RTP Payload Format for Opus Speech and Audio Codec
draft-spittka-payload-rtp-opus-02

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Last updated 2012-11-22
Replaced by rfc7587, draft-ietf-payload-rtp-opus
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Network Working Group                                         J. Spittka
Internet-Draft
Intended status: Informational                                    K. Vos
Expires: May 26, 2013                            Skype Technologies S.A.
                                                               JM. Valin
                                                                 Mozilla
                                                       November 22, 2012

           RTP Payload Format for Opus Speech and Audio Codec
                   draft-spittka-payload-rtp-opus-02

Abstract

   This document defines the Real-time Transport Protocol (RTP) payload
   format for packetization of Opus encoded speech and audio data that
   is essential to integrate the codec in the most compatible way.
   Further, media type registrations are described for the RTP payload
   format.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 26, 2013.

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   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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Spittka, et al.           Expires May 26, 2013                  [Page 1]
Internet-Draft      RTP Payload Format for Opus Codec      November 2012

   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions, Definitions and Acronyms used in this document  .  4
     2.1.  Audio Bandwidth  . . . . . . . . . . . . . . . . . . . . .  4
   3.  Opus Codec . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Network Bandwidth  . . . . . . . . . . . . . . . . . . . .  5
       3.1.1.  Recommended Bitrate  . . . . . . . . . . . . . . . . .  5
       3.1.2.  Variable versus Constant Bit Rate  . . . . . . . . . .  5
       3.1.3.  Discontinuous Transmission (DTX) . . . . . . . . . . .  6
     3.2.  Complexity . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.3.  Forward Error Correction (FEC) . . . . . . . . . . . . . .  6
     3.4.  Stereo Operation . . . . . . . . . . . . . . . . . . . . .  7
   4.  Opus RTP Payload Format  . . . . . . . . . . . . . . . . . . .  8
     4.1.  RTP Header Usage . . . . . . . . . . . . . . . . . . . . .  8
     4.2.  Payload Structure  . . . . . . . . . . . . . . . . . . . .  9
   5.  Congestion Control . . . . . . . . . . . . . . . . . . . . . . 11
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
     6.1.  Opus Media Type Registration . . . . . . . . . . . . . . . 12
     6.2.  Mapping to SDP Parameters  . . . . . . . . . . . . . . . . 15
       6.2.1.  Offer-Answer Model Considerations for Opus . . . . . . 17
       6.2.2.  Declarative SDP Considerations for Opus  . . . . . . . 18
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   9.  Normative References . . . . . . . . . . . . . . . . . . . . . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22

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1.  Introduction

   The Opus codec is a speech and audio codec developed within the IETF
   Internet Wideband Audio Codec working group (codec).  The codec has a
   very low algorithmic delay and is 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
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