Navigator.getUserMedia()

The Navigator.getUserMedia() method prompts the user for permission to use up to one video input device (such as a camera or shared screen) and up to one audio input device (such as a microphone). If permission is granted, a MediaStream whose video and/or audio tracks come from those devices is delivered to the specified success callback. If permission is denied, no compatible input devices exist, or any other error condition occurs, the error callback is executed with a MediaStreamError object describing what went wrong. If the user instead doesn't make a choice at all, neither callback is executed.

Syntax

navigator.getUserMedia(constraints, successCallback, errorCallback);

Parameters

constraints

A MediaStreamConstaints object specifying the types of media to request, along with any requirements for each type. For details, see the constraints section under the modern MediaDevices.getUserMedia() method, as well as the article Capabilities, constraints, and settings.

successCallback

A function which is invoked when the request for media access is approved. The function is called with one parameter: the MediaStream object that contains the media stream. Your callback can then assign the stream to the desired object (such as an <audio> or <video> element), as shown in the following example:

function(stream) {
   var video = document.querySelector('video');
   video.src = window.URL.createObjectURL(stream);
   video.onloadedmetadata = function(e) {
      // Do something with the video here.
   };
}

errorCallback

When the call fails, the function specified in the errorCallback is invokedwith a MediaStreamError object as its sole argument; this object is is modeled on DOMException. See {anch("Errors")}} below for a list of the errors which can occur.

Return value

undefined.

Errors

Rejections of the returned promise are made by passing a DOMException error object to the promise's failure handler. Possible errors are:

AbortError

Although the user and operating system both granted access to the hardware device, and no hardware issues occurred that would cause a NotReadableError, some problem occurred which prevented the device from being used.

NotAllowedError

The user has specified that the current browsing instance is not permitted access to the device; or the user has denied access for the current session; or the user has denied all access to user media devices globally.

Older versions of the specification used SecurityError for this instead; SecurityError has taken on a new meaning.

NotFoundError

No media tracks of the type specified were found that satisfy the given constraints.

NotReadableError

Although the user granted permission to use the matching devices, a hardware error occurred at the operating system, browser, or Web page level which prevented access to the device.

OverConstrainedError

The specified constraints resulted in no candidate devices which met the criteria requested. The error is an object of type OverconstrainedError, and has a constraint property whose string value is the name of a constraint which was impossible to meet, and a message property containing a human-readable string explaining the problem.

Because this error can occur even when the user has not yet granted permission to use the underlying device, it can potentially be used as a fingerprinting surface.

SecurityError

User media support is disabled on the Document on which getUserMedia() was called. The mechanism by which user media support is enabled and disabled is left up to the individual user agent.

TypeError

The list of constraints specified is empty, or has all constraints set to false.

Examples

Width and height

Here's an example of using getUserMedia(), including code to cope with various browsers' prefixes. Note that this is the deprecated way of doing it: See the Examples section under the MediaDevices.getUserMedia() for modern examples.

navigator.getUserMedia = navigator.getUserMedia ||
                         navigator.webkitGetUserMedia ||
                         navigator.mozGetUserMedia;

if (navigator.getUserMedia) {
   navigator.getUserMedia({ audio: true, video: { width: 1280, height: 720 } },
      function(stream) {
         var video = document.querySelector('video');
         video.src = window.URL.createObjectURL(stream);
         video.onloadedmetadata = function(e) {
           video.play();
         };
      },
      function(err) {
         console.log("The following error occurred: " + err.name);
      }
   );
} else {
   console.log("getUserMedia not supported");
}

Permissions

To use getUserMedia() in an installable app (for example, a Firefox OS app), you need to specify one or both of the following fields inside your manifest file:

"permissions": {
  "audio-capture": {
    "description": "Required to capture audio using getUserMedia()"
  },
  "video-capture": {
    "description": "Required to capture video using getUserMedia()"
  }
}

See permission: audio-capture and permission: video-capture for more information.

Specifications

Browser compatibility

[1] Later versions of Chrome support unprefixed MediaDevices.getUserMedia(), that replaced this deprecated method.

[2] Chrome and Opera still use an outdated constraint syntax, but the syntax described here is available through the adapter.js polyfill.

[3] The constraint syntax described here is available as of Firefox 38. Earlier versions (32-37) used an outdated constraint syntax, but the syntax described here is available there through the adapter.js polyfill.

[4] In Firefox OS 1.2 only audio was supported, 1.4 added support for video.

See also

• MediaDevices.getUserMedia() that replaces this deprecated method.
• WebRTC - the introductory page to the API
• MediaStream API - the API for the media stream objects
• Taking webcam photos - a tutorial on using getUserMedia() for taking photos rather than video.