Subject: [codec] another charter update

From: Peter Saint-Andre <[email-masked]>
Date: Wed, 28 Oct 2009 14:11:46 -0600

The following text incorporates all feedback received to date.

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Proposed Charter for Codec WG
Last Updated: 2009-10-28

Problem Statement

There are no standardized, high-quality audio codecs that are optimized
for use in interactive Internet applications and that can be widely
implemented and easily distributed among application developers,
service operators, and end users.  This gap in the Internet protocol
stack has hindered protocol designers from being able to specify
mandatory-to-implement codecs in their protocols for the sake of
interoperability, developers from building innovative, interactive
applications, service operators from deploying affordable, high-quality
services, and end users from enjoying an optimal user experience.

Objectives

The goal of this group is to develop one or more high-quality audio
codecs that are optimized for use over the Internet and that can be
widely implemented and easily distributed among application developers,
service operators, and end users. Core technical considerations include
but are not necessarily limited to the following:

1. Use in interactive applications (examples include but are not
limited to point-to-point voice calls, multi-party voice conferencing,
telepresence, teleoperation, in-game voice chat, and live music
performance)

2. Addressing the real transport conditions of the Internet as
identified and prioritized by the group

3. Ensuring interoperability with the Real-time Transport Protocol
(RTP), including secure transport via SRTP

4. Ensuring interoperability with Internet signalling technologies such
as Session Initiation Protocol (SIP), Session Description Protocol
(SDP), and Extensible Messaging and Presence Protocol (XMPP); however,
the result should not depend on the details of any particular signalling
technology

Codecs optimized for very low bit rates (typically below 2.4 kbps) and
codecs for non-interactive audio are out of scope because they might
necessitate specialized optimizations.

Although the codec(s) produced by the group might be used as
mandatory-to-implement technologies by designers of particular Internet
protocols, it is explicitly not a goal of the group to produce a codec
that will be mandated for use across the entire IETF or Internet community.

The group might produce only one codec or it might produce multiple
codecs; however, to reduce confusion in the marketplace it shall
endeavor to produce as few codecs as possible, and in any case shall not
function as a "codec factory" that produces a large number of codecs.

In completing its work, the group should collaborate with other IETF
working groups to complete particular tasks.  These might include but
would not be limited to the following:

- - Within the AVT WG, define the codec's payload format for use with
  the Real-time Transport Protocol (RTP).

- - Collaborate with working groups in the Transport area to identify
  important aspects of packet transmission over the Internet.

- - Collaborate with working groups in the Transport area to understand
  the degree of rate adaptation desirable, and to reflect that
  understanding in the design of a codec that can adjust its
  transmission in a way that minimizes disruption to the audio.

- - Collaborate with working groups in the RAI area to ensure that
  information about and negotiation of the codec can be easily
  represented at the signalling layer.

Work processes and technical requirements for achieving the foregoing
objectives are outlined in draft-valin-codec-guidelines and
draft-valin-codec-requirements respectively; these documents will form
the starting point for working toward consensus and will be refined by
the group in accordance with the usual IETF procedures.

The group would prefer to produce a codec that can be widely
implemented and easily distributed among application developers,
service operators, and end users.  This is important because many
existing codecs that might fulfill some or most of the technical
attributes listed above are encumbered in various ways.  For example,
patent holders might require that those wishing to implement the codec
in software, deploy the codec in a service, or distribute the codec
in software or hardware need to request a license, enter into a
business agreement, pay licensing fees or royalties, or adhere to
other special conditions or restrictions.

Because such encumbrances have made it difficult to widely implement
and easily distribute high-quality audio codecs across the entire
Internet community, the group shall prefer unencumbered technologies in
a way that is consistent with BCP 78 and BCP 79.  In particular, the
group shall heed the preference stated in BCP 79: "In general, IETF
working groups prefer technologies with no known IPR claims or, for
technologies with claims against them, an offer of royalty-free
licensing."  Although this preference cannot guarantee that the group
will produce an unencumbered codec, the group shall attempt to adhere
to the spirit of BCP 79.  This preference does not explicitly rule out
the possibility of adapting encumbered technologies; such decisions
will be made in accordance with the rough consensus of the group.

Deliverables

1. Guidelines that define the work process of the group. This
document shall be Informational.

2. Detailed technical requirements. This document shall be
Informational.

3. Specification of one or more codecs that meet the agreed-upon
requirements, in the form of Internet-Drafts that define the codec
algorithm and source code for a reference implementation, as well as
any specific technical requirements for which the codec has been
optimized. The text description of each codec shall indicate which
components of the encoder and decoder are mandatory, recommended, and
optional.  It is envisioned that each such specification shall be a
Proposed Standard document.

Milestones

Mar-2010: WGLC on Codec Standardization Guidelines
May-2010: Codec Standardization Guidelines to IESG (Informational)
May-2010: WGLC on Requirements
Jul-2010: Requirements to IESG (Infomational)
Mar-2011: WGLC on codec specification(s)
Jun-2011: Submit codec specification(s) to IESG (Standards Track)

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From: Michael Knappe <[email-masked]>
Date: Thu, 29 Oct 2009 11:06:58 -0700

Catching up on the charter discussion, please disregard if content below has already been covered...

Scoping for potentially more than one candidate codec is a real strength of the proposed charter, and will help avoid many potential process pitfalls, but it does open up challenges.

Given the often differing or differently prioritized requirements for each class of interactive audio application, a one-size-fits-all set of criteria is most likely intractable. As we move further with this selection process, it may be helpful to set up selection 'gates' that begin with meeting a common set of basic and relatively high level criteria, followed by subsequent more narrow gates with stricter selection criteria dependent on the class(es) of application targeted by the codec. These subsequent candidate selection paths and gates would run in parallel as resources permit. This should allow concentration on the true merits of a particular codec, and not on the relative importance of the application(s) it is best suited for.

Thoughts?

Mike

On 10/28/09 1:11 PM, "Peter Saint-Andre" <[email-masked]> wrote:

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Problem Statement

Objectives

Deliverables

Milestones

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