Audio filters in Rust

A port of the WebAudio API filters to Rust.

Description

Audio or DSP filters, allow you to attenuate or accentuate some frequencies or range of frequencies in a signal. The signal can be of any kind, but in here, we will focus on 1D signals. Like audio signals. There can also occur differences in the signal phases, that vary with the filter and the frequency components of the signal.
This is a port of Audio filters, from Python to Rust. My port was made from TheAlgorithms GitHub in Python (see references below). That is, by it self a port from WebAudio API C++ filters implementation used by the browsers.

The following filters are implemented over a BiQuad IIR filter

1. low-pass
2. high-pass
3. band-pass
4. all-pass
5. peak
6. low-shelf
7. high-shelf
8. notch
9. 10 band equalizer

Plots of the filters Gain (dB) and phase shift response

low-pass - freq = 5.000 Hz - sample_rate = 48.000 samples/sec

high-pass - freq = 5.000 Hz - sample_rate = 48.000 samples/sec

band-pass - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - q_factor = 1.0

all-pass - freq = 10.000 Hz - sample_rate = 48.000 samples/sec

peak - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - gain = 6 dB

peakEQ_const_Q G_pos - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - gain = 5 dB

q_factor = 2 * sqrt(2) = 2.828

peakEQ_const_Q G_neg - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - gain = -5 dB

q_factor = 2 * sqrt(2) = 2.828

low-shelf - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - gain = 6 dB

high-shelf - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - gain = 6 dB

notch - freq = 10.000 Hz - sample_rate = 48.000 samples/sec - q_factor = 0.05

10 band Equalizer - sample_rate = 48.000 samples/sec - q_factor = 2.828

10 Band Equalizer

band_0:     29 Hz, gain: -10 dB
band_1:     59 Hz, gain:   0 dB
band_2:    119 Hz, gain:  -5 dB
band_3:    237 Hz, gain:   5 dB
band_4:    474 Hz, gain:   0 dB
band_5:    947 Hz, gain:  -5 dB
band_6:  1.889 Hz, gain:   0 dB
band_7:  3.770 Hz, gain:   5 dB
band_8:  7.523 Hz, gain:  10 dB
band_9: 15.011 Hz, gain:  12 dB

How to run the code

To make a project for this files do:
    -Install Rust your computer (Linux, Win, Mac, Raspberry Pi).
     
    cargo new audio_filters_in_rust
    cd audio_filters_in_rust
     
    -Copy the repository files to this directory and overlap them.
 
To compile do:
    cargo build --release
 
To run do:
    cargo run --release
 
to run the tests do:
    cargo test

References:

1. GitHub - TheAlgorithms / Python / audio_filters
   https://github.com/TheAlgorithms/Python/tree/master/audio_filters

2. WebAudio - Cookbook formulae for audio equalizer biquad filter coefficients
   https://webaudio.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html

3. Good resources on DSP – Digital Signal Processing
   https://github.com/joaocarvalhoopen/How_to_learn_modern_electronics#dsp--digital-signal-programming

4. Biquads - EarLevel
   http://www.earlevel.com/main/2003/02/28/biquads/

5. Biquad C++ source code - EarLevel
   https://www.earlevel.com/main/2012/11/26/biquad-c-source-code/

6. A biquad calculator v3 - EarLevel
   https://www.earlevel.com/main/2021/09/02/biquad-calculator-v3/

7. WebAudio API - Mozilla Docs
   https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API

8. Audio Filters - Theory and Practice
   by Ethan Winer
   http://ethanwiner.com/filters.html

9. Audio filter - Wikipedia
   https://en.wikipedia.org/wiki/Audio_filter

10. Electronic filter - Wikipedia
    https://en.wikipedia.org/wiki/Electronic_filter

10 Bands Equalizer

12. Making an EQ from cascading filters
    https://dsp.stackexchange.com/questions/10309/making-an-eq-from-cascading-filters

13. Peak / Notch filter design
    https://www.dsprelated.com/showcode/169.php

14. The Equivalence of Various Methods of Computing
    Biquad Coefficients for Audio Parametric Equalizers
    http://www.thesounddesign.com/MIO/EQ-Coefficients.pdf

15. How to learn modern Rust
    https://github.com/joaocarvalhoopen/How_to_learn_modern_Rust

License

• MIT Open Source License, like the original license from
  GitHub - TheAlgorithms / Python / audio_filters
  https://github.com/TheAlgorithms/Python/tree/master/audio_filters

Have fun!

Best regards,
Joao Nuno Carvalho