In BMS, the affine model seeds are stored in the top-left, top-right and bottom-left 4x4 sub-blocks in the considered CU. In the proposed solution, the affine model seeds are stored separately as a motion information associated to the whole CU.
No action. No impact on performance, and the optimization in terms of storage saving might better be done after stabilization of affine approaches.
CE4.2: Merge mode enhancements (discussed in Track B Thu. 1500-1900, chaired by JRO)
Proposals on CU based candidate – Long distance spatial candidates
Non-adjacent spatial merge candidates (number of candidates is 5)
Non-adjacent spatial merge candidate candidates (number of candidates is 5)
Possible explanations for decoding time increase are, 1) constructing longer list, 2) searching for valid motion info within a search range.
From test 4.2.3 and 4.2.13, it seems the coding gain saturate as the number of candidates increase. 5 looks like the magic number.
Test 4.2.15a shows -1.14% coding gain which is the highest coding gain in this category. On the other hand, the number of RD checks should be taken into account when making a comparison since it may have an impact on the coding gain.
Generally speaking, techniques in this category requires accessing more motion data in the coded area, additional buffer including the line number may be required.
From the data given, it is obvious that the merge performance can be significantly increased when the number of candidates checked is highly increased, the more the better. A reasonable assessment of complexity impact is missing.