void MFPlayerSession::close()
{
...
    HRESULT hr = S_OK;
    if (m_session) {
        m_closing = true;
        hr = m_session->Close();
        if (SUCCEEDED(hr)) {
            DWORD dwWaitResult = WaitForSingleObject(m_hCloseEvent, 100);
            if (dwWaitResult == WAIT_TIMEOUT) {
                qWarning() << "session close time out!";
            }
        }
         m_closing = false;
    }
...
}