NipkowTester

package com.anmipo.nipkow;

import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;
import javax.sound.sampled.LineUnavailableException;

import com.sun.media.sound.WaveFileWriter;

public class NipkowTester {
    //display resolution
    public static final int ROWS = 32;
    public static final int COLS = 22;
    //frames (disk rotations) per second
    public static final float FPS = 12.5f;
    //clip duration
    public static final int PLAY_DURATION_SECONDS = 10 * 60;

    //image data (scanned left-to-right, top-to-bottom)
    //values denote brightness (0 - min, 9 - max)
    public static final byte[] IMAGE = new byte[] {
        //      5          10         15         20
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //01
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //02
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //03
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //04
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //05
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //06
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,0,0,0,0, 0,0, //07
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,0,0,0,0, 0,0, //08
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,0,0,0,0, 0,0, //09
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,0,0,0,0, 0,0, //10
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //11
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //12
        0,0,0,9,9, 9,9,9,9,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //13
        0,0,0,9,9, 9,9,9,9,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //14
        0,0,0,9,9, 9,9,9,9,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //15
        0,0,0,9,9, 9,9,9,9,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //16
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //17
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //18
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //19
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //20
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //21
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //22
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //23
        0,0,0,9,9, 0,0,0,0,9, 9,0,0,0,0, 0,9,9,0,0, 0,0, //24
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //25
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //26
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //27
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //28
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //29
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //30
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //31
        0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0,0,0,0, 0,0, //32
    };

    //sound sampling frequency
    public static final int SAMPLE_RATE = 44100; //Hz
    //career sound wave frequency to be modulated by pixel data
    public static final int CAREER_FREQUENCY = 22050; //Hz
    //each sound sample is multiplied by this number
    public static final int VOLUME = 13;
    //output audio format
    public static final AudioFormat AUDIO_FORMAT =
        new AudioFormat(
                SAMPLE_RATE,  //sample rate
                8,        //sample size in bits
                1,        //number of channels
                true,     //signed
                false);   //bigEndian


    public static void main(String[] args) {
        try {
            byte[] samples = buildFrame(IMAGE, ROWS, COLS, FPS);
            //saveToWav(samples, "d://temp//nipkov.wav");
            playFrame(samples, (int)(PLAY_DURATION_SECONDS * FPS));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Constructs a sequence of raw audio samples representing the given image.
     * @param image     the image to convert
     * @param rows      vertical image size
     * @param cols      horizontal image size
     * @param fps       desired output frame rate
     * @return array of raw audio samples in {@link #AUDIO_FORMAT} format
     */
    protected static byte[] buildFrame(byte[] image, int rows, int cols, float fps) {
        if (image.length != (rows * cols))
            throw new java.lang.IllegalArgumentException(
                    String.format("The image is not %d by %d", rows, cols));

        float frameDuration = 1/fps; //seconds per frame
        float pixelDuration = frameDuration / (cols * rows); //seconds per pixel
        //number of sound samples per pixel
        int samplesPerPixel = Math.round(
                pixelDuration * AUDIO_FORMAT.getSampleRate());

        //number of samples between career meander change
        int careerPeriod = SAMPLE_RATE / CAREER_FREQUENCY;

        int bufferLength = (int)(samplesPerPixel * cols * rows);
        byte[] buf = new byte[bufferLength];
        int iPixel = 0; //current pixel of the IMAGE
        int careerValue = -1; //current career meander state (+1 or -1)

        int pixelCounter = samplesPerPixel;
        int careerCounter = careerPeriod;
        for (int i = 0; i < bufferLength; i++) {
            buf[i] = (byte)(VOLUME * careerValue * image[iPixel]);
            if (--pixelCounter == 0) {
                pixelCounter = samplesPerPixel;
                iPixel++;
                careerValue = -careerValue;
            } else if (--careerCounter == 0) {
                careerValue = -careerValue;
                careerCounter = careerPeriod;
            }

        }
        return buf;
    }

    /**
     * Outputs the given audio <tt>samples</tt> to sound card.
     * Does not return until playing is done.
     * @param samples         audio samples to play, representing
     *                        one image frame (in {@link #AUDIO_FORMAT}).
     * @param loopCount       number of times to repeat the samples
     * @throws LineUnavailableException
     * @throws InterruptedException
     */
    protected static void playFrame(byte[] samples, int loopCount)
            throws LineUnavailableException, InterruptedException {
        Clip clickClip = AudioSystem.getClip();
        clickClip.open(AUDIO_FORMAT, samples, 0, samples.length);
        try {
            System.out.print("Playing... ");
            clickClip.setFramePosition(0);
            clickClip.loop(loopCount);
            clickClip.drain();
            //sleep until all the sound is played
            Thread.sleep((1000 * samples.length/SAMPLE_RATE) * loopCount);
        } finally {
            clickClip.close();
            System.out.println("Done");
        }
    }

    /**
     * Saves raw audio samples (in {@link #AUDIO_FORMAT} format) to a wave file.
     * @param samples   audio samples to save
     * @param fileName  fully specified output file name
     * @throws IOException
     */
    protected static void saveToWav(byte[] samples, String fileName) throws IOException {
        AudioInputStream in = new AudioInputStream(
                new ByteArrayInputStream(samples),
                AUDIO_FORMAT, samples.length/AUDIO_FORMAT.getFrameSize());
        try {
            BufferedOutputStream out = new BufferedOutputStream(
                    new FileOutputStream(fileName));
            try {
                WaveFileWriter writer = new WaveFileWriter();
                writer.write(in, AudioFileFormat.Type.WAVE, out);
            } finally {
                out.close();
            }
        } finally {
            in.close();
        }
    }

}