| Fourier Translation | Transform from time domain to discrete fourier spectrum | |
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Jean Joseph Baptiste Fourier (the guy depicted in the splash screen ;) became famous for his theorems known as the Fourier Analysis. In his model each signal (e.g. a sound) can be represented by a weighted sum of sines and cosines. The Fourier Analysis (more precisely the discrete fourier transform) calculates those sine/cosine coefficients which we call the fourier spectrum. The forward transform is paralleled by the possibility of a lossless inverse transform (the synthesis). This module allows a translation from one domain to the other. Once you transformed a sound to the fourier domain you can apply all algorithms that you would normally apply to the time signal. Finally you can go back to the time domain. | |
Input file: Time domain or frequency domain signal. Generally the Fourier
transform is defined for complex signals, i.e. those represented by complex numbers. Complex numbers are made
of a socalled real and a socalled imaginary part. Because ordinary sound file formats do not support complex
numbers, I decided to use separate files for real and imag parts. Usually you start from a real time signal
(uncheck "imag" in the input) and do a forward transform resulting in the complex spectrum (check "imag" in
the output). Then you manipulate the spectrum (e.g. crop a portion) and translate it backward again (here
you supply both real and imag so you should check "imag" for the input) to get a time signal (often real so
uncheck "imag" for output).
Toolbar: Popup menus for loading and saving settings, presets and
options. Refer to a the basic chapter on process windows.
Known bugs: None To be done: Optimize for real transforms. Allow signal sizes other than 2^n. Implement the spectral format modes.
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| Contents | last modified: 25-Feb-02 | |