$ (time ffmpeg -v error -i test.mp4 -c copy -f hash -; time sha256sum test.mp4) 2>&1
SHA256=594591d0c7e7a355917fa3c3b90ca2af079e58f77c19c185b36a9887b63d55c8

real	0m0.775s
user	0m0.922s
sys	0m0.188s
c412d5694afe73ad8c98d0d8cb71ba669b83c00324d2bd7f38be0df123865418  test.mp4

real	0m0.225s
user	0m0.156s
sys	0m0.047s