Real-time Transport Protocol (RTP) Payload Format for Enhanced AC-3 (E-AC-3) Audio
RFC 4598
Network Working Group B. Link
Request for Comments: 4598 Dolby Laboratories
Category: Standards Track July 2006
Real-time Transport Protocol (RTP)
Payload Format for Enhanced AC-3 (E-AC-3) Audio
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 describes a Real-time Transport Protocol (RTP) payload
format for transporting Enhanced AC-3 (E-AC-3) encoded audio data.
E-AC-3 is a high-quality, multichannel audio coding format and is an
extension of the AC-3 audio coding format, which is used in US High-
Definition Television (HDTV), DVD, cable and satellite television,
and other media. E-AC-3 is an optional audio format in US and world
wide digital television and high-definition DVD formats. The RTP
payload format as presented in this document includes support for
data fragmentation.
Link Standards Track [Page 1]
RFC 4598 RTP Payload Format for E-AC-3-Audio July 2006
Table of Contents
1. Introduction ....................................................2
2. Overview of Enhanced-AC-3 .......................................3
2.1. E-AC-3 Bit Stream ..........................................5
2.1.1. Sync Frames and Audio Blocks ........................5
2.1.2. Programs and Substreams .............................6
2.1.3. Frame Sets ..........................................7
3. RTP E-AC-3 Header Fields ........................................7
4. RTP E-AC-3 Payload Format .......................................8
4.1. Payload Specific Header ....................................8
4.2. Fragmentation of E-AC-3 Frames .............................9
4.3. Concatenation of E-AC-3 Frames .............................9
4.4. Carriage of AC-3 Frames ...................................10
5. Types and Names ................................................10
5.1. Media Type Registration ...................................10
5.2. SDP Usage .................................................13
6. Security Considerations ........................................14
7. Congestion Control .............................................15
8. IANA Considerations ............................................15
9. References .....................................................15
9.1. Normative References ......................................15
9.2. Informative References ....................................16
1. Introduction
The Enhanced AC-3 (E-AC-3) [ETSI] audio coding system is built on a
foundation of AC-3. It is an enhancement and extension to AC-3,
which is an existing audio coding standard commonly used for DVD,
broadcast, cable, and satellite television content. E-AC-3 is
designed to enable operation at both higher and lower data rates than
AC-3, provide expanded channel configurations, and provide greater
flexibility for carriage of multiple audio program elements. The
relationship between E-AC-3 and AC-3 provides for low-loss, low-cost
conversion between the two and makes E-AC-3 especially suitable in
applications that require compatibility with the existing broadcast-
reception and audio/video decoding infrastructure. Dolby Digital
Plus is a branded version of Enhanced AC-3.
E-AC-3 has been standardized within both the European
Telecommunications Standards Institute (ETSI) and the Advanced
Television Systems Committee (ATSC). It is an optional audio format
for use in US (ATSC) and Digital Video Broadcasting (DVB) television
transmission. It is also a required audio format for use in the High
Definition (HD)-DVD optical-storage media format and included in the
Blu-ray Disc format.
Link Standards Track [Page 2]
RFC 4598 RTP Payload Format for E-AC-3-Audio July 2006
There is a need to stream E-AC-3 content over IP networks. E-AC-3 is
primarily used in audio-for-video applications, so RTP serves well as
a transport solution with its mechanism for synchronizing streams.
Applications for streaming E-AC-3 include Internet Protocol
television (IPTV), video on demand, interactive features of next
generation DVD formats, and transfer of movies across a home network.
Section 2 gives a brief overview of the E-AC-3 algorithm. Section 3
Show full document text