Media Capture Prototype: Improved Support for Real World Web Apps


Internet Explorer Team Blog

Media Capture Prototype: Improved Support for Real World Web Apps

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Today we updated on HTML5 Labs the previously released Media Capture prototype to better align it to the latest W3C editor draft.

The HTML Media Capture working draft continues to evolve alongside related discussions in the Web RTC workgroup, and we have blogged previously about why this feature is important and how our Media Capture prototype implemented it in the past.

Because the API surface for this feature is far from final, we are supporting a simple capture syntax with this update, which is based on the most current proposal. We expect the capture syntax to change as the requirements for media capture are clarified in the task force.

Latest Updates

In this update, we are specifically adding support for a version of the getUserMedia method (function names are ms-prefixed for prototyping purposes), the MediaStream interface, and its associated events and callbacks. getUserMedia allows Web developers to suggest what specific capture devices are desired. This then allows end users to authorize the browser to access the device they selected for the duration of the capture session.

function onLoad() {

navigator.msGetUserMedia(options, cameraStarted);



function cameraStarted(mediaStream) {

msMediaStream = mediaStream;


document.getElementById("previewWindow").style.display = "block";

document["imgPreview"].src = URL.createObjectURL(mediaStream);


The advantage of this is two-fold: it protects user security and privacy and lets them pick the optimal device for the capture task from the many options available to them on a modern PC.

Looking back at our earlier proposals, we believe those scenarios are still important and relevant to this update: last March we released a prototype implementation of the audio portion of a working draft of the W3C Media Capture API on HTML5 Labs. This prototype publicized some proposed API enhancements described in section 6.1 of Microsoft’s HTML Speech XG Speech API Proposal. We then updated the prototype to include the image and video capture features described in the proposal to support scenarios we’ve heard are important for Web developers, and incorporated your feedback on audio.

This past November, we took our experience with the development of this prototype and interest in media capture for the browser to the W3C's technical plenary meeting (TPAC). Travis Leithead shared some of our feedback with the Device APIs (DAP) Working Group and we continued existing discussions within the HTML Speech Incubator Group. One result of our engagement was the formation of a media capture joint task force in order to bring the best of local media capture and real-time communication scenarios together. We are actively participating in the task force and support the getUserMedia approach to capture.

We then released an updated prototype in December that gives Web developers early access to photo, video and audio media capture APIs in the browser. We anticipate evolving the prototype to share implementation feedback and experience with the new media capture task force. The end goal remains to create the best possible standard for the benefit of the whole Web community.

Then, as discussed earlier, today we have updated the previously released Media Capture prototype to better align it to the latest W3C editor draft, which supports a simple capture syntax that is based on the most current proposal.

Microsoft remains actively engaged in the Media Capture task force and continues to advocate for the creation of the highest quality API to support these scenarios.

We Welcome Your Feedback

As always, we look forward to hearing from you, especially your questions and comments on how we can make this feature as good as possible for both the Developer community and end users. Please contact us either in the comment section on this blog or here.

—Adalberto Foresti, Senior Program Manager, Interoperability Strategy Team
Travis Leithead, Program Manager, Internet Explorer

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