How to know if a given track or media stream is being transmitted

Hi,

I wonder if the following scenarios are considered in the WebRTC API.

Alice and Bob have a peerConnection each. Both have a mediaStream loaded in
their peerConnection. The mediaStream in Alice's peerConnection has one
audio track and zero video tracks, Bob's has one audio and one video track.

Alice sends a SDP offer to Bob. She wants to establish an audio media
session. Bob receives the offer and answers Alice. Both SDPs have an audio
only media description.

After a while Bob decides to share his video with Alice. He looks at his
peerConnection and he notices he actually has a video track, but he doesn't
know whether he is already sending that video to Alice or not.

How does Bob know if he is sending his video to Alice by looking at his
peerConnection?

Another scenario is the one where Carol offers Alice a SDP offer containing
audio and video media description and Alice only accepts the audio, she is
not willing to receive any video from Carol.

How does Carol know she is not sharing her video?

Same for entire mediaStreams in a peerConnection.

I can't figure out how to achieve it. Have this been considered?

Regards,

-- 
José Luis Millán