Changable pointer

[NMTop40]

It looks like you do need polymorphism, and I addressed this in a different post with regard to adapters.

Ideally you would not need to look up type then cast, but would call a single method in your base class, thus:

rendererBasePtr->callFunction();

Now the adapters could work as follows:

class FilterAdapterBase
{
public:
   virtual void callFunction() /*const ?*/= 0;
};

class FilterAdapterVR : public FilterAdapterBase
{
  IVideoRenderer * m_pImpl;
public:
   void callFunction() { m_pImpl->function1(); }
};

class FilterAdapterVMR7 : public FilterAdapterBase
{
  IVideoRenderer7 * m_pImpl;
public:
   void callFunction() { m_pImpl->function2(); }
};

class FilterAdapterVMR9 : public FilterAdapterBase
{
  IVideoRenderer9 * m_pImpl;
public:
   void callFunction() { m_pImpl->function3(); }
};

That's just an illustration to start you on your way. I'd need to see more code and more information to know exactly what you need.