My 2 cents.
Im running Orange PI PC+ and so far my best option for mpv is :
vo=x11
hwdec-codecs=all
hwdec=auto
That way , nonscaled movie (an xvid avi) plays smooth, but full screen is jaggy, with noticeable banding, but it plays... you can watch a movie... kind of like streaming from video sites.
I don't know if is relevant: I've previously installed ffmpeg and the Codecs Pack from The Software Boutique. Probably not.