This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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The appendWindowEnd property of the SourceBuffer interface controls the timestamp for the end of the append window, a timestamp range that can be used to filter what media data is appended to the SourceBuffer. Coded media frames with timestamps wthin this range will be appended, whereas those outside the range will be filtered out.

The default value of appendWindowEnd is positive infinity.


var myAppendWindowEnd = sourceBuffer.appendWindowEnd;

sourceBuffer.appendWindowEnd = 120.0;


A double, indicating the end time of the append window, in seconds.


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

Error Explanation
InvalidAccessError An attempt was made to set the value to less than or equal to SourceBuffer.appendWindowStart, or NaN.
InvalidStateError One or more of the SourceBuffer objects in MediaSource.sourceBuffers are being updated (i.e. their SourceBuffer.updating property is currently true), or this SourceBuffer has been removed from the MediaSource.




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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 23 25.0 (25.0)[1]
42.0 (42.0)
11[2] 15 9
Feature Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 4.4.4

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

Document Tags and Contributors

 Contributors to this page: joeyparrish, chrisdavidmills
 Last updated by: joeyparrish,