hmm...

libx264-best.ffpreset

# ffmpeg -i "input" -vcodec libx264 -threads 0 -vpre best -crf 25 out.mp4

coder=1
trellis=2
mbd=2
sc_threshold=40
flags=+loop
flags2=+bpyramid+wpred+mixed_refs+mbtree+dct8x8-fastpskip
partitions=+parti4x4+parti8x8+partp4x4+partp8x8+partb8x8
i_qfactor=0.71
refs=12
me_method=tesa
me_range=16
cmp=chroma
bf=16
b_strategy=2
bidir_refine=1
directpred=3
g=250
keyint_min=25
qmin=10
qmax=51
qdiff=4
qcomp=0.6
subq=10