gistfile1.txt

# how encoding is generated
ffmpeg -i original.mp4 -vcodec libx264 -an -r 32 -psnr tmp.r.32.mp4
[libx264 @ 0x55eeb882f740] PSNR Mean Y:50.209 U:53.879 V:54.116 Avg:51.126 Global:50.895 kb/s:5677.83
# baseline psnr is ~51

# how lossless versions are generated.
ffmpeg -i original.mp4 -vcodec libx264 -an -r 32 -crf 0 tmp.r.32.lossless.mp4
ffmpeg -i original.mp4 -vcodec libx264 -an -r 32 -crf 0 tmp.r.32.lossless.mkv


# psnr filter with lossless mp4 as ref gives ~50
ffmpeg -i tmp.r.32.mp4 -i tmp.r.32.lossless.mp4 -filter_complex psnr -f null -
[Parsed_psnr_0 @ 0x56137786f160] PSNR y:49.973142 u:53.836934 v:54.030499 average:50.938918 min:48.695024 max:52.921619

# psnr filter with lossless mkv as ref gives ~18
ffmpeg -i tmp.r.32.mp4 -i tmp.r.32.lossless.mkv -filter_complex psnr -f null -
[Parsed_psnr_0 @ 0x55573e102520] PSNR y:16.786297 u:27.223216 v:25.669281 average:18.314932 min:12.491270 max:52.826369