Intent to Experiment: WebRTC encoded transform - Modify Metadata functions
Guido Urdaneta
Contact emails
h...@chromium.org, agp...@chromium.org, top...@chromium.org, gui...@chromium.org
Explainer
Specification
Design docs
Summary
Add features to the WebRTC Encoded Transform API that allow manipulating audio and video frame metadata Background: A number of use cases have been identified that require the manipulation of WebRTC encoded media without decoding them first. These include: - Sending data that has been encoded previously - Sending data that has been received in encoded form - Receiving data in encoded form and forwarding it.
In particular, we want to support the use case of glitch-free forwarding of media coming from multiple redundant peer connections that provide the same media payloads but with different metadata.
https://github.com/w3c/webrtc-nv-use-cases/issues/77
https://github.com/w3c/webrtc-nv-use-cases/issues/122
Blink component
TAG review
The original full spec was reviewed by TAG here: https://github.com/w3ctag/design-reviews/issues/531
No TAG review has been requested for this incremental change, since it is a small addition and its API surface might change as a result of feedback from the origin trial and ongoing discussions in the WebRTC working group.
TAG review status
Pending
Chromium Trial Name
RTCEncodedFrameSetMetadata
WebFeature UseCounter name
V8RTCEncodedVideoFrame_SetMetadata_Method
Risks
Interoperability and Compatibility
Interoperability risk: There is the risk that other browsers will not implement this feature. We try to mitigate this risk by providing a detailed specification of the new behavior and discussing it in the WebRTC working group, so that it becomes part of the encoded transform spec, which currently has consensus. Compatibility test: This is a new feature intended to support a new use case. It introduces no breaking changes, so we do not expect any compatibility issues.
Gecko: No signal
WebKit: No signal
Web developers: No signals.
Other signals:
Ergonomics
This feature is an extension to WebRTC Encoded Transform, which itself is an extension to WebRTC/RTCPeerConnection.
Activation
N/A
Security
No new security risks identified.
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
No
Goals for experimentation
Our goal is to validate that the proposed API can support the intended use case. More specifically, we want to confirm using setMetadata() can help achieve glitch-free forwarding of media using redundant input peer connections in real-world settings.
Ongoing technical constraints
None
Debuggability
N/A
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
Yes
Is this feature fully tested by web-platform-tests?
No. Currently tested using unit and web tests. WPTs will be added once the final API shape is confirmed.
Flag name on chrome://flags
N/A
Finch feature name
N/A
Non-finch justification
Currently guarded by a Blink RuntimeEnabledFeature: RTCEncodedFrameSetMetadata.
Requires code in //chrome?
No
Tracking bug
Estimated milestones
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5116073827893248
Links to previous Intent discussions
Intent to prototype: https://groups.google.com/a/chromium.org/g/blink-dev/c/x2ZACgXrqp0
Mike Taylor
LGTM to experiment from 118 to 123 inclusive.
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