All I want to do is write a spectrum analyzer module for MAME to show a spectrograph of the VGM player driver. Why is it so hard to find a bloody Discrete Fourier Transform algorithm in C or C++ that just does what it says on the tin and doesn't have external dependencies?!
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The FFT outputs are permuted (you’d use WDL_fft_permute() to index it), and scaled (divide by the fft size). For purposes of a spectrograph, you’ll want to apply a window to the input, too. REAPER includes a spectrograph jsfx which would be trivial to port to C
As I understand it, FFT will work for arbitrary sizes as long as I pad out the sample count to a power of two. I'm assuming for unsigned audio data, the best choice would be to pad with zeroes.
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If you can point me at a link to the repo for REAPER, I'd be happy to take a look. Thanks for the advice already!
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I've already got a one-liner for a straightforward Hann window, but if you have a suggestion for a better windowing algorithm for a bar-chart style spectrograph, I'm all ears!
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Personally I would convert unsigned audio data to signed, and fill with 0s yes. and apply your hann window to the length of the data you're using before zero-padding.
Kiitos. Käytämme tätä aikajanasi parantamiseen. KumoaKumoa
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