Ambisonics in an Ogg Opus Container
draft-ietf-codec-ambisonics-02

Document Type Active Internet-Draft (codec WG)
Last updated 2017-03-27
Replaces draft-graczyk-codec-ambisonics
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codec                                                        J. Skoglund
Internet-Draft                                                M. Graczyk
Intended status: Standards Track                             Google Inc.
Expires: September 28, 2017                               March 27, 2017

                  Ambisonics in an Ogg Opus Container
                     draft-ietf-codec-ambisonics-02

Abstract

   This document defines an extension to the Ogg format to encapsulate
   ambisonics coded using the Opus audio codec.

Status of This Memo

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

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   This Internet-Draft will expire on September 28, 2017.

Copyright Notice

   Copyright (c) 2017 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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Skoglund & Graczyk     Expires September 28, 2017               [Page 1]
Internet-Draft               Opus Ambisonics                  March 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Ambisonics With Ogg Opus  . . . . . . . . . . . . . . . . . .   3
     3.1.  Channel Mapping Family 2  . . . . . . . . . . . . . . . .   3
     3.2.  Channel Mapping Family 3  . . . . . . . . . . . . . . . .   4
   4.  Downmixing  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Ambisonics is a representation format for three dimensional sound
   fields which can be used for surround sound and immersive virtual
   reality playback.  See [gerzon75] and [daniel04] for technical
   details on the ambisonics format.  For the purposes of this document,
   ambisonics can be considered a multichannel audio stream.  A separate
   stereo stream can be used alongside the ambisonics in a head-tracked
   virtual reality experience to provide so-called non-diegetic audio -
   audio which should remain unchanged by listener head rotation; e.g.,
   narration or stereo music.  Ogg is a general purpose container,
   supporting audio, video, and other media.  It can be used to
   encapsulate audio streams coded using the Opus codec.  See [RFC6716]
   and [RFC7845] for technical details on the Opus codec and its
   encapsulation in the Ogg container respectively.

   This document extends the Ogg format by defining two new channel
   mapping families for encoding ambisonics.  The Ogg Opus format is
   extended indirectly by adding an item with value 2 or 3 to the IANA
   "Opus Channel Mapping Families" registry.  When 2 or 3 are used as
   the Channel Mapping Family Number in an Ogg stream, the semantic
   meaning of the channels in the multichannel Opus stream is one of the
   ambisonics layouts defined in this document.  This mapping can also
   be used in other contexts which make use of the channel mappings
   defined by the Opus Channel Mapping Families registry.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
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