Weighted single motion search is implemented for obmc predictor.
When NEWMV mode is used, to determine the MV for the current block,
we run weighted motion search to compare the weighted prediction
with (source - weighted prediction using neighbors' MVs), in which
the distortion is the actual prediction error of obmc prediction.
Coding gain: 0.404/0.425/0.366 for lowres/midres/hdres
Speed impact: +14% encoding time
(obmc w/o mv search 13%-> obmc w/ mv search 27%)
Change-Id: Id7ad3fc6ba295b23d9c53c8a16a4ac1677ad835c
Optimized 2 up-sampled reference prediction functions in high-bit
depth case. This reduced the HBD encoding time by 3%.
Change-Id: I8663ffb5234f5e70168c0fc9ca676309fe8e98f2
Using the up-sampled reference frames in sub-pixel motion search is
enabled as a speed feature for good-quality mode speed 0 and speed 1.
Change-Id: Ieb454bf8c646ddb99e87bd64c8e74dbd78d84a50
Up-sampled the reference frames to 8 times in each dimension using
the 8-tap interpolation filter. In sub-pixel motion search, use the
up-sampled reference frames to find the best matching blocks. This
largely improved the motion search precision, and thus, improved
the compression quality. There was no change in decoder side.
Borg test and speed test results:
1. On derflr set,
Overall PSNR gain: 1.306%, and SSIM gain: 1.512%.
Average speed loss on derf set was 6.0%.
2. On stdhd set,
Overall PSNR gain: 0.754%, and SSIM gain: 0.814%.
On hevchd set,
Overall PSNR gain: 0.465%, and SSIM gain: 0.527%.
Speed loss on HD clips was 3.5%.
Change-Id: I300ebaafff57e88914f3dedc8784cb21d316b04f
