HRESULT SetBuffer( DWORD cbSize, BYTE *pbData, DWORD dwFlags );
Size of memory pointed to by pbData, in bytes.
Pointer to memory that this object will use.
Reserved for flag data. Must be zero.
Returns S_OK if successful or E_INVALIDARG if cbSize is zero or pbData is NULL.
This method can be called as often as needed. When using IStreamSample::Update to update samples asynchronously, make sure that SetBuffer is never called before an update is completed.