Real-time Media, RTP, and QUIC
Jörg Ott gave a short presentation in the AVTCORE working group at the IETF 103 meeting in Bangkok, previewing some work we've been doing on real-time media delivery using the QUIC transport protocol, and how this relates to RTP-based media transport.
Jörg noted that there has been quite a bit of ad-hoc engineering around running real-time traffic over QUIC. Some has focussed on how to run DASH-style streaming applications over HTTP/3 (i.e., HTTP over QUIC), while other work has considered running WebRTC media traffic over QUIC. Our interest is primarily in this latter aspect, and in particular how to effectively run interactive real-time applications over a QUIC-based transport. We've reviewed the limitations of prior approaches, and taken a step back to analyse how QUIC and RTP could co-evolve to better match the needs of such applications. Jörg briefly outlined the key features of our resulting RT-streams proposal, adding ADU sequence numbers, media-specific timestamps, and partial reliability to QUIC, as a preview of a paper we will present in the ACM CoNEXT workshop on Evolution, Performance, and Interoperability of QUIC (EPIQ) in December 2018.
Following this, we participated in a side meeting organised by Tommy Pauly from Apple, considering the relation between his draft adding UDP-style datagram support to QUIC, our work on RT-streams, and the various other proposals for adding datagrams and real-time features to QUIC. There was some good discussion of the various design issues, considering what features are critical, what can feasibly be added to QUIC later, and what's politically feasible to add in the near-term while the first version of the IETF QUIC standard is being finalised. The intent is that a revised version of Tommy's draft will be submitted in the next few weeks, reflecting this discussion.