Updates to the Opus Audio Codec
draft-ietf-codec-opus-update-05

Document Type Active Internet-Draft (codec WG)
Last updated 2016-12-19
Replaces draft-valin-codec-opus-update
Stream IETF
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Stream WG state WG Document Feb 2017
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Network Working Group                                          JM. Valin
Internet-Draft                                       Mozilla Corporation
Intended status: Standards Track                                  K. Vos
Expires: June 22, 2017                                           vocTone
                                                       December 19, 2016

                    Updates to the Opus Audio Codec
                    draft-ietf-codec-opus-update-05

Abstract

   This document addresses minor issues that were found in the
   specification of the Opus audio codec in RFC 6716 [RFC6716].

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 22, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://trustee.ietf.org/license-info) 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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Stereo State Reset in SILK  . . . . . . . . . . . . . . . . .   3
   4.  Parsing of the Opus Packet Padding  . . . . . . . . . . . . .   3
   5.  Resampler buffer  . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Integer wrap-around in inverse gain computation . . . . . . .   5
   7.  Integer wrap-around in LSF decoding . . . . . . . . . . . . .   6
   8.  Cap on Band Energy  . . . . . . . . . . . . . . . . . . . . .   6
   9.  Hybrid Folding  . . . . . . . . . . . . . . . . . . . . . . .   7
   10. Downmix to Mono . . . . . . . . . . . . . . . . . . . . . . .   9
   11. New Test Vectors  . . . . . . . . . . . . . . . . . . . . . .   9
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document addresses minor issues that were discovered in the
   reference implementation of the Opus codec that serves as the
   specification in RFC 6716 [RFC6716].  Only issues affecting the
   decoder are listed here.  An up-to-date implementation of the Opus
   encoder can be found at https://opus-codec.org/.

   Some of the changes in this document update normative behaviour in a
   way that requires new test vectors.  The English text of the
   specification is unaffected, only the C implementation is.  The
   updated specification remains fully compatible with the original
   specification.

   Note: due to RFC formatting conventions, lines exceeding the column
   width in the patch above are split using a backslash character.  The
   backslashes at the end of a line and the white space at the beginning
   of the following line are not part of the patch.  A properly
   formatted patch including the three changes above is available at
   <https://jmvalin.ca/misc_stuff/opus_update.patch>.  (EDITOR: change
   to an ietf.org link when ready)

2.  Terminology

   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 RFC 2119 [RFC2119].

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