Update to Remove DVI4 from the Recommended Codecs for the RTP Profile

for Audio and Video Conferences with Minimal Control (RTP/AVP)

Abstract

The RTP Profile for Audio and Video Conferences with Minimal Control (RTP/AVP) is the basis for many other profiles, such as the Secure Real-time Transport Protocol (RTP/SAVP), the Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF), and the Extended Secure RTP Profile for RTCP-Based Feedback (RTP/SAVPF). This document updates RFC 3551, the RTP/AVP profile (and by extension, the profiles that build upon it), to reflect changes in audio codec usage since that document was originally published.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7007.

Copyright Notice

Copyright © 2013 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................2
   3. Updates to RFC 3551 .............................................3
      3.1. Updates to Section 6 of RFC 3551 ...........................3
   4. Security Considerations .........................................3
   5. Acknowledgments .................................................3
   6. References ......................................................4
      6.1. Normative References .......................................4
      6.2. Informative References .....................................4

1. Introduction

[RFC3551] says that audio applications operating under the RTP/AVP profile SHOULD be able to send and receive PCMU and DVI4. However, in practice, many RTP deployments do not support DVI4, and there is little reason to use it when much more modern codecs are available. This document updates the recommended audio codec selection for the RTP/AVP profile and removes the SHOULD for DVI4. By extension, this also updates the profiles that build on RTP/AVP, including RTP/SAVP [RFC3711], RTP/AVPF [RFC4585], and RTP/SAVPF [RFC5124].

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

3. Updates to RFC 3551

The following text of [RFC3551] is hereby updated as set forth in Section 3.1:

Audio applications operating under this profile SHOULD, at a minimum, be able to send and/or receive payload types 0 (PCMU) and 5 (DVI4). This allows interoperability without format negotiation and ensures successful negotiation with a conference control protocol.

3.1. Updates to Section 6 of RFC 3551

This document updates the final paragraph of Section 6 of RFC 3551 by replacing "payload types 0 (PCMU) and 5 (DVI4)" with "payload type 0 (PCMU)". We also add a final sentence to that paragraph that states, "Some environments necessitate support for PCMU". This results in the following paragraph:

Audio applications operating under this profile SHOULD, at a minimum, be able to send and/or receive payload type 0 (PCMU). This allows interoperability without format negotiation and ensures successful negotiation with a conference control protocol. Some environments necessitate support for PCMU.

4. Security Considerations

This document does not introduce any new security considerations for [RFC3551].

5. Acknowledgments

Thanks to Colin Perkins for suggesting this update.

6. References

6.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
   
   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", STD 65, RFC 3551,
              July 2003.

6.2. Informative References

   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol (SRTP)",
              RFC 3711, March 2004.
   
   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
              "Extended RTP Profile for Real-time Transport Control
              Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July
              2006.
   
   [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for
              Real-time Transport Control Protocol (RTCP)-Based Feedback
              (RTP/SAVPF)", RFC 5124, February 2008.

Author's Address

   Timothy B. Terriberry
   Mozilla Corporation
   650 Castro Street
   Mountain View, CA  94041
   USA
   
   Phone: +1 650 903-0800
   EMail: tterribe@xiph.org