Constant libmpv_sys::mpv_format_MPV_FORMAT_NONE

pub const mpv_format_MPV_FORMAT_NONE: mpv_format = 0;

Invalid. Sometimes used for empty values. This is always defined to 0, so a normal 0-init of mpv_format (or e.g. mpv_node) is guaranteed to set this it to MPV_FORMAT_NONE (which makes some things saner as consequence).