private void TestStreamNumber()
        {
            int hr;
            int i;

            hr = m_pSource1Src.SetStreamNumber(1);
            DESError.ThrowExceptionForHR(hr);

            hr = m_pSource1Src.GetStreamNumber(out i);
            DESError.ThrowExceptionForHR(hr);

            Debug.Assert(i == 1, "StreamNumber");
        }