Random Guy Developer Blog: Creating the frequencies spectrum frame

Following what we did for the waveform, we are gonna create a panel that shows the frequencies spectrum of the current song signal. The process is the same, the idea is that each time the pcmdata is sent to the frame the signal is processed using an implementation of the fast fourier trasnform and then updated on screen. Here is what are we gonna do:
create a N_TASK of tasks to work on a portion of the signal
each task uses FFT on part of the pcmdata and calculate the frequencies
the last task doing the job merges all the results together making the avg of each result provided from the tasks for each frequency.
in the end we call repaint() to update the panel.
package it.pievis.GUI;

import gov.nasa.jpf.jvm.Verify;
import it.pievis.utils.BackgroundExecutor;
import it.pievis.utils.BarrierMonitorLock;
import it.pievis.utils.Timer;
import it.pievis.utils.Utils;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Label;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.geom.Rectangle2D;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

import it.pievis.utils.Complex;

public class FFTParallelFrame extends JFrame {
 
 private int N_TASK = 2;
 private int pcmLenght = 0;
 private int pow2FreqLenght; //max power of 2 we can select
 private boolean canWriteOnScreen = false;
 private boolean updatedOnScreen = true;

 private int WIDTH = 450;
 private int HEIGHT = 100;
 private FreqDiagPanel fdp;
 private Rectangle2D[] recs;
 private Complex[][] frequencies; //Frequencies calculated for every task at a given time
 
 private int taskCount = 0; //Necessary for ugly way to coordinate tasks over frequencies
 
 //Icons
 ImageIcon frameIcon = new ImageIcon(getClass().getResource("/res/waveicon.png"));
 
 //
 Timer timer = new Timer(); //timer for max/min drawtime
 
 public FFTParallelFrame() {
  super();
  setIconImage(frameIcon.getImage());
  setSize(WIDTH, HEIGHT+20); //+20 is the title gap
  setTitle("Frequency Diagram Frame");
  setName("Main FRAME");
  fdp = new FreqDiagPanel();
  fdp.setSize(WIDTH, HEIGHT);
  fdp.setName("FreqDiag PANEL");
  add(fdp);
 }
 
 public void updateWave(byte[] pcmdata)
 {
  fdp.updateWave(pcmdata);
 }
 
 /**
  * JPanel that contains the frequency spectrum
  * every frequency is drawn on screen as a rectangle
  * every times a new pcmdata is received, N_TASK tasks process a portion of the signal (that is pcmdata)
  * @author Pierluigi
  */
 class FreqDiagPanel extends JPanel
 {
  byte[] pcmdata = null;
  Label cdtlmx; //Label per il drawtime massimo
  Label cdtlmn; //Label per il drawtime minimo
  Label cdtlavg; //Label per il drawtime medio
  
  public FreqDiagPanel()
  {
   super();
   ///
   frequencies = new Complex[N_TASK][]; //Instantiate first array
   initAmbient(); //Instantiate the arrays
   
   //Label for drawing time
   setLayout(null);
   cdtlmx = new Label("DrawTime max");
   cdtlmx.setBounds(0, 0, 80, 10);
   add(cdtlmx);
   cdtlmn = new Label("DrawTime min");
   cdtlmn.setBounds(0, 10, 80, 10);
   add(cdtlmn);
   cdtlavg = new Label("DrawTime avg");
   cdtlavg.setBounds(160, 0, 80, 10);
   add(cdtlavg);
  }
  
  /**
   * Refresh the wave every times a new pcmdata arrives
   */
  public void updateWave(byte[] pcmdata)
  {
   //log("pcmdata received");
   synchronized (fdp) {
    if(!updatedOnScreen) //scarta tutti i pcm che non posso disegnare
     return;
    updatedOnScreen = false;
   }
   this.pcmdata = pcmdata;
   callTask();
  }
  
  /**
   * Calls all the task with the canon executor
   */
  private void callTask()
  {
   timer.start();
   if(pcmdata.length == 0){
    //May happen when we seek
    updatedOnScreen = true;
    return;
   }
   
   //Instantiate arrays every time pcmdata change length
   if(pcmdata.length != pcmLenght)
   {
    initAmbient(); //Reinstantiate the arrays
   }
   int HEIGHT = getHeight();
   int WIDTH = getWidth();
   
   //Let more tasks do the math
   for(int i=0; i<N_TASK; i++)
    BackgroundExecutor.get().execute(new FftTask(WIDTH, HEIGHT, i));
  }
  
  /**
   * Handle the refresh of the diagram
   * @param g
   */
  private void doDrawing(Graphics g){
   
   Graphics2D g2d = (Graphics2D) g;
   g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_OFF);
   
   if(pcmdata == null || pcmdata.length == 0){
          //Render something
    Rectangle rect0 = new Rectangle(new Point(10,10), new Dimension(WIDTH-20, HEIGHT-20));
    g2d.draw(rect0);
    g2d.fill(rect0);
    return;
         }
   //Let swing handle the drawing
   drawRects(g2d);
  }
  
  /**
   * Splitted computation for each part of the signal
   * Each task calculate the frequencies using a different part of the signal
   * One task do the math for the rectangles positions and lengths
   * @author Pierluigi
   */
  class FftTask implements Runnable
  {
   Graphics2D g2d;
   int HEIGHT;
   int WIDTH;
   int N;
   
   public FftTask(int width, int height, int n) {
    HEIGHT = height;
    WIDTH = width;
    N = n; //to identify wich part of the pcmdata it should process
   }
   
   @Override
   public void run() {
    calcFrequency(); //set freqencies[N] with the result of the fft
    synchronized (FFTParallelFrame.this) {
     //Verify.beginAtomic();
     taskCount++;
     //Only one will calculate the rectangle position relative to the frequencies
     if(taskCount == N_TASK){
      taskCount = 0;
      calcRects();
      canWriteOnScreen = true;
      repaint();
     }
     //Verify.endAtomic();
    }
   }
   
   /**
    * Calculates frequencies[N] using fft on part of the signal
    */
   private void calcFrequency(){
    //int windowSize = pcmdata.length / N_TASK;
    int windowSize = pow2FreqLenght;
    int winSizeHalf = windowSize/2;
    int from = (windowSize) * N;
    int to = windowSize * (N+1);
    Complex[] data = new Complex[winSizeHalf]; //2channel to 1 wave rappresentation for the task
    int j = 0;
    for(int i = from; i<to; i+=2){
     data[j] = new Complex(Utils.getSixteenBitSample(pcmdata[i+1], pcmdata[i]),0);
     j++;
    }
    Complex[] freqs = Utils.fft(data);
    frequencies[N] = freqs;
   }
    
   /**
    * Calculate positions of the rectangles on screen
    */
   private void calcRects()
   {
    //log("CalcRects called " + Thread.currentThread().getName());
    int nRects = frequencies[0].length/2; //Number of data (rectangles) on screen, only half of the fft returned frequencies are useful
    //log("STAMPA: " + nRects  + "  " + frequencies[0][0]);
    float recWidth = (float) WIDTH/nRects;
    float scale = (float) HEIGHT/1000000;
    for(int i = 0; i<nRects; i++)
    {
     double value = 0;
     for(int j = 0; j < N_TASK; j++)
     {
      assert (frequencies[j][i] != null);
      if(frequencies[j][i] != null)
       value += frequencies[j][i].abs(); //take the value from every vector frequency
       //(calculated from different part of the wave by the tasks)
     }
     value = (value / N_TASK) * scale; //avarege value between calcs, scaled & inverted
     float posx = recWidth * i;
     Rectangle2D r = new Rectangle();
     r.setRect(posx, HEIGHT-value, recWidth, value);
     recs[i] = r; //
    }
   }
  }
  
  /**
   * This should draw rectangles stored in recs
   * @param g2d
   */
  void drawRects(Graphics2D g2d)
  {
   assert(recs != null);
   if(canWriteOnScreen){ //repaint() might be called by something else
    for(int i = 0; i<recs.length; i++)
    {
     g2d.draw(recs[i]);
     g2d.fill(recs[i]);
     if(i%2==0)
      g2d.setColor(Color.darkGray);
     else
      g2d.setColor(Color.lightGray);
    }
    g2d.dispose();
    timer.stop(); //stop the timer for the draw time
    synchronized (fdp) {
     canWriteOnScreen = false;
     updatedOnScreen = true;
    }
   }
  }
  
  /**
   * Called each time the UI is rendered
   */
  @Override
  protected void paintComponent(Graphics g) {
   super.paintComponent(g);
   doDrawing(g);
   cdtlmx.setText(timer.getMax() + "");
   cdtlmn.setText(timer.getMin() + "");
   cdtlavg.setText(timer.getAvg() + "");
  }
  
  /**
   * Instantiate all the needs of the panel, like the arrays
   */
  private void initAmbient(){
   if(pcmdata != null)
    pcmLenght = pcmdata.length;
   else
    pcmLenght = 4608;
   int freqLenght = (pcmLenght/N_TASK)/2;
   int log2 = Utils.log(freqLenght, 2);
   pow2FreqLenght = (int) Math.pow(2, log2);
   log("Total rectangles/frequencies to draw: " + pow2FreqLenght +"/2");
   for(int i = 0; i<N_TASK; i++)
    frequencies[i] = new Complex[pow2FreqLenght];
   recs = new Rectangle2D[pow2FreqLenght/4]; //we use 16bit data and only half of the fft freqencies are useful
   canWriteOnScreen = false; //don't write until we have recalculated the frequencies
  }
 }
 /// END OF JPANEL CLASS
 
 private void log(String line)
 {
  System.out.println("FD out] " + line);
 }
}
Random Guy Developer Blog

giovedì 24 luglio 2014

Creating the frequencies spectrum frame

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