Processing Blogs

In Saying this, I wanted to get a decent amount of research done into FFT and Frequency analysis.

Processing Problems
Before I start anything, I’ve got problems. I wanted to start uploading my processing “sketches”. However I’ve encountered a problem. I spent a large portion of time yesterday afternoon attempting to get the sketches to work as a java applet from within a browser – no joy there, and now I’ve found that something has broken, and I can’t even export as a standalone application – BIG PROBLEM.

The error I get is : “File sonia_v2_9.jar,JSynClasses.jar,JSynV142.dll,libJSynV142.jnilib does not exist”
If anyone knows anything about processing and can help me, I’d appreciate it. I’ve also posted for support on the processing website here. Until I get this fixed, I can’t show you where I’m up to in my experiments – as a last resort I’m sure I can export them from my laptop, so I will have to try that later.

FFT Research
Now to the intersting part …
I’ve been doing some research into FFT and Spectrum Analysis. Just so I know what I’m dealing with here. I suppose I should start from the beginning.

In order to work with sound, I need to understand the format in which I can access it. Using processing, and one of the various sound libraries ( In my case, I am using ‘Sonia‘ I can access the live stream of music via my soundcard. This data is intepreted via FFT ( More on this later ), and then outputted into a spectrum array. This array can then be accessed and the music or sound can be intepreted.

So firstly, What is FFT ?
FFT ( or Fast Fourier Transform ) is an “Algorithm to compute the “Discrete Fourier Transform” and it’s inverse.” Ok, so what is a Fourier Transform ?
The Fourier Transform Produces a Spectrum. It saves the Magnitidue of each frequency component. This data can then be represented as a graph or plot.

So how does this tie in with processing ?
The FFT Data is collated and stored in the array. Each array element is an “FFT Bin”. These “bins” are basically storage elements for a *collection* of frequency ranges – not a single frequency. So how are you meant to know what frequencies are contained in which bins ?

Say you have a file with a Sample Rate of 44100Hz. A frequency range of 22050Hz is equally split into 512 bins. Each bin is : 22050 / 512 : 43.066Hz Wide.
The Left most bin ( Lowest Frequency ) has *half* the width of all other bins. ( contains frequencies 0.000Hz to 21.5Hz ).

So what does all this mean ?
This means that I can get data from a sound source, live streaming sound data – examine the frequencies, and calculate which elements represent which aspects of music ( kicks, snares, synths etc ).

And where will this lead ?
Eventually with a sufficiant understanding of the backbone behind the software, and an understanding of the data input and how it is aquired, I can isolate parts of my motion system to react to different parts / types of music in different ways. A greater understanding will help me to create a project of greater impressivenessnessness.

Any Questions ? Any Comments ? Any Suggestions ?

Where now ?
So what I have to do now, is try and get processing working. From there, the experiments continue.

– Anthony