Pass a C# function to a COM interface that wants a function pointe

[Travis]

I have a Directshow filter I wrote in C++. I've created an interface to set
a callback function. The app I want to use the filter in is in C#. How do I
pass a function pointer from C# to a COM interface?

I have not been able to find much in the way of examples but I have tried
this:

//COM Object
typdef HRESULT (*MYCALLBACK) (IMediaSample * pSample);
DECLARE_INTERFA CE_(IMyFilter, IUknown)
{
STDMETHOD(SetCa llbackPointer)( LPVOID FnAddress);
}
MYCALLBACK m_callback;
STDMETHODIMP SetCallbackPoin ter(LPVOID FnAddress)
{
m_callback = (MYCALLBACK)FnA ddress;
}
void InvokeCallback( IMediaSample * pSample)
{
(m_callback)(pS ample);
}
HRESULT Transform(IMedi aSample *pSample)
{
InvokeCallback( pSample);
}

//C#
public delegate int CallBackDelegat e(ref IMediaSample mediaSample);
public class MyClass
{
public CallBackDelegat e myDelegate;
public MyClass()
{
myDelegate = new CallBackDelegat e(CallbackFunct ion);

//all the stuff to create the COM object and get the interface
myInterface.Set CallbackPointer (myDelegate);
}
public int CallbackFunctio n(ref IMediaSample mediaSample)
{
//my intention is get a copy of the mediaSample
MessageBox.Show ("Here");
return 0;
}
}