（原）Microsoft Source Reader的简单使用

感觉Microsoft Source Reader还是比较坑的，只是由于需要，不得不使用。其实按照Microsoft提供的示例，基本上可以正常的调试出程序来。

下面的例子，简单的给出了Source Reader的代码。同时，HRESULT CreateVideoDeviceSource(IMFMediaSource **ppSource)函数中，使用了指针的指针，能正确的传出ppSource，不是NULL。之前调试时，使用HRESULT CreateVideoDeviceSource(IMFMediaSource *ppSource)，出来后，ppSource依旧为NULL。后来直接把代码展开，没有继续深入考虑。感谢前两天@wuruifang  的建议，之后在网上搜了一下，指针的指针可以使得输入参数为NULL时输出正常。因而此处重新写成一个函数（以前不清楚为啥用指针的指针时出错，现在倒是没有）。

主要代码：

 int _tmain(int argc, _TCHAR* argv[])
 {
     IMFMediaSource *ppSource = NULL;
     CreateVideoDeviceSource(&ppSource);

 //     hr = EnumerateCaptureFormats(ppSource);  // This can show the formats the camera support. Notice that output window of visual studio shows the infomation.
 //     if (FAILED(hr))
 //         abort();
     HRESULT hr;
     IMFSourceReader *pReader;
     hr = MFCreateSourceReaderFromMediaSource(ppSource, NULL, &pReader);
     if (FAILED(hr))
         abort();

     hr = SetDeviceFormat(ppSource, );   //I need to configure the camera to format 6.
     if (FAILED(hr))
         abort();

     ProcessSamples(pReader);

     SafeRelease(&pReader);
     SafeRelease(&ppSource);
     MFShutdown();
     CoUninitialize();
 }

 HRESULT ProcessSamples(IMFSourceReader *pReader)
 {
     HRESULT hr = S_OK;
     IMFSample *pSample = NULL;
     size_t  cSamples = ;

     _LARGE_INTEGER time_start;    /*begin time */
     _LARGE_INTEGER time_over;        /*end time*/
     double dqFreq;                /*timer frequence*/
     LARGE_INTEGER f;            /*timer frequence*/
     QueryPerformanceFrequency(&f);
     dqFreq = (double)f.QuadPart;

     QueryPerformanceCounter(&time_start);

     bool quit = false;
     while (!quit)
     {
         DWORD streamIndex, flags;
         LONGLONG llTimeStamp;

         hr = pReader->ReadSample(
             MF_SOURCE_READER_ANY_STREAM,    // Stream index.
             ,                              // Flags.
             &streamIndex,                   // Receives the actual stream index.
             &flags,                         // Receives status flags.
             &llTimeStamp,                   // Receives the time stamp.
             &pSample                        // Receives the sample or NULL.
             );

         if (FAILED(hr))
             break;

         if (flags & MF_SOURCE_READERF_ENDOFSTREAM)
         {
             wprintf(L"\tEnd of stream\n");
             quit = true;
         }

         if (pSample)
         {
             BYTE* data;
             IMFMediaBuffer* buffer;
             DWORD max, current;

             //        printf(" cSamples = %d\n", cSamples);
             ++cSamples;
             pSample->GetBufferByIndex(, &buffer);
             buffer->Lock(&data, &max, &current);

         //    saveBMP(data, cSamples, IMGWIDTH, IMGHEIGHT);

             buffer->Unlock();
             SafeRelease(&buffer);

             QueryPerformanceCounter(&time_over);          //In order to find the frames per second of the camera.
             double usedtime = ((time_over.QuadPart - time_start.QuadPart) / dqFreq);
             if (usedtime>)
             {
                 printf(" cSamples = %d\n", cSamples);
                 cSamples = ;
                 QueryPerformanceCounter(&time_start);
             }
         }
         SafeRelease(&pSample);
     }

     SafeRelease(&pSample);
     return hr;
 }

 HRESULT CreateVideoDeviceSource(IMFMediaSource **ppSource)
 {
     HRESULT hr;
     hr = CoInitialize(NULL);
     if (FAILED(hr))
         abort();
     hr = MFStartup(MF_VERSION, MFSTARTUP_NOSOCKET);
     if (FAILED(hr))
         abort();

     *ppSource = NULL;

     IMFMediaSource *pSource = NULL;
     IMFAttributes *pAttributes = NULL;
     IMFActivate **ppDevices = NULL;

     // Create an attribute store to specify the enumeration parameters.
     /*HRESULT*/ hr = MFCreateAttributes(&pAttributes, );
     if (FAILED(hr))
         abort();

     // Source type: video capture devices
     hr = pAttributes->SetGUID( MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE,
         MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID );
     if (FAILED(hr))
         abort();

     // Enumerate devices.
     UINT32 count;
     hr = MFEnumDeviceSources(pAttributes, &ppDevices, &count);
     if (FAILED(hr))
         abort();
     if (count == )
     {
         hr = E_FAIL;
         return hr;
     }

     // Create the media source object.
     hr = ppDevices[]->ActivateObject(IID_PPV_ARGS(&pSource));
     if (FAILED(hr))
         abort();

     *ppSource = pSource;
     (*ppSource)->AddRef();

     // release part
     SafeRelease(&pAttributes);

     for (DWORD i = ; i < count; i++)
     {
         SafeRelease(&ppDevices[i]);
     }
     CoTaskMemFree(ppDevices);
     SafeRelease(&pSource);    //此处不确定，是否需要SafeRelease。
     return hr;
 }

得到的图片（程序中保存的是BMP图片，由于cnblogs不支持BMP，因而转成jpg）：

完整代码（不会插入超链接，抱歉）见：https://github.com/darkknightzh/Microsoft-Source-Reader

参考（其他的记不清了，见谅）：

Microsoft ：http://msdn.microsoft.com/en-us/library/windows/desktop/dd389281(v=vs.85).aspx

指针的指针（详见4楼，14楼） ：http://bbs.csdn.net/topics/210076970