Using C++11 smart pointers as C function arguments

While this should be a trivial question I was unable to find an answer this far. In C APIs there are lots of functions that take pointers and pointers to pointers as arguments. How can I use PROPERLY smart pointers as arguments with C APIs.

Here is an example that I'd like to convert to using std::unique_ptr:

FMOD_SYSTEM* system = nullptr;
result = FMOD_System_Create(&system); // Create the main system object

FMOD_SOUND* musicStream;
result = FMOD_System_CreateSound(system,
                                 musicStreamPath,
                                 FMOD_CREATESTREAM,
                                 nullptr,
                                 &musicStream);

Reference: FMOD_System_Create FMOD_System_CreateSound

I start declaring the smart pointers as:

std::unique_ptr<FMOD_SYSTEM> system = nullptr;
std::unique_ptr<FMOD_SOUND> musicStream = nullptr;