Of itu-t sg16 wp3 and iso/iec jtc1/SC29/WG11

JCTVC-O0019 JCT-VC AHG report: Verification test preparation (AHG19) [T.K. Tan, V. Baroncini, M. Mrak, W. Wan, M. Karczewicz, J. Wen]

Reviewed Tue. 29th (GJS).

The encoding conditions proposed appear to be stable and no further discussions were made. However, as the changes in the HM12.0 are minimal, the bitstreams that were already encoded in HM11.0 were used for the selection of the test sequences

Candidate test sequences were obtained from the following sources:

• 
  NTIA site: http://www.cdvl.org/index.php
  
• 
  Technicolor
  
• 
  Vidyo
  
• 
  Plannet, Inc
  
• 
  National Institute of Information and Communications Technology (NICT)
  

There were also content proposed by BBC (see JCTVC-O0332) and Elemental, but these content have not been included in the assessment thus far.

The following methodology for selecting sequences and bitrates were used.

• 
  Sequences were encoded with HM11.0 and JM18.5 with QP values of 22, 27, 32 and 37.
  
• 
  Sequences were screen subjectively and sequences that exhibit visible quality degradation when the QP values are increased were shortlisted.
  
• 
  Shortlisted sequences were encoded with additional QP values using the results of 1) as a guide to obtain matching pairs of bitstreams where HM11.0 encoded bitrate is approximately half of the JM18.5 encoded bitstreams.
  
• 
  4 sets of matching pairs of bitstreams were selected (QP values ranging from 25 to 44) such that the quality levels of the sequences cover the widest range of the mean opinion score (MOS) possible.
  

The following numbers of test sequences were shortlisted:

• 
  3 (out of a target of 4) for 4K
  
• 
  5 (out of a target of 5) for 1080p
  
• 
  4 (out of a target of 5) for 720p
  
• 
  2 (out of a target of 5) for 480p
  

Please refer to document JCTVC-O0267 for details of the shortlisted sequences and suggested bit rates.

The question of using the BT.2020 color format for the 4K sequences was raised. However, after some offline discussions it was concluded that this might not be practical as it was reportedly unlikely that 4K displays would be available that adequately support the BT2020 specification.

It was remarked that perhaps an objective measurement based evaluation (e.g. PSNR-based) of BT.2020 coding could be done as part of the VT effort. It was encouraged to explore this possibility in future AHG work.

The group viewed some of the available test sequences.

Participants were encouraged to contribute test sequences suitable as subjective test material covering test resolutions that have yet to achieve the targeted number of sequences.

It was agreed to target completion of the subjective testing by the March/April meeting.