The loopStart
property of the AudioBufferSourceNode
interface is a floating-point value indicating, in seconds, where in the AudioBuffer
the restart of the play must happen.
The loopStart
property's default value is 0
.
Syntax
AudioBufferSourceNode.loopStart = startOffsetInSeconds; startOffsetInSeconds = AudioBufferSourceNode.loopStart;
Value
A floating-point number indicating the offset, in seconds, into the audio buffer at which each loop should begin during playback. This value is only used when the loop
parameter is true
.
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.
For a full working example, see [[../../../../../../../mdn.github.io/webaudio-examples/decode-audio-data/index|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 APIThe definition of 'loopStart' in that specification. | Working Draft |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
loopStart
|
Chrome
Full support 24 |
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 25 |
Firefox Android
Full support 26 |
Opera Android
Full support 14 |
Safari iOS
Full support 6 |
Samsung Internet Android
Full support 1.5 |
Legend
- Full support
- Full support
- No support
- No support
See also
AudioBufferSourceNode.loopStart by Mozilla Contributors is licensed under CC-BY-SA 2.5.