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 = AudioContext.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 ([[../../../../../../../mdn.github.io/webaudio-examples/output-timestamp/index|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 | Status | Comment |
Web Audio APIThe definition of 'getOutputTimestamp()' in that specification. | Working Draft | Initial definition. |
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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Chrome
Full support 57 |
Edge
Full support 79 |
Firefox
Full support 70 |
IE
No support No |
Opera
Full support 44 |
Safari
No support No |
WebView Android
Full support 57 |
Chrome Android
Full support 57 |
Firefox Android
No support No |
Opera Android
Full support 43 |
Safari iOS
No support No |
Samsung Internet Android
Full support 7.0 |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.'
- Experimental. Expect behavior to change in the future.
AudioContext.getOutputTimestamp() by Mozilla Contributors is licensed under CC-BY-SA 2.5.