These are encapsulation and signaling protocols, but don't really cover the questions of when to send each compressed video frame, how big it should be on the wire, and how to write an encoder that can compress it to hit that target size accurately. Some of the schemes we compared against (WebRTC reference implementation in Chrome, Hangouts, FaceTime, Skype) certainly use various parts of the standard protocol suite (with different engines to decide when and how much to send). But the call setup and encapsulation are not the focus here -- I'm sure we could do Salsify within SIP or WebRTC if necessary.