The MediaSource.isTypeSupported() static method returns a Boolean value which is true if the given MIME type is likely to be supported by the current user agent. That is, if it can successfully create SourceBuffer objects for that MIME type. If the returned value is false, then the user agent is certain that it cannot access media of the specified format.


var isItSupported = mediaSource.isTypeSupported(mimeType);


The MIME media type that you want to test support for in the current browser. This may include the codecs parameter to provide added details about the codecs used within the file.

Return value

A Boolean which is true if the browser feels that it can probably play media of the specified type. This is not a guarantee, however, and your code must be prepared for the possibility that the media will not play correctly if at all. A value of false is a guarantee that media of the given type will not play, however.

All web APIs that work with media files use a "no/maybe/probably" approach (or, in this case, "no or probably") when determining if a media type can be used. This is because media files are complex, intricate constructs with far too many subtle variations to be absolutely certain of anything until you actually use the contents of the media.


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

var assetURL = 'frag_bunny.mp4';
// Need to be specific for Blink regarding codecs
// ./mp4info frag_bunny.mp4 | grep Codec
var mimeCodec = 'video/mp4; codecs="avc1.42E01E, mp4a.40.2"';

if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) {
  var mediaSource = new MediaSource;
  //console.log(mediaSource.readyState); // closed
  video.src = URL.createObjectURL(mediaSource);
  mediaSource.addEventListener('sourceopen', sourceOpen);
} else {
  console.error('Unsupported MIME type or codec: ', mimeCodec);

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


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

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 23Edge Full support 12Firefox Full support 42
Full support 42
No support 25 — 42
Notes Disabled
Notes Limited support to an allowed list of sites, for example YouTube, Netflix, and other popular streaming sites. The limitation was removed when Media Source Extensions was enabled by default in Firefox 42.
Disabled From version 25 until version 42 (exclusive): this feature is behind the media.mediasource.enabled preference. To change preferences in Firefox, visit about:config.
IE Full support 11
Full support 11
Notes Only works on Windows 8+.
Opera Full support 15Safari Full support 8WebView Android Full support 4.4.3Chrome Android Full support 25Firefox Android Full support 41Opera Android Full support 14Safari iOS No support NoSamsung Internet Android Full support 1.5


Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also