A no_std Rust library to filter out the frequencies of a digital signal (e.g. audio) using FFT. The main goal of this
crate is to be educational to the world and myself. This is not a bullet-proof or ideal solution! It tries to show in
Rust code how to get frequencies from a signal as simple as possible (many code comments etc). Feel free to contribute,
improve, and point out possible errors/bugs/wrong assumptions.
I'm not an expert on digital signal processing. Code contributions are highly welcome! :)
If you need DSP (digital signal processing) this crate may be useful for you too: https://crates.io/crates/dsp
```rust use spectrumanalyzer::{hannwindow, samplesfftto_spectrum};
fn main() {
// This lib also works in no_std environments!
let samples = getsamples(); // TODO implement
// apply hann window for smoothing; length must be a power of 2 for the FFT
let hannwindow = hannwindow(&samples[0..4096]);
// calc spectrum
let spectrum = samplesffttospectrum(
&hann_window,
44100,
Some(&|x| 20.0 * x.log10()),
None,
);
// print out Hz => magnitude mapping (in log scale)
for (fr, vol) in spectrum.iter() {
println!("{}Hz => {}", fr, vol);
}
}
```
``` 21Hz => 133.63696740490568 ... 43Hz => 141.81170212599122 88Hz => 130.9031874924785
// all other values above 100 Hz are smaller // values are in logarithmic scale; see scale function above ```