ffmpeg -i full-hd-input.mp4 -c:v libvpx-vp9 -b:v 0 -r 35 -crf 30 -pass 1 -an -f null /dev/null && ffmpeg -i full-hd-input.mp4 -c:v libvpx-vp9 -b:v 0 -crf 35 -pass 2 -c:a libopus -b:a 64k -filter:v scale=800:-1 output.webm