@Jona yes, thats kind of what Im looking for, but I still need to find a way to take a whole audio file and print the spectrum all at once. Im thinking this is more of a pure data question than an Ofelia one.

Hi, Im working on a pure data vanilla and Ofelia project. Its a granular synth that works on only some selected parts of a frequency spectrum. kind of like IZtope Iris. What I want is to choose an audio file, generate a spectrum off of it, and display it all at once. it needs to be accurate to the frequencies.
The highest frequency in the spectrum would be 7536.62hz, all spaced 43.0664hz apart, making 175 bands.
would anyone know how to do this in Ofelia?
Im looking for something like this: Example image

I would like a more flat, linear, even scale on this, so that I can have some sort of keyboard display on the left side relating to the pitches of the frequencies like the image.

@seb-harmonik.ar sorry for the very late response, ive been trying all these methods, and the fft example is probably best for the task. is there a way i can do this controlled with a single number cutoff point instead of a whole table? maybe one for the lower and one for the upper limit, making a square shape?

PS, I also am not a master with fft, and looking at this is slightly confusing, ive been trying to figure it out for days.

"Hi, im kind of at an alright level with pure data, and im working on a project, a spectral synthesizer in pd vanilla and Ofelia,
The way im planning on handling this is to have a lowpass and a highpass squeezing in one one chunk of audio. ive realized that the lop~ object and the hip~ object have a frequency rolloff that smoothens out the cutoff over time. its like a gradual slope that gets quieter before completely choking out the audio. i am aware that this is how most filters work,

but is there a way i can have a square shape filter that just completely straight up does not let any frequencies above the limit at all? im fine with using externals if i need to, or if there's some kind of vanilla work around. it needs to be done in real time."

SOLUTION: My friend Mike Moreno found a way to do this with the "I03 resynthesis" patch, shaping the table itself with sliders and an until loop. it creates a square shape on the frequency table itself. heres the patch: resynth-1024.pd
Credits to @mianmogra