Revision 935897 of MediaSource

<p>{{APIRef("Media Source Extensions")}}{{SeeCompatTable}}</p>

<p>The <strong><code>MediaSource</code></strong> interface represents a source of media data for an {{domxref("HTMLMediaElement")}} object. A <code>MediaSource</code> object can be attached to a {{domxref("HTMLMediaElement")}} to be played in the user agent.</p>

<h2 id="Constructor">Constructor</h2>

<dl>
 <dt>{{domxref("MediaSource.MediaSource", "MediaSource()")}}</dt>
 <dd>Constructs and returns a new <code>MediaSource</code> object with no associated source buffers.</dd>
</dl>

<h2 id="Properties">Properties</h2>

<p><em>Inherits properties from its parent interface, {{domxref("EventTarget")}}.</em></p>

<dl>
 <dt>{{domxref("MediaSource.sourceBuffers")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("SourceBufferList")}} object containing the list of {{domxref("SourceBuffer")}} objects associated with this <code>MediaSource</code>.</dd>
 <dt>{{domxref("MediaSource.activeSourceBuffers")}} {{readonlyInline}}</dt>
 <dd>Returns a {{domxref("SourceBufferList")}} object containing a subset of the&nbsp;{{domxref("SourceBuffer")}} objects contained within {{domxref("SourceBuffers")}} — the list of objects providing the selected video track,&nbsp; enabled audio tracks, and shown/hidden text tracks.</dd>
 <dt>{{domxref("MediaSource.readyState")}} {{readonlyInline}}</dt>
 <dd>Returns an enum representing the state of the current <code>MediaSource</code>, whether it is not currently attached to a media element (<code>closed</code>), attached and ready to receive {{domxref("SourceBuffer")}} objects (<code>open</code>), or attached but the stream has been ended via {{domxref("MediaSource.endOfStream()")}} (<code>ended</code>.)</dd>
 <dt>{{domxref("MediaSource.duration")}}</dt>
 <dd>Gets and sets the duration of the current media being presented.</dd>
</dl>

<dl>
</dl>

<dl>
</dl>

<h2 id="Methods">Methods</h2>

<p><em>Inherits properties from its parent interface, {{domxref("EventTarget")}}.</em></p>

<dl>
 <dt>{{domxref("MediaSource.addSourceBuffer()")}}</dt>
 <dd>Creates a new {{domxref("SourceBuffer")}} of the given MIME type and adds it to the <code>MediaSource</code>'s {{domxref("SourceBuffers")}} list.</dd>
 <dt>{{domxref("MediaSource.removeSourceBuffer()")}}</dt>
 <dd>Removes the given {{domxref("SourceBuffer")}} from the {{domxref("SourceBuffers")}} list associated with this <code>MediaSource</code> object.</dd>
 <dt>{{domxref("MediaSource.endOfStream()")}}</dt>
 <dd>Signals the end of the stream.</dd>
 <dt>
 <h2 id="Static_methods">Static methods</h2>
 </dt>
 <dt>{{domxref("MediaSource.isTypeSupported()")}}</dt>
 <dd>Returns a {{domxref("Boolean")}} value indicating if the given MIME type is supported by the current user agent — this is, if it can successfully create {{domxref("SourceBuffer")}} objects for that MIME type.</dd>
</dl>

<h2 id="Examples">Examples</h2>

<p>The following simple example loads a video chunk by chunk as fast as possible, playing it as soon as it can. This example was written by Nick Desaulniers and can be <a href="https://nickdesaulniers.github.io/netfix/demo/bufferAll.html">viewed live here</a> (you can also <a href="https://github.com/nickdesaulniers/netfix/blob/gh-pages/demo/bufferAll.html">download the source</a> for further investigation.)</p>

<pre class="brush: js">
var video = document.querySelector('video');

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 &amp;&amp; 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 (_) {
      mediaSource.endOfStream();
      video.play();
      //console.log(mediaSource.readyState); // ended
    });
    sourceBuffer.appendBuffer(buf);
  });
};

function fetchAB (url, cb) {
  console.log(url);
  var xhr = new XMLHttpRequest;
  xhr.open('get', url);
  xhr.responseType = 'arraybuffer';
  xhr.onload = function () {
    cb(xhr.response);
  };
  xhr.send();
};</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Media Source Extensions', '#mediasource', 'MediaSource')}}</td>
   <td>{{Spec2('Media Source Extensions')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>23</td>
   <td>{{CompatGeckoDesktop("25.0")}}<sup>[1]</sup><br />
    {{CompatGeckoDesktop("42.0")}}</td>
   <td>11<sup>[2]</sup></td>
   <td>15</td>
   <td>8</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS (Gecko)</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>4.4.4</td>
   <td>
    <p>{{CompatNo}}</p>
   </td>
   <td>{{CompatNo}}</td>
   <td>11</td>
   <td>30</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1] Available after switching the <code>about:config</code> preference <code>media.mediasource.enabled</code> to <code>true</code>. 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.</p>

<p>[2] Only works on Windows 8+.</p>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{domxref("SourceBuffer")}}</li>
 <li>{{domxref("SourceBufferList")}}</li>
</ul>