protected unsafe void EnableActionPrevious()
        {
            iCallbackPrevious = new CallbackPrevious(DoPrevious);
            IntPtr ptr = GCHandle.ToIntPtr(iGch);

            DvServiceUpnpOrgAVTransport2EnableActionPrevious(iHandle, iCallbackPrevious, ptr);
        }
 static extern void DvServiceUpnpOrgAVTransport2EnableActionPrevious(uint aHandle, CallbackPrevious aCallback, IntPtr aPtr);