fit-hack 2017 - LEDflashing - WriteUp

import java.awt.image.BufferedImage;
import java.io.StringWriter;

public class LEDflashing {

    // check collors to determine if the led is on or off
    private boolean led(int rgb, int l) {
        
        int r = (rgb >> 16) &0xff;
        int g = (rgb >>  8) &0xff;
        int b = (rgb >>  0) &0xff;
        
        if (r>0xa0 && g>0x50 && b>0x30)
            return true;
        
        return false;
        
    }

    public LEDflashing() {
        JFFMPEG.initFFMPEG("LED flashing-P7yKZqAk2OY.mp4");

        StringWriter sw = new StringWriter();
        
        boolean getNext = false;
        JFFMPEG.get();
        try {
        for (int i=1; i<50251; i++) {
            if (i%500==0) 
                System.out.print(".");
            
            BufferedImage frame = JFFMPEG.get();
            
            if (frame==null)
                break;
            
            boolean led1 = led(frame.getRGB(182, 122), 0);
            boolean led2 = led(frame.getRGB(208, 122), 1);
            
            if (led1 && led2) {
                throw new RuntimeException("check Frame "+i);
            }
            if (!led1 && !led2) {
                getNext = true;
            } else if (getNext) {
                if (led1) {
                    sw.append('0');
                } else {
                    sw.append('1');
                }
                getNext = false;
            }
        }
        } catch(Exception e) {
            e.printStackTrace();
        }
        System.out.println(sw.toString());
        String bits = sw.toString();
        while (bits.length()>0) {
            int c = Integer.parseInt(bits.substring(0,7),2);
            System.out.print((char)c);
            bits = bits.substring(7);
        }
        JFFMPEG.exitFFMPEG();
    }
    
    public static void main(String[] args) {
        new LEDflashing();
    }

}