在phonon_ds9d4.dll中使用phonon崩溃

Question

使用代码：

Phonon::VideoPlayer *player = new Phonon::VideoPlayer(Phonon::MusicCategory, NULL);
QObject::connect(player, SIGNAL(finished()), player, SLOT(deleteLater()));
player->play(Phonon::MediaSource("c:/yaodong.mkv"));

但崩溃了。 env是win7和vs2008，qt 4.7.1 windows sdk是7.1 dx sdk是Microsoft DirectX SDK（2009年3月） 我发现堆栈是 mediaobject.cpp（第233行）图为空

            } else if (!m_currentWork.url.isEmpty()) {
                //let's render a url (blocking call)
                hr = m_currentWork.graph->RenderFile(reinterpret_cast<const wchar_t *>(m_currentWork.url.utf16()), 0);
            }

然后我找到了执行该功能的步骤：

   quint16 WorkerThread::addUrlToRender(const QString &url)
    {
        QMutexLocker locker(&m_mutex);
        Work w;
        w.task = Render;
        //we create a new graph
        w.graph = Graph(CLSID_FilterGraph, IID_IGraphBuilder);
        w.url = url;
        w.url.detach();
        w.id = m_currentWorkId++;
        m_queue.enqueue(w);
        m_waitCondition.set();
        return w.id;
    }

行：w.graph = Graph（CLSID_FilterGraph，IID_IGraphBuilder）; w.graph为空。

但我在外面写了代码：

IGraphBuilder *pGraph = NULL;
::CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER, IID_IGraphBuilder,
    reinterpret_cast<void**>(&pGraph));

pGraph不为空。

帮助。谢谢！