opencv学习笔记三十九：视频读写

 VideoCapture：视频抓取的类

VideoWriter ：写视频的类

fps（frame per second）帧率：每秒抓取显示多少帧

#include<opencv2\opencv.hpp>
using namespace cv;

int main(int arc, char** argv) {
	VideoCapture capture(0);//打开摄像头
	//VideoCapture capture;//实例化一个类的对象
	//capture.open("vtest.avi");//打开视频
	if (!capture.isOpened()) {
		printf("could not load video data\n");
		return -1;
	}
	Size size = Size(capture.get(CV_CAP_PROP_FRAME_WIDTH),capture.get( CV_CAP_PROP_FRAME_HEIGHT));
	VideoWriter writer("write_demo.avi",-1, 10, size, false);
	Mat frame;
	while (capture.read(frame))//读取每一帧，读完自动返回false
	{
		
		writer.write(frame);//写视频
		namedWindow("frame");
		cvtColor(frame, frame, CV_BGR2GRAY);
		threshold(frame, frame, THRESH_BINARY | THRESH_OTSU,255,CV_8