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.
Candidate Recommendation Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23 (Yes) 25.0 (25.0)[1]
42.0 (42.0)
11[2] 15 8
Feature Android Edge Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 4.4.4 (Yes)

No support

No support 11 30 No support

[1] Available after switching the about:config preference media.mediasource.enabled to true. In addition, support was limited to a whitelist of sites, for example YouTube, Netflix, and other popular streaming sites. The whitelist was removed and Media Source Extensions was enabled by default in 42+ for all sites.

[2] Only works on Windows 8+.

See also

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