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This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The duration property of the MediaSource interface gets and sets the duration of the current media being presented.


mediaSource.duration = 5.5; // 5.5 seconds

var myDuration = mediaSource.duration;


A double. A value in seconds is expected.


The following errors may be thrown when setting a new value for this property.

Error Explanation
InvalidAccessError An attempt was made to set a duration value that was negative, or NaN.
InvalidStateError MediaSource.readyState is not equal to open, or one or more of the SourceBuffer objects in MediaSource.sourceBuffers are being updated (i.e. their SourceBuffer.updating property is true.)


The following snippet is based on a simple example written by Nick Desaulniers (view the full demo live, or download the source for further investigation.)

function sourceOpen (_) {
  //console.log(this.readyState); // open
  var mediaSource = this;
  var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  fetchAB(assetURL, function (buf) {
    sourceBuffer.addEventListener('updateend', function (_) {
      mediaSource.duration = 120;
      //console.log(mediaSource.readyState); // ended



Specification Status Comment
Media Source Extensions
The definition of 'duration' in that specification.
Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support


23 — 31 -webkit-



25 — 421 2

FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support3333 Yes4130 No ?

1. Limited support to a whitelist of sites, for example YouTube, Netflix, and other popular streaming sites. The whitelist was removed when Media Source Extensions was enabled by default in Firefox 42.

2. From version 25 until version 42 (exclusive): this feature is behind the media.mediasource.enabled preference. To change preferences in Firefox, visit about:config.

3. Only works on Windows 8+.

See also

Document Tags and Contributors

 Contributors to this page: fscholz, libbymc, chrisdavidmills
 Last updated by: fscholz,