Function vaGetDisplayAttributes 

pub unsafe extern "C" fn vaGetDisplayAttributes(
    dpy: VADisplay,
    attr_list: *mut VADisplayAttribute,
    num_attributes: c_int,
) -> VAStatus

Get display attributes This function returns the current attribute values in “attr_list”. Only attributes returned with VA_DISPLAY_ATTRIB_GETTABLE set in the “flags” field from vaQueryDisplayAttributes() can have their values retrieved.