OpenCV学习记录1

测试代码：

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace std;
using namespace cv;

int main(int argc, char **argv)
{
  VideoCapture video("cap.mp4");

  if(video.isOpened())
  {
    cout <<"width:" << video.get(CAP_PROP_FRAME_WIDTH) << endl;
    cout <<"height:" << video.get(CAP_PROP_FRAME_HEIGHT) << endl;
    cout <<"fps:" << video.get(CAP_PROP_FPS) << endl;
    cout <<"total fps:" << video.get(CAP_PROP_FRAME_COUNT) << endl;
  }
  else
  {
    cout << "please confirm the open opeartion" << endl;
    return -1;
  }

  while(1)
  {
    Mat frame;
    video >> frame;
    if(frame.empty())
    {
      break;
    }

    imshow("video", frame);

    waitKey(1000/video.get(CAP_PROP_FPS));
  }

  waitKey();
  return 0;
}

编译：

g++ videocapture.cpp `pkg-config --cflags --libs opencv`

在同级目录下存放cap.mp4

运行./a.out

---

修改代码，改成从摄像头获取数据,只需要将"cap.mp4"修改为视频设备ID 0即可。

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace std;
using namespace cv;

int main(int argc, char **argv)
{
  VideoCapture video(0);

  if(video.isOpened())
  {
    cout <<"width:" << video.get(CAP_PROP_FRAME_WIDTH) << endl;
    cout <<"height:" << video.get(CAP_PROP_FRAME_HEIGHT) << endl;
    cout <<"fps:" << video.get(CAP_PROP_FPS) << endl;
    cout <<"total fps:" << video.get(CAP_PROP_FRAME_COUNT) << endl;
  }
  else
  {
    cout << "please confirm the open opeartion" << endl;
    return -1;
  }

  while(1)
  {
    Mat frame;
    video >> frame;
    if(frame.empty())
    {
      break;
    }

    imshow("video", frame);

    waitKey(1000/video.get(CAP_PROP_FPS));
  }

  waitKey();
  return 0;
}

 设备打开情况：

可以看到，OpenCV基于的是V4L2框架。

---

结束！