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Creating a Virtual Function Table for a Stream Handler

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[The feature associated with this page, Custom File and Stream Handlers, is a legacy feature. It has been superseded by MediaStreamSource class. MediaStreamSource class has been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaStreamSource class instead of Custom File and Stream Handlers, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The following example (written in C) shows how an application (AVIBall) creates the virtual function table used to reference its services.

HRESULT STDMETHODCALLTYPE AVIBallQueryInterface (PAVISTREAM ps, 
    REFIID riid, LPVOID FAR* ppvObj); 
HRESULT STDMETHODCALLTYPE AVIBallCreate (PAVISTREAM ps, 
    LONG lParam1, LONG lParam2); 
ULONG STDMETHODCALLTYPE AVIBallAddRef (PAVISTREAM ps); 
ULONG STDMETHODCALLTYPE AVIBallRelease (PAVISTREAM ps); 
HRESULT STDMETHODCALLTYPE AVIBallInfo (PAVISTREAM ps, 
    AVIStreamHeader FAR * psi, LONG lSize); 
LONG STDMETHODCALLTYPE AVIBallFindSample (PAVISTREAM ps, 
    LONG lPos, LONG lFlags); 
HRESULT STDMETHODCALLTYPE AVIBallReadFormat (PAVISTREAM ps, 
    LONG lPos, LPVOID lpFormat, LONG FAR *lpcbFormat); 
HRESULT STDMETHODCALLTYPE AVIBallSetFormat (PAVISTREAM ps, 
    LONG lPos, LPVOID lpFormat, LONG cbFormat); 
HRESULT STDMETHODCALLTYPE AVIBallRead (PAVISTREAM ps, 
    LONG lStart, LONG lSamples, LPVOID lpBuffer, LONG cbBuffer, 
    LONG FAR * plBytes,LONG FAR * plSamples); 
HRESULT STDMETHODCALLTYPE AVIBallWrite (PAVISTREAM ps, LONG lStart, 
    LONG lSamples, LPVOID lpBuffer, LONG cbBuffer, DWORD dwFlags); 
HRESULT STDMETHODCALLTYPE AVIBallDelete (PAVISTREAM ps, 
    LONG lStart, LONG lSamples); 
HRESULT STDMETHODCALLTYPE AVIBallReadData (PAVISTREAM ps, 
    DWORD fcc, LPVOID lp,LONG FAR *lpcb); 
HRESULT STDMETHODCALLTYPE AVIBallWriteData (PAVISTREAM ps, 
    DWORD fcc, LPVOID lp,LONG cb); 
 
IAVIStreamVtbl AVIBallHandler = { 
    AVIBallQueryInterface,  // Function pointer for ::QueryInterface 
    AVIBallAddRef,          // Function pointer for ::AddRef 
    AVIBallRelease,         // Function pointer for ::Release 
    AVIBallCreate,          // Function pointer for ::Create 
    AVIBallInfo,            // Function pointer for ::Info 
    AVIBallFindSample,      // Function pointer for ::FindSample 
    AVIBallReadFormat,      // Function pointer for ::ReadFormat 
    AVIBallSetFormat,       // Function pointer for ::SetFormat 
    AVIBallRead,            // Function pointer for ::Read 
    AVIBallWrite,           // Function pointer for ::Write 
    AVIBallDelete,          // Function pointer for ::Delete 
    AVIBallReadData,        // Function pointer for ::ReadData 
    AVIBallWriteData        // Function pointer for ::WriteData 
};

File handlers use a similar procedure, except they use a different definition for the virtual function table.