Scrolling Spectrogram in Processing using Sound library

scrolling_spectrogram.java

import processing.sound.*;

FFT fft;
AudioIn in;
int bands = 512;
float[] spectrum = new float[bands];

void setup() {
  size(512, 600);
  background(255);
    
  // Create an Input stream which is routed into the Amplitude analyzer
  fft = new FFT(this, bands);
  in = new AudioIn(this, 0);
  
  // start the Audio Input
  in.start();
  
  // patch the AudioIn
  fft.input(in);
}      

void draw() { 
  if(frameCount % height == 0) {
    background(255);
  }
  fft.analyze(spectrum);
  stroke(0, 0, 0, 10);
  
  for(int i = 0; i < bands; i++){
    // The result of the FFT is normalized
    line(i, (height + frameCount)%height, i, (height + frameCount)%height  - spectrum[i]*height*100);
  } 
}