AudioBufferSourceNode.loopStart
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.
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;
}
Specifications
Specification |
---|
Web Audio API # dom-audiobuffersourcenode-loopstart |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
loopStart |
24 |
12 |
25 |
No |
15 |
6 |
≤37 |
25 |
25 |
14 |
6 |
1.5 |
See also
© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/AudioBufferSourceNode/loopStart