The IDirectMusic::EnumPort method is used to enumerate and get the capabilities of the DirectMusic ports connected to the system. Each time it is called, this method retrieves information about a single port.
HRESULT EnumPort(
  DWORD dwIndex, 
  LPDMUS_PORTCAPS pPortCaps 
);
 If the method succeeds, the return value is S_OK, or S_FALSE if there is no port with that index value.
If it fails, the method may return one of the following error values:
| E_INVALIDARG | 
| E_NOINTERFACE | 
| E_POINTER | 
Applications should not rely on or store the index number of a port. Rebooting or adding or removing ports could cause the index number of a port to change.
  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in dmusicc.h.