使用opencv c ++每1分钟创建一次新的视频文件

Question

我正在使用 opencv 开发一个小“行车记录仪”。原理很简单，我想创建一个以当前日期和时间命名的新视频文件。这些视频文件的内容就是网络摄像头的框架。

但是，第一分钟过去后，不再生成视频文件。

这是我的注释代码：

#include <iostream>
#include <windows.h>
#include <ctime>
#include <time.h>
#include <fstream>
#include <opencv2/core/core.hpp>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;


int record_video()
{
    VideoCapture cam(0);
    if (!cam.isOpened())
    {
        cout << "Error from webcam" << endl;
        return -1;
    }

    time_t t = time(0);
    struct tm* now = localtime( & t );
    char buffer[80];

    strftime(buffer, 80, "%F_%Hh%M.wmv", now); //get the date and time for my file

    VideoWriter video(buffer, CV_FOURCC('W', 'M', 'V', '2'), 30, Size(640, 480), true); //Creation of my video file from my webcam

    int chrono = 0; //start the chrono at 
    bool record = false;

    while (1)
    {
        Mat frame;
        cam >> frame;
        if (frame.empty())
        {
            cout << "frame is empty" << endl;
            return -1;
        }
        cout << chrono << endl;
        if ((chrono == 1) && (record == false)) //we start from the begining at 0 seconds and the recording has to be false to record again with the last condition (3rd condition)
        {
            cout << "new recording in file: " << buffer << endl; //display the name of video file on the console
            record = true;
        }
        if (record == true) //The condition here is to activate 
        {
            video.write(frame); //copy the frame from the webcam to the video file
            imshow("webcam", frame); //display what we record on a window
        }
        if (chrono == 1800) //the 1800 chrono = 60 seconds
        {
            record = false; //record is equal at false to repeat the first condition
            chrono = 1; //record is equal at false to repeat the first condition
        }

        chrono++; //incrementation of the chrono

        char c = (char)waitKey(1);
        if (c == 27)
            video.write(frame);     
    }
    cam.release();
    destroyAllWindows();
    return 0;
}

int main()
{
    record_video();
    return 0;
}

Answer 1

    if (chrono == 1800) //the 1800 chrono = 60 seconds
    {
        record = false; //record is equal at false to repeat the first condition
        chrono = 1; //record is equal at false to repeat the first condition
    }

    chrono++; //incrementation of the chrono

在此之后，chrono 将是 2，record 将是 false，因此您的代码将永远不会再次记录（因为 (chrono == 1) && (record == false) 永远不会是 true）。您需要在该 if-body 中将 chrono 设置为 0，因此它会在之后递增到 1，或者将递增移动到 if (record == true) 的主体中，因此当您使用时它不会递增没有录音。

任一：

    if (record == true) //The condition here is to activate 
    {
        video.write(frame); //copy the frame from the webcam to the video file
        imshow("webcam", frame); //display what we record on a window
        chrono++; //incrementation of the chrono
    }

（并进一步向下删除chrono++）

或者：

    if (chrono == 1800) //the 1800 chrono = 60 seconds
    {
        record = false; //record is equal at false to repeat the first condition
        chrono = 0; //record is equal at false to repeat the first condition
    }

    chrono++; //incrementation of the chrono

---

在站点节点上，您当前不是每分钟创建一个新视频，而是添加到同一个视频中。您可能希望将创建VideoWriter 的行移到循环中，特别是在if ((chrono == 1) && (record == false)) 中。在循环之外，只需保留VideoWriter video; 并使用open 来初始化一个新的视频文件：

    if ((chrono == 1) && (record == false)) //we start from the begining at 0 seconds and the recording has to be false to record again with the last condition (3rd condition)
    {
        time_t t = time(0);
        struct tm* now = localtime( & t );
        char buffer[80];

        strftime(buffer, 80, "%F_%Hh%M.wmv", now); //get the date and time for my file

        video.open(buffer, CV_FOURCC('W', 'M', 'V', '2'), 30, Size(640, 480), true); //Creation of my video file from my webcam

        cout << "new recording in file: " << buffer << endl; //display the name of video file on the console
        record = true;
    }

您的代码也跳过了第一帧，不确定这是否是故意的。您可以通过将条件更改为 if ((chrono == 0) && (record == false)) 来解决此问题，然后修改上述修复以重置 chrono 以确保将其重置为 0（而不是 1 或 2）。