MediaRecorder.onstart

The MediaRecorder.onstart event handler (part of the MediaRecorder API) handles the start event, allowing you to run code in response to media recording being started by a MediaRecorder.

The start event is thrown as a result of the MediaRecorder.start() method being invoked. At this point, the data starts being gathered into a Blob.

Syntax

attribute EventHandler       onstart;

Example

if (navigator.getUserMedia) {
   console.log('getUserMedia supported.');
   navigator.getUserMedia (
      // constraints - only audio needed for this app
      {
         audio: true
      },

      // Success callback
      function(stream) {
           var mediaRecorder = new MediaRecorder(stream);

           record.onclick = function() {
               mediaRecorder.start();
               console.log("recorder started");
           }

           stop.onclick = function() {
               mediaRecorder.stop();
               console.log("recorder stopped");
           }

           mediaRecorder.onstart = function() {
             // do something in response to
             // recording being started
           }

           mediaRecorder.onstop = function() {
             // do something in response to
             // recording being stopped
           }

           ...

Properties

None.

Browser compatibility

[1] The current Gecko implementation currently only supports audio recording.

Specifications

See also

• Using the MediaRecorder API
• Web Dictaphone: MediaRecorder + getUserMedia + Web Audio API visualization demo, by Chris Mills (source on Github.)
• simpl.info MediaStream Recording demo, by Sam Dutton.
• Navigator.getUserMedia