FrequencyAnalyzer.md

FrequencyAnalyzer class

This FrequencyAnalyzer class is used at the Maastricht Institute of Arts exposition during the "Generative Art" semester. Students create sketches that react in realtime to audio input (line-in, audio file or microphone).

This library adds functionality like:

• easily switch between input modes (audio file, microphone, line-in)
• toggle mute (audio file playing) or monitoring (microphone or line-in)

todo:

• return raw or normalized values of specific frequency bands
• reset the max value that is used for mapping normalized values of frequency amplitudes. Can be set to an interval.

Usage

// Import the library to your sketch
import bpm.library.frequencyanalyzer.*;

// Import the minim library
import ddf.minim.*;
import ddf.minim.analysis.*;

Minim minim;
FrequencyAnalyzer fa;

void setup() {
  size(500, 500);

  minim = new Minim(this);
  fa = new FrequencyAnalyzer(this)
    .addMinim(minim)
    .setFile("https://github.com/vincentsijben/bpm-timings-for-processing/raw/main/assets/infraction_music_-_ritmo.mp3")
    .setAudioInputMode(AudioInputMode.AUDIO_FILE)
    ;
}

void draw() {
  background(50);

  circle(width/4*1, height/2, fa.getAvgRaw(0));
  circle(width/4*2, height/2, fa.getAvgRaw(10));
  circle(width/4*3, height/2, fa.getAvgRaw(20));
}

The FrequencyAnalyzer class provides the following main functions:

• getAvgRaw(1) returns non-normalized "raw" averaged amplitude for frequency band 1. The index ranges from 0 to logAverages(22, 3) which is 30 by default.
  • getAvgRawLeft(1) same as getAvgRaw(1) but specific for the left channel.
  • getAvgRawRight(1) same as getAvgRaw(1) but specific for the right channel.

todo:

• getBand(1) returns the amplitude for frequency band 1. Used for a very specific and narrow frequency range. The index ranges from 0 to specSize().
  • getBandLeft(1) same as getBand(1) but specific for the left channel.
  • getBandRight(1) same as getBand(1) but specific for the right channel.
• ~~specSize() returns the total amount of bands used. Typically 1025 ~~
• avgSize() returns the total amount of bands used in the logAverages function. Typically 30
• getAudioBuffer() returns the mixed (mono) audio buffer.
  • getLeftChannelBuffer() returns the left audio buffer.
  • getRightChannelBuffer() returns the right audio buffer.

You can tweak the behaviour of this library with the following functions (you can also chain them when initializing your frequencyanalyzer object for clarity):

• .addMinim(minim) mandatory to add the global minim object to the class.
• .setFile("example.mp3") to set the file for the audioplayer. Defaults to "https://github.com/vincentsijben/bpm-timings-for-processing/raw/main/assets/infraction_music_-_ritmo.mp3"
• .setAudioInputMode(AudioInputMode.AUDIO_FILE) to set the input mode to AudioInputMode.AUDIO_FILE. You can also set it to AudioInputMode.LINE_IN or AudioInputMode.MICROPHONE. Defaults to AudioInputMode.MICROPHONE.
• .setAudioInputMode(AudioInputMode.AUDIO_FILE, n) same as previous one, but you can also set the bufferSize. Needs to be a power of 2. A lower amount results in less audio resolution and decreases delay . Defaults to 1024.
• .setAudioOutputMode(AudioOutputMode.STEREO) to set the output mode to AudioOutputMode.STEREO. Defaults to AudioOutputMode.MONO. Use it to get access to both left and right channel analysis.
• .showInfoPanel() to show the infopanel.
• .setInfoPanelY(n) to offset the starting y-position of the infopanel by n pixels. Useful for when you have multiple infopanels to get them all lined up.
• .setInfoPanelKey('u') to change the hotkey to toggle the infopanel. Useful for when you have multiple infopanels. Defaults to 'i'.
• .disableKeyPress() to disable listening for keypresses. If you don't disable keypresses, then these keypresses will work:
  • CTRL + 1 switch to FILE mode
  • CTRL + 2 switch to MONO mode
  • CTRL + 3 switch to STEREO mode
  • CTRL + M toggle monitoring on LINE_IN or MICROPHONE input

Examples

You can find all these examples in Processing -> File - Examples - Contributed Libraries - BPM timings - FrequencyAnalyzer.

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