AudioBufferSourceNode: loopEnd property
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
.
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.
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, 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).
Note: For a full working example, see this code running live, or view the source.
js
function getData() {
source = audioCtx.createBufferSource();
request = new XMLHttpRequest();
request.open("GET", "viper.ogg", true);
request.responseType = "arraybuffer";
request.onload = () => {
const audioData = request.response;
audioCtx.decodeAudioData(
audioData,
(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));
},
(e) => console.error(`Error with decoding audio data: ${e.err}`)
);
};
request.send();
}
// …
loopstartControl.oninput = () => {
source.loopStart = loopstartControl.value;
loopstartValue.innerHTML = loopstartControl.value;
};
loopendControl.oninput = () => {
source.loopEnd = loopendControl.value;
loopendValue.innerHTML = loopendControl.value;
};
Specifications
Specification |
---|
Web Audio API # dom-audiobuffersourcenode-loopend |
Browser compatibility
BCD tables only load in the browser