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.

Motivation

Display-capturing applications can offer the user improved functionality if they know what they are capturing, assuming the captured application collaborates. This is already possible using steganography. We offer a simpler, more reliable and more secure mechanism, by which an application may advertise select information - origin, handle, ID, etc. Additionally, the mechanism we propose allows the captured application to select the audience - the entire web or select origins. Finally, our mechanism offers some confidence in the capturer that certain parts of the message, if included, are not spoofed: 1. Only the top-level application can set the capture-handle, whereas steganography-based methods are exposed to messages being displayed by embedded content. 2. The browser provides the origin of the captured application (if it opts-in to exposing it).

Demos

Specification

Specification link


Specification being incubated in a Community Group

Status in Chromium

Blink>GetUserMedia>Tab


No active development (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

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Owner

Intent to Prototype url

Intent to Prototype thread

Last updated on 2021-08-23