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Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN) (RFC3389)

IP.com Disclosure Number: IPCOM000009937D
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2002-Oct-01
Document File: 9 page(s) / 17K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Zopf: AUTHOR

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.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 17% of the total text.

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                     [Page 1]

RFC 3389             RTP Payload for Comfort Noise        September 2002

   However, an example solution for G.711 has been tested and is

   described in the Appendix [8].  It uses the VAD and DTX of G.729

   Annex B [9] and a comfort noise generation algorithm (CNG) which is

   provided in the Appendix for information.

   The comfort noise payload, which is also known as a Silence Insertion

   Descriptor (SID) frame, consists of a single octet description of the

   noise level and MAY contain spectral information in subsequent

   octets.  An earlier version of the CN payl...