index.md

---

title: AudioContext.getOutputTimestamp()
slug: Web/API/AudioContext/getOutputTimestamp
page-type: web-api-instance-method
browser-compat: api.AudioContext.getOutputTimestamp

---

{{APIRef("Web Audio API")}}

The getOutputTimestamp() property of the {{domxref("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's {{domxref("BaseAudioContext/currentTime", "AudioContext.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 stored contextTime value was rendered by the audio output device, in the same units and origin as {{domxref("performance.now()")}}. This is the time after the document containing the audio context was first rendered.

Syntax

getOutputTimestamp()

Parameters

None.

Return value

An AudioTimestamp object, which has the following properties.

• contextTime: A point in the time coordinate system of the {{domxref("BaseAudioContext/currentTime","currentTime")}} for the BaseAudioContext; the time after the audio context was first created.

• performanceTime: A point in the time coordinate system of a Performance 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).

// Press the play button
playBtn.addEventListener("click", () => {
  // We can create the audioCtx as there has been some user action
  if (!audioCtx) {
    audioCtx = new AudioContext();
  }
  source = new AudioBufferSourceNode(audioCtx);
  getData();
  source.start(0);
  playBtn.disabled = true;
  stopBtn.disabled = false;
  rAF = requestAnimationFrame(outputTimestamps);
});

// Press the stop button
stopBtn.addEventListener("click", () => {
  source.stop(0);
  playBtn.disabled = false;
  stopBtn.disabled = true;
  cancelAnimationFrame(rAF);
});

// Helper function to output timestamps
function outputTimestamps() {
  const ts = audioCtx.getOutputTimestamp();
  output.textContent = `Context time: ${ts.contextTime} | Performance time: ${ts.performanceTime}`;
  rAF = requestAnimationFrame(outputTimestamps); // Reregister itself
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}