ffmpeg -i video.mp4 -c:v libvpx -threads 1 -slices 6 -b:v 2730k -ss 00:02:19 -t 9 -quality good -cpu-used 0 -r 60 -auto-alt-ref 1 -lag-in-frames 16 -an -metadata title="KF2" -vf scale=-1:640 -pass 1 -f webm null
ffmpeg -i video.mp4 -c:v libvpx -threads 1 -slices 6 -b:v 2730k -ss 00:02:19 -t 9 -quality good -cpu-used 0 -r 60 -auto-alt-ref 1 -lag-in-frames 16 -an -metadata title="KF2" -vf scale=-1:640 -pass 2 -f webm video.webm