I don't think most of these things should live at the Transport Layer personally. I am certainly a fan of SCTP but SCTP hasn't yet received widespread middlebox adoption. Unfortunately, the state of IP Media is pretty terrible. SIP/RTP/RTMP are all very complicated and fiddly to get working. The WebRTC stack, which wraps some of these protocols up, is its own beast. XMPP media stacks tend to be IMO the "simplest" and even they are quite complicated.