChannel(): Copies the samples from the specified channel of the AudioBuffer to the destination array.
AudioBuffer.copyToChannel(): Copies the samples to the specified channel of the AudioBuffer, from the source array.

Example

The following simple example shows how to create an AudioBuffer and fill it with random white noise. You can find the full source code at our webaudio-examples repository; a [[../../../../../../mdn.github.io/webaudio-examples/audio-buffer/index|running live]] version is also available.

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();

// Create an empty three-second stereo buffer at the sample rate of the AudioContext
var myArrayBuffer = audioCtx.createBuffer(2, audioCtx.sampleRate * 3, audioCtx.sampleRate);

// Fill the buffer with white noise;
// just random values between -1.0 and 1.0
for (var channel = 0; channel < myArrayBuffer.numberOfChannels; channel++) {
  // This gives us the actual array that contains the data
  var nowBuffering = myArrayBuffer.getChannelData(channel);
  for (var i = 0; i < myArrayBuffer.length; i++) {
    // Math.random() is in [0; 1.0]
    // audio needs to be in [-1.0; 1.0]
    nowBuffering[i] = Math.random() * 2 - 1;
  }
}

// Get an AudioBufferSourceNode.
// This is the AudioNode to use when we want to play an AudioBuffer
var source = audioCtx.createBufferSource();

// set the buffer in the AudioBufferSourceNode
source.buffer = myArrayBuffer;

// connect the AudioBufferSourceNode to the
// destination so we can hear the sound
source.connect(audioCtx.destination);

// start the source playing
source.start();

Specifications

Specification	Status	Comment
Web Audio APIThe definition of 'AudioBuffer' in that specification.	Working Draft	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`AudioBuffer`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`AudioBuffer()` constructor	Chrome Full support 55 Notes' Full support 55 Notes' Notes' The `context` parameter was supported up until version 57, but has now been removed.	Edge Full support 79	Firefox Full support 53	IE No support No	Opera Full support 42 Notes' Full support 42 Notes' Notes' The `context` parameter was supported up until version 44, but has now been removed.	Safari No support No	WebView Android Full support 55 Notes' Full support 55 Notes' Notes' The `context` parameter was supported up until version 57, but has now been removed.	Chrome Android Full support 55 Notes' Full support 55 Notes' Notes' The `context` parameter was supported up until version 57, but has now been removed.	Firefox Android Full support 53	Opera Android Full support 42 Notes' Full support 42 Notes' Notes' The `context` parameter was supported up until version 44, but has now been removed.	Safari iOS No support No	Samsung Internet Android Full support 6.0 Notes' Full support 6.0 Notes' Notes' The `context` parameter was supported up until Samsung Internet 7.0, but has now been removed.
`copyFromChannel`	Chrome Full support 43	Edge Full support 13	Firefox Full support 25	IE No support No	Opera Full support 30	Safari No support No	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 26	Opera Android Full support 30	Safari iOS No support No	Samsung Internet Android Full support 4.0
`copyToChannel`	Chrome Full support 43	Edge Full support 13	Firefox Full support 25	IE No support No	Opera Full support 30	Safari No support No	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 26	Opera Android Full support 30	Safari iOS No support No	Samsung Internet Android Full support 4.0
`duration`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`getChannelData`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`length`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`numberOfChannels`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0
`sampleRate`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.