Creating a Side-by-Side Video with FFmpeg
$ ffmpeg -i input.mp4 -vf hue=s=0 -acodec copy grayScale.mp4
$ ffmpeg -i input.mp4 -i grayScale.mp4 -filter_complex '[0:v]pad=iw*2:ih[int];[int][1:v]overlay=W/2:0[vid]' -map [vid] -map 0:a -acodec copy sideBySide.mp4
More details here: https://dragonquest64.blogspot.com/20...