RTP Payload Format for the Opus Speech and Audio Codec
RFC 7587
Internet Engineering Task Force (IETF) J. Spittka
Request for Comments: 7587
Category: Standards Track K. Vos
ISSN: 2070-1721 vocTone
JM. Valin
Mozilla
June 2015
RTP Payload Format for the Opus Speech and Audio Codec
Abstract
This document defines the Real-time Transport Protocol (RTP) payload
format for packetization of Opus-encoded speech and audio data
necessary to integrate the codec in the most compatible way. It also
provides an applicability statement for the use of Opus over RTP.
Further, it describes media type registrations for the RTP payload
format.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7587.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Spittka, et al. Standards Track [Page 1]
RFC 7587 RTP Payload Format for Opus June 2015
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions, Definitions, and Acronyms Used in This Document 3
3. Opus Codec . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Network Bandwidth . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Recommended Bitrate . . . . . . . . . . . . . . . . . 4
3.1.2. Variable versus Constant Bitrate . . . . . . . . . . 4
3.1.3. Discontinuous Transmission (DTX) . . . . . . . . . . 5
3.2. Complexity . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Forward Error Correction (FEC) . . . . . . . . . . . . . 6
3.4. Stereo Operation . . . . . . . . . . . . . . . . . . . . 6
4. Opus RTP Payload Format . . . . . . . . . . . . . . . . . . . 7
4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 7
4.2. Payload Structure . . . . . . . . . . . . . . . . . . . . 7
5. Congestion Control . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6.1. Opus Media Type Registration . . . . . . . . . . . . . . 9
7. SDP Considerations . . . . . . . . . . . . . . . . . . . . . 12
7.1. SDP Offer/Answer Considerations . . . . . . . . . . . . . 13
7.2. Declarative SDP Considerations for Opus . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 17
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
Opus [RFC6716] is a speech and audio codec developed within the IETF
Internet Wideband Audio Codec working group. The codec has a very
low algorithmic delay, and it is highly scalable in terms of audio
bandwidth, bitrate, and complexity. Further, it provides different
modes to efficiently encode speech signals as well as music signals,
thus making it the codec of choice for various applications using the
Internet or similar networks.
This document defines the Real-time Transport Protocol (RTP)
[RFC3550] payload format for packetization of Opus-encoded speech and
audio data necessary to integrate Opus in the most compatible way.
It also provides an applicability statement for the use of Opus over
RTP. Further, it describes media type registrations for the RTP
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