The IESG has approved the Internet-Draft 'An RTP Payload Format for Generic Forward Error Correction' <draft-ietf-avt-fec-08.txt> as a Proposed Standard. This document is the product of the Audio/Video Transport Working Group. The IESG contact persons are Scott Bradner and Vern Paxson. Technical Summary The document provides a means of providing FEC for an RTP flow by XOR'ing together data packets to generate a separate FEC stream. The FEC format is generic in the sense that it works with arbitrary algorithms for deciding which data packets to combine and how many FEC packets to generate. There are two ways in which the FEC data may be transported: as a separate RTP flow, or by piggy-backing onto the original flow using the RFC2198 "redundant audio" payload format. Working Group Summary The FEC process was not controversial in AVT, and the draft includes appropriate warnings about misuse. The draft was held up in the working group for some time because it proved difficult to define SDP parameters to describe transport of FEC as a separate flow. A clean solution would require grouping the FEC flow with the original media flow, but SDP doesn't support grouping. The solution adopted in the draft is to include an SDP connection specification as a codec parameter, indicating where the FEC information for a flow is to be found. This is ugly, but the only workable solution the WG found. Protocol Quality The document was reviewed for the IESG by Vern Paxson.
