DirectShow在调用Stop的时候出错

程序加了一个压缩的Filter，这个Filter也没做什么很多事，就是枚举出系统的压缩器，然后选中ffdshow video encoder绑定进行压缩，我单独写了个压缩已经生成好了的AVI文件，这个就没问题，但是我把这个压缩器加进来让它实时压缩采集的视频，就会在m_pMC->Stop();这里出错，报内存不可读的错误，Call stack信息为
FFDSHOW! 086cbf78()
FFDSHOW! 086c97ed()
QUARTZ! 7cfa8523()
CCaptureVideo::CaptureImagesToAVI(CString {"D:\data\0000173_wqwqwq\20110810183804.avi"}) line 157 + 20 bytes
CTHIRD::OnCapture() line 111

我不加压缩这块，就预览和采集已经实现，程序没问题，我在程序开启的时候在OnInitDialog中调用压缩Filter,Filter代码如下

	//枚举压缩器

////////////////////////////////////////////////////////////////////////////////////////////////////

	HRESULT hr;

	ICreateDevEnum *pSysDevEnum = NULL;           //创建枚举器指针

	pCompress = NULL;

	

	hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,

		IID_ICreateDevEnum, (void **)&pSysDevEnum);               //创建枚举器

	

	// Obtain a class enumerator for the video compressor category.

	IEnumMoniker *pEnumCat = NULL;

	hr = pSysDevEnum->CreateClassEnumerator(CLSID_VideoCompressorCategory, &pEnumCat, 0);    //返回枚举参数

	

	if (hr == S_OK) 

	{

		// Enumerate the monikers.

		IMoniker *pMoniker;            

		ULONG cFetched;

		while(pEnumCat->Next(1, &pMoniker, &cFetched) == S_OK)                   //开始枚举压缩器

		{

			IPropertyBag *pPropBag;

			pMoniker->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pPropBag);

			

			// To retrieve the friendly name of the filter, do the following:

			VARIANT varName;

			VariantInit(&varName);

			

			hr = pPropBag->Read(L"FriendlyName", &varName, 0);

			if (SUCCEEDED(hr))

			{

				CString str(varName.bstrVal);

				SysFreeString(varName.bstrVal);

				if(str == "ffdshow video encoder")

				{

					hr = pMoniker->BindToObject(0,0,IID_IBaseFilter,(void**)&pCompress);

					pMoniker->Release();

					break;

				}

			

			}

			VariantClear(&varName);

			

		}

		pEnumCat->Release();

		pMoniker->Release();

		m_pGB->AddFilter(pCompress,L"Compressor");          //添加过滤器

		HRESULT ret =NULL;

		IPin * pSourceOut = NULL;

		IPin* pCompressIn,* pCompressOut=NULL;

		IAMVideoCompression * pAMCompress = NULL;           //压缩参数设置

		pCompressIn  =  FindPin(pCompress,PINDIR_INPUT) ;   //查找输入引脚

		pCompressOut =  FindPin(pCompress,PINDIR_OUTPUT);   //查找输出引脚

	

		pCompressOut->QueryInterface(IID_IAMVideoCompression,(void**)&pAMCompress);	



	}



	pSysDevEnum->Release();

然后在点击采集按钮的时候进行实时采集压缩，代码如下

	HRESULT hr=0;

	if(m_pMC)

	{

		m_pMC->Stop();          ////////////////////此处出现问题	}



	hr = m_pCapture->SetOutputFileName( &MEDIASUBTYPE_Avi,inFileName.AllocSysString(), &pMux, NULL );



	//渲染媒体，链接所有滤波器

	m_pCapture->RenderStream(&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,m_pBF,pCompress,pMux);

	HRESULT ret = pMux->QueryInterface(IID_IMediaSeeking, (void**)&pSeek);

	pMux->Release();

	m_pMC->Run();//回复视频

	return hr;

就在上面的m_pMC->Stop();处出问题
我在GraphEdit里配置图表没有问题

为什么会出现这种情况啊，请高手帮帮忙，谢谢了，实在是急死了都