pro MPEG_SAVE, mpegID, FILENAME = filename

    ON_ERROR,2                    ;Return to caller if an error occurs

    ; let user know about demo mode limitation.
    ; mpeg object is disabled in demo mode
    if (LMGR(/DEMO)) then begin
        MESSAGE, 'Feature disabled for demo mode.'
        return
    endif

    if (not OBJ_ISA(mpegID, 'IDLgrMPEG')) then $
      MESSAGE,'Argument must be an IDLgrMPEG object reference.'

    if (N_ELEMENTS(filename) gt 0) then $
      mpegID->Save, FILENAME = filename $
    else $
      mpegID->Save 

end