home	Daniel Iglesia

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Java FFT Toolkit

An application and java API for spectral manipulation

So I wanted to manipulate spectral data in java code, and I couldn't find any useful code libraries out there fore it, so I buckled down and wrote one myself. It has methods for vector addition, creating an average frame out of a range of frames (an aggregate), comparing FFT frames for similarity, and more. I then used it to make an application that runs three of my ideas for a spectrum-based manipulation, that implement spectral-analysis based splicing, morphing and reconstitution. Use it and have fun.

Download

source, classes, documentation, and sample sound files (~24MB)
as above, but no sample sound files (~200KB)

To use the API, just copy FFTToolkit.jar into your classpath. To use the app, just double click "runMeOnAPC.bat" or "runMeOnAMac.command"

Java API

There are a few java classes that may be useful to you, specifically the following:

FFTSettings - holds values for FFTSize, WindowSize, and HopSize.
FFTFile - holds an array of FFTFrame for each channel of a sound file.
Create one by passing the file name of a sound file (currently only 16bit, 44.1K aiff and wave formats are accepted), and of an instance of the class FFTSettings. Write an FFTFile to a sound file with the writefile(String outputname) method.
FFTFrame - holds a single frame as an array of PolarPhasor
PolarPhasor - holds a single phasor as two floats, "mag" and "phase"

Here's all you really need to get started, check the docs for more:

FFTSettings mySettings = new FFTSettings(); FFTFile myFFTFile = new FFTFile("soundfile.wav", myFFTSettings); //get the magnitude and phase value of channel 0, frame 50, bin 25 float specificMag = myFFTFile.frame[0][50].bin[25].mag; float specificPhase = myFFTFile.frame[0][50].bin[25].phase; //create a new blank FFTFile of 2 channels, length 1000 frames FFTFile myBlankFFT = new FFTFile(2,1000,mySettings); //fill it in however you want, here I'll fill the first frame of the left channel with a morph of two other frames, 35% morph with minimum bin threshold of 2 myBlankFFT.frame[0][0] = MorphEngine.interpolatedFrame(mySourceFFTFrame1, mySourceFFTFrame2, .35, 2.); //write to file myBlankFFT.write("outputFilename.wav");

New algorithms and GUI application for your fun

I used this API to make a application that implements 3 spectral tasks I had been toying with.

Splice: create a sequence of splices amongst a bank of sound files between moments of spectral similarity
(research page on the topic)
--mp3 example: splicing between Giant Steps and Lonely Woman
Morph: draw a path morphing between two sound files
(really old presentation on the topic)
--mp3 example: morphing from water drops to gunshots
Reconstitute: replace every slice of a source sound with the most similar slice from a bank of sounds
--mp3 example: reconstituting Kraftwerks "The Robots" out of Philip Glass' "Rubric"

No compiling or java knowledge necessary! Just play with the sliders...