error[E0308]: mismatched types
  --> gstreamer-rtsp-server/src/r_t_s_p_media_factory.rs:15:92
   |
15 |         ffi::gst_rtsp_media_factory_add_role(self.to_glib_none().0, role.to_glib_none().0, T::static_type(), v.to_glib_none().0, ptr::null_mut());
   |                                                                                            ^^^^^^^^^^^^^^^^ expected *-ptr, found enum `glib::Type`
   |
   = note: expected type `*const i8`
              found type `glib::Type