AudioContext.getOutputTimestamp()
The
getOutputTimestamp()
property of the
AudioContext
interface returns a new AudioTimestamp
object
containing two audio timestamp values relating to the current audio context.
The two values are as follows:
-
AudioTimestamp.contextTime
: The time of the sample frame currently being rendered by the audio output device (i.e., output audio stream position), in the same units and origin as the context'sAudioContext.currentTime
. Basically, this is the time after the audio context was first created. -
AudioTimestamp.performanceTime
: An estimation of the moment when the sample frame corresponding to the storedcontextTime
value was rendered by the audio output device, in the same units and origin asperformance.now()
. This is the time after the document containing the audio context was first rendered.
Syntax
var timestamp = context.getOutputTimestamp()
Parameters
None.
Returns
An AudioTimestamp
object, which has the following properties.
-
contextTime
: A point in the time coordinate system of thecurrentTime
for theBaseAudioContext
; the time after the audio context was first created. -
performanceTime
: A point in the time coordinate system of aPerformance
interface; the time after the document containing the audio context was first rendered
Examples
In the following code we start to play an audio file after a play button is clicked,
and start off a requestAnimationFrame
loop running, which constantly
outputs the contextTime
and performanceTime
.
You can see full code of this example at output-timestamp (see it live also).
play.addEventListener('click', () => {
if(!audioCtx) {
audioCtx = new window.AudioContext();
}
getData();
source.start(0);
play.setAttribute('disabled', 'disabled');
rAF = requestAnimationFrame(outputTimestamps);
});
stop.addEventListener('click', () => {
source.stop(0);
play.removeAttribute('disabled');
cancelAnimationFrame(rAF);
});
// function to output timestamps
function outputTimestamps() {
let ts = audioCtx.getOutputTimestamp()
console.log('Context time: ' + ts.contextTime + ' | Performance time: ' + ts.performanceTime);
rAF = requestAnimationFrame(outputTimestamps);
}
Specifications
Specification |
---|
Web Audio API # dom-audiocontext-getoutputtimestamp |
Browser compatibility
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