Ambisonics in an Ogg Opus Container
draft-ietf-codec-ambisonics-00

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Document Type Active Internet-Draft (codec WG)
Last updated 2016-07-19
Replaces draft-graczyk-codec-ambisonics
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codec                                                         M. Graczyk
Internet-Draft                                               Google Inc.
Intended status: Standards Track                           July 19, 2016
Expires: January 20, 2017

                  Ambisonics in an Ogg Opus Container
                     draft-ietf-codec-ambisonics-00

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.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on January 20, 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
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   described in the Simplified BSD License.

Graczyk                 Expires January 20, 2017                [Page 1]
Internet-Draft               Opus Ambisonics                   July 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Ambisonics With Ogg Opus  . . . . . . . . . . . . . . . . . .   3
     3.1.  Channel Mapping Family 2  . . . . . . . . . . . . . . . .   3
     3.2.  Downmixing  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

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 the this
   document, ambisonics can be considered a multichannel audio stream.
   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 a new channel
   mapping family for encoding ambisonics.  The Ogg Opus format is
   extended indirectly by adding an item with value 2 to the IANA "Opus
   Channel Mapping Families" registry.  When 2 is used as the Channel
   Mapping Family Number in an Ogg stream, the semantic meaning of the
   channels in the multichannel Opus stream is the ambisonics layout
   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
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

Graczyk                 Expires January 20, 2017                [Page 2]
Internet-Draft               Opus Ambisonics                   July 2016

3.  Ambisonics With Ogg Opus

   Ambisonics MAY be encapsulated in the Ogg format by encoding with the
   Opus codec and setting the Channel Mapping Family value to 2 in the
   Ogg Identification Header.  A demuxer implmentation encountering
   Channel Mapping Family 2 MUST interpret the Opus stream as containing
   ambisonics with the format described in Section 3.1.

3.1.  Channel Mapping Family 2
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