JVET-AE0288 Results of expert viewing for the spatial scalability category of the VVC multilayer VT [M. Wien (RWTH Aachen University), K. Andersson (Ericsson), P. de Lagrange (InterDigital)]

This document reports the results of an on-site expert viewing performed at the 31^st JVET meeting in Geneva, CH.

The evaluation targets at the spatial scalability category of the test plan document JVET-AD2021, comparing the compression performance of dual layer (DL) coding with a downscaled base layer at scaling ratio 2 to single layer coding at the low resolution with upscaling to the target resolution using the VVC interpolation filters (UP) as well as single layer coding at the target resolution (SL).

A total of 29 experts participated in the expert viewing. Based on this larger database, the results reveal small confidence intervals and can reportedly be considered quite reliable.

With respect to the goals of this experiment, the following observations were made:

• DL shows a slight benefit over UP for DrivingPOV3 (overlapping confidence intervals), very minor for MountainBay2.
• No benefit or slight loss for DL compared to UP for Procession.
• More loss for DL compared to UP for CorsaireJoy, Marathon2, and, partially significant, for TallBuilding2.
• Relation of SL, DL, UP somewhat according to expectations on MountainBay2 (SL gaining at high rates, while DL, UP gaining at low rates.
• ISSUE observed for TallBuildings2: UP better than SL and DL for lower two rate points. Possible reason: less pumping artefacts for UP streams which are coded at a lower QP. Better detail of SL or DL does not...

JVET-AJ0010 JVET AHG report: Encoding algorithm optimization (AHG10) [P. de Lagrange, A. Duenas, R. Sjöberg, A. Tourapis (AHG chairs)]

• Activity

The regular JVET e-mail reflector was used for discussions (jvet@lists.rwth-aachen.de).

Teleconferences were held on August 20^th, September 5^th, September 26^th and October 14^th, and a few related organizational and reporting e-mails were sent to the JVET reflector. No other e-mail related to AHG10 activity was sent during the AHG period.

• Related contributions

Four contributions, not including cross-checks, were identified relating to AHG10, and summarized in the following sections.

• Scalability
• JVET-AJ0042 - AHG10: Teleconference on encoder optimization for multi-layer coding

This document summarizes discussions during teleconferences on encoder optimization for multi-layer coding, focusing on the mandate related to multi-layer coding.

The work is related to an issue found during visual tests of spatial scalability in Geneva (31^st meeting), where the VTM encoder could create an enhancement layer that degrades visual quality (see JVET-AE0288), introducing coding artefacts that outweigh the benefits of detail enhancement. The situation was improved at the following meeting (see JVET-AF0186 and JVET-AF0311) but is still not satisfying.

The goal of the teleconference was to organize encodings and preliminary checks (both objective metrics and informal visual reports) with different configuration and/or new ideas and spread the load, so that meaningful visual tests can be conducted with AHG4/AG5.

Suggested tests included evaluating the...

JVET-AF0311 Results of expert viewing at AF meeting for the spatial scalability category of the VVC multilayer VT M. Wien (RWTH Aachen University)

See section 7.5 for the initial discussion in a joint session. This document reports the results of an on-site expert viewing performed at the 32^nd JVET meeting in Hannover, DE.

The evaluation targets at the spatial scalability category of the test plan document JVET-AE2021, comparing the compression performance of dual layer (DL) coding with a downscaled base layer at scaling ratio 2 to single layer coding at the low resolution with upscaling to the target resolution using the VVC interpolation filters (UP) as well as single layer coding at the target resolution (SL).

19 experts participated in the expert viewing. With a comparably low number of valid scores, the results should be considered as an indication of tendencies. They are not regarded as a necessarily conclusive result.

With respect to the goals of this experiment, the following observations are made:

• Since the UP sequences represent the extracted base layer of the DL streams, the impact of the enhancement layer can be studied. It can be seen that in most cases, the MOS only slightly increases with the inclusion of the enhancement layer. This might be attributed to the fact that other effects overlay the benefit of enhanced detail provided with the DL stream.
• The result show a similar relation of the SL, DL, and UP results compared to JVET-AE0288 for the sequences CorsaireJoy. For TallBuildings2, the results seem to indicate a visual improvement of the DL...