[AVTCORE] Draft Publication Request for draft-ietf-avtcore-rtp-evc

[Bernard Aboba <[e-mail]>]

Request for Publication
Document: RTP Payload Format for Essential Video Coding (EVC)
Link: https://datatracker.ietf.org/doc/html/draft-ietf-avtcore-rtp-evc
Intended Status: Proposed Standard
Document Shepard: Bernard Aboba

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the
responsibilities is
answering the questions in this write-up to give helpful context to Last
Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the
authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be
sure
to answer all of them.

## Technical and Working Group Summary

Technical Summary:

   This document describes the RTP payload format for the Essential
   Video Coding (EVC) standard, published as ISO/IEC 23094-1.
   The RTP payload format, which is applicable to video conferencing,
   video streaming and high-bitrate entertainment-quality video,
   allows for packetization of Network Abstraction Layer (NAL) units
   in an RTP packet payload as well as fragmentation of a NAL
   unit into multiple RTP packets.

   EVC inherits the basic systems and transport interfaces designs from
   VVC, HEVC and AVC. These include the NAL-unit-based syntax structure,
   the hierarchical syntax and data unit structure and the Supplemental
   Enhancement Information (SEI) message mechanism. However, EVC supports
   a subset of VVC feature set.  For example, EVC supports
   temporal but not spatial or quality scalability.

Working Group Summary:

   The EVC payload specification closely resembles the RTP payload
   specification for VVC (RFC 9328), so discussion in the WG focused
   on the differences between the EVC and VVC codecs and the impact
   on the RTP payload format.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence
of a
   few individuals, with others being silent, or did it reach broad
agreement?

WG consensus behind this document appears solid. A summary of the WGLC was
posted to the AVTCORE mailing list on May 2, 2023:
https://mailarchive.ietf.org/arch/msg/avt/9KnvogwIX6Wi77VtYNmV3Sjfhik/

5 responses were received to the WGLC announcement, all supporting
publication.
There were no objections.

2. Was there controversy about particular points, or were there decisions
where
   the consensus was particularly rough?

The EVC RTP payload format is derived from RFC 9328, the VVC RTP payload
format.
Since the WG previously came to consensus on RFC 9328, the development of
the
EVC payload format went smoothly.

3. Has anyone threatened an appeal or otherwise indicated extreme
discontent? If
   so, please summarize the areas of conflict in separate email messages to
the
   responsible Area Director. (It should be in a separate email because this
   questionnaire is publicly available.)

No appeal threats or extreme discontent expressed.

4. For protocol documents, are there existing implementations of the
contents of
   the document? Have a significant number of potential implementers
indicated
   plans to implement? Are any existing implementations reported somewhere,
   either in the document itself (as [RFC 7942][3] recommends) or elsewhere
   (where)?

Tencent has developed a prototype of the EVC RTP payload format, which is
almost identical to the media plane of RFC 9328.
See: https://mailarchive.ietf.org/arch/msg/avt/2ihJhUi4OKaj80RrUAeW_6lt5LI/

There are no known implementation of the SDP signaling. So far, there have
not been any interop events relating to the EVC RTP payload specification.

## Additional Reviews

5. Do the contents of this document closely interact with technologies in
other
   IETF working groups or external organizations, and would it therefore
benefit
   from their review? Have those reviews occurred? If yes, describe which
   reviews took place.

The EVC RTP payload format document is based on the EVC specification
developed in ISO.
The authors of the EVC payload format include the IETF liaison to SC29
(Stephan Wenger)
so there has been close coordination.

6. Describe how the document meets any required formal expert review
criteria,
   such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

The document does not define any MIBs, YANG modules or URIs. It does
include a
Media Type Registration in Section 7.1. This is based on the Media Type
Registration in RFC 9328, so it has started from a stable foundation.

7. If the document contains a YANG module, has the final version of the
module
   been checked with any of the [recommended validation tools][4] for
syntax and
   formatting validation? If there are any resulting errors or warnings,
what is
   the justification for not fixing them at this time? Does the YANG module
   comply with the Network Management Datastore Architecture (NMDA) as
specified
   in [RFC 8342][5]?

No YANG module.

8. Describe reviews and automated checks performed to validate sections of
the
   final version of the document written in a formal language, such as XML
code,
   BNF rules, MIB definitions, CBOR's CDDL, etc.

No formal languages are used in this specification.

## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that
this
   document is needed, clearly written, complete, correctly designed, and
ready
   to be handed off to the responsible Area Director?

The document is motivated by the desire to offer a royalty-free codec
utilizing
some of the technology developed in VVC. That goal seems useful if it can be
achieved (see the IPR concerns, below).

The approach to RTP packetization utilized by EVC has been previously
applied in
the VVC, HEVC and AVC RTP payload specifications, so that the design is well
understood.  As the design has evolved from the AVC specification to HEVC
and VVC, the approach has been simplified with infrequently used options
being
eliminated, reducing implementation complexity and improving
interoperability.
This trend continues with EVC, which offers a limited feature set compared
with VVC (e.g. support for temporal scalability, but not spatial or
quality).

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been
identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

None of the issues detailed in [6] apply to this document, other than Media
Type registration.

11. What type of RFC publication is being requested on the IETF stream
([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper
type
    of RFC? Do all Datatracker state attributes correctly reflect this
intent?

Publication as a Proposed Standard is requested. This is reflected in
Datatracker.
RFC 9328, which is closely related to this document, was also published as a
Proposed Standard.

12. Have reasonable efforts been made to remind all authors of the
intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]?
To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including
links
    to publicly-available messages when applicable.

On June 16, 2023 a request for author confirmation was posted to the
AVTCORE WG mailing list:
https://mailarchive.ietf.org/arch/msg/avt/-lVJ9hRTn0Y7iz369pW88N6jy-4/

A response was received from each of the authors:

Stephan Wenger:
https://mailarchive.ietf.org/arch/msg/avt/Eqb8TWcVzaOaBTmr9-op65UQXFY/
Shuai Zhao:
https://mailarchive.ietf.org/arch/msg/avt/oZceElHTOKvifqThAl5gCczHQlY/
Youngkwon Lim:
https://mailarchive.ietf.org/arch/msg/avt/fH6_1ES0kl3u8QAqksOpiGzS9Ms/

An IPR declaration has been filed:
https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-ietf-avtcore-rtp-evc

As noted in draft-ietf-avtcore-rtp-evc Section 1:

"The Essential Video Coding [EVC] standard, which is formally designated as
ISO/IEC International Standard 23094-1
[ISO23094-1] has been published in 2020. One goal of MPEG is to keep
[EVC]'s Baseline profile essentially
royalty-free by using technologies published more than 20 years ago or
otherwise known to be available for use
without a requirement for paying royalties, whereas more advanced profiles
follow a reasonable and
non-discriminatory licensing terms policy."

Given the EVC development goals, the filing of an IPR declaration is a
potential concern.
On June 16, 2023 the AVTCORE WG was solicited as to whether wished to
continue to proceed to publication:
https://mailarchive.ietf.org/arch/msg/avt/JUDZDgW31xjHMO-kMb6NSr-Buj0/

Responses from the authors indicated a willingness to proceed:
Stephan Wenger:
https://mailarchive.ietf.org/arch/msg/avt/f5H_Sqz3bSzMGFWccNosnrmnYGk/
Shuai Zhao:
https://mailarchive.ietf.org/arch/msg/avt/IVFbH1nb6aPjmByc-hX7VEwemhA/
Youngkwon Ling:
https://mailarchive.ietf.org/arch/msg/avt/CQLmSbVscmFBNtEeLs94qNph9FQ/
Roman Chernyak:
https://mailarchive.ietf.org/arch/msg/avt/Tp81f2zPTyj8ikOC3SMcPUWc9H0/

No objections to publication were received on the AVTCORE WG mailing list.

The issue will also be brought up at the IETF 117 AVTCORE WG meeting.

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front
page
    is greater than five, please provide a justification.

On June 26, 2023 I posted a message to the AVTCORE WG mailing list,
requesting the
agreement of authors, editors and contributor to be listed as such:
https://mailarchive.ietf.org/arch/msg/avt/GpbLyMJVRu0cf44MGbp9DZbEm84/

The authors and acknowledged contributors have affirmed their willingness
to be listed:

Stephan Wenger:
https://mailarchive.ietf.org/arch/msg/avt/AGKjtH5idZThJ6HPvK3teig7gJw/
Youngkwon Lim:
https://mailarchive.ietf.org/arch/msg/avt/zPbyT2GXAGgtWPsZ0maVM5hZ1Gc/
Shuai Zhao:
https://mailarchive.ietf.org/arch/msg/avt/9opVmOWsRFlCknrp6fw9l789_Jk/
Roman Chernyak:
https://mailarchive.ietf.org/arch/msg/avt/CPGFxFs5aS8z93DQY2LDqQzSiSM/

14. Document any remaining I-D nits in this document. Simply running the
[idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

An ID nits check run on -04 discloses 0 errors, 0 flaws and 1 warning.

Section 12 has two spelling errors:

   Large parts of this specification share text with the RTP payload
   format for VVC [RFC9328].  Roman Chernyak is thanksed for his

s/thansked/thanked/

   valueable review comments.  We thank the authors of that
s/valueable/valuable/

15. Should any informative references be normative or vice-versa? See the
[IESG
    Statement on Normative and Informative References][16].

The normative and informative references appear to be appropriate.

16. List any normative references that are not freely available to anyone.
Did
    the community have sufficient access to review any such normative
    references?

The EVC RTP Payload format has a normative reference to the EVC
specification,
"ISO/IEC 23094-1 Essential Video Coding", 2020, <
https://www.iso.org/standard/57797.html>

This specification is behind a paywall.  However, to assist reviewers
interested in the
specification, Stephan Wenger (IETF liaison to SC29) has worked with
ISO/IEC to make the
specification free of charge to reviewers requesting it:
https://mailarchive.ietf.org/arch/msg/avt/HmTrkqKQFr406LLjAYFfZ0MODvI/

To test the process, I have requested the specification and it has been
provided to me.

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If
so,
    list them.

No.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear
state?
    If so, what is the plan for their completion?

There are no normative references to documents in an unclear state.

19. Will publication of this document change the status of any existing
RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those
RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is
discussed.

The document does not change the status of any existing RFC.

20. Describe the document shepherd's review of the IANA considerations
section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified.
Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

The IANA considerations section, which includes the Media Registration,
is based on RFC 9325, albeit with a smaller range of options and
parameters.

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]:
https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/