c++ - 未处理的异常 - OpenCV - cvReleaseCapture 和 cvReleaseImage - C++

Question

我有一个程序使用 OpenCV 库(版本 2.4.1)从笔记本电脑的网络摄像头(或任何其他连接的摄像头)捕获视频并将其保存为 .avi 文件。当我在 Visual Studio 2010 中调试时，在程序的最后，当 CvCapture 或 IplImage 被释放时，我得到一个未处理的异常。这是代码:

    // WriteRealTimeCapturedVideo.cpp : Defines the entry point for the console application.
    #include "stdafx.h"
    #include "cv.h"
    #include "highgui.h"
    #include <stdio.h>

    int main()
    {
        CvCapture* capture = cvCaptureFromCAM( 1 ); //CV_CAP_ANY
        if ( !capture )
        {
            fprintf( stderr, "ERROR: capture is NULL \n" );
            getchar();
            return -1;
        }
        // Create a window in which the captured images will be presented
        cvNamedWindow( "mywindow", CV_WINDOW_AUTOSIZE );

        double fps = cvGetCaptureProperty (capture, CV_CAP_PROP_FPS);

        CvSize size = cvSize((int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH), (int)cvGetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT));

        #ifndef NOWRITE
        CvVideoWriter* writer = cvCreateVideoWriter("Capture.avi", CV_FOURCC('M','J','P','G'), fps, size); //CV_FOURCC('M','J','P','G')
        #endif

        int width = (int)(cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH));
        int height = (int)(cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT));

        IplImage* frame = cvCreateImage( cvSize( width,height ), IPL_DEPTH_8U, 1);

        while ( 1 )
        {
            // Get one frame
            frame = cvQueryFrame( capture );
            if ( !frame ) 
            {
                fprintf( stderr, "ERROR: frame is null...\n" );
                getchar();
                break;
            }
            cvShowImage( "mywindow", frame );
            #ifndef NOWRITE
            cvWriteToAVI( writer, frame );
            #endif
            char c = cvWaitKey(33);
            if( c == 27 ) break;
        }
        #ifndef NOWRITE
        cvReleaseVideoWriter( &writer );
        #endif
        cvDestroyWindow( "mywindow" );
        cvReleaseImage( &frame );
        cvReleaseCapture( &capture );
        return 0;
    }

我发现我必须将 tbb.dll 和 tbb_debug.dll 放在与源代码(.cpp 文件)相同的目录中，程序才能运行。这些 dll 可以从 Intel 下载。

视频采集正常，即出现窗口并显示视频，但无论我如何重新排列发布语句，都会出现异常。如果我删除发布声明(VideoWriter 除外)，我不会得到异常，但无法打开生成的 .avi 文件。当用户按下 Esc 键时，程序退出 while 循环。

Answer 1

来自 openCV 文档:

cvQueryFrame

Grabs and returns a frame from camera or file

IplImage* cvQueryFrame( CvCapture* capture );

capture video capturing structure.

The function cvQueryFrame grabs a frame from camera or video file, decompresses and returns it. This function is just a combination of cvGrabFrame and cvRetrieveFrame in one call. The returned image should not be released or modified by user.

所以你不必分配或释放“框架”

删除:

IplImage* frame = cvCreateImage( cvSize( width,height ), IPL_DEPTH_8U, 1);

和

cvReleaseImage( &frame );

并替换

frame = cvQueryFrame( capture );

与

IplImage* frame = cvQueryFrame( capture );