NULL pointer crash in MFPlayerSession::handleMediaSourceReady()

 
void MFPlayerSession::handleMediaSourceReady()
{
    if (QMediaPlayer::LoadingMedia != m_status || !m_sourceResolver)
        return;
#ifdef DEBUG_MEDIAFOUNDATION
    qDebug() << "handleMediaSourceReady";
#endif
    HRESULT hr = S_OK;
    IMFPresentationDescriptor* sourcePD;
    IMFMediaSource* mediaSource = m_sourceResolver->mediaSource();
    hr = mediaSource->CreatePresentationDescriptor(&sourcePD);
    if (SUCCEEDED(hr)) {
        m_duration = 0;
        m_playerService->metaDataControl()->updateSource(sourcePD, mediaSource);
        sourcePD->GetUINT64(MF_PD_DURATION, &m_duration);
        //convert from 100 nanosecond to milisecond
        emit durationUpdate(qint64(m_duration / 10000));
        setupPlaybackTopology(mediaSource, sourcePD);
    } else {
        changeStatus(QMediaPlayer::InvalidMedia);
        emit error(QMediaPlayer::ResourceError, tr("Cannot create presentation descriptor."), true);
    }
}