ffmpeg -i %1 -codec:v libvpx -b:v 3*1024*1024*8/[duration in seconds]*0.975 -ss [start time in HH:MM:SS] -t [stop time in HH:MM:SS] -quality best -vf scale=640:-1 -fs 3M -cpu-used 0 -bufsize 1000k -an -pass 1 -f webm %1.null
del %1.null
ffmpeg -i %1 -codec:v libvpx -b:v 3*1024*1024*8/[duration in seconds]*0.975 -ss [start time in HH:MM:SS] -t [stop time in HH:MM:SS] -quality best -vf scale=640:-1 -fs 3M -cpu-used 0 -bufsize 1000k -an -pass 2 -f webm %1.webm
del ffmpeg2pass-0.log