http://video.stackexchange.com/questions/17637/which-measure

ffmpeg -ss 8 -i "L:\DCIM\100MEDIA\FILE0129.MOV" -t 3 -c:v libx264 -crf 18 -c:a copy -map 0 "Test\compressed18.mp4"
ffmpeg -i "Test\compressed18.mp4" -ss 8 -i "L:\DCIM\100MEDIA\FILE0129.MOV" -t 3 -lavfi "ssim;[0:v][1:v]psnr" -f null - > "Test\compressed18.txt" 2>&1
...
ffmpeg -ss 8 -i "L:\DCIM\100MEDIA\FILE0129.MOV" -t 3 -c:v libx264 -crf 37 -c:a copy -map 0 "Test\compressed37.mp4"
ffmpeg -i "Test\compressed37.mp4" -ss 8 -i "L:\DCIM\100MEDIA\FILE0129.MOV" -t 3 -lavfi "ssim;[0:v][1:v]psnr" -f null - > "Test\compressed37.txt" 2>&1