Frequency Energy Beat Detection with the audio output

Hello there,

Just a simple question I hope. :grinning:
I would like to adapt the program from the Minim example. Rather to detect the beat of a mp3 in the sketch folder as it has done in the example, I would like to be able to detect the audio signal of the music I’m playing with the audio output of my Mac. While I’m playing music of a software like Ableton Live or a web radio for example.

I put the example of the minim library here. We have to put in a folder called data, a MP3 with the exact same name in this line of the code: song = minim.loadFile(“marcus_kellis_theme.mp3”, 1024);

Thanks for your help and attention.

  * This sketch demonstrates how to use the BeatDetect object in FREQ_ENERGY mode.<br />
  * You can use <code>isKick</code>, <code>isSnare</code>, </code>isHat</code>, <code>isRange</code>, 
  * and <code>isOnset(int)</code> to track whatever kind of beats you are looking to track, they will report 
  * true or false based on the state of the analysis. To "tick" the analysis you must call <code>detect</code> 
  * with successive buffers of audio. You can do this inside of <code>draw</code>, but you are likely to miss some 
  * audio buffers if you do this. The sketch implements an <code>AudioListener</code> called <code>BeatListener</code> 
  * so that it can call <code>detect</code> on every buffer of audio processed by the system without repeating a buffer 
  * or missing one.
  * <p>
  * This sketch plays an entire song so it may be a little slow to load.
  * <p>
  * For more information about Minim and additional features, 
  * visit

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

Minim minim;
AudioPlayer song;
BeatDetect beat;
BeatListener bl;

float kickSize, snareSize, hatSize;

class BeatListener implements AudioListener
  private BeatDetect beat;
  private AudioPlayer source;
  BeatListener(BeatDetect beat, AudioPlayer source)
    this.source = source;
    this.beat = beat;
  void samples(float[] samps)
  void samples(float[] sampsL, float[] sampsR)

void setup()
  size(512, 200, P3D);
  minim = new Minim(this);
  song = minim.loadFile("marcus_kellis_theme.mp3", 1024);;
  // a beat detection object that is FREQ_ENERGY mode that 
  // expects buffers the length of song's buffer size
  // and samples captured at songs's sample rate
  beat = new BeatDetect(song.bufferSize(), song.sampleRate());
  // set the sensitivity to 300 milliseconds
  // After a beat has been detected, the algorithm will wait for 300 milliseconds 
  // before allowing another beat to be reported. You can use this to dampen the 
  // algorithm if it is giving too many false-positives. The default value is 10, 
  // which is essentially no damping. If you try to set the sensitivity to a negative value, 
  // an error will be reported and it will be set to 10 instead. 
  // note that what sensitivity you choose will depend a lot on what kind of audio 
  // you are analyzing. in this example, we use the same BeatDetect object for 
  // detecting kick, snare, and hat, but that this sensitivity is not especially great
  // for detecting snare reliably (though it's also possible that the range of frequencies
  // used by the isSnare method are not appropriate for the song).
  kickSize = snareSize = hatSize = 16;
  // make a new beat listener, so that we won't miss any buffers for the analysis
  bl = new BeatListener(beat, song);  
  textFont(createFont("Helvetica", 16));

void draw()
  // draw a green rectangle for every detect band
  // that had an onset this frame
  float rectW = width / beat.detectSize();
  for(int i = 0; i < beat.detectSize(); ++i)
    // test one frequency band for an onset
    if ( beat.isOnset(i) )
      rect( i*rectW, 0, rectW, height);
  // draw an orange rectangle over the bands in 
  // the range we are querying
  int lowBand = 5;
  int highBand = 15;
  // at least this many bands must have an onset 
  // for isRange to return true
  int numberOfOnsetsThreshold = 4;
  if ( beat.isRange(lowBand, highBand, numberOfOnsetsThreshold) )
    rect(rectW*lowBand, 0, (highBand-lowBand)*rectW, height);
  if ( beat.isKick() ) kickSize = 32;
  if ( beat.isSnare() ) snareSize = 32;
  if ( beat.isHat() ) hatSize = 32;
  text("KICK", width/4, height/2);
  text("SNARE", width/2, height/2);
  text("HAT", 3*width/4, height/2);
  kickSize = constrain(kickSize * 0.95, 16, 32);
  snareSize = constrain(snareSize * 0.95, 16, 32);
  hatSize = constrain(hatSize * 0.95, 16, 32);