RFC 4585 - Extended RTP Profile for RTCP-Based Feedback (RTP/AVPF)

Authors: J. Ott, S. Wenger, N. Sato, C. Burmeister, J. Rey
Category: Standards Track
Published: July 2006

Status of This Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2006).

Abstract

Real-time media streams that use RTP are, to some degree, resilient against packet losses. Receivers may use the base mechanisms of the Real-time Transport Control Protocol (RTCP) to report packet reception statistics and thus allow a sender to adapt its transmission behavior in the mid-term. This is the sole means for feedback and feedback-based error repair (besides a few codec-specific mechanisms). This document defines an extension to the Audio-visual Profile (AVP) that enables receivers to provide, statistically, more immediate feedback to the senders and thus allows for short-term adaptation and efficient feedback-based repair mechanisms to be implemented. This early feedback profile (AVPF) maintains the AVP bandwidth constraints for RTCP and preserves scalability to large groups.

Contents

• 1. Introduction
  • 1.1. Definitions
  • 1.2. Terminology
• 2. RTP and RTCP Packet Formats and Protocol Behavior
  • 2.1. RTP
  • 2.2. Underlying Transport Protocols
• 3. Rules for RTCP Feedback
  • 3.1. Compound RTCP Feedback Packets
  • 3.2. Algorithm Outline
  • 3.3. Modes of Operation
  • 3.4. Definitions and Algorithm Overview
  • 3.5. AVPF RTCP Scheduling Algorithm
  • 3.6. Considerations on the Group Size
  • 3.7. Summary of Decision Steps
• 4. SDP Definitions
• 5. Interworking and Coexistence of AVP and AVPF Entities
• 6. Format of RTCP Feedback Messages
• 7. Early Feedback and Congestion Control
• 8. Security Considerations
• 9. IANA Considerations
• 10. Acknowledgements
• 11. References
• Authors' Addresses

See Also

RFC source: https://www.rfc-editor.org/info/rfc4585