OpenCV打开视频失败问题追踪！

首先遇到这种问题，多半出在FFMPEG上，找不到ffmpeg库，linux下记得编译进去，Windows下呢？当然一样，不过我们基本上是优先使用官方预编译版本！

这时，怎么办呢？找呗！！！

贴出OpenCV初始化FFMPEG的核心代码：

class icvInitFFMPEG
{
public:
    static void Init()
    {
        cv::AutoLock al(_icvInitFFMPEG_mutex);
        static icvInitFFMPEG init;
    }

private:
    #if defined WIN32 || defined _WIN32
    HMODULE icvFFOpenCV;

    ~icvInitFFMPEG()
    {
        if (icvFFOpenCV)
        {
            FreeLibrary(icvFFOpenCV);
            icvFFOpenCV = 0;
        }
    }
    #endif

    icvInitFFMPEG()
    {
    #if defined WIN32 || defined _WIN32
    # ifdef HAVE_WINRT
        const wchar_t* module_name = L"opencv_ffmpeg"
            CVAUX_STRW(CV_MAJOR_VERSION) CVAUX_STRW(CV_MINOR_VERSION) CVAUX_STRW(CV_SUBMINOR_VERSION)
        #if (defined _MSC_VER && defined _M_X64) || (defined __GNUC__ && defined __x86_64__)
            L"_64"
        #endif
            L".dll";

        icvFFOpenCV = LoadPackagedLibrary( module_name, 0 );
    # else
        const char* module_name = "opencv_ffmpeg"
            CVAUX_STR(CV_MAJOR_VERSION) CVAUX_STR(CV_MINOR_VERSION) CVAUX_STR(CV_SUBMINOR_VERSION)
        #if (defined _MSC_VER && defined _M_X64) || (defined __GNUC__ && defined __x86_64__)
            "_64"
        #endif
            ".dll";

        icvFFOpenCV = LoadLibrary( module_name );
    # endif

        if( icvFFOpenCV )
        {
            icvCreateFileCapture_FFMPEG_p =
                (CvCreateFileCapture_Plugin)GetProcAddress(icvFFOpenCV, "cvCreateFileCapture_FFMPEG");
            icvReleaseCapture_FFMPEG_p =
                (CvReleaseCapture_Plugin)GetProcAddress(icvFFOpenCV, "cvReleaseCapture_FFMPEG");
            icvGrabFrame_FFMPEG_p =
                (CvGrabFrame_Plugin)GetProcAddress(icvFFOpenCV, "cvGrabFrame_FFMPEG");
            icvRetrieveFrame_FFMPEG_p =
                (CvRetrieveFrame_Plugin)GetProcAddress(icvFFOpenCV, "cvRetrieveFrame_FFMPEG");
            icvSetCaptureProperty_FFMPEG_p =
                (CvSetCaptureProperty_Plugin)GetProcAddress(icvFFOpenCV, "cvSetCaptureProperty_FFMPEG");
            icvGetCaptureProperty_FFMPEG_p =
                (CvGetCaptureProperty_Plugin)GetProcAddress(icvFFOpenCV, "cvGetCaptureProperty_FFMPEG");
            icvCreateVideoWriter_FFMPEG_p =
                (CvCreateVideoWriter_Plugin)GetProcAddress(icvFFOpenCV, "cvCreateVideoWriter_FFMPEG");
            icvReleaseVideoWriter_FFMPEG_p =
                (CvReleaseVideoWriter_Plugin)GetProcAddress(icvFFOpenCV, "cvReleaseVideoWriter_FFMPEG");
            icvWriteFrame_FFMPEG_p =
                (CvWriteFrame_Plugin)GetProcAddress(icvFFOpenCV, "cvWriteFrame_FFMPEG");

#if 0
            if( icvCreateFileCapture_FFMPEG_p != 0 &&
                icvReleaseCapture_FFMPEG_p != 0 &&
                icvGrabFrame_FFMPEG_p != 0 &&
                icvRetrieveFrame_FFMPEG_p != 0 &&
                icvSetCaptureProperty_FFMPEG_p != 0 &&
                icvGetCaptureProperty_FFMPEG_p != 0 &&
                icvCreateVideoWriter_FFMPEG_p != 0 &&
                icvReleaseVideoWriter_FFMPEG_p != 0 &&
                icvWriteFrame_FFMPEG_p != 0 )
            {
                printf("Successfully initialized ffmpeg plugin!\n");
            }
            else
            {
                printf("Failed to load FFMPEG plugin: module handle=%p\n", icvFFOpenCV);
            }
#endif
        }
    #elif defined HAVE_FFMPEG
        icvCreateFileCapture_FFMPEG_p = (CvCreateFileCapture_Plugin)cvCreateFileCapture_FFMPEG;
        icvReleaseCapture_FFMPEG_p = (CvReleaseCapture_Plugin)cvReleaseCapture_FFMPEG;
        icvGrabFrame_FFMPEG_p = (CvGrabFrame_Plugin)cvGrabFrame_FFMPEG;
        icvRetrieveFrame_FFMPEG_p = (CvRetrieveFrame_Plugin)cvRetrieveFrame_FFMPEG;
        icvSetCaptureProperty_FFMPEG_p = (CvSetCaptureProperty_Plugin)cvSetCaptureProperty_FFMPEG;
        icvGetCaptureProperty_FFMPEG_p = (CvGetCaptureProperty_Plugin)cvGetCaptureProperty_FFMPEG;
        icvCreateVideoWriter_FFMPEG_p = (CvCreateVideoWriter_Plugin)cvCreateVideoWriter_FFMPEG;
        icvReleaseVideoWriter_FFMPEG_p = (CvReleaseVideoWriter_Plugin)cvReleaseVideoWriter_FFMPEG;
        icvWriteFrame_FFMPEG_p = (CvWriteFrame_Plugin)cvWriteFrame_FFMPEG;
    #endif
    }
};
           

看到没，就是那个

const wchar_t* module_name = L"opencv_ffmpeg"
           

在sources\3rdparty\ffmpeg下的确有opencv_ffmpeg.dll的库，不过不能直接用，紧接着一行又改变了文件名加上了版本号，即opencv_ffmpeg2411.dll，其他以此类推！

好了，路已指明，赶紧改为相应的吧！熟悉的视频框架又回来了！！！