mediaControl = new IMediaControl(p[0]);
hr = graphBuilder.QueryInterface(Com.IID_IMediaSeeking, p);
if (Com.FAILED(hr))
throw new ComException(hr);
mediaSeeking = new IMediaSeeking(p[0]);
hr = graphBuilder.QueryInterface(Com.IID_IVideoWindow, p);
if (Com.FAILED(hr))
throw new ComException(hr);