> Even more: you do NOT remove the video stream, but just put it "inactive" or, even if it gets really removed from the SDP, re-adding it is fast since typically the video uses the same "UDP connection" (multiplexed with the audio track).

I don't want to send a re-INVITE for that.

> But forcing the remote to see a black video window seems really ugly IMHO. You don't have such a useless and confussing option in any existing VoIP software.

Well, are we copying all VoIP software now? No. FWIW, Skype has it, though I don't know if it's signaled or not and IIRC eyeBeam did have a mute thing for video.