Function vaGetImage 

pub unsafe extern "C" fn vaGetImage(
    dpy: VADisplay,
    surface: VASurfaceID,
    x: c_int,
    y: c_int,
    width: c_uint,
    height: c_uint,
    image: VAImageID,
) -> VAStatus

Retrive surface data into a VAImage Image must be in a format supported by the implementation