Intent to Experiment: Capture handle

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Elad Alon

May 12, 2021, 6:04:45 AM5/12/21
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To be published later, but the explainer currently contains all necessary details.


We introduce a mechanism that allows an application to opt-in to exposing certain information to other applications which are video-capturing it. This allows collaboration between capturing and captured applications. For example, a VC application that's video-capturing a tab where a presentation application lives, could expose user-facing controls in the VC tab for navigating the presentation in the captured tab.

Blink component


TAG review


TAG review status



Interoperability and Compatibility


Gecko: No official signal. Some resistance voiced over the argument that this makes getDisplayMedia "too attractive" and could hinder adoption of getViewportMedia. (There are no current plans to deprecate getDisplayMedia, and getViewportMedia is not even specified yet.)

WebKit: No official signal, but they contributed ideas to early revisions and seemed generally positive.

Web developers: We have a partner who's very interested. Additional developers will be approached soon.

Goals for experimentation

Evaluate usefulness of the feature and get early feedback from web-developers.

Reason this experiment is being extended


Ongoing technical constraints


Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

No, only only on desktop platforms.

Is this feature fully tested by web-platform-tests?


Flag name


Tracking bug

Launch bug

Link to entry on the Chrome Platform Status

Links to previous Intent discussions

Intent to prototype:

This intent message was generated by Chrome Platform Status.

Chris Harrelson

May 13, 2021, 5:15:57 PM5/13/21
to Elad Alon, blink-dev

This looks like a useful feature.

A request: could you convert the explainer to markdown and publish on github in a repo? This makes it a lot easier to get feedback and discuss improvements.

Second: Once you've done the above, I think an early-design TAG review makes sense to file at this point.

Third: please specify the desired milestones on which this experiment will run.

Fourth: is there a technical reason why the feature would not work on Android?

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Elad Alon

May 13, 2021, 5:38:10 PM5/13/21
to blink-dev, Chris Harrelson, blink-dev, Elad Alon

Thank you for the very quick feedback!

We are targeting OT for M92-M94. Because the M92 cut is very close, I am trying to concentrate my efforts on implementation. After that, I plan the following:
a. Present this in the 2021-05-25 W3C WebRTC WG meeting.
b. Either post a full proposal to this Github repo or create a WICG repo for it.
c. Apply for TAG review well ahead of intent-to-ship.
d. After a while, intent-to-ship.

getDisplayMedia is not currently fully supported on Android, so to reduce scope for the initial implementation, I am not targeting Android either. There's nothing preventing us from expanding scope later on.

I hope these answers are sufficient and experimentation can be approved? :-)


Chris Harrelson

May 13, 2021, 5:39:55 PM5/13/21
to Elad Alon, blink-dev
Got it, thanks for those replies. The plan of action sounds great to me.


May 14, 2021, 7:25:51 PM5/14/21
to blink-dev, Chris Harrelson, blink-dev, Elad Alon
Also, can you update the Chromestatus entry?

Elad Alon

May 15, 2021, 7:35:37 AM5/15/21
to blink-dev,, Chris Harrelson, blink-dev, Elad Alon
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