I want to extract frames of a video file in c++ in visual studio. Below is the code that I am using.
The vidfile.mp4
video file is in the same folder with the source file. The code compiles. But when I run the solution I get an error saying that can not open the video file
. I am guessing that there may be a problem with the filename in VideoCapture cap("vidfile.mp4");
. But I do not know the true cause of this error. How can I solve this problem?
#include <iostream>
#include "opencv2/opencv.hpp"
#include "opencv2/video.hpp"
#include "opencv2/core.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <vector>
#include <opencv2/imgcodecs.hpp>
#include "opencv2/highgui/highgui.hpp"
#include <highlevelmonitorconfigurationapi.h>
using std::cout; using std::cerr; using std::endl;
using namespace cv;
using namespace std;
int main()
{
int i = 0;
string str;
VideoCapture cap("vidfile.mp4");
// cap is the object of class video capture that tries to capture Bumpy.mp4
if (!cap.isOpened()) // isOpened() returns true if capturing has been initialized.
{
cout << "Cannot open the video file. \n";
return -1;
}
//double fps = cap.get(CV_CAP_PROP_FPS); //get the frames per seconds of the video
// The function get is used to derive a property from the element.
// Example:
// CV_CAP_PROP_POS_MSEC : Current Video capture timestamp.
// CV_CAP_PROP_POS_FRAMES : Index of the next frame.
//namedWindow("A_good_name", CV_WINDOW_AUTOSIZE); //create a window called "MyVideo"
// first argument: name of the window.
// second argument: flag- types:
// WINDOW_NORMAL : The user can resize the window.
// WINDOW_AUTOSIZE : The window size is automatically adjusted to fit the displayed image() ), and you cannot change the window size manually.
// WINDOW_OPENGL : The window will be created with OpenGL support.
while (1)
{
Mat frame;
// Mat object is a basic image container. frame is an object of Mat.
if (!cap.read(frame)) // if not success, break loop
// read() decodes and captures the next frame.
{
cout << "\n Cannot read the video file. \n";
break;
}
i = i + 1;
str = "MyImage" + std::to_string(i) + ".jpg";
//imshow("A_good_name", frame);
imwrite(str, frame);
// first argument: name of the window.
// second argument: image to be shown(Mat object).
if (waitKey(30) == 27) // Wait for 'esc' key press to exit
{
break;
}
}
return 0;
}