Intent to Ship: Timestamps for RTC Encoded Frames

[Chromestatus]

Contact emails

gui...@chromium.org

Explainer

https://github.com/guidou/webrtc-encoded-transform/blob/master/timestamps.md

Specification

https://w3c.github.io/webrtc-encoded-transform/#dom-rtcencodedaudioframemetadata-receivetime

Summary

This feature consists in exposing to the Web some timestamps that are present in WebRTC encoded frames transmitted via RTCPeerConnection. The timestamps in question are: -Capture timestamp: the timestamp when a frame was originally captured -Receive timestamp: the timestamp when a frame was received

Blink component

Blink>WebRTC

TAG review

https://github.com/w3ctag/design-reviews/issues/1049

TAG review status

Pending

Risks

Interoperability and Compatibility

Interoperability risk: The main risk is that other browser do not implement this change. However, this change has the support of other major browsers and it is small enough that it should not be difficult to support. Compatibility risk: No compatibility risk as the change is strictly additive.

Gecko: Positive (https://github.com/w3c/webrtc-encoded-transform/pull/240) No position requested at https://github.com/mozilla/standards-positions since this is a minor addition to an existing spec. Linked to PRs instead (merged into spec or "editors can integrate").

WebKit: Positive (https://github.com/w3c/webrtc-encoded-transform/pull/237) No position requested at https://github.com/WebKit/standards-positions/ since this is a minor addition to an existing spec. Linked to PRs instead (merged into spec or "editors can integrate").

Web developers: Positive (https://github.com/w3c/webrtc-encoded-transform/issues/225)

Other signals:

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?

N/A

Debuggability

None

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes

https://wpt.fyi/results/webrtc-encoded-transform/tentative/RTCEncodedFrame-timestamps.html?label=experimental&label=master&aligned

Flag name on about://flags

None

Finch feature name

None

Non-finch justification

None

Requires code in //chrome?

False

Tracking bug

https://crbug.com/391114797

Availability expectation

Feature is available in Chromium in the short term, and eventually available in other browsers.

Adoption expectation

Feature is used by multiple partners to provide functionality within 12 months of launch in Chrome.

Non-OSS dependencies

Does the feature depend on any code or APIs outside the Chromium open source repository and its open-source dependencies to function?

N/A

Estimated milestones

Shipping on desktop	135
Shipping on Android	135
Shipping on WebView	135

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

None

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/6294486420029440?gate=5205778715377664

This intent message was generated by Chrome Platform Status.

[Chris Harrelson]

On Tue, Feb 25, 2025 at 5:28 AM Chromestatus <ad...@cr-status.appspotmail.com> wrote:

Contact emails

gui...@chromium.org

Explainer

https://github.com/guidou/webrtc-encoded-transform/blob/master/timestamps.md

Specification

https://w3c.github.io/webrtc-encoded-transform/#dom-rtcencodedaudioframemetadata-receivetime

Summary

This feature consists in exposing to the Web some timestamps that are present in WebRTC encoded frames transmitted via RTCPeerConnection. The timestamps in question are: -Capture timestamp: the timestamp when a frame was originally captured -Receive timestamp: the timestamp when a frame was received

I see receive timestamp in the spec, but not capture timestamp?

 

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[Guido Urdaneta]

The capture timestamp is in an "Editors can integrate" PR, and is expected to be merged into the spec tomorrow.

[Guido Urdaneta]

The capture timestamp is now merged in the spec.

https://w3c.github.io/webrtc-encoded-transform/#dom-rtcencodedvideoframemetadata-capturetime

https://w3c.github.io/webrtc-encoded-transform/#dom-rtcencodedaudioframemetadata-capturetime

[Chris Harrelson]

Thanks!

LGTM1

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CA%2BBuZxYeHYT7dbXzxWARu9ZGMfwhBxUc74BMDM2JSm6r%2BeLBaw%40mail.gmail.com.

[Mike Taylor]

LGTM2

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw_A7-gi7_V8ZtEQr%2Bj-zuRjpgSsXDejnmMZzEP6MCW0OQ%40mail.gmail.com.

[Domenic Denicola]

LGTM3

Thanks!

LGTM1

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