[mediacapture-screen-share] Add ability to crop a MediaStream obtained through the share-this-tab API (#158)

eladalon1983 has just created a new issue for https://github.com/w3c/mediacapture-screen-share:

== Add ability to crop a MediaStream obtained through the share-this-tab API ==
Assume a MediaStream is obtained through the [share-this-tab API](https://github.com/w3c/mediacapture-screen-share/pull/148) (which is still under discussion). The application in question might wish to crop the video before sharing it remote; for example remove a portion of the viewport where it displays private information. One possible use case is an application like Google Slides streaming itself to a Google Meet session, after cropping away speaker notes.

However, user-browser interaction such as window-resizing, scrolling or zooming, can move DOM elements in the viewport. This happens asynchronously from the JS event loop. An application holding a frame, does not know whether said frame was captured before or after a resize/scroll/zoom event, and therefore **cannot crop robustly**.

Some non-solutions were briefly explored in [January's WG Slides](https://docs.google.com/presentation/d/1crumgYj4eHkjo04faLktPTg0QoYJhTFoosEBudfJBuw/edit#slide=id.g7954c29f8a_2_0), leading to the conclusion that an API addition/modification is necessary in order to support cropping functionality. An initial draft of a solution was presented in the slides. We did not finish the discussion during the meeting. I suggest we continue it here.

Please view or discuss this issue at https://github.com/w3c/mediacapture-screen-share/issues/158 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Tuesday, 19 January 2021 21:31:34 UTC