Recompile OpenCV Java for Eclipse

Question

I'm using OpenCV for a object detection project. I'm trying to read frames from a stored video file using VideoCapture, but in OpenCV Java there is no current implementation. I followed instructions in this post: open video file with opencv java, to edit the source files of OpenCV Java to allow this functionality. The problem is I don't know how to recompile the files? - since I just added the downloaded opencv jar file into my eclipse project originally.

Answer 1

You should probably try JavaCV, an OpenCV wrapper for Java.

This post shows what you need to download/install to get things working on your system, but I'm sure you can find more updated posts around the Web.

One of the demos I present during my OpenCV mini-courses contains a source code that uses JavaCV to load a video file and display it on a window:

import static com.googlecode.javacv.cpp.opencv_core.*;
import static com.googlecode.javacv.cpp.opencv_imgproc.*;
import static com.googlecode.javacv.cpp.opencv_highgui.*;
import com.googlecode.javacv.OpenCVFrameGrabber;
import com.googlecode.javacv.FrameGrabber;

public class OpenCV_tut4 
{
    public static void main(String[] args) 
    {
        FrameGrabber grabber = new OpenCVFrameGrabber("demo.avi");
        if (grabber == null)
        {
            System.out.println("!!! Failed OpenCVFrameGrabber");
            return;
        }

        cvNamedWindow("video_demo");

        try            
        {
            grabber.start();            // initialize video capture
            IplImage frame = null;  

            while (true)
            {
                frame = grabber.grab(); // capture a single frame               
                if (frame == null)
                {
                    System.out.println("!!! Failed grab");
                    break;
                }

                cvShowImage("video_demo", frame);
                int key = cvWaitKey(33);
                if (key == 27)          // ESC was pressed, abort!
                    break;
            }

        }
        catch (Exception e) 
        {    
            System.out.println("!!! An exception occurred");
        }
    }
}