This looks sweet, thanks Frank! Hoping to have a play with this as soon as I get to do some actual music making later this week. By the way, I thought I'd clarify what I meant with the example of Plogue Bidule. The website invites one to: "Transform audio in the spectral domain, with Bidule's FFT modules. Time domain audio is split into two types of data, frequencies and magnitudes, which can be manipulated using a wide variety of spectral bidules." http://www.plogue.com/img/Spectral.png
So basically, in most of the "simple" fft software, they split the signal into freq and amplitude. You can see in the screenshot this is represented by yellow and orange connectors, and they have specific objects so you can play with a whole bunch of crazy transformations on both freq and amp, and then you can resynthesize it back with an inverse fft module.
I see that I can also get the freq and amplitude info from PD's fft, once I'm awake enough to follow your math anyway! But I'm wondering where the phase comes in exactly - in Plogue I'm assuming the phases are somehow calculated auto-magically? They DO let you set the blocksize of the signal with the fft. Also, how does this relate to [fiddle~], because fiddle I understand, it gives me a fundamental freq and the amplitude of some number of harmonics, and I could take that info (for instance) to resynthesize stuff in some additive synth.
~David
On 2/21/07, Frank Barknecht fbar@footils.org wrote:
Hallo, David Powers hat gesagt: // David Powers wrote:
I wish there was an "fft for dumbies" ... or, I guess, some kind of fft "black boxes" to play with, where you don't need to understand the math. Frank's recent post completely lost me,
Now I'm disappointed ...
though given a bit of study I can probably decode it.
... ah, and relieved a bit again. ;)
But, for instance, in Reaktor or Plogue Bidule, you can move stuff into fft, mess with it, and resynthesize, without having any idea what the hell the math is. In comparison, I really couldn't understand the PD fft examples at all, it's just been too many years since I had a math class.
The power of Pd of course is, that you can influence things on a much lower level than NI allows you to do in Reaktor - although I admit, that I only know Reaktor from screenshots. The downside is, that you have to dig deeper to make the most out of Pd. This is especially true for FFT applications. The actual FFT patches often are very simple and they contain just of a handful of objects. It's the knowledge hidden inside that makes them difficult to understand.
While you can skip a lot of the math, you cannot do FFT in Pd without at least understanding what kind of data is generated by the two [rfft~] outlets. Because without understanding this, you cannot even "fool around" with the data in between [rfft~] and [rifft~] in a meaningful way.
Anyway, to give you a blackbox maybe like in Reaktor, attached is a Spectral Delay GOP abstraction ready to be dropped into any glitch patch.
Ciao
Frank Barknecht _ ______footils.org_ __goto10.org__
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