Get the signal source list.
BOOL NET_DVR_GetInputSignalList_V40( LONG lUserID, DWORD dwDevNum, NET_DVR_INPUT_SIGNAL_LIST *lpInputSignalList );
[IN] Value returned by NET_DVR_Login_V40.
Reserved, set to 0.
[OUT] Signal source list, see details in the structure NET_DVR_INPUT_SIGNAL_LIST.
Return TRUE for success, and return FALSE for failure.
If FALSE is returned, you can call NET_DVR_GetLastError to get the error code.