Description

Signature

void setFreq(float freq, float a)

Parameters

Returns

None

Related

Example

/**
 * This sketch demonstrates very simply how you might use the inverse FFT to modify an audio signal.<br />
 * Press 's' to set frequency band corresponding to 600 Hz in the FFT to 300.<br />
 * Now press 'd' to take the inverse FFT. You will see a wave form appear in the top of the sketch.
 * <p>
 * For more information about Minim and additional features, visit http://code.compartmental.net/minim/
 */

import ddf.minim.analysis.*;
import ddf.minim.*;

FFT fft;
float[] buffer;
int bsize = 512;

void setup()
{
  size(512, 300, P3D);
  // create an FFT with a time-domain size the same as the size of buffer
  // it is required that these two values be the same
  // and also that the value is a power of two
  fft = new FFT(bsize, 44100);
  buffer = new float[bsize];
}

void draw()
{
  background(0);
  noStroke();
  fill(255, 128);
  // draw the waveform
  for(int i = 0; i < buffer.length; i++)
  {
    ellipse(i, 50 + buffer[i]*10, 2, 2);
  }
  noFill();
  stroke(255);
  // draw the spectrum
  for(int i = 0; i < fft.specSize(); i++)
  {
    line(i, height, i, height - fft.getBand(i));
  }
  stroke(255, 0, 0);
  line(width/2, height, width/2, 0);
}


void keyReleased()
{
  if ( key == 'd' ) 
  {
    println("Performing an Inverse FFT and putting the result in buffer.");
    fft.inverse(buffer);
  }
  if ( key == 's' )
  {
    // When changing the spectrum using setFreq() it is necessary to
    // tell the FFT what the sampling rate of the time-domain is
    // The reason for this is that which frequency band gets changed
    // depends on what the sampling rate of the time-domain being represented
    // by the spectrum is.
    println("Setting 600 Hz to 300 in the frequency spectrum.");
    fft.setFreq(600, 300);
  }
}

Usage