opencvCreating a Video

Introduction

Whenever you work with video feeds you may eventually want to save your image processing result in a form of a new video file. For simple video outputs you can use the OpenCV built-in VideoWriter class, designed for this. It is useful to look at some concepts before using them. These concepts are codec ie decoder and FourCC (Four character code).

Creating a video with OpenCV (Java)

VideoWriter videoWriter;
videoWriter = new VideoWriter(outputFile, VideoWriter.fourcc('x', '2','6','4'),
                fps, frameSize, isRGB);
//We have stated that we will use x264 as codec with FourCC
//For writing, we add the following method and it will write the image we give as parameter in this call.
 public void Write(Mat frame) {
        if(videoWriter.isOpened()==false){
            videoWriter.release();
            throw new IllegalArgumentException("Video Writer Exception: VideoWriter not opened,"
                    + "check parameters.");        
        }
        //Write video
        videoWriter.write(frame);
    }

//With Video Capture for example, we can read images from the camera and write the same video

VideoCapture videoCapture = new VideoCapture(0);
Size frameSize = new Size((int) videoCapture.get(Videoio.CAP_PROP_FRAME_WIDTH), (int) videoCapture.get(Videoio.CAP_PROP_FRAME_HEIGHT));
VideoWriter videoWriter = new VideoWriter("test.avi", VideoWriter.fourcc('x', '2','6','4'),
                videoCapture.get(Videoio.CAP_PROP_FPS), frameSize, true);
while (videoCapture.read(mat)) {
            videoWriter.write(mat);         
        }
        videoCapture.release();
        videoWriter.release();