Error with showing video using Raspberry Pi Camera and Open Cv

Question

When myself and my friend run this code, the output is just a black window. We expected it to start streaming video from our RaspberryPi camera. We're using a RaspberryPi, the RaspberryPi Camera, openCv, and the Raspicam Library.

Here is our code:

#include <opencv2/opencv.hpp>
#include "opencv2/highgui/highgui.hpp"
#include <raspicam_cv.h>
#include <iostream>

using namespace std;
using namespace cv;

int main()
{
  raspicam::RaspiCam_Cv Camera;
  namedWindow("color", CV_WINDOW_AUTOSIZE);
  while(1)
  {
    Mat image;
    Camera.grab();
    Camera.retrieve(image);
    imshow("color", image);
    waitKey(33);
  }
  return (0);
}

Here is a link to a tutorial we used to install the RaspiCam library. If you need any more information, please let me know. Thanks!

Answer 1

You need to open the camera in order to use it.

Before your loop:

if( !Camera.open() ) 
{
   std::cerr << "Cannot open the camera" << std::endl;
}

The grab() method return a boolean. You can check if there is an error or not when you want to grab a picture.

Moreover, you should specify the color encoding you want. The default is RGB, but it consume many CPU.