International organisation for standardisation organisation internationale de normalisation

No.	Title	TBP
Available
12736	Text of ISO/IEC 23001-4:2011/DAM1 CAL Language Extensions	N	12/05/04
12738	Disposition of comments on ISO/IEC 23002-4 DCOR1	N	12/05/04
12739	Text of ISO/IEC 23002-4 COR1	N	12/05/04

73D video coding

7.1General status

Following discussions and a request made at the 99^th meeting, an overall investigation of the compression benefit of the different investigated solutions was made (referred to as “CE0” or “CE annex A”. This included

1. 
   the MVC plus depth extension of 14496-10:2012 PDAM2, with no changes at the macroblock level and below
   
2. 
   the “AVC compatible” extension described in N12732 and N12743, which include changes at macroblock level and below
   
3. 
   “hybrid” solutions, where the base view is encoded by AVC, and dependent view(s) and/or depth maps are coded by HEVC
   
4. 
   HEVC-only solutions without changing CTB level and below (for encoding video and optionally depth)
   
5. 
   HEVC-only solutions with changes at CTB level and below for encoding of depth maps and dependent view(s).
   

Detailed results are provided in m24968, which measures the PSNR versus rate benefits for the encoded views only (not the synthesized views). Following prior communication with the Qualinet group, for the case of encoded views, the PSNR results show some correlation with the subjective quality. The following numbers provide average bit rate (BR) reductions (Bjöntegaard delta) compared to case a) (MVC+depth, PDAM2), for both 3-view/2-view cases:

b) AVC compatible 10.7/8.3% BR reduction

c) hybrid AVC/HEVC 34.1/24.8% BR reduction

d) MV-HEVC 48/46.98% BR reduction

e) HTM-HEVC 53.6/51.4% BR reduction

It was also remarked that the bit rate reductions would probably be lower with the use of more challenging material (higher amount of motion, scenes with larger depth variations). On the other hand, subjective assessment of the quality might indicate higher gains.
More detail can be found in subsection “Appendix A” under 7.2. As a general conclusion, it was discussed together with the Requirements subgroup that it would be undesirable to define a second standard (i.e. incompatible codec design for stereoscopic video) when the benefit is not obvious and no additional functionality is supported. It was agreed that, when considering subjective quality, roughly a 25% reduction in bit rate may be sufficient to justify such an incompatible solution, i.e., solution b) versus a) or solution e) versus d). It was generally observed that significantly more improvement would be required than is currently being reported (in terms of compression gain).