private void TestMediaLength()
{
int hr;
long ml;
const long LEN = 1000;
hr = m_pSource1Src.SetMediaLength(LEN);
DESError.ThrowExceptionForHR(hr);
hr = m_pSource1Src.GetMediaLength(out ml);
DESError.ThrowExceptionForHR(hr);
Debug.Assert(ml == LEN, "MediaLength");
}