如何使用 OpenCV 在 2 分钟的间隔内从网络摄像头捕获视频

Question

我正在尝试从网络摄像头 (Logitech C170) 捕捉视频。到目前为止，我能够捕获视频并将其保存在 .avi 容器中。

我的 C++ 代码是这样的

using namespace std;
using namespace cv;

int main(int, char**)
{
    VideoCapture capture(0);
    .
    .
    .
    .
    VideoWriter video("record.avi", CV_FOURCC('M', 'J', 'P', 'G'), frame_rate, Size(frame_width,frame_height), true);
    .
    .
    .
    .

    Mat frame;
    .
    .
    .
    .
    for(;;)
    {
       capture >> frame;
       video.write(frame);

    }

    return 0;
}

我的下一个目标是

     Record         Sleep          Record
|<------------>|<------------>|<------------>| Goes for infinite loop...
    3 Minutes      2 Minutes      3 Minutes
        |              |              |
        |              |              |
        v              v              v
     save to   Cam goes to sleep    save to
  /records/1.avi                /records/2.avi

我用的是opencv-2.4.3，代码是c++。

如果我需要任何其他信息，请告诉我。

我怎样才能做到这一点？请提出您宝贵的建议？

提前致谢。

Answer 1

我建议使用时钟来测量时间。

在循环运行时继续检查时钟，一旦达到 3 分钟，切换到睡眠模式功能，并计时，一旦达到 2 分钟，再次切换回来。

下面是一些代码，用于计时从 this SO 答案中部分蚕食的函数。

我确定您可以编辑它以保留您的录音时间并允许您在录音和睡眠之间切换。

希望对您有所帮助。

#include <iostream>
#include <cstdio>
#include <ctime>

int main()
{
    std::clock_t start;
    double duration;

    start = std::clock();

    // Run your frame grabbing code here //

    duration = ( std::clock() - start ) / (double) CLOCKS_PER_SEC;
}

Answer 2

所以，这是解决方案。

#include<iostream>
#include<unistd.h>
#include<sstream>
#include<string>
#include<ctime>
#include<opencv/cv.h>
#include<opencv2/opencv.hpp>
#include<opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>

using namespace std;
using namespace cv;

string currentDateTime() {
    time_t     now = time(0);
    struct tm  tstruct;
    char       buf[80];
    tstruct = *localtime(&now);
    strftime(buf, sizeof(buf), "%X", &tstruct);
    return buf;
}

int main(int, char**)
{
    VideoCapture capture(0);
    .
    .
    .
    .
    int frame_rate = 10;
    .
    .
    .
    .
    for(int i = 0; i<4 ; i++)    // for infinite loop remove iteration
    {   
        time_t timer_start, timer_stop;
        Mat frame;
        stringstream recordstr;
        recordstr << "records/" << i << ".avi";
        string recordfile = recordstr.str();

        VideoWriter video(recordfile, CV_FOURCC('M', 'J', 'P', 'G'), frame_rate, Size(frame_width,frame_height), true);

        cout<<"video "<<i<<".avi started capturing at "<< currentDateTime() <<endl;
        time (&timer_start);
        for(int j = 0; j < numFrames; j++){
            capture >> frame;
            if(frame.empty()){
                cout << "Failed to capture an image" << endl;
                return -1;
            }
            video.write(frame);
        }
        time (&timer_stop);
        double timeDifference = difftime (timer_stop, timer_start);
        cout<<"video "<<i<<".avi stopped capturing at "<< currentDateTime() <<" & took "<<timeDifference<<" seconds"<<endl;
        sleep(60);
    }
    return 0;
}

输出为：

video 0.avi started capturing at 12:09:18
video 0.avi stopped capturing at 12:09:55 & took 37 seconds
video 1.avi started capturing at 12:10:55
video 1.avi stopped capturing at 12:11:32 & took 37 seconds
video 2.avi started capturing at 12:12:32
video 2.avi stopped capturing at 12:13:09 & took 37 seconds

我将不胜感激任何其他解决方案。所以请post，如果你有

谢谢

如何使用 OpenCV 在 2 分钟的间隔内从网络摄像头捕获视频

How to capture the video from webcam in the interval of 2 minutes using OpenCV

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