Aalto University Cisco Systems Cisco This document defines new RTP payload formats for the Forward Error Correction (FEC) packets that are generated by the non-interleaved and interleaved parity codes from a source media encapsulated in RTP. These parity codes are systematic codes, where a number of repair symbols are generated from a set of source symbols. These repair symbols are sent in a repair flow separate from the source flow that carries the source symbols. The non-interleaved and interleaved parity codes offer a good protection against random and bursty packet losses, respectively, at a cost of decent complexity. The RTP payload formats that are defined in this document address the scalability issues experienced with the earlier specifications including RFC 2733, RFC 5109 and SMPTE 2022-1, and offer several improvements. Due to these changes, the new payload formats are not backward compatible with the earlier specifications, but endpoints that do not implement the scheme can still work by simply ignoring the FEC packets.