video track "black" vs. "frozen frame"

We talked about this in Lisbon,

and I recall us saying something like, in a situation where we have a

MST -> RtpSender -> RtpReceiver -> MST -> <video element>

(MST == MediaStreamTrack) setup, that the video element should:

* Render black if the send side MST was disabled (or muted upstream)
* Render a frozen video frame if the RtpSender was "stopped"

Is this correct?

And if so, my question is: How to stop the sender? There is no .stop() 
method. The RtpTransceiver has a .stop() method, but that would also 
stop the local RtpReceiver, which may not be desirable, and would not 
have any action until after a negotiation.

Bernard mentions [1] "active=false", but it is a long time since we had 
"active" on RtpSenders. It seems like that would be a good fit though.


[1] https://www.w3.org/2016/09/23-webrtc-minutes#item09

Stefan