MSE changes from 0.04890000 to 0.02969844
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

no changes in either standard deviation or PSNR is seen in any of the changed fate
cases

MSE changes from 0.05012422 to 0.04890000
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This replaces 64 additions by 8 additions

MSE Changes from 0.04873672 to 0.05012422
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Fixes out of array writes
No FFmpeg release is affected by this

This also fixes some artifacts

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>