Crate biquad

biquad

biquad is a library for creating 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.

Examples

fn main() {
    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));
    }
}

Errors

Coefficients::from_params(...) can error if the cutoff frequency does not adhere to the Nyquist Frequency, or if the Q value is negative.

Hertz::from_hz(...) and Hertz::from_dt(...) will error if the frequency is negative.

Panics

x.hz(), x.khz(), x.mhz(), x.dt() will panic for f32/f64 if they are negative.

Re-exports

pub use crate::coefficients::*;

pub use crate::frequency::*;

Modules

coefficients

coefficients

frequency

frequency

Structs

DirectForm1

Internal states and coefficients of the Direct Form 1 form

DirectForm2Transposed

Internal states and coefficients of the Direct Form 2 Transposed form

Enums

Errors

Possible errors

Traits

Biquad

The required functions of a biquad implementation