0702fft

// the fast fourier transform (FFT)

// jean-baptiste joseph fourier

// fourier theorem:

// a periodic signal may be expressed 

// as the sum of a series of sine waves, 

// each of which has a specific 

// amplitude and phase.

​

var themic; // this is the audio input

var thefft; // this is an FFT object

var x = 0;

var ystep = 0;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(0);

  themic = new p5.AudioIn(); // listen to the mic

  themic.start();

  thefft = new p5.FFT();

  thefft.setInput(themic); // listen to the microphone

}

​

function draw() {

  //background(0);

  stroke(255, 100);

  let thespectrum = thefft.analyze();

  for(let i = 0;i<thespectrum.length;i++)

  {

    let x = sqrt(i/thespectrum.length) * width; // exponential frequency spacing

    let y = height - thespectrum[i]*1;

    point(x, y - ystep);

  }

  ystep++;

  if(ystep>height)

  {

    background(0);

    ystep = 0;

  }

}

​

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