Minim - Log Averages & Isolating Frequencies in the Spectrum

LogAvgRange.pde
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import ddf.minim.*;
import ddf.minim.analysis.*;
​
Minim minim;
AudioPlayer song;
FFT fft;
​
int sampleRate = 44100;
​
/* a bufferSize of 512 results in the sharpest, most responsive movement - change 
 bufferSize to 1024 or 2048 and note how the movement appears more sluggish */
​
int bufferSize = 512; // this is actually called timeSize
​
/* if the number for fft_band_per_oct is higher than 1, it will still result in 9 octaves / bands 
 because the number of bands you get is equal to log2 of bufferSize ie. log2(512) = 9 */
​
// 512 returns 86hz bandwidth which allows 9 octaves / bands
// 1024 returns 43hz bandwidth which allows 10 octaves / bands
// 2048 returns 21hz bandwidth which allows 11 octaves / bands
​
int fft_base_freq = 86; // size of the smallest octave to use (in Hz) so we calculate averages based on a miminum octave width of 86 Hz 
int  fft_band_per_oct = 1; // how many bands to split each octave into? in this case split each octave into 1 band
​
int numZones = 0;
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int yPos = 270;
​
void setup() {
  size(960, 540);
  smooth();
  colorMode(HSB, 360, 100, 100);
​
  minim = new Minim(this);
  song = minim.loadFile("flim.mp3", bufferSize);
  song.loop();
​
  fft = new FFT( bufferSize, sampleRate ); // make a new fft
​
  // first parameter specifies the size of the smallest octave to use (in Hz), second is how many bands to split each octave into.
  fft.logAverages(fft_base_freq, fft_band_per_oct); // results in 9 bands
​
  fft.window(FFT.HAMMING);
​
  numZones = fft.avgSize(); // avgSize() returns the number of averages currently being calculated
  // println("numZones: " + numZones); // returns 9 bands
​
  rectMode(CENTER);
  noStroke();
}
​
void draw() {
  background(0);
​
  fft.forward(song.mix); // perform forward FFT on songs mix buffer
​
  // println("Bandwidth: " + fft.getBandWidth() + " Hz"); // returns 86 Hz
​
  int highZone = numZones - 1;
​
  for (int i = 0; i < numZones; i++) { // 9 bands / zones / averages
​
    float average = fft.getAvg(i); // return the value of the requested average band, ie. returns averages[i]
    // println("Averages " + i + " : " + average);
​
    float avg = 0;
    int lowFreq;
​
    if ( i == 0 ) {
      lowFreq = 0;
    } 
    else {
      lowFreq = (int)((sampleRate/2) / (float)Math.pow(2, numZones - i)); // 0, 86, 172, 344, 689, 1378, 2756, 5512, 11025
    }
    int hiFreq = (int)((sampleRate/2) / (float)Math.pow(2, highZone - i)); // 86, 172, 344, 689, 1378, 2756, 5512, 11025, 22050
​
    // ***** ASK FOR THE INDEX OF lowFreq & hiFreq USING freqToIndex ***** //
​
    // freqToIndex returns the index of the frequency band that contains the requested frequency
​
    int lowBound = fft.freqToIndex(lowFreq);
    int hiBound = fft.freqToIndex(hiFreq);
​
    // println("lowFreq: " + lowFreq + " Hz");
    // println("hiFreq: " + hiFreq + " Hz");
    // println("lowBound: " + lowBound);
    // println("hiBound: " + hiBound);
​
    // ***** NB: THE BELOW PRINTS THE RANGES 0 - 8, THEIR RESPECTIVE FREQENCIES & INDEXES ***** //
​
    // println("range " + i + " = " + "Freq: " + lowFreq + " Hz - " + hiFreq + " Hz " + "indexes: " + lowBound + "-" + hiBound);
​
    for (int j = lowBound; j <= hiBound; j++) { // j is 0 - 256
​
      float spectrum = fft.getBand(j); // return the amplitude of the requested frequency band, ie. returns spectrum[offset]
      // println("Spectrum " + j + " : " +  spectrum); // j is 0 - 256
​
      avg += spectrum; // avg += spectrum[j];
      // println("avg: " + avg);
    }
​
    avg /= (hiBound - lowBound + 1);
    average = avg; // averages[i] = avg;
​
    // ***** THIS IS WHERE WE CAN ISOLATE SPECIFIC FREQUENCIES. THERE ARE 9 FREQUENCY BANDS (0 - 8) ***** //
​
    // ***** 0 Hz - 86 Hz ***** //
​
    if (i == 0) {  // if the frequency band is equal to 0 ie. between 0 Hz and 86 Hz
​
      // println(average); // printing the average to the console is super helpful as you can see the loudness of each frequency band & further isolate parts of a track, for example just the peak
​
      if (average > 40.0) {
        fill(96, 100, 100);
      }
      else {
        fill(255, 100, 100);
      }
​
      if (average > 20.0) {
        rect(75, yPos, average * 3, average * 3);
      }
      else {
        rect(75, yPos, 50, 50);
      }
    }
​
    // ***** 86 Hz - 172 Hz ***** //
​
    if (i == 1) { 
​
      fill(265, 100, 100); 
      if (average > 20) {
        rect(176, yPos, average * 2, average * 2);
      }
      else {
        rect(176, yPos, 50, 50);
      }
​
      if (average > 40 && average < 50) {
        strokeWeight(20); 
        stroke(96, 100, 100);
      } 
      else {
        strokeWeight(5); 
        stroke(0, 0, 100);
      }
​
      if (average > 20 && average < 50) {
        line(0, 0, width, height);
      }
    }
​
    // ***** 172 Hz - 344 Hz ***** //
​
    if (i == 2) { 
​
      fill(272, 100, 100);
      if (average > 20) {
        rect(277, yPos, average * 2, average * 2);
      }
      else {
        rect(277, yPos, 50, 50);
      }
    }
​
    // ***** 344 Hz - 689 Hz ***** //
​
    if (i == 3) { 
​
      fill(281, 100, 100);
      if (average > 8) {
        rect(378, yPos, average * 2, height);
      }
      else {
        rect(378, yPos, 1, height);
      }    
​
      strokeWeight(6);
​
      if (average > 10.0 && average < 20.0) {
​
        for (int y = 60; y < height; y += 150) { 
          for (int x = 40; x < width; x += 150) { 
            stroke(0, 0, 100);
            point (x, y);
          }
        }
      }
    }
​
    noStroke();
​
    // ***** 689 Hz - 1378 Hz ***** //
​
    if (i == 4) { 
​
      if (average > 2) {
        fill(96, 100, 100);
        rect(480, yPos, average * 20, average * 20);
      }
      else {
        fill(287, 100, 100);
        rect(480, yPos, 50, 50);
      }
    }
​
    // ***** 1378 Hz - 2756 Hz ***** //
​
    if (i == 5) { 
​
      fill(295, 100, 100);     
      if (average > 1) {
        rect(581, yPos, average * 40, average * 40);
      }
      else {
        rect(581, yPos, 50, 50);
      }
    }
​
    // ***** 2756 Hz - 5512 Hz ***** //
​
    if (i == 6) { 
​
      if (average > 2) {
        fill(96, 100, 100);
      }
      else {
        fill(312, 100, 100);
      }
​
      if (average > 1) {
        rect(682, yPos, average * 40, average * 40);
      }
      else {
        rect(682, yPos, 50, 50);
      }
    }
​
    // ***** 5512 Hz - 11025 Hz ***** //
​
    if (i == 7) { 
​
      fill(332, 100, 100);
​
      if (average > 1) {
        rect(783, yPos, average * 60, average * 60);
      }
      else {
        rect(783, yPos, 50, 50);
      }
    }
​
    // ***** 11025 Hz - 22050 Hz ***** //
​
    if (i == 8) { 
​
      fill(349, 100, 100);      
      float newSize = map(average, 0.0, 0.3, 50.0, 150.0);     
      rect(885, yPos, newSize, newSize);
    }
​
    // ********** //
  }
}
​
void stop() {
  song.close(); // always close Minim audio classes when you are finished with them
  minim.stop(); // always stop Minim before exiting
}
​
​
Archived Sketch

Minim - Log Averages & Isolating Frequencies in the Spectrum
