RTP Payload Format for Vorbis Encoded Audio
RFC 5215
Network Working Group L. Barbato
Request for Comments: 5215 Xiph
Category: Standards Track August 2008
RTP Payload Format for Vorbis Encoded 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.
Abstract
This document describes an RTP payload format for transporting Vorbis
encoded audio. It details the RTP encapsulation mechanism for raw
Vorbis data and the delivery mechanisms for the decoder probability
model (referred to as a codebook), as well as other setup
information.
Also included within this memo are media type registrations and the
details necessary for the use of Vorbis with the Session Description
Protocol (SDP).
Barbato Standards Track [Page 1]
RFC 5215 Vorbis RTP Payload Format August 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conformance and Document Conventions . . . . . . . . . . . 3
2. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. RTP Header . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Payload Header . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Payload Data . . . . . . . . . . . . . . . . . . . . . . . 6
2.4. Example RTP Packet . . . . . . . . . . . . . . . . . . . . 8
3. Configuration Headers . . . . . . . . . . . . . . . . . . . . 8
3.1. In-band Header Transmission . . . . . . . . . . . . . . . 9
3.1.1. Packed Configuration . . . . . . . . . . . . . . . . . 10
3.2. Out of Band Transmission . . . . . . . . . . . . . . . . . 12
3.2.1. Packed Headers . . . . . . . . . . . . . . . . . . . . 12
3.3. Loss of Configuration Headers . . . . . . . . . . . . . . 13
4. Comment Headers . . . . . . . . . . . . . . . . . . . . . . . 13
5. Frame Packetization . . . . . . . . . . . . . . . . . . . . . 14
5.1. Example Fragmented Vorbis Packet . . . . . . . . . . . . . 15
5.2. Packet Loss . . . . . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.1. Packed Headers IANA Considerations . . . . . . . . . . . . 19
7. SDP Related Considerations . . . . . . . . . . . . . . . . . . 20
7.1. Mapping Media Type Parameters into SDP . . . . . . . . . . 20
7.1.1. SDP Example . . . . . . . . . . . . . . . . . . . . . 21
7.2. Usage with the SDP Offer/Answer Model . . . . . . . . . . 22
8. Congestion Control . . . . . . . . . . . . . . . . . . . . . . 22
9. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1. Stream Radio . . . . . . . . . . . . . . . . . . . . . . . 22
10. Security Considerations . . . . . . . . . . . . . . . . . . . 23
11. Copying Conditions . . . . . . . . . . . . . . . . . . . . . . 23
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
13.1. Normative References . . . . . . . . . . . . . . . . . . . 24
13.2. Informative References . . . . . . . . . . . . . . . . . . 25
Barbato Standards Track [Page 2]
RFC 5215 Vorbis RTP Payload Format August 2008
1. Introduction
Vorbis is a general purpose perceptual audio codec intended to allow
maximum encoder flexibility, thus allowing it to scale competitively
over an exceptionally wide range of bit rates. At the high quality/
bitrate end of the scale (CD or DAT rate stereo, 16/24 bits), it is
in the same league as MPEG-4 AAC. Vorbis is also intended for lower
and higher sample rates (from 8kHz telephony to 192kHz digital
masters) and a range of channel representations (monaural,
polyphonic, stereo, quadraphonic, 5.1, ambisonic, or up to 255
discrete channels).
Vorbis encoded audio is generally encapsulated within an Ogg format
bitstream [RFC3533], which provides framing and synchronization. For
the purposes of RTP transport, this layer is unnecessary, and so raw
Vorbis packets are used in the payload.
1.1. Conformance and Document Conventions
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 BCP 14, [RFC2119] and
indicate requirement levels for compliant implementations.
Requirements apply to all implementations unless otherwise stated.
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