AudioBufferSourceNode.playbackRate

The default value is 1.0. When set to another value, the AudioBufferSourceNode resamples the audio before sending it to the output.

Syntax

var source = audioCtx.createBufferSource();
source.playbackRate.value = 1.25; // play 25% faster than normal speed (1)

Value

An AudioParam.

Example

In this example, the AudioContext.decodeAudioData function is used to decode an audio track and put it into an AudioBufferSourceNode. Buttons are provided to play and stop the audio playback, and a slider control is used to change the playbackRate property value on the fly.

<input class="playback-rate-control" type="range" min="0.25" max="3" step="0.05" value="1">
<span class="playback-rate-value">1.0</span>

function getData() {
  source = audioCtx.createBufferSource();
  request = new XMLHttpRequest();

  request.open('GET', 'viper.ogg', true);

  request.responseType = 'arraybuffer';

  request.onload = function() {
    var audioData = request.response;

    audioCtx.decodeAudioData(audioData, function(buffer) {
        myBuffer = buffer;
        source.buffer = myBuffer;
        source.playbackRate.value = playbackControl.value;
        source.connect(audioCtx.destination);
        source.loop = true;
      },

      function(e){"Error with decoding audio data" + e.err});

  }

  request.send();
}

// wire up buttons to stop and play audio, and range slider control

play.onclick = function() {
  getData();
  source.start(0);
  play.setAttribute('disabled', 'disabled');
  playbackControl.removeAttribute('disabled');
}

stop.onclick = function() {
  source.stop(0);
  play.removeAttribute('disabled');
  playbackControl.setAttribute('disabled', 'disabled');
}

playbackControl.oninput = function() {
  source.playbackRate.value = playbackControl.value;
  playbackValue.innerHTML = playbackControl.value;
}

Specification

Browser compatibility

See also

• Using the Web Audio API