import ddf.minim.*;
  import ddf.minim.effects.*;
  
  Minim minim;
  AudioPlayer groove;
  BandPass bpf;
  
  void setup()
  {
    size(512, 200, P3D);
    
    minim = new Minim(this);
    
    groove = minim.loadFile("groove.mp3");
    groove.loop();
    // make a band pass filter with a center frequency of 440 Hz and a bandwidth of 20 Hz
    // the third argument is the sample rate of the audio that will be filtered
    // it is required to correctly compute values used by the filter
    bpf = new BandPass(440, 20, groove.sampleRate());
    groove.addEffect(bpf);
  }
  
  void draw()
  {
    background(0);
    stroke(255);
    // draw the waveforms
    // the values returned by left.get() and right.get() will be between -1 and 1,
    // so we need to scale them up to see the waveform
    for(int i = 0; i < groove.right.size()-1; i++)
    {
      float x1 = map(i, 0, groove.bufferSize(), 0, width);
      float x2 = map(i+1, 0, groove.bufferSize(), 0, width);
      line(x1, height/4 - groove.left.get(i)*50, x2, height/4 - groove.left.get(i+1)*50);
      line(x1, 3*height/4 - groove.right.get(i)*50, x2, 3*height/4 - groove.right.get(i+1)*50);
    }
    // draw a rectangle to represent the pass band
    noStroke();
    fill(255, 0, 0, 60);
    rect(mouseX - bpf.getBandWidth()/20, 0, bpf.getBandWidth()/10, height);
  }
  
  void mouseMoved()
  {
    // map the mouse position to the range [100, 10000], an arbitrary range of passBand frequencies
    float passBand = map(mouseX, 0, width, 100, 2000);
    bpf.setFreq(passBand);
    float bandWidth = map(mouseY, 0, height, 50, 500);
    bpf.setBandWidth(bandWidth);
    // prints the new values of the coefficients in the console
    bpf.printCoeff();
  }
  
  void stop()
  {
    // always close Minim audio classes when you finish with them
    groove.close();
    // always stop Minim before exiting
    minim.stop();
    
    super.stop();
  }