The loopStart
property of the AudioBufferSourceNode
interface is a double value indicating, in seconds, where in the AudioBuffer
the restart of the play must happen.
The loopStart
property's default value is 0
.
Syntax
var source = audioCtx.createBufferSource(); source.loopStart = 3;
Value
A double.
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, the audio will start to loop between 20 and 25 seconds in to the track.
Note: 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; }
Specification
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'loopStart' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 14 webkit | 23 | Not supported | 15 webkit 22 (unprefixed) |
6 webkit |
Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | Not supported | 28 webkit | 25 | 1.2 | Not supported | Not supported | 6 webkit |