从文件opencv读取视频 [英] reading video from file opencv

问题描述

Hi所以我写了这段代码来捕获文件中的视频

Hi So I have written this code to capture a video from file

#include <stdio.h>
#include <cv.h>
#include "highgui.h"
#include <iostream>

//using namespace cv

int main(int argc, char** argv)
{
    CvCapture* capture=0;
    IplImage* frame=0;
    capture = cvCaptureFromAVI(char const* filename); // read AVI video    
    if( !capture )
        throw "Error when reading steam_avi";

    cvNamedWindow( "w", 1);
    for( ; ; )
    {
        frame = cvQueryFrame( capture );
        if(!frame)
            break;
        cvShowImage("w", frame);
    }
    cvWaitKey(0); // key press to close window
    cvDestroyWindow("w");
    cvReleaseImage(&frame);
}

每次我运行它，我得到以下错误：

Everytime I run it, I get the following error:

CaptureVideo.cpp：在函数'int main（int，char **）'中：

CaptureVideo.cpp: In function ‘int main(int, char**)’:

CaptureVideo.cpp：13：28：错误：'char'之前的主表达式

CaptureVideo.cpp:13:28: error: expected primary-expression before ‘char’

任何帮助将非常感激。 p>

Any help will be much appreciated.

推荐答案

这是C ++的问题，所以你应该使用C ++接口。

This is C++ question, so you should use the C++ interface.

原始程式码中的错误：

• 您忘记移除 c $ c> c $ c> c code>


• 您不等待框架显示。 ShowImage 只有在它后面跟着WaitKey才有效。


• 我不知道如果capture = NULL意味着你的文件不是打开。

• You forgot to remove char const* in cvCaptureFromAVI.
• You don't wait for the frame to be displayed. ShowImage only works if it is followed by WaitKey.
• I'm not sure if capture=NULL would mean that your file was not opened. Use isOpened instead.

我已经更正了您的代码，并将其放入C ++接口，因此现在是一个合适的C ++代码。我的重写与您的程序一样，逐行执行。

I have corrected your code and put it into the C++ interface, so it is a proper C++ code now. My rewrite does line-by-line the same as your program did.

//#include <stdio.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
//#include <iostream>

using namespace cv

int main(int argc, char** argv)
{
    string filename = "yourfile.avi";
    VideoCapture capture(filename);
    Mat frame;

    if( !capture.isOpened() )
        throw "Error when reading steam_avi";

    namedWindow( "w", 1);
    for( ; ; )
    {
        capture >> frame;
        if(frame.empty())
            break;
        imshow("w", frame);
        waitKey(20); // waits to display frame
    }
    waitKey(0); // key press to close window
    // releases and window destroy are automatic in C++ interface
}

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