function setup() {
  createCanvas(fftBands, 256);
  noFill();

  soundFile.loop();

  /**
   *  Create an FFT object.
   *  Accepts optional parameters for
   *    - Smoothing 
   *    - Length of the FFT's analyze/waveform array. Must be a power of two between 16 and 1024 (default).
   */
  fft = new p5.FFT(.99, fftBands);

  p = createP('press any key to pause / play');
}
DEMO: Draw the waveform of a sound as it plays using p5.FFT.waveform()