Intent to Experiment: Capture handle

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Elad Alon

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May 12, 2021, 6:04:45 AMMay 12
to blink-dev

Contact emails

elad...@chromium.org

Explainer

https://docs.google.com/document/d/1oSDmBPYVlxFJxb7ZB_rV6yaAaYIBFDphbkx5bXLnzFg/edit?usp=sharing

Specification

To be published later, but the explainer currently contains all necessary details.

Summary

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

Blink>GetDisplayMedia

TAG review

None

TAG review status

Pending

Risks

Interoperability and Compatibility

None


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

None



Ongoing technical constraints

None



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?

No

Flag name

CaptureHandle

Tracking bug

https://bugs.chromium.org/p/chromium/issues/detail?id=1200910

Launch bug

https://bugs.chromium.org/p/chromium/issues/detail?id=1200907

Link to entry on the Chrome Platform Status

https://www.chromestatus.com/feature/4854125411958784

Links to previous Intent discussions

Intent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/yLTykllpNmI


This intent message was generated by Chrome Platform Status.

Chris Harrelson

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May 13, 2021, 5:15:57 PMMay 13
to Elad Alon, blink-dev
Hi,

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

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May 13, 2021, 5:38:10 PMMay 13
to blink-dev, Chris Harrelson, blink-dev, Elad Alon
Hi,

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? :-)

Thanks,
Elad

Chris Harrelson

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

LGTM!

cwi...@google.com

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

Elad Alon

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May 15, 2021, 7:35:37 AMMay 15
to blink-dev, cwi...@google.com, Chris Harrelson, blink-dev, Elad Alon
Updated.
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