Processing 1.0 - Processing Discourse - Bouncing balls with sound

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Index › Programming Questions & Help › Sound, Music Libraries › Bouncing balls with sound

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Bouncing balls with sound (Read 2825 times)

junebug

Bouncing balls with sound
May 2^nd, 2010, 7:13pm

I'm working on a sketch that draws balls that bounce. The size is chosen according to the volume of sound input, and I would like the bounciness of the balls to be determined by the pitch of the sound input.

This is what my draw function looks like right now:

Code:

void draw() {
  background(190,50,360);

  //iterate through buffer, draw a ball for each with random X position and size dictated by volume
  for(int i = 0; i < in.bufferSize() - 1; i+=8){ //to create fewer balls, only check every eighth one
    Ball newBall = new Ball(int(random(width)), abs(int(in.left.get(i)*100)), 4);
    balls.add(newBall); //adds the ball to a vector
  }
}

The 4 represents the bounciness of the ball. The bounciness should stay between 2 and 10. How would I go about using the pitch to determine the pitch? I was told to use ForwardFFT, but I've been staring at the example forever and I don't understand how to incorporate it into my program.

« Last Edit: May 2^nd, 2010, 8:59pm by junebug »

antiplastik

Re: Bouncing balls with sound
Reply #1 - May 3^rd, 2010, 5:33am

When you proceed a FFT analysis, you get a spectrum. Like column charts in a spreasheet.

You can get the spectrum result in fft.getBand(). You know how much bands there are thanks to fft.specSize().

You want to find the higher level band? Just iterate and compare the values.

Quote:

int higher_band = -1;
float higher_value = -1.0;
for (int i = 0; i < fft.specSize(); i++) {
  float current_value = fft.getBand(i);
  if (current_value > higher_value) {
    higher_value = current_value;
    higher_band = i;
  }
}

Then you can use higher_band which should be a value between 0 and fft.specSize().

junebug YaBB Newbies Offline Posts: 5	Re: Bouncing balls with sound Reply #2 - May 3^rd, 2010, 7:59am I'm sorry, I'm afraid I still don't understand. If I'm iterating through a buffer and using the volume of the sound input to create the balls, is there a way to simultaneously isolate the pitch of the sound? I apologize if I'm being dense -- I'm very new to Processing.

Autodidact

Re: Bouncing balls with sound
Reply #3 - May 15^th, 2010, 8:49pm

There's a way but it ain't easy...

lessee... I may have something for you later, I made a ptich follower in supercollider once, maybe I can dust it off and port it.

It basically counted the samples between zero crossings... that is, when the waveform crosses the zero line... uh... but it can get confused and produce weird results when the input contains more than one tone. Like a guitar octaver pedal does. Undecided

Autodidact YaBB Newbies Offline Posts: 17	Re: Bouncing balls with sound Reply #4 - May 16^th, 2010, 2:52am Err... this thing works pretty badly lol http://openprocessing.org/visuals/?visualID=9739

Autodidact YaBB Newbies Offline Posts: 17	Re: Bouncing balls with sound Reply #5 - May 16^th, 2010, 2:55am I guess I should learn more than I ever wanted to know about Fast Fourier Transforms, too

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