Smooth movement (live audio input)

Core Library Questions

coloresque

Smooth movement (live audio input)

in Core Library Questions • 2 years ago

I have found this code on the internet, and I am working on my own audio visualiser. Everything works but I want to apply a smooth movement. (for instance if you would take the example I post here with eclipses slowly appearing, in my example they would appear at the moment of sound without fading in and out)

I think it has to do with the 'flux' part or Open GL.. So the following code is NOT the code that I have written, but the code that contains a 'fade' statement somewhere I can't figure out. Hope someone can tell me what part it is about the code that I need.

import javax.media.opengl.*;
import processing.opengl.*;
import ddf.minim.*;
import ddf.minim.analysis.*;
Minim minim;
AudioInput in;
FFT fft;
int index;
float[]x = new float[width];
float[]y = new float[width];
float[] spectrum;
float[] lastspectrum;
void setup()
{
size(720, 480, OPENGL);
hint(DISABLE_OPENGL_2X_SMOOTH);
background ( 0 ) ;
smooth();
noStroke();
x = new float[width];
y = new float[width];
for (int i = 0; i < x.length ; i++)
x[i] = (float)i ;
minim = new Minim(this);
in = minim.getLineIn(Minim.STEREO, 512);
fft = new FFT(in.bufferSize(), in.sampleRate());
fft.noAverages();
spectrum = new float[fft.specSize()];
lastspectrum = new float[fft.specSize()];
Arrays.fill( lastspectrum, 0 );
}
void draw()
{
smooth();
fft.forward(in.mix);
///------------------------
// SPECTRAL FLUX
///------------------------
float flux = 0;
for( int i = 0 ; i < fft.specSize() ; i++)
{
spectrum[i] = fft.getBand(i);
flux += spectrum[i] - lastspectrum[i];
// rectified flux
// float fluxval = spectrum[i] - lastspectrum[i];
// flux += (fluxval > 0.0 ) ? fluxval : 0.0;
}
System.arraycopy( spectrum, 0, lastspectrum, 0, spectrum.length );
///------------------------
fill(0,6);
rect ( 0,0, width, height );
fill(200,60);
translate(0,height/2);
for ( int i = 0 ; i < x.length ; i++)
ellipse(x[i],y[i],abs(flux),abs(flux));
y[index++%width] = flux;
}
void stop()
{
in.close();
minim.stop();
super.stop();
}
void mouseClicked()
{
saveFrame();
}

Replies(1)

drart

Re: Smooth movement (live audio input)

2 years ago

Hi,

I wrote this code. There is no fade statement as such. There is no background() function called for this code, so every frame layers on top of each other with transparency giving a fading look that you describe. This is an old trick that I first saw in either one of Ben Fry's patches or Casey Reas' patches, I forget exactly whose.

If you replace this:

fill(0,6);
rect ( 0,0, width, height );

With:

background(0);

Inside of the draw loop then you should get the beginnings of the behavior you are looking for.

FYI the flux value refers to spectral flux. It is a great measure for detecting onsets (if you tweak it). I got the basics from a wonderful set of tutorials online. I have linked the relevant one below. Enjoy!

http://www.badlogicgames.com/wordpress/?p=161

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