biquad

biquad is a #![no_std] library for creating first and second order IIR filters for signal processing based on Biquads. Both a Direct Form 1 (DF1) and Direct Form 2 Transposed (DF2T) implementation is available, where the DF1 is better used when the filter needs retuning online, as it has the property to introduce minimal artifacts under retuning, while the DF2T is best used for static filters as it has the least computational complexity and best numerical stability.

The coefficient type is generic over Float (in practice f32 and f64), and the input/output/state type can be chosen independently (e.g. for SIMD), defaulting to the coefficient type.

Example

use biquad::*;

// Cutoff and sampling frequencies
let f0 = 10.hz();
let fs = 1.khz();

// Create coefficients for the biquads
let coeffs = Coefficients::<f32>::from_params(Type::LowPass, fs, f0, Q_BUTTERWORTH_F32).unwrap();

// Create two different biquads
let mut biquad1 = DirectForm1::<f32>::new(coeffs);
let mut biquad2 = DirectForm2Transposed::<f32>::new(coeffs);

let input_vec = vec![0.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0];
let mut output_vec1 = Vec::new();
let mut output_vec2 = Vec::new();

// Run for all the inputs
for elem in input_vec {
    output_vec1.push(biquad1.run(elem));
    output_vec2.push(biquad2.run(elem));
}

Documentation

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.