Opencv VideoCapture打开摄像头接口讲解

VideoCapture打开摄像头接口讲解

* VideoCapture
* bool open (int index)
* VideoCapture cap(index)
* open(int cameraNum, int apiPreference)
源码
cap_ffmpeg_impl.hpp

VideoCapture打开视频流文件

* bool open (const String& filename)
* VideoCapture cap(const String & filename)
* bool open(const String & filename, int apiPreference)
VideoCapture 关闭和空间释放

* 关闭和空间释放
* ~VideoCapture
* release（）
读取一帧视频
read(OutputArray image)//cap.cpp bool grab() //读取并解码 virtual bool
retrieve(OutputArray image,int flag = 0);//图像色彩转化 vc >> mat bool
VideoCapture::read(OutputArray image) { CV_INSTRUMENT_REGION()if(grab())
retrieve(image);else image.release(); return !image.empty(); }
#include<iostream> #include<stdio.h> #include <opencv2/core.hpp> #include
<opencv2/imgcodecs.hpp> #include <opencv2/highgui.hpp> #include
<opencv2/imgproc.hpp> #include <opencv2/videoio.hpp> using namespace cv; using
namespace std; int main(int argc, char *argv) { VideoCapture video; video.open(
"1.mp4"); if (!video.isOpened()) { cout << "open video failed!" << endl;
getchar();return -1; } cout << "open video success!" << endl; namedWindow(
"video"); Mat frame; for (;;) { if (!video.read(frame)) { break; } if
(frame.empty())break; imshow("video", frame); waitKey(5); } getchar(); return 0
; }#include<iostream> #include<stdio.h> #include <opencv2/core.hpp> #include
<opencv2/imgcodecs.hpp> #include <opencv2/highgui.hpp> #include
<opencv2/imgproc.hpp> #include <opencv2/videoio.hpp> using namespace cv; using
namespace std; int main(int argc, char *argv) { VideoCapture video; video.open(
"1.mp4"); if (!video.isOpened()) { cout << "open video failed!" << endl;
getchar();return -1; } cout << "open video success!" << endl; namedWindow(
"video"); Mat frame; for (;;) { //if (!video.read(frame)) //{ // break; //}
//读帧与解码 if (!video.grab()) { break; } //转换颜色格式 if (!video.retrieve(frame)) {
break; } if (frame.empty()) break; imshow("video", frame); waitKey(5); }
getchar();return 0; }

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