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 iq:s 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) as well as individuals involved in the development of the ISO
EVC specification, 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:
https://iana.org/assignments/media-types/video/H266
A review request sent to the media-types mailing list by Stephan Wenger on
March 29, 2023:
https://mailarchive.ietf.org/arch/msg/media-types/5cThdv2nppJbe7nc6vxG0SLOQnk/
A review by Roni Even was posted on April 03, 2023:
https://mailarchive.ietf.org/arch/msg/media-types/AOesp9XTwX29lVgahETowZOMS1w/
Other than recommending that IETF AVTCORE WG be listed as the change controller,
no other issues were found.
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?
I believe that the document is clearly written, complete and correctly designed.
Whether it will ultimately be widely deployed will be determined largely by
factors outside the control of the IETF, such as the performance of EVC in
comparison to other codecs which have either been specified or are under
development (e.g. AV1 and AV2).
The document is motivated by the desire to offer a royalty-free codec utilizing
a subset of the tools in VVC. This goal, if achieved, would assist in the
deployment of EVC (see note relating to IPR declarations 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 the Media
Type registration, which has been reviewed.
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 was brought
to the attention of the WG on the mailing list as well as at IETF 117.
On June 16, 2023 the AVTCORE WG was asked whether, in view of the IPR
declaration, it wished to continue to proceed to publication:
https://mailarchive.ietf.org/arch/msg/avt/JUDZDgW31xjHMO-kMb6NSr-Buj0/
Responses on the mailing list 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 expressed on the AVTCORE WG mailing list.
At IETF 117, the issue was brought up at the AVTCORE WG meeting. No objections
were voiced.
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 sent email to Stephan Wenger <stewe@stewe.org>,
requesting access to the EVC specification, and it was 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/