RTP Payload Format for the G.729.1 Audio Codec
RFC 4749
Document | Type |
RFC - Proposed Standard
(October 2006; No errata)
Updated by RFC 5459
|
|
---|---|---|---|
Author | Aurelien Sollaud | ||
Last updated | 2015-10-14 | ||
Replaces | draft-sollaud-avt-rtp-g729-scal-wb-ext | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4749 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Cullen Jennings | ||
Send notices to | (None) |
Network Working Group A. Sollaud Request for Comments: 4749 France Telecom Category: Standards Track October 2006 RTP Payload Format for the G.729.1 Audio Codec 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 (2006). Abstract This document specifies a Real-time Transport Protocol (RTP) payload format to be used for the International Telecommunication Union (ITU-T) G.729.1 audio codec. A media type registration is included for this payload format. Table of Contents 1. Introduction ....................................................2 2. Background ......................................................2 3. Embedded Bit Rates Considerations ...............................3 4. RTP Header Usage ................................................3 5. Payload Format ..................................................4 5.1. Payload Structure ..........................................4 5.2. Payload Header: MBS Field ..................................4 5.3. Payload Header: FT Field ...................................6 5.4. Audio Data .................................................6 6. Payload Format Parameters .......................................7 6.1. Media Type Registration ....................................7 6.2. Mapping to SDP Parameters ..................................8 6.2.1. Offer-Answer Model Considerations ...................9 6.2.2. Declarative SDP Considerations .....................11 7. Congestion Control .............................................11 8. Security Considerations ........................................11 9. IANA Considerations ............................................12 10. References ....................................................12 10.1. Normative References .....................................12 10.2. Informative References ...................................12 Sollaud Standards Track [Page 1] RFC 4749 RTP Payload Format for G.729.1 October 2006 1. Introduction The International Telecommunication Union (ITU-T) recommendation G.729.1 [1] is a scalable and wideband extension of the recommendation G.729 [9] audio codec. This document specifies the payload format for packetization of G.729.1 encoded audio signals into the Real-time Transport Protocol (RTP). The payload format itself is described in Section 5. A media type registration and the details for the use of G.729.1 with SDP are given in Section 6. 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 [2]. 2. Background G.729.1 is an 8-32 kbps scalable wideband (50-7000 Hz) speech and audio coding algorithm interoperable with G.729, G.729 Annex A, and G.729 Annex B. It provides a standardized solution for packetized voice applications that allows a smooth transition from narrowband to wideband telephony. The most important services addressed are IP telephony and videoconferencing, either for enterprise corporate networks or for mass market (like Public Switched Telephone Network (PSTN) emulation over DSL or wireless access). Target devices can be IP phones or other VoIP handsets, home gateways, media gateways, IP Private Branch Exchange (IPBX), trunking equipment, voice messaging servers, etc. For all those applications, the scalability feature allows tuning the bit rate versus quality trade-off, possibly in a dynamic way during a session, taking into account service requirements and network transport constraints. The G.729.1 coder produces an embedded bitstream structured in 12 layers corresponding to 12 available bit rates between 8 and 32 kbps. The first layer, at 8 kbps, is called the core layer and is bitstream compatible with the ITU-T G.729/G.729A coder. At 12 kbps, a second layer improves the narrowband quality. Upper layers provide wideband audio (50-7000 Hz) between 14 and 32 kbps, with a 2 kbps granularity allowing graceful quality improvements. Only the core layer is mandatory to decode understandable speech; upper layers provide quality enhancement and wideband enlargement. Sollaud Standards Track [Page 2] RFC 4749 RTP Payload Format for G.729.1 October 2006Show full document text