Add an option -- what should be shown as metric value (arithmetic mean, harmonic mean, min, 1st perc, etc)

[fifonik]

[ls-milkyway]

This cannot be decided universally ...it depends upon project to project ....and what emphasis one wants to pay to media encoding quality. Generally an average is mostly used by the encoders....i.e average VMAF scores of the 2 encodes can be compared to select better encoded video. But this is not valid in all cases ...say while encoding an action flick ...only VMAF scores of the frames with high action can be considered ....rest an average score or can be completely discarded, It will be better if results are shown in percentage ...i,e % of frames below vmaf score 93 ...% of frames above vmaf score 97....depending upon model used.