HRESULT QueryInterface(REFIID riid, LPVOID * ppvObj);
Determines if the DirectSound object supports a particular COM interface. If it does, the system increases the reference count for the object, and the application can begin using that interface immediately. This method is part of the IUnknown interface inherited by DirectSound.
·Returns DS_OK if successful, or one of the following error values otherwise:
DSERR_GENERIC DSERR_INVALIDPARAM
riid
Reference identifier of the interface being requested.
ppvObj
Address of a location to be filled with the returned interface pointer if the query is successful.
If the application does not need to use the interface retrieved by a call to this method, it must call the Release method for that interface to free it. The IDirectSound::QueryInterface method allows DirectSound objects to be extended by Microsoft and third parties without interfering with each other's existing or future functionality.