Constant libmpv_sys::mpv_render_param_type_MPV_RENDER_PARAM_INVALID

pub const mpv_render_param_type_MPV_RENDER_PARAM_INVALID: mpv_render_param_type = 0;

Not a valid value, but also used to terminate a params array. Its value is always guaranteed to be 0 (even if the ABI changes in the future).