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
.
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
.
Examples
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
BCD tables only load in the browser