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AudioBufferSourceNode.loopEnd

The loopEnd property of the AudioBufferSourceNode interface specifies is a floating point number specifying, in seconds, at what offset into playing the AudioBuffer playback should loop back to the time indicated by the loopStart property. This is only used if the loop property is true.

Syntax

AudioBufferSourceNode.loopEnd = endOffsetInSeconds;

var endOffsetInSeconds = AudioBufferSourceNode.loopEnd;

Value

A floating-point number indicating the offset, in seconds, into the audio buffer at which each loop will loop return to the beginning of the loop (that is, the current play time gets reset to AudioBufferSourceNode.loopStart). This property is only used if the loop property is true.

The default value is 0.

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 slider controls are used to change the playbackRate, loopStart and loopEnd properties on the fly.

When the audio is played to the end, it loops, but you can control how long the loops last by altering loopStart and loopEnd. For example, if you set their values to 20 and 25, respectively, then begin playback, the sound will play normally until it reaches the 25 second mark. Then the current play position will loop back to the 20 second mark and continue playing until the 25 second mark, ad infinitum (or at least until stop() is called).

For a full working example, see this code running live, or view the source.

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;
        songLength = buffer.duration;
        source.buffer = myBuffer;
        source.playbackRate.value = playbackControl.value;
        source.connect(audioCtx.destination);
        source.loop = true;

        loopstartControl.setAttribute('max', Math.floor(songLength));
        loopendControl.setAttribute('max', Math.floor(songLength));
      },

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

  }

  request.send();
}

  ...

loopstartControl.oninput = function() {
  source.loopStart = loopstartControl.value;
  loopstartValue.innerHTML = loopstartControl.value;
}

loopendControl.oninput = function() {
  source.loopEnd = loopendControl.value;
  loopendValue.innerHTML = loopendControl.value;
}

Specifications

Specification Status Comment
Web Audio API
The definition of 'loopEnd' in that specification.
Working Draft

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 14 Yes 25 No 15 6
Feature Android webview Chrome for Android Edge mobile Firefox for Android IE mobile Opera Android iOS Safari
Basic support Yes 14 Yes 26 No 15 ?

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/AudioBufferSourceNode/loopEnd