[FFmpeg-user] How to ffplay side-by-side 2 videos which are of different size?

[Phil Forneur]

Hello,

If 2 videos do have the same width and height, one can view them side by
side with

ffplay -f lavfi
"movie='LEFT.mp4',scale=iw/2:ih[v0];movie='RIGHT.mp4',scale=iw/2:ih[v1];[v0][v1]hstack"


What now if the 2 videos are of different size???

I wish that my monitor is divided into 2 panes, left video being smaller
that right one, if need be the smaller video will be black padded.

Actually, I want to compare the output on the LEFT with a video with a low
CRF and on the RIGHT with a video with a higher CRF but with upsaling.

Videos to be compared
ffmpeg -y -i "M4H03893.mp4" -vf
"crop=in_w-36*20:in_h-10*20:18*20:3*20,hqdn3d" -c:a copy -c:v libx264 -crf
12 -preset:v slow -async 1 -t 153 "LEFT.mkv"

ffmpeg -y -i "M4H03893.mp4" -vf
"crop=in_w-36*20:in_h-10*20:18*20:3*20,hqdn3d,scale=-2:720" -c:a copy -c:v
libx264 -crf 25 -preset:v slow -async 1 -t 153 "RIGHT.mkv"

Thanks