(一)、What is video save？

本次课程讲：If we save the code of the video recorded by the computer camera to our file,And determine whether the image we loaded was successfully entered.

（二）、知道什么APL？

（1）、VideoWriter 类:Multiple video frames can be saved as a file.

1.1参数一为:输出文件（路径）;

"E:\\视频\\out.mp4"

1.2参数二为:多媒体文件格式（int型）;

JPMG(.mp4)、XVID(.val)

int coder = VideoWriter::fourcc('J','P','M','G');

1.3参数三为:video frame rate (int型);25/24

1.4参数四为:清晰度（Size型(wideth,height)）;

Get the clarity of the native computer:

int width = cap.get(CAP_PROP_FRAME_WIDTH);
int height = cap.get(CAP_PROP_FRAME_HEIGHT);

1.5参数五为:色彩 (bool型)（true为真.0为假）;

1.6总结:

VideoWriter vw("E:\\视频\\out.mp4",coder,25.0,Size(width, height),true);

(2)、write方法、写入文件（把frame写入文件中去）、and compressed encoding.

Videowrite的对象.write（图像）;

vw.write(fram1);

（3）、release在关闭文件的时候,And forcibly output the data in the buffer to the disk.

Videowrite的对象.release（）

(三)、What is the idea of ​​the article？

首先我们要设置opencv的头文件、Then make window settings,Then build againVideoCaptureObject gets our camera,然后设置VideoWriter保存文件对象、Do constructor padding、然后进行whileThe loop judges whether the opening of the photographic device is successful,If successful, read the data frame,Then judge whether to read the data frame,If reading in a data frame,Then help start showing the image,并进行写入操作,Then set the keyboard wait time to 25,进行录制,最后
Turn off photographic equipment、Close the read-in device.

（四）、实战项目:

1.代码展现:

#include <iostream>
#include <string.h>
#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;
int main()
{
    
	Mat fram1;	
	namedWindow("视频", WINDOW_AUTOSIZE);
	VideoCapture  cap(0);
	int coder = VideoWriter::fourcc('J','P','M','G');
	int width = cap.get(CAP_PROP_FRAME_WIDTH);
	int height = cap.get(CAP_PROP_FRAME_HEIGHT);
	VideoWriter vw("E:\\视频\\out.mp4",coder,25.0,Size(width, height),true);         //
	while (cap.isOpened())           //True if it is opened
	{
    
		//cap >> fram1;
		
		cap.read(fram1);  
		if (fram1.empty())break;
		imshow("视频", fram1);
		vw.write(fram1);
		if (waitKey(25) == 27)break;
	}
	cout << "已经退出程序！" << endl;
	cap.release();
	vw.release();
	return 0;

}

2.效果展现