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！！！