RTP Payload Format for the Enhanced Variable Rate Narrowband-Wideband Codec (EVRC-NW)
RFC 6884

Internet Engineering Task Force (IETF)                           Z. Fang
Request for Comments: 6884                         Qualcomm Incorporated
Category: Standards Track                                     March 2013
ISSN: 2070-1721

                           RTP Payload Format
   for the Enhanced Variable Rate Narrowband-Wideband Codec (EVRC-NW)

Abstract

   This document specifies Real-time Transport Protocol (RTP) payload
   formats to be used for the Enhanced Variable Rate Narrowband-Wideband
   Codec (EVRC-NW).  Three media type registrations are included for
   EVRC-NW RTP payload formats.  In addition, a file format is specified
   for transport of EVRC-NW speech data in storage mode applications
   such as email.

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/rfc6884.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Fang                         Standards Track                    [Page 1]
RFC 6884               EVRC-NW RTP Payload Format             March 2013

Table of Contents

   1. Introduction ....................................................2
   2. Conventions .....................................................2
   3. Background ......................................................3
   4. EVRC-NW Codec ...................................................3
   5. RTP Header Usage ................................................4
   6. Payload Format ..................................................4
      6.1. Encoding Capability Identification in EVRC-NW
           Interleaved/Bundled Format .................................5
   7. Congestion Control Considerations ...............................6
   8. Storage Format for the EVRC-NW Codec ............................6
   9. IANA Considerations .............................................7
      9.1. Media Type Registrations ...................................7
           9.1.1. Registration of Media Type audio/EVRCNW .............7
           9.1.2. Registration of Media Type audio/EVRCNW0 ............9
           9.1.3. Registration of Media Type audio/EVRCNW1 ...........10
   10. SDP Mode Attributes for EVRC-NW ...............................12
   11. Mode Change Request/Response Considerations ...................13
   12. Mapping EVRC-NW Media Type Parameters into SDP ................14
   13. Offer-Answer Model Considerations for EVRC-NW .................14
   14. Declarative SDP Considerations ................................16
   15. Examples ......................................................16
   16. Security Considerations .......................................19
   17. References ....................................................19
      17.1. Normative References .....................................19
      17.2. Informative References ...................................20

1.  Introduction

   This document specifies the payload formats for packetization of
   EVRC-NW encoded speech signals into the Real-time Transport Protocol
   (RTP).  It defines support for the header-free, interleaved/bundled,
   and compact bundle packet formats for the EVRC-NW codec as well as
   discontinuous transmission (DTX) support for EVRC-NW encoded speech
   transported via RTP.  The EVRC-NW codec offers better speech quality
   than the EVRC and EVRC-B codecs and better capacity than the Enhanced
   Variable Rate Wideband Codec (EVRC-WB).  EVRC-NW belongs to the EVRC
   family of codecs.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this