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Track-bars are controllable bars which are used to control various parameters in OpenCV. Using track-bars, we can make it easier and change the parameters graphically. Track-bar removes this limitation and enables to create of dynamic effects using OpenCV.The following program demonstrates how to add track-bars in OpenCV using C++.Example#include #include using namespace cv; using namespace std; int main() { Mat original;//Declaring a matrix// original = imread("sky.jpg");//loading the image in the matrix// namedWindow("Slider");//Declaring window to show the image// int light = 50;//starting value of the trackbar// createTrackbar("Brightness", "Slider", &light, 100);//creating a trackbar// int contrast = ... Read More
To get the FPS value, we used the 'get()' command of and 'CAP_PROP_FPS' as the argument of the 'get()'. This argument returns the FPS in integer form.At the starting of the program, we have taken an integer variable named 'FPS'. Then we used FPS = cap.get(CAP_PROP_FPS); to store the FPS value in the variable.The following program gets the FPS of a video and shows it in the console window.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; int main() { int FPS;//Declaring an integer variable to store the number of total frames// VideoCapture cap("video1.mp4");//Declaring ... Read More
Here, we will understand how to calculate the elapsed time using OpenCV.The following program calculates the elapsed time in OpenCV using C++.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; int main() { Mat myImage;//Declaring a matrix to load the frames// namedWindow("Video Player");//Declaring the video to show the video// VideoCapture cap("video.mp4");//Declaring an object to load video from device// if (!cap.isOpened()){ //This section prompt an error message if no video stream is found// cout myImage; int elapsed_time;//Declaring an integer variable to store the elapsed time// ... Read More
The current frame means that you are playing a video and the frame shown now is the current frame. It is also referred to as the active frame. In many application, you can require to get the number of the current frame.The following program reads the position of the current frame and shows it in the console window.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; int main() { Mat myImage;//Declaring a matrix to load the frames// namedWindow("Video Player");//Declaring the video to show the video// VideoCapture cap("video.mp4");//Declaring an object to load video from ... Read More
We will learn how to calculate the total number of frames in OpenCV. Using OpenCV, it is elementary to count and show the total number of frames of a video. However, you have to store one thing in mind that we cannot count the total number of real-time video frames. Because a real-time video does not have a specific number of frames.The following program counts the number of total frames and shows it in the console window.Example#include #include using namespace std; using namespace cv; int main() { int frame_Number;//Declaring an integervariable to store the number of total frames// ... Read More
When we want to store a video, we have to define the location we want to store. Then we need to specify FourCC, FourCC stands for 'Four Character Code'. It is a sequence of 4-byte characters that identifies data formats. We also need to declare the FPS to store a video and frame size is also necessary for this storing process. The following program takes real-time video stream from the default camera and stores the video in C directory.The following program demonstrates how to store video in your computer in OpenCV using C++.Example#include//OpenCV header to use VideoCapture class and VideoWriter// ... Read More
We used 'set()' class of OpenCV. Using 'set()' class, we can set the height and width of the frames. The following lines are setting the height and width of the video in our program.set(CAP_PROP_FRAME_WIDTH, 320);set(CAP_PROP_FRAME_HEIGHT, 240);The first line is setting the width of the frames into 320 pixel and the second line is setting the height of the frames to 240 pixels. These two lines together is forming a 320 x 240 resolution video stream. This is how we can simply change the resolution of video using OpenCV.The following program changes the resolution of the video stream taken from default ... Read More
In this topic, we will know how to load a video file and play it using OpenCV, and we have to use a similar method that we have learned in the previous topic. The only difference is instead of putting the number as arguments of the object of 'VideoCapture' class, and we have to put the path of the video.The following program demonstrates how to load the video from your computer in OpenCV using C++.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; int main() { Mat myImage;//Declaring a matrix to load the frames// ... Read More
In this topic, we will determine how to use OpenCV to capture videos from the other cameras. The accessing of cameras other than the default camera is similar to accessing the default camera. There is only one difference that is instead of using 'VideoCapture cap(0)', we have to assign the camera number. The camera number is as per the sequence of a USB port. If the camera is connected to the third USB port, then the number of the camera is 3.The following program access the third camera and show the real-time video stream taken from the camera.Example#include//OpenCV header to ... Read More
Here, we will understand how to access the default camera and show the video stream from that camera. In a laptop, the fixed webcam is the default camera. In desktops, the default camera depends on the serial port's sequence where the camera is connected. When we want to capture the video stream from default webcam, we do not need to know anything about the camera and ensure that the camera is connected.The following program takes video stream from default camera and shows it on the screen in real-time.Example#include//OpenCV header to use VideoCapture class// #include using namespace std; using namespace cv; ... Read More