JVET-S0126 AHG8: On scaling window constraint [Y.-J. Chang, V. Seregin, Y. He, A. K. Ramasubramonian, M. Coban, M. Karczewicz (Qualcomm)]
Plenary meetings, joint meetings, BoG reports, and summary of actions taken
Joint meeting with MPEG Systems Monday 29 June 1430-1500
A joint meeting was held of JVET, JCT-VC, and MPEG Video, led by MPEG Systems.
The discussion was primarily a review of MPEG document m54772, re-registered as JVET-S0268, providing an overview of MPEG systems work related to coded video bitstreams.
See the notes for that contribution in section 4.1.
It was noted that SEI manifest and SEI prefix SEI messages are not specified in the draft of the SEI specification. See the notes for JVET-S0269, which was submitted in response to this discussion.
Joint meeting with JCT-VC, VCEG (Q6/16) and MPEG Requirements Tuesday 30 June 1300-1500
Profiles and the tools included in the profiles were discussed (see section 4.9).
- JVET-S0187 proposing a profile without scalability and subpicture support
- m54735 advocating support for subpictures for 360° video streaming
The following NB ballot comment was also noted.
- FINB request for higher frame rates than 300 fps and higher buffering capacity than 16 frames.
Make high tier support up to ~960?
Decision: OK. (Further discussed at 2310 on 30 June in JVET and confirmed as 960.)
It was noted that temporal sublayers could be decoded at lower frame rate.
No change to the maximum buffering capacity was agreed.
Issuing a TP/TR on BD-PSNR coding efficiency measurement was discussed and agreed.
- PDTR in MPEG, Approval in SG 16 at the current meeting.
Future work
With JCT-VC not so active, and VVC v1 finished, and some future work overlapping (e.g., SEI messages), it is expected for SG 16 to request merging JCT-VC into JVET. This was generally supported in the discussion. JVET would have a scope to include all of the joint video coding work. JCT-VC AHGs established at this meeting may report into JVET, pending SC29 consideration. Some website functionality support would be desirable to distinguish document.
See section 4.5 for technical work on the coding of content with bit depths beyond what is supported in VVC v1.
- This should be studied in JVET for potential development of a v2 of VVC
See JVET-S0091 aspect 1 and JVET-S0202 aspect 2 regarding scalability support in still picture profiles, esp. to consider whether such a profile should be specified in a future version of VVC. The “progressive refinement SEI message” and multiview, multi-camera, multiexposure, multi-focal-length usage were mentioned as related.
- It was commented that this could be done in v1, considering that we have agreed to establish a profile separation based on layering support. However, we have not been planning to have multilayer support in the still picture profile and there seemed to be no pressing need for immediate action.
- So for v1, it was agreed to just have a single-layer still picture profile.
- This is to be further studied pending industry input for future work.
VVC v1 was agreed to have the following specified profiles:
- “Main 10 Still Picture” profile and “Main 10 4:4:4 Still Picture” profile
- “Main 10” and “Multilayer Main 10”
- “Main 10 4:4:4” and “Multilayer Main 10 4:4:4”
It was agreed that some additional types of scalability, such as ROI scalability, should also be studied in future work of JVET.
3–5 SEI messages had also been proposed that can be considered in further work of JVET, as recorded in section 6.1.9.
- JVET is to issue a TuC toward consideration of potential additional SEI messages
Potential errata work will also be planned for JVET future work.
JVET is to study toward a v2 of SEI (H.274 | 23002-7) and VVC (H.266 | 23090-3).
“VSEI” (Versatile SEI) was agreed as a nickname for ITU-T H.274 | ISO/IEC 23002-7.
The development of a TR v3 on usage of codepoints for video (correction/clarification) is to move forward in JCT-VC (pending potential merger into JVET).
Contribution JVET-S0267 was discussed, which proposed establishing an AHG on neural network based coding tools investigation for potential further work. It was agreed to establish such an AHG. A record of the discussion is found in section 4.1.
Closing plenary meeting sessions Tuesday 30 June and Wednesday 1 July
Closing plenary discussions were held as follows:
- Tue. 30 June, 9th day
- 1900–2100 Conformance, remainders, AHGs, etc.
- 2120–2320 Remainders, AHGs, etc.
- Wed. 1 July, 10th day
- 1420–1540 General closing plenary sessions
- 1615–1800 Tickets and editors' notes, AHG planning, outputs review, closing plenary sessions
- 1900–2100 General closing plenary sessions
The status of work was discussed, including review of the status of work on the following:
- CTC
- Open input reviews and revisits
- Project development discussion (section 4.1)
- Output documents & dates
- AHG plans
- Meeting plans
- Discussion of the verification test plan and procedure (future planning for scalability was noted)
- Review of actions taken
- Doc deadline for the next meeting
BoGs
No formal break-out groups were established at this meeting that produced reports, although some offline studies were reported.
Project planning
Core experiment planning
No CEs were planned at this meeting.
Drafting of specification text, encoder algorithm descriptions, and software
The following agreement has been established: the editorial team has the discretion to not integrate recorded adoptions for which the available text is grossly inadequate (and cannot be fixed with a reasonable degree of effort), if such a situation hypothetically arises. In such an event, the text would record the intent expressed by the committee without including a full integration of the available inadequate text.
Plans for improved efficiency and contribution consideration
The group considered it important to have the full design of proposals documented to enable proper study.
Adoptions need to be based on properly drafted working draft text (on normative elements) and HM encoder algorithm descriptions – relative to the existing drafts. Proposal contributions should also provide a software implementation (or at least such software should be made available for study and testing by other participants at the meeting, and software must be made available to cross-checkers in EEs).
Suggestions for future meetings included the following generally supported principles:
- No review of normative contributions without draft specification text
- VTM algorithm description text is strongly encouraged for non-normative contributions
- Early upload deadline to enable substantial study prior to the meeting
- Using a clock timer to ensure efficient proposal presentations (5 min) and discussions
The document upload deadline for the next meeting was planned to be Wednesday 30 Sep. 2020.
As general guidance, it was suggested to avoid usage of company names in document titles, software modules etc., and not to describe a technology by using a company name.
General issues for experiments
It was emphasized that those rules which had been set up or refined during the 12th meeting should be observed. In particular, for some CEs of some previous meetings, results were available late, and some changes in the experimental setup had not been sufficiently discussed on the JVET reflector.
No group coordinated experiments were established at the current meeting. General practices for such experiments have been planned as follows:
- “Core experiments” (CEs) are the coordinated experiments on coding tools which are deemed to be interesting but require more investigation and could potentially become part of the draft standard by the next meeting.
- A CE is a test of a specific fully described technology in a specific agreed way. It is not a forum for thinking of new ideas (like an AHG). The CE coordinators are responsible for making sure tha the CE description is complete and correct and has adequate detail. Reflector discussions about CE description clarity and other aspects of CE plans are encouraged.
- A description of each experiment is to be approved at the meeting at which the experiment plan is established. This should include the issues that were raised by other experts when the tool was presented, e.g., interference with other tools, contribution of different elements that are part of a package, etc. The experiment description document should provide the names of individual people, not just company names.
- Software for tools investigated in a CE will be provided in one or more separate branches of the software repository. Each CE will have a “fork” of the software, and within the CE there may be multiple branches established by the CE coordinator. The software coordinator will help coordinate the creation of these forks and branches and their naming. All JVET members will have read access to the CE software branches (using shared read-only credentials as described below).
- During the experiment, revisions of the experiment plans can be made, but not substantial changes to the proposed technology.
- The CE description must match the CE testing that is done. The CE description needs to be revised if there has been some change of plans.
- The CE summary report must describe any changes that were made in the process of finalizing the CE.
- By the next meeting it is expected that at least one independent cross-checker will report a detailed analysis of each proposed feature that has been tested and confirm that the implementation is correct. Commentary on the potential benefits and disadvantages of the proposed technology in cross-checking reports is highly encouraged. Having multiple cross-checking reports is also highly encouraged (especially if the cross-checking involves more than confirmation of correct test results). The reports of cross-checking activities may (and generally should) be integrated into the CE report rather than submitted as separate documents.
It is possible to define sub-experiments within particular CEs, for example designated as CEX.a, CEX.b, etc., where X is the basic CE number.
As a general rule, it was agreed that each CE should be run under the same testing conditions using one software codebase, which should be based on the group test model software codebase. An experiment is not to be established as a CE unless there is access given to the participants in (any part of) the CE to the software used to perform the experiments.
The general agreed common conditions for single-layer coding efficiency experiments are described in the output document JVET-N1010.
Experiment descriptions should be written in a way such that it is understood as a JVET output document (written from an objective “third party perspective”, not a proponent perspective – e.g. not referring to methods as “improved”, “optimized”, etc.). The experiment descriptions should generally not express opinions or suggest conclusions – rather, they should just describe what technology will be tested, how it will be tested, who will participate, etc. Responsibilities for contributions to CE work should identify individuals in addition to company names.
CE descriptions contain a basic description of the technology under test, but should not contain excessively verbose descriptions of a technology (at least not unless the technology is not adequately documented elsewhere). Instead, the CE descriptions should refer to the relevant proposal contributions for any necessary further detail. However, the complete detail of what technology will be tested must be available – either in the CE description itself or in documents that are referenced in the CE description that are also available in the JVET document archive.
Any technology must have at least one cross-check partner to establish a CE – a single proponent is not enough. It is highly desirable have more than just one proponent and one cross-checker.
The CE development workflow is described at:
https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/wikis/Core-experiment-development-workflow
CE read access is available using shared accounts: One account exists for MPEG members, which uses the usual MPEG account data. A second account exists for VCEG members with account information available in the TIES system at:
https://www.itu.int/ifa/t/2017/sg16/exchange/wp3/q06/vceg_account.txt
Some agreements relating to CE activities were established as follows:
- Only qualified JVET members can participate in a CE.
- Participation in a CE is possible without a commitment of submitting an input document to the next meeting. Participation is requested by contacting the CE coordinator.
- All software, results, and documents produced in the CE should be announced and made available to JVET in a timely manner.
- A JVET CE reflector will be established and announced on the main JVET reflector. Discussion of logistics arrangements, exchange of data, minor refinement of the test plans, and preparation of documents shall be conducted on the JVET CE reflector, with subject lines prefixed by “[CEx: ]”, where “x” is the number of the CE. All substantial communications about a CE other than such details shall take place on main JVET reflector. In the case that large amounts of data are to be distributed, it is recommended to send a link to the data rather than the data itself, or upload the data as an input contribution to the next meeting.
General timeline for CEs
T1= 3 weeks after the JVET meeting: To revise the CE description and refine questions to be answered. Questions should be discussed and agreed on JVET reflector. Any changes of planned tests after this time need to be announced and discussed on the JVET reflector. Initially assigned description numbers shall not be changed later. If a test is skipped, it is to marked as “withdrawn”.
T2 = Test model software release + 2 weeks: Integration of all tools into a separate CE branch of the VTM is completed and announced to JVET reflector.
- Initial study by cross-checkers can begin.
- Proponents may continue to modify the software in this branch until T3
- 3rd parties are encouraged to study and make contributions to the next meeting with proposed changes
T3: 3 weeks before the next JVET meeting or T2 + 1 week, whichever is later: Any changes to the CE test branches of the software must be frozen, so the cross-checkers can know exactly what they are cross-checking. A software version tag should be created at this time. The name of the cross-checkers and list of specific tests for each tool under study in the CE plan description shall be documented in an updated CE description by this time.
T4: Regular document deadline – 1 week: CE contribution documents including specification text and complete test results shall be uploaded to the JVET document repository (particularly for proposals targeting to be promoted to the draft standard at the next meeting).
The CE summary reports shall be available by the regular deadline. This shall include documentation about crosscheck of software, matching of CE description and confirmation of the appropriateness of the text change, as well as sufficient crosscheck results to create evidence about correctness (crosscheckers must send this information to the CE coordinator at least 3 days ahead of the document deadline). Furthermore, any deviations from the timelines above shall be documented. The numbers used in the summary report shall not be changed relative to the description document.
CE reports may contain additional information about tests of straightforwared combinations of the identified technologies. Such supplemental testing needs to be clearly identified in the report if it was not part of the CE plan.
New branches may be created which combine two or more tools included in the CE document or the VTM (as applicable).
It is not necessary to formally name cross-checkers in the initial version of the CE description document. To adopt a proposed feature at the next meeting, we would like see comprehensive cross-checking done, with analysis that the description matches the software, and recommendation of value of the tool given tradeoffs.
The establishment of a CE does not indicate that a proposed technology is mature for adoption or that the testing conducted in the CE is fully adequate for assessing the merits of the technology, and a favourable outcome of CE does not indicate a need for adoption of the technology.
Availability of spec text is important to have a detailed understanding of the technology and also to judge what its impact on the complexity of the spec will be. There must also be sufficient time to study it in detail. CE contributions without sufficiently mature draft spec text in the CE input document should not be considered for adoption.
Lists of participants in CE documents should be pruned to include only the active participants. Read access to software will be available to all members.
Establishment of ad hoc groups
The ad hoc groups established to progress work on particular subject areas until the next meeting are described in the table below. The discussion list for all of these ad hoc groups was agreed to be the main JVET reflector (jvet@lists.rwth-aachen.de).
Title and Email Reflector | Chairs | Mtg |
Project Management (AHG1)
| J.-R. Ohm, G. J. Sullivan (co-chairs) | N |
Draft text and test model algorithm description editing (AHG2)
| B. Bross, J. Chen (co-chairs), J. Boyce, S. Kim, S. Liu, Y.-K. Wang, Y. Ye (vice-chairs) | N |
Test model software development (AHG3)
| F. Bossen, X. Li, K. Sühring (co-chairs) | N |
Test material and visual assessment (AHG4)
| V. Baroncini, T. Suzuki, M. Wien (co-chairs), A. Norkin, A. Segall, Y. Ye (vice-chairs) | Tel. 2 weeks notice |
Conformance testing (AHG5)
| J. Boyce and W. Wan (co-chairs), E. Alshina, F. Bossen, I. Moccagatta, K. Kawamura, K. Sühring, X. Xu (vice-chairs) | N |
360° video coding, software and test conditions (AHG6)
| J. Boyce and Y. He (co-chairs), K. Choi, J.-L. Lin, Y. Ye (vice-chairs) | N |
Coding of HDR/WCG material (AHG7)
| A. Segall (chair), E. François, W. Husak, S. Iwamura, D. Rusanovskyy (vice-chairs) | N |
Layered coding and resolution adaptivity (AHG8)
| S. Wenger and A. Segall (co-chairs), M. M. Hannuksela, Hendry, S. McCarthy, Y.-C. Sun, P. Topiwala, Y.-K. Wang (vice-chairs) | N |
SEI message studies (AHG9)
| S. McCarthy (chair), J. Boyce, P. de Lagrange, A. Luthra, A. Tourapis, Y.-K. Wang, S. Wenger (vice-chairs) | N |
Encoding algorithm optimization (AHG10)
| A. Duenas, A. Tourapis (co-chairs), S. Ikonin, A. Norkin, R. Sjöberg, J. Le Tanou, J.-M. Thiesse (vice-chairs) | N |
Neural-network-based video coding (AHG11)
| E. Alshina, S. Liu, J. Pfaff, M. Wien, P. Wu, Y. Ye (co-chairs) | Tel. 2 weeks notice |
High bit depth, high bit rate, and high frame rate coding (AHG12)
| A. Browne, T. Ikai, X. Xiu (co-chairs) | N |
Tool reporting procedure and testing (AHG13)
| W.-J. Chien, J. Boyce (co-chairs), Y.-W. Chen, R. Chernyak, K. Choi, R. Hashimoto, Y.-W. Huang, H. Jang, R.-L. Liao, S. Liu (vice-chairs) | N |
Output documents
The following documents were agreed to be produced or endorsed as outputs of the meeting. Names recorded below indicate the editors responsible for the document production. Where applicable, dates of planned finalization and corresponding parent-body document numbers are also noted.
It was reminded that in cases where the JVET document is also made available as MPEG output document, a separate version under the MPEG document header should be generated. This version should be sent to GJS and JRO for upload.