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The MediaRecorder.mimeType read-only property returns the MIME type that is being used as the recording container when it was created. This is the file format of the file that would result from writing all of the recorded data to disk. Keep in mind, of course, that the file format and the codecs associated with the individual tracks are different things entirely; writing tracks that work just fine in a WebM video into an MP4 wrapper may not result in a file that plays everywhere you want  it to.


var mimeType = MediaRecorder.mimeType


The MIME type being used as the container format for the recorded media, in DOMString form.



if (navigator.mediaDevices) {
  console.log('getUserMedia supported.');

  var constraints = { audio: true, video: true };
  var chunks = [];

    .then(function(stream) {
      var options = {
        audioBitsPerSecond : 128000,
        videoBitsPerSecond : 2500000,
        mimeType : 'video/mp4'
      var mediaRecorder = new MediaRecorder(stream,options);
      m = mediaRecorder;

      m.mimeType; // would return 'video/mp4'
    .catch(function(error) {


Specification Status Comment
MediaStream Recording
The definition of 'MediaRecorder.mimeType' in that specification.
Working Draft Initial definition

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 47[2] 25.0 (25.0) No support No support No support
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support No support No support 25.0 (25.0) 1.3[1] No support No support No support No support

[1] The intial Firefox OS implementation only supported audio recording.

[2] To try this feature on Chrome, enable Experimental Web Platform features from chrome://flags . Currently only video is supported, not audio.

See also

Document Tags and Contributors

 Contributors to this page: Jib, Sheppy, j1mr10rd4n, jpmedley, chrisdavidmills
 Last updated by: Jib,