lowpass-filter

Simple first-order digital lowpass filters, compatible with no_std. You can use it, for example, to get the low frequencies from a song.

Difference to biquad

⚠ TL;DR: biquad might be a better option in some use-cases.

This crate provides a basic and simple to understand, first order lowpass filter. The biquad crate offers second order filters, with higher accuracy. From my testing, a lowpass filter created with biquad has higher computational costs as this crate, but offers a better resolution for actually cutting of signals above the cut-off frequency while the preserved signal will be less attenuated.

So for production use-cases, please also consider using biquad. You can run benchmark and check your data (e.g., by plotting) to make that decision.

Usage

You can either use the LowpassFilter type to integrate the filter in iterator chains or you can use a convenient function such as lowpass_filter and lowpass_filter_f64. The first approach is more flexible.

Example with LowpassFilter type

See implementation of lowpass_filter function.

Example with lowpass_filter function

use lowpass_filter::lowpass_filter;

// some samples
let mut mono_audio_data = [0.0, 1.0, -5.0, 1551.0, 141.0, 24.0];
// mutates the input buffer
lowpass_filter(&mut mono_audio_data, 44100.0, 120.0);

Visual Examples

#1: Original Waveform of a short sample

#1: Lowpassed Waveform

#2: Original Waveform of a song

#2: Lowpassed Waveform

#2: 3x Lowpassed Waveform

MSRV

The MSRV is 1.85.0.