BaseAudioContext: createBufferSource() method

The createBufferSource() method of the BaseAudioContext Interface is used to create a new AudioBufferSourceNode, which can be used to play audio data contained within an AudioBuffer object. AudioBuffers are created using BaseAudioContext.createBuffer or returned by BaseAudioContext.decodeAudioData when it successfully decodes an audio track.

Note: The AudioBufferSourceNode() constructor is the recommended way to create a AudioBufferSourceNode; see Creating an AudioNode.

Syntax

js

createBufferSource()

Parameters

None.

Return value

An AudioBufferSourceNode.

Examples

In this example, we create a two second buffer, fill it with white noise, and then play it via an AudioBufferSourceNode. The comments should clearly explain what is going on.

Note: You can also run the code live, or view the source.

js

const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
const button = document.querySelector("button");
const pre = document.querySelector("pre");
const myScript = document.querySelector("script");

pre.innerHTML = myScript.innerHTML;

// Stereo
const channels = 2;
// Create an empty two second stereo buffer at the
// sample rate of the AudioContext
const frameCount = audioCtx.sampleRate * 2.0;

const myArrayBuffer = audioCtx.createBuffer(
  channels,
  frameCount,
  audioCtx.sampleRate
);

button.onclick = () => {
  // Fill the buffer with white noise;
  //just random values between -1.0 and 1.0
  for (let channel = 0; channel < channels; channel++) {
    // This gives us the actual ArrayBuffer that contains the data
    const nowBuffering = myArrayBuffer.getChannelData(channel);
    for (let i = 0; i < frameCount; 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
  const 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
Web Audio API
# dom-baseaudiocontext-createbuffersource

Browser compatibility

BCD tables only load in the browser

See also