private void TestMediaLength2()
        {
            int          hr;
            double       ml;
            const double LEN = 1000.1234;

            hr = m_pSource1Src.SetMediaLength2(LEN);
            DESError.ThrowExceptionForHR(hr);

            hr = m_pSource1Src.GetMediaLength2(out ml);
            DESError.ThrowExceptionForHR(hr);

            Debug.Assert(ml == LEN, "MediaLength2");
        }