Re: [codec] WG Review: Internet Wideband Audio Codec (codec)
2010-01-11 14:19:18
Hi,
We fully share the points 1) and 2) stated in the e-mail below from
Cullen since implementing and deploying a new codec in networks
(gateways, service plate-forms, mediaservers...) and in terminals
represents high costs for service providers, manufacturers and chipset
providers in terms of development, deployment and testing with risks
to create bugs and problems affecting customers. Furthermore, this
multiplies the problems of interoperability with already deployed
codecs and the transcoding needs to be addressed with related costs
(gateways) and quality degradations.
Therefore, the 3 stages mentionned are essential to be run sequentially:
"(1) get consensus on the requirements, (2) see if an existing codec
meets the requirements, and (3) specify a new codec only if none are
found in stage 2. Initially the WG would be chartered for (1) and when
that was done it would be re-charted for (2) and so on. "
Requirements established first in stage 1 shall be sent for stage 2 to
other SDOs as stated in the current version of the Charter:
" The working group will communicate detailed description of the
requirements and goals to other SDOs including the ITU-T, 3GPP, and
MPEG to help determine if existing codecs meet the requirements
"(however in the current version of the Charter, it is inconsistent to
state first that the goal of the WG is to develop of a new codec and
to state some lines after that existing codecs will be considered...)
Based on the answers collected from these SDOs, conclusion for stage 2
shall be delivered and constitute the input and prerequisit for any
decision to continue in stage 3 to produce a new codec and re-Charter
the Group for this
We therefore propose to limit the Charter to stage 1 and re-formulate
it as follows :
---------------------------------------------------------------------------------
Developers of Internet audio applications
and operators of Internet audio services have expressed the need for
high-quality audio codecs that meet all of the following three
conditions:
1. Are optimized for use in interactive Internet applications.
2. Are published by a recognized standards development organization
(SDO) and therefore subject to clear change control.
3. Can be widely implemented and easily distributed among application
developers, service operators, and end users.
According to application developers and service operators, an audio
codec that meets all three of these would: (1) enable protocol
designers to more easily specify a mandatory-to-implement codec in
their protocols and thus improve interoperability; (2) enable
developers to more easily easily build innovative, interactive
applications for the Internet; (3) enable service operators to more
easily deploy affordable, high-quality audio services on the Internet;
and (4) enable end users of Internet applications and services to
enjoy an improved user experience.
Objectives
The goal of this working group is to produce a set of requirements for an
audio codec that is 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. Designing for 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 working group
3. Ensuring interoperability with the Real-time Transport Protocol
(RTP), including secure transport via SRTP
4. Ensuring interoperability with Internet signaling 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
signaling technology
Optimizing for very low bit rates (typically below 2.4 kbps) and for
non-interactive audio is out of scope because such work might
necessitate specialized optimizations.
Once the first requirement establishment stage completed, the working group
will then communicate detailed description
of the requirements and goals to other SDOs including the
ITU-T, 3GPP, and MPEG to jointly analyse and determine if existing
standardized codecs meet the requirements or can be efficiently adapted
to meet them. This work will constitute a second stage that will be
discussed and agreed with the relevant SDOs and the WG Charter will be
updated accordingly
If no existing standardized codec fullfill the requirements nor can be
easily adapted to meet them, the working group will analyse and decide
if such codec can be produced which may constitute the last stage of
the work for which the WG will be re-chartered again.
In completing its work, the working group should collaborate with
other IETF working groups to complete particular tasks. These might
include, but would not be limited to, the following:
- 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 signaling layer.
Deliverables
1. A set of technical Requirements. This document shall be
Informational.
Milestones
May-2010: WGLC on Requirements
Jul-2010: Requirements to IESG (Informational)
Jul-2010: Requirements sent to other SDOs (including 3GPP, ITU-T, MPEG)
_______________________________________________
Cheers,
Xavier and colleagues of him
PS: Here is a Word diff version of the charter
http://xavier.marjou.pagesperso-orange.fr/modified-charter.doc
On Thu, Jan 7, 2010 at 6:27 PM, Cullen Jennings <fluffy(_at_)cisco(_dot_)com>
wrote:
Before the IESG sent the proposed CODEC charter out for community review, we
received some concerns about this proposed charter. I had hoped these would
be discussed during the WG charter review. I'm raising these issues now to
make sure that the IESG has an opportunity to hear from the whole community.
As a starting point for the discussion, I am providing some of my own
thoughts on these issues.
1) The charter should allow for the proposed WG to decide to select an
existing codec
My read of the current charter is that selecting an existing codec is
allowed, and this would be a very good outcome. This topic has been
discussed in the past; my recollection is that people that have expressed
opinions on existing codecs also believe that it would be a good thing for
the WG to be able to choose an existing one as long as it meets the goals. If
there is something that needs to be clarified in the proposed charter to make
this clear, please help by suggesting wording.
2) Some people have proposed the WG should be chartered in three stages. (1)
get consensus on the requirements, (2) see if an existing codec meets the
requirements, and (3) specify a new codec only if none are found in stage 2.
Initially the WG would be chartered for (1) and when that was done it would
be re-charted for (2) and so on.
We have received excellent liaison about existing codecs and their IPR status
and many of the participants on the list have a reasonable knowledge of the
currently available codecs. I have not heard people making strong arguments
that one of the existing codecs meets the requirements and goals that the
list seems to be converging on. The key issues here is that even *after*
codec work is started, the WG still needs to be able to choose an existing
codec as the IPR status of existing codec. Specifically if some patent
holders of one of the existing codecs decided to make the codec royalty free,
the WG very well could choose to abandon ongoing work and choose the existing
codec. Also as the work evolves, participants will get better information
about the quality of any codec being developed and this may change the
consensus regarding the need to develop a new codec. Given all of these,
chartering in multiple stages seems to add to the process burden and does not
seem to have a
strong benefit in producing a better final outcome one way or the other.
3) There should be a only a single codec coming out of the proposed WG and
forbid more than one
Most codecs of this type end of having various algorithm parameter values in
the payload that make it hard to enforce something like this. Various codec
experts have explained to me that it is easy to make a codec where one of the
bits ends up selecting which coding technique to use. Adding constraints like
this is likely to just create incentives for a WG to do patchwork designs to
work around process constraints. In the end, I suspect we need to rely on the
WG consensus process to cause the correct thing to happen.
4) Some people suggested that the WG needs to demonstrate the codec is
superior to all existing codecs in ways other than just IPR considerations
I observe it is unlikely that a codec that tries to avoid any modern IPR
would end up being better in all other ways to codecs that incorporated
modern advances in codec design that are patented. My current read of the
input from the list discussion and BOFs is that that the bulk of the
participants do not view this as a needed to meet the envisioned use cases.
5) The WG should have consensus that any codec they select is not IPR
encumbered or is royalty free.
The IETF IPR policy attempts to get relevant information from the
participants of the a WG about IPR associated with contributions. This
allows the WG to make informed decisions when deciding on mechanisms. All
chartered WGs must work within the current IETF IPR rules. The proposed
codec WG is no exception, and this has been very clearly stated in the BOFs
and other discussions about this work. BCP 79 says the IETF "will take no
position on the validity or scope of any such IPR claims".
Thanks, Cullen <RAI AD>
On Dec 23, 2009, at 9:15 , IESG Secretary wrote:
A new IETF working group has been proposed in the Real-time Applications
and Infrastructure Area. The IESG has not made any determination as yet.
The following draft charter was submitted, and is provided for
informational purposes only. Please send your comments to the IESG
mailing list (iesg(_at_)ietf(_dot_)org) by January 20, 2010.
Internet Wideband Audio Codec (codec)
-------------------------------------------------------------------------
Last Modified: 2009-12-17
Proposed Chair(s):
* TBD
Real-time Applications and Infrastructure Area Director(s):
* Robert Sparks <rjsparks(_at_)nostrum(_dot_)com>
* Cullen Jennings <fluffy(_at_)cisco(_dot_)com>
Real-time Applications and Infrastructure Area Advisor:
* Cullen Jennings <fluffy(_at_)cisco(_dot_)com>
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Description of Working Group
Problem Statement
According to reports from developers of Internet audio applications and
operators of Internet audio services, there are no standardized,
high-quality audio codecs that meet all of the following three
conditions:
1. Are optimized for use in interactive Internet applications.
2. Are published by a recognized standards development organization
(SDO) and therefore subject to clear change control.
3. Can be widely implemented and easily distributed among application
developers, service operators, and end users.
There exist codecs that provide high quality encoding of audio
information, but that are not optimized for the actual conditions of the
Internet; according to reports, this mismatch between design and
deployment has hindered adoption of such codecs in interactive Internet
applications.
There exist codecs that can be widely implemented and easily
distributed, but that are not standardized through any SDO; according to
reports, this lack of standardization and clear change control has
hindered adoption of such codecs in interactive Internet applications.
There exist codecs that are standardized, but that cannot be widely
implemented and easily distributed; according to reports, the presence
of various usage restrictions (e.g., in the form of requirements to pay
royalty fees, obtain a license, enter into a business agreement, or meet
other special conditions imposed by a patent holder) has hindered
adoptions of such codecs in interactive Internet applications.
According to application developers and service operators, an audio
codec that meets all three of these would: (1) enable protocol
designers to more easily specify a mandatory-to-implement codec in
their protocols and thus improve interoperability; (2) enable
developers to more easily easily build innovative, interactive
applications for the Internet; (3) enable service operators to more
easily deploy affordable, high-quality audio services on the Internet;
and (4) enable end users of Internet applications and services to enjoy
an improved user experience.
Objectives
The goal of this working group is to develop a single high-quality audio
codec that is 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. Designing for 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 working group
3. Ensuring interoperability with the Real-time Transport Protocol
(RTP), including secure transport via SRTP
4. Ensuring interoperability with Internet signaling 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 signaling
technology
Optimizing for very low bit rates (typically below 2.4 kbps) and for
non-interactive audio is out of scope because such work might
necessitate specialized optimizations.
Although the codec produced by the working group might be used as a
mandatory-to-implement technology by designers of particular Internet
protocols, it is explicitly not a goal of the working group to produce a
codec that will be mandated for use across the entire IETF or Internet
community nor would their be any expectation that this would be the only
mandatory-to-implement codec.
The goal of the working group is to produce only one codec. Based on
the working group's analysis of the design space, the working group
might determine that it needs to produce more than one codec, or a codec
with multiple modes; however, it is not the goal of working group to
produce more than one codec, and to reduce confusion in the marketplace
the working group shall endeavor to produce as few codecs as possible.
In completing its work, the working 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 signaling layer.
The working group will inform the ITU-T (Study group 16) of each new
revision of working group drafts, with the intent of submitting the
completed codec RFC for co-publication by the ITU-T if the ITU-T finds
that appropriate. The working group will communicate detailed
description of the requirements and goals to other SDOs including the
ITU-T, 3GPP, and MPEG to help determine if existing codecs meet the
requirements and would therefore enable co-publication of an existing
standard at the IETF. The working group will also continue to discuss
with other standards bodies to determine if it becomes possible to
satisfy the IETF requirements through a new or revised standard at other
bodies.
Suggested Codec Standardization Guidelines and Requirements for
achieving the foregoing objectives are provisionally outlined in
draft-valin-codec-guidelines and draft-valin-codec-requirements
respectively; these documents will form the starting point for working
toward consensus and, if accepted as work items of the working group,
will be refined by the working group in accordance with the usual IETF
procedures.
A codec that can be widely implemented and easily distributed among
application developers, service operators, and end users is preferred.
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 attempt to 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 working group prefers unencumbered technologies in a way
that is consistent with BCP 78 and BCP 79. In particular, the working
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 working
group will produce an unencumbered codec, the working 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 working group.
Deliverables
1. A set of Codec Standardization Guidelines that define the work
processes of the working group. This document shall be Informational.
2. A set of technical Requirements. This document shall be
Informational.
3. Specification of a codec that meets the agreed-upon requirements, in
the form of an Internet-Draft that defines the codec algorithm along
with source code for a reference implementation. The text description
of the codec shall indicate which components of the encoder and decoder
are mandatory, recommended, and optional. It is envisioned that this
document 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 (Informational)
Dec-2010: Freeze codec structure
Jun-2011: Finalize codec parameters
Jul-2011: WGLC on codec specification
Oct-2011: Submit codec specification to IESG (Standards Track)
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