Closed Bug 1676855 Opened 3 years ago Closed 6 months ago



(Core :: WebRTC: Signaling, enhancement, P2)




110 Branch
Tracking Status
firefox110 --- fixed


(Reporter: jib, Assigned: bwc)



(Keywords: dev-doc-complete)


(1 file)

Being able to use active to turn on/off specific simulcast layers has been an oft requested feature from application developers, is in the spec and is supported in Chrome.


  • set maxBitrate: 1 (use at least 1 since 0 appears to be ignored)
  • and scaleResolutionDownBy: 240 for good measure (seems needed in single-layer case at least).

The downside of the workaround is it still signals the SFU that the browser tries to send data on that layer. 😕

Lack of support complicates web compat in the already complicated area of simulcast.

Lack of support complicates web compat in the already complicated area of simulcast.

Note the web compat table says Firefox supports active but this is incorrect (likely an artifact of us implementing the WebIDL but not the underlying code for it).

Its also supported (and working as expected) in safari starting with r73 (January 2019)

Priority: P4 → P2

Just chiming in here to mention that Jitsi is waiting this feature. Without it Firefox sends all simulcast streams all the time and wastes upstream bandwidth, e.g. the sender only appears in a small preview video at all receivers. So with this API Jitsi could then temporarily turn off the high and medium resolution could be marked inactive to save the send bandwidth.

Adding a note to implementer to double-check we don't send RTCP BYE when implementing this, since this appears to be an issue upstream still.

Depends on: 1704947

Depends on D156836

Assignee: nobody → docfaraday
Attachment #9293709 - Attachment description: WIP: Bug 1676855: Support → Bug 1676855: Support r?jib,mjf
Severity: normal → S3
No longer depends on: 1704947
Pushed by
Support r=jib,mjf
Created web-platform-tests PR for changes under testing/web-platform/tests
Pushed by
Support r=jib,mjf
Closed: 6 months ago
Resolution: --- → FIXED
Target Milestone: --- → 110 Branch
Upstream PR merged by moz-wptsync-bot
Regressions: 1807193
No longer regressions: 1807193

Tracking issue for MDN work

Regressions: 1812293
No longer regressions: 1812293
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