RFC 3389 (rfc3389) - Page 1 of 8

Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN)

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Network Working Group                                            R. Zopf
Request for Comments: 3389                           Lucent Technologies
Category: Standards Track                                 September 2002


   Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN)

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) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes a Real-time Transport Protocol (RTP) payload
   format for transporting comfort noise (CN).  The CN payload type is
   primarily for use with audio codecs that do not support comfort noise
   as part of the codec itself such as ITU-T Recommendations G.711,
   G.726, G.727, G.728, and G.722.

1. Conventions Used in This Document

   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 RFC-2119 [7].

2. Introduction

   This document describes a RTP [1] payload format for transporting
   comfort noise.  The payload format is based on Appendix II of ITU-T
   Recommendation G.711 [8] which defines a comfort noise payload format
   (or bit-stream) for ITU-T G.711 [2] use in packet-based multimedia
   communication systems.  The payload format is generic and may also be
   used with other audio codecs without built-in Discontinuous
   Transmission (DTX) capability such as ITU-T Recommendations G.726
   [3], G.727 [4], G.728 [5], and G.722 [6].  The payload format
   provides a minimum interoperability specification for communication
   of comfort noise parameters.  The comfort noise analysis and
   synthesis as well as the Voice Activity Detection (VAD) and DTX
   algorithms are unspecified and left implementation-specific.




Zopf                        Standards Track
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