Some sites are calling setParameters with an empty encodings array (for audio, at least), and other browsers are (incorrectly) allowing it. We should let this slide in setParameters compat mode. We'll also want to add some telemetry for this in a follow-up.

FWIW, we have telemetry for this failure that has not pinged once, so maybe not a big problem? It is weird that we did not get a ping from this:

https://mediasoup.discourse.group/t/no-mic-on-mediasoup-2-and-latest-firefox/4933

other browsers are (incorrectly) allowing it

Other browsers and Firefox release, so marking this a regression.

For other vendors pointed here:

Even audio transceivers have a single encoding to allow for modifications like params.encodings[0].maxBitrate = bps, so changing the length from 1 to 0 is InvalidModificationError according to spec:

• "Let N be the number of RTCRtpEncodingParameters stored in sender.[[SendEncodings]]. ... If any of the following conditions are met, return a promise rejected with a newly created InvalidModificationError: 1. encodings.length is different from N. "

Also add some wpt for this (invalid) case.

https://treeherder.mozilla.org/jobs?repo=try&revision=d0da63c7d35f3fdd2b8f6188ef7637c2c8bda987
https://treeherder.mozilla.org/jobs?repo=try&revision=ba6bff7dbb8002fb992ff392a82a069ff8db095b

So this not throwing in Chrome is an artifact of https://crbug.com/1372603
But the real issue is we broke web compat with Firefox release

In Firefox release 109 https://jsfiddle.net/jib1/1mspnv42/9/ emits (before and after the affected setParameters call):

sender.getParameters() = {}
sender.getParameters() = {
  "encodings": []
}

...whereas in 110 it's InvalidModificationError: Cannot set an empty encodings array

My guess would be this isn't affecting a lot of services.

https://treeherder.mozilla.org/jobs?repo=try&revision=7899719fec791239a391dff2c2a0f6e2c0b7b9be
https://treeherder.mozilla.org/jobs?repo=try&revision=68e258a1cc9d1370baf4e09fe4774b79eaca24da

Try looks fine.

Comment on attachment 9317123 [details]
Bug 1816160: Warn (and no-op) on setParameters with empty encodings if the compat mode is enabled. r?jib

Beta/Release Uplift Approval Request

• User impact if declined: Potential breakage in web teleconferencing.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This is a very small change that lets an uncommon error slide.
• String changes made/needed: None.
• Is Android affected?: Yes

https://hg.mozilla.org/mozilla-central/rev/54bd793585af

Comment on attachment 9317123 [details]
Bug 1816160: Warn (and no-op) on setParameters with empty encodings if the compat mode is enabled. r?jib

Fx110 is already in RC, switching to release uplift request

This bug has the keyword regression, so its type should be defect.

Comment on attachment 9317123 [details]
Bug 1816160: Warn (and no-op) on setParameters with empty encodings if the compat mode is enabled. r?jib

Low risk, baked on beta with no regression reported, improves webcompat, uplift approved for 110.0.1, thanks.

https://hg.mozilla.org/releases/mozilla-release/rev/2fc03a401b55