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Definition of the Opus Audio Codec (RFC6716) Disclosure Number: IPCOM000221563D
Original Publication Date: 2012-Sep-01
Included in the Prior Art Database: 2012-Sep-11

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

JM. Valin: AUTHOR [+3]


The Opus codec is a real-time interactive audio codec designed to meet the requirements described in [REQUIREMENTS]. It is composed of a layer based on Linear Prediction (LP) [LPC] and a layer based on the Modified Discrete Cosine Transform (MDCT) [MDCT]. The main idea behind using two layers is as follows: in speech, linear prediction techniques (such as Code-Excited Linear Prediction, or CELP) code low frequencies more efficiently than transform (e.g., MDCT) domain techniques, while the situation is reversed for music and higher speech frequencies. Thus, a codec with both layers available can operate over a wider range than either one alone and can achieve better quality by combining them than by using either one individually.

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Internet Engineering Task Force (IETF)                         JM. Valin Request for Comments: 6716                           Mozilla Corporation Category: Standards Track                                         K. Vos ISSN: 2070-1721                                  Skype Technologies S.A.                                                            T. Terriberry                                                      Mozilla Corporation                                                           September 2012

                    Definition of the Opus Audio Codec


   This document defines the Opus interactive speech and audio codec.    Opus is designed to handle a wide range of interactive audio    applications, including Voice over IP, videoconferencing, in-game    chat, and even live, distributed music performances.  It scales from    low bitrate narrowband speech at 6 kbit/s to very high quality stereo    music at 510 kbit/s.  Opus uses both Linear Prediction (LP) and the    Modified Discrete Cosine Transform (MDCT) to achieve good compression    of both speech and music.

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

 Valin, et al.                Standards Track                    [Page 1]
 RFC 6716                 Interactive Audio Codec          September 2012

 Copyright Notice

   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    Provisions Relating to IETF Documents    ( in effect on the date of    publication of this document.  Please review these documents    carefully, as they describe your rights and restrictions with respect    to this document.  Code Components extracted from this document must    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.

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