RTP Payload Format for Vorbis Encoded Audio
RFC 5215

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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.