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Internet Engineering Task Force (IETF)                     T. TerriberryRequest for Comments: 7007                           Mozilla CorporationUpdates:3551                                                August 2013Category: Standards TrackISSN: 2070-1721Update to Remove DVI4 from the Recommended Codecs for the RTP Profilefor 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 updatesRFC 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 inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7007.Terriberry                   Standards Track                    [Page 1]

RFC 7007                     RTP/AVP Codecs                  August 2013Copyright Notice   Copyright (c) 2013 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents1. Introduction ....................................................22. Terminology .....................................................23. Updates toRFC 3551 .............................................33.1. Updates toSection 6 of RFC 3551 ...........................34. Security Considerations .........................................35. Acknowledgments .................................................36. References ......................................................46.1. Normative References .......................................46.2. Informative References .....................................41.  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].Terriberry                   Standards Track                    [Page 2]

RFC 7007                     RTP/AVP Codecs                  August 20133.  Updates toRFC 3551   The following text of [RFC3551] is hereby updated as set forth inSection 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 toSection 6 of RFC 3551   This document updates the final paragraph ofSection 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.Terriberry                   Standards Track                    [Page 3]

RFC 7007                     RTP/AVP Codecs                  August 20136.  References6.1.  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.orgTerriberry                   Standards Track                    [Page 4]