RTP Payload Format for mU-law EMbedded Codec for Low-delay IP Communication (UEMCLIP) Speech Codec
RFC 5686

 
Document Type RFC - Proposed Standard (October 2009; No errata)
Last updated 2013-03-02
Replaces draft-hiwasaki-avt-rtp-uemclip
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IESG IESG state RFC 5686 (Proposed Standard)
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Responsible AD Cullen Jennings
Send notices to avt-chairs@ietf.org, draft-ietf-avt-rtp-uemclip@ietf.org, ron.even.tlv@gmail.com
Network Working Group                                        Y. Hiwasaki
Request for Comments: 5686                                     H. Ohmuro
Category: Standards Track                                NTT Corporation
                                                            October 2009

     RTP Payload Format for mU-law EMbedded Codec for Low-delay IP
                  Communication (UEMCLIP) Speech Codec

Abstract

   This document describes the RTP payload format of a mU-law EMbedded
   Coder for Low-delay IP communication (UEMCLIP), an enhanced speech
   codec of ITU-T G.711.  The bitstream has a scalable structure with an
   embedded u-law bitstream, also known as PCMU, thus providing a handy
   transcoding operation between narrowband and wideband speech.

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) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
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   outside the IETF Standards Process, and derivative works of it may

Hiwasaki & Ohmuro           Standards Track                     [Page 1]
RFC 5686             RTP Payload Format for UEMCLIP         October 2009

   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................3
   2. Media Format Background .........................................3
   3. Payload Format ..................................................5
      3.1. RTP Header Usage ...........................................6
      3.2. Multiple Frames in an RTP Packet ...........................6
      3.3. Payload Data ...............................................7
           3.3.1. Main Header .........................................7
           3.3.2. Sub-Layer ..........................................10
   4. Transcoding between UEMCLIP and G.711 ..........................11
   5. Congestion Control Considerations ..............................12
   6. Payload Format Parameters ......................................13
      6.1. Media Type Registration ...................................13
      6.2. Mapping to SDP Parameters .................................14
           6.2.1. Mode Specification .................................15
      6.3. Offer-Answer Model Considerations .........................16
           6.3.1. Offer-Answer Guidelines ............................16
           6.3.2. Examples ...........................................17
   7. Security Considerations ........................................19
   8. IANA Considerations ............................................19
   9. References .....................................................19
      9.1. Normative References ......................................19
      9.2. Informative References ....................................20

1.  Introduction

   This document specifies the payload format for sending UEMCLIP-
   encoded (mU-law EMbedded Coder for Low-delay IP communication) speech
   using the Real-time Transport Protocol (RTP) [RFC3550].  UEMCLIP is a
   proprietary codec that enhances u-law ITU-T G.711 [ITU-T-G.711] and
   that is designed to help the market for smooth transition towards the
   forthcoming wideband communication environment while achieving a very
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