#include <opencv2/core/core.hpp>

#include <opencv2/highgui/highgui.hpp>

#include <opencv2/imgproc/imgproc.hpp>

#include <iostream>

using namespace std;

using namespace cv;

int main()

{

	//打开视频文件：其实就是建立一个VideoCapture结构

	String videopath = "F:/dongdong/0tool/3D/2模型/相机阵列/1_12cam亿级相机/数据/giga1014  2/";

	String imagepath = "F:/dongdong/0tool/3D/2模型/相机阵列/1_12cam亿级相机/数据/giga1014  2/jpg/1/";

	VideoCapture capture(videopath + "ch11_20191014175459.mp4");

	//检测是否正常打开:成功打开时，isOpened返回ture

	if (!capture.isOpened())

		cout << "fail toopen!" << endl;

	//获取整个帧数

	long totalFrameNumber = capture.get(CV_CAP_PROP_FRAME_COUNT);

	cout << "整个视频共" << totalFrameNumber << "帧" << endl;

	//设置开始帧()

	long frameToStart =33;

	capture.set(CV_CAP_PROP_POS_FRAMES, frameToStart);

	cout << "从第" << frameToStart << "帧开始读" << endl;

	//设置结束帧

	int frameToStop = 66;

	if (frameToStop < frameToStart)

	{

		cout << "结束帧小于开始帧，程序错误，即将退出！" << endl;

		return -1;

	}

	else

	{

		cout << "结束帧为：第" << frameToStop << "帧" << endl;

	}

	//获取帧率

	double rate = capture.get(CV_CAP_PROP_FPS);

	cout << "帧率为:" << rate << endl;

	//定义一个用来控制读取视频循环结束的变量

	bool stop = false;

	//承载每一帧的图像

	Mat frame;

	//显示每一帧的窗口

	//namedWindow( "Extractedframe" );

	//两帧间的间隔时间:

	//int delay = 1000/rate;

	double delay = 1000 / rate;

	//利用while循环读取帧

	//currentFrame是在循环体中控制读取到指定的帧后循环结束的变量

	long currentFrame = frameToStart;

	while (!stop)

	{

		//读取下一帧

		if (!capture.read(frame))

		{

			cout << "读取视频失败" << endl;

			return -1;

		}

		cout << "正在读取第" << currentFrame << "帧" << endl;

		cvNamedWindow("Extractedframe",0);

		imshow( "Extractedframe", frame );

		//此处为跳帧操作

		if (currentFrame % 1 == 0) //此处为帧数间隔，修改这里就可以了

		{

			cout << "正在写第" << currentFrame << "帧" << endl;

			stringstream str;

			str << imagepath << currentFrame << ".jpg";        /*图片存储位置*/

			cout << str.str() << endl;

			imwrite(str.str(), frame);

		}

		//waitKey(intdelay=0)当delay≤ 0时会永远等待；当delay>0时会等待delay毫秒

		//当时间结束前没有按键按下时，返回值为-1；否则返回按键

		int c = waitKey(delay);

		//按下ESC或者到达指定的结束帧后退出读取视频

		if ((char)c == 27 || currentFrame > frameToStop)

		{

			stop = true;

		}

		//按下按键后会停留在当前帧，等待下一次按键

		if (c >= 0)

		{

			waitKey(0);

		}

		currentFrame++;

	}

	//关闭视频文件

	capture.release();

	waitKey(0);

	return 0;

}