Internet Engineering Task Force (IETF)                     T. Terriberry
Request for Comments: 7007                           Mozilla Corporation
Updates: 3551                                                August 2013
Category: Standards Track
ISSN: 2070-1721

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

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

   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