Minim
core | ugens | analysis
 

BeatDetect

setSensitivity

Description

Sets the sensitivity of the algorithm. After a beat has been detected, the algorithm will wait for millis 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.

Signature

void setSensitivity(int millis)

Parameters

millis — int: the sensitivity in milliseconds

Returns

None

Related

BeatDetect

Example

/**
  * 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 http://code.compartmental.net/minim/
  */

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.source.addListener(this);
    this.beat = beat;
  }
  
  void samples(float[] samps)
  {
    beat.detect(source.mix);
  }
  
  void samples(float[] sampsL, float[] sampsR)
  {
    beat.detect(source.mix);
  }
}

void setup()
{
  size(512, 200, P3D);
  
  minim = new Minim(this);
  
  song = minim.loadFile("marcus_kellis_theme.mp3", 1024);
  song.play();
  // 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).
  beat.setSensitivity(300);  
  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));
  textAlign(CENTER);
}

void draw()
{
  background(0);
  
  // 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) )
    {
      fill(0,200,0);
      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) )
  {
    fill(232,179,2,200);
    rect(rectW*lowBand, 0, (highBand-lowBand)*rectW, height);
  }
  
  if ( beat.isKick() ) kickSize = 32;
  if ( beat.isSnare() ) snareSize = 32;
  if ( beat.isHat() ) hatSize = 32;
  
  fill(255);
    
  textSize(kickSize);
  text("KICK", width/4, height/2);
  
  textSize(snareSize);
  text("SNARE", width/2, height/2);
  
  textSize(hatSize);
  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);
}

Usage

Web & Application