Bugzilla

A few things:
1. setParameters is async; you will not see any modifications you have made if you call getParameters immediately afterward.
2. RTCRtpEncodingParameters.active does not have any implications for SDP. The simulcast pause syntax (a '~' in front of the rid) is not used in the webrtc standard, and almost certainly never will be. RTCRtpEncodingParameters.active only effects what the RTP engine is doing under the hood.
3. RTCRtpEncodingParameters.active was only ever intended for simulcast, so we did not implement for audio. It might be worth doing.

With these things in mind, can you verify whether setting active is having the expected effect?

A few things:
1. setParameters is async; you will not see any modifications you have made if you call getParameters immediately afterward.
2. RTCRtpEncodingParameters.active does not have any effect on SDP. The simulcast pause syntax (a '~' in front of the rid) is not used in the webrtc standard, and almost certainly never will be. RTCRtpEncodingParameters.active only effects what the RTP engine is doing under the hood.
3. RTCRtpEncodingParameters.active was only ever intended for simulcast, so we did not implement for audio. It might be worth doing.

With these things in mind, can you verify whether setting active is having the expected effect?