Joint Collaborative Team on Video Coding (jct-vc) Contribution

6.3BoGs

JCTVC-T0229 BoG report on test sequences for SCC [H. Yu (BoG coordinator)]

(Consideration of this BoG report was chaired by GJS on Sunday 02-15 p.m.)

The BoG met on the morning of Feb. 15, 2015. The purpose of this BoG was to make recommendations on the test sequences to be used after this meeting. About 15 experts attended the discussion.

According to the relevant comments made in the discussion of T0006 in the meeting notes, the BoG suggested to add more 4:2:0 sequences to the CTC. Specifically, the BoG suggested converting the following CTC sequences into 4:2:0 format:

• 
  6 TGM (i.e. all except SlideShow) [glossary TGM]
  
• 
  3 mixed content
  
• 
  1 animation
  

In addition, the BoG suggested using the following sequences from Class F:

• 
  SlideShow
  
• 
  ChinaSpeed
  

A table showing all the selected test sequences and their classifications was presented in the BoG report.

The BoG suggested using a simple filter to do the conversion. Qualcomm offered a 2-tap filter [0.5, 0.5] for the initial conversion.

In the subsequent JCT-VC discussion it was noted that properly the horizontal filter should be an odd length filter, and agreed that [0.25, 0.50, 0.25] will be used horizontally (with adjustment for edges of the picture as needed).

Sample converted sequences will be available for review during this meeting.

The BoG suggested that it would be good to have new test material with non-alphabetical texts, e.g. Chinese text in a browser. However since we do not have such sequences at present time, we cannot add such a sequence yet. The BoG suggested to encourage participants to bring new sequences in the next meeting.

The recommendations of the BoG were agreed by the JCT-VC (with the noted revision of the filtering method to be applied).

JCTVC-T0230 BoG report on IBC memory bandwidth reduction [K. Rapaka, M. Zhou (BoG coordinators)]

(Consideration of this BoG report was chaired by GJS on Sunday 02-15 p.m.)

This document provides a report of the BoG on intra block copy (IBC) memory bandwidth reduction.

Relevant proposals were identified as T0045, T0051, and S0145.

In the BoG, it was suggested to investigate the IBC memory bandwidth analysis under the full frame search area configuration. The bandwidth analysis includes the worst-case and average case memory bandwidth.

Methods recommended to be investigated by the BoG:

1. 
   JCTVC-T0045/ JCTVC-T0051: signal the CTBs which are available for IBC prediction. For these CTBs, the filtering is disabled.
   
2. 
   Combination Test: The encoder method of JCTVC-T0045 is added over JCTVC-T0051
   
3. 
   Signal the CTBs which are available for IBC prediction without disabling filtering operation (JCTVC-S0145).
   
4. 
   Restrict that the any reference pixel for Intra BC cannot be from bi-predicted blocks. This method will have same worst case bandwidth as HEVC.
   
5. 
   Sequence and picture level control: – The filtering is disabled sequence level and adaptively at picture level.
   
6. 
   Under CTC, further reduce the number of inter reference pictures for RA/LD-B by 1.
   

The IBC search range configurations recommended to be tested by the BoG are specified in the following table:

Configuration	8x4	4x8/8x8/16x16/32x32
Config 1	2x1-CTU	Full-frame
Config 2	4x1-CTU	4x1-CTU

In the review of the BoG report, it was remarked that this table may just be reflecting the ordinary planned CTC encoding method, and thus the table may not be needed – and further remarked that we should just use the ordinary CTC in any case.

Additional test configuration recommended by the BoG: CTU size of 16x16 and local search area size in terms of samples is kept same as config 1 (128x64).

Expert subjective analysis was suggested by the BoG to be performed for the methods that change filtering operations (Deblock/SAO).

It was suggested by the BoG to use higher QP (in the range of QP=37) for the visual testing purposes.

It was also suggested by the BoG to test under LD-P configuration for the visual testing purposes, in addition to the usual LD-B configuration.

It was agreed in the BoG that the methods 1, 2, and 4 are reasonable only with use of local cache.

The BoG recommended that there be a CE on the topic.

In the JCT-VC discussion of the BoG report, the rationale for reducing the number of reference pictures was questioned somewhat, and it was not entirely clear what is to be tested for item 5 and its need was somewhat questioned. (Items 5 and 6 were suggested by non-proponents, and the proponents indicated some doubts about those aspects.)

The BoG outcome will be taken into account in the CE plan.

6.4Summary of normative decisions

The following is a summary of the normative decisions made at the meeting for the draft screen content coding extensions:

• 
  …
  
  • 
    …
    

For further detail, see notes in other sections. The above list is only provided as a summary.

7Project planning

7.1WD drafting and software

The following agreement was 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.