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

• https://w3c.github.io/mediacapture-handle/identity/demos/remote_control/capturer.html
• https://w3c.github.io/mediacapture-handle//identity/demos/self_capture_detection/index.html

Specification

Specification link

Status: Specification currently under development in a Working Group

Status in Chromium

Blink components: A-N/A

Implementation status: Enabled by default (tracking bug)

Consensus & Standardization

• Firefox: No signal
• Safari: No signal
• Web Developers: Strongly positive

Owner

• eladalon@chromium.org

Intent to Prototype url

Last updated on 2022-05-12