14 July 2019
I've recently updated
our draft on RTP Congestion Control Feedback to address
feedback based on implementation experience from the hackathon
at IETF 104, held in Prague earlier this year.
The updates were minor this time, comprising a series of clarifications
around signalling, what packets should be included in congestion
feedback reports, and on the implications of congestion feedback for
retransmission. None of these changes the packet format or signalling,
but should hopefully improve interoperability by addressing common
The only remaining open issue is to add some discussion on how this
format relates to the proprietary congestion control feedback used by
Google Chrome, in particular on the costs and benefits of using
per-flow feedback rather than adding a single congestion control
sequence number as a header extension in RTP packets.
I'll give talks about these changes in the AVTCORE and RMCAT working
group meetings at IETF 105 in Montreal next week. My hope is that the
draft will be ready for working group last call soon thereafter.