How to increase bitrate in ffmpeg?

Question

fmpeg

Good afternoon!
on command

ffmpeg -i 800.mov -c:v libvpx -pix_fmt yuva420p -metadata:s:v:0 alpha_mode="1" -auto-alt-ref 0 -strict -2 PES_800.webm

ffmpeg -i 800.mov -c:v libvpx -pix_fmt yuva420p -metadata:s:v:0 alpha_mode="1" -auto-alt-ref 0 -strict -2 PES_800.webm
i convert *.mov file to *. webm with alpha channel preserved. But the bitrate has deteriorated by 20 times.
Tell me how to save the bitrate or specify your own?
Thank you!

Answer 1

Try this answer :
and pay attention to the first comment to it:
thank you! exactly I needed minrateand maxrate.