Browse Prior Art Database

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...