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The MediaRecorder interface of the MediaStream Recording API provides functionality to easily record media. It is created by the invocation of the MediaRecorder() constructor.

Constructor

MediaRecorder.MediaRecorder()
Creates a new MediaRecorder object, given a MediaStream to record. Options are available to do things like set the container's MIME type (such as "video/webm" or "video/mp4") and the bit rates of the audio and video tracks or a single overall bit rate.

Properties

MediaRecorder.mimeType Read only
Returns the MIME type that was selected as the recording container for the MediaRecorder object when it was created.
MediaRecorder.state Read only
Returns the current state of the MediaRecorder object (inactive, recording, or paused.)
MediaRecorder.stream Read only
Returns the stream that was passed into the constructor when the MediaRecorder was created.
MediaRecorder.ignoreMutedMedia
Indicates whether the MediaRecorder instance will record input when the input MediaStreamTrack is muted. If this attribute is false, MediaRecorder will record silence for audio and black frames for video. The default is false.
MediaRecorder.videoBitsPerSecond Read only
Returns the video encoding bit rate in use. This may differ from the bit rate specified in the constructor (if it was provided).
MediaRecorder.audioBitsPerSecond Read only
Returns the audio encoding bit rate in use. This may differ from the bit rate specified in the constructor (if it was provided).

Methods

MediaRecorder.isTypeSupported()
 Returns a Boolean value indicating if the given MIME type is supported by the current user agent . 
MediaRecorder.pause()
Pauses the recording of media.
MediaRecorder.requestData()
Requests a Blob containing the saved data received thus far (or since the last time requestData() was called. After calling this method, recording continues, but in a new Blob.
MediaRecorder.resume()
Resumes recording of media after having been paused.
MediaRecorder.start()
Begins recording media; this method can optionally be passed a timeslice argument with a value in milliseconds. If this is specified, the media will be captured in separate chunks of that duration, rather than the default behavior of recording the media in a single large chunk.
MediaRecorder.stop()
Stops recording, at which point a dataavailable event containing the final Blob of saved data is fired. No more recording occurs.

Event Handlers

MediaRecorder.ondataavailable
Called to handle the dataavailable event, which can be used to grab the recorded media (which is made available as a Blob object in the event's data attribute.)
MediaRecorder.onerror
An EventHandler called to handle the recordingerror event, including reporting errors that arise with media recording. These are fatal errors that stop recording.
MediaRecorder.onpause
An EventHandler called to handle the pause event, which occurs when media recording is paused.
MediaRecorder.onresume
An EventHandler called to handle the resume event, which occurs when media recording resumes after being paused.
MediaRecorder.onstart
An EventHandler called to handle the start event, which occurs when media recording starts.
MediaRecorder.onstop
An EventHandler called to handle the stop event, which occurs when media recording ends, either when the MediaStream ends — or after the MediaRecorder.stop() method is called.

Example

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

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

  navigator.mediaDevices.getUserMedia(constraints)
  .then(function(stream) {

    var mediaRecorder = new MediaRecorder(stream);

    visualize(stream);

    record.onclick = function() {
      mediaRecorder.start();
      console.log(mediaRecorder.state);
      console.log("recorder started");
      record.style.background = "red";
      record.style.color = "black";
    }

    stop.onclick = function() {
      mediaRecorder.stop();
      console.log(mediaRecorder.state);
      console.log("recorder stopped");
      record.style.background = "";
      record.style.color = "";
    }

    mediaRecorder.onstop = function(e) {
      console.log("data available after MediaRecorder.stop() called.");

      var clipName = prompt('Enter a name for your sound clip');

      var clipContainer = document.createElement('article');
      var clipLabel = document.createElement('p');
      var audio = document.createElement('audio');
      var deleteButton = document.createElement('button');
     
      clipContainer.classList.add('clip');
      audio.setAttribute('controls', '');
      deleteButton.innerHTML = "Delete";
      clipLabel.innerHTML = clipName;

      clipContainer.appendChild(audio);
      clipContainer.appendChild(clipLabel);
      clipContainer.appendChild(deleteButton);
      soundClips.appendChild(clipContainer);

      audio.controls = true;
      var blob = new Blob(chunks, { 'type' : 'audio/ogg; codecs=opus' });
      chunks = [];
      var audioURL = URL.createObjectURL(blob);
      audio.src = audioURL;
      console.log("recorder stopped");

      deleteButton.onclick = function(e) {
        evtTgt = e.target;
        evtTgt.parentNode.parentNode.removeChild(evtTgt.parentNode);
      }
    }

    mediaRecorder.ondataavailable = function(e) {
      chunks.push(e.data);
    }
  })
  .catch(function(err) {
    console.log('The following error occured: ' + err);
  })
}

This code sample is inspired by the Web Dictaphone demo. Some lines have been omitted for brevity; refer to the source for the complete code.

Specifications

Specification Status Comment
MediaStream Recording Working Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 47.0 25.0 (25.0) No support No support No support
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support 47.0 47.0 25.0 (25.0) 1.3[1] No support No support No support
  • [1] The initial Firefox OS implementation only supported audio recording.

See also

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