Audio Filters - WIP

A collection of filters for real-time audio processing

The overall design is in progress, there can be frequent (usually minor) breaking changes.

Feature Progress

• #![no_std] (via libm)
• f32 & f64 capable (via num-traits)
• SIMD (Some experimental support)
• Documentation
• Tests

Filter Types

• Bell
• Low Pass
• High Pass
• Low Shelf
• High Shelf
• Notch
• Band Pass
• All Pass
• Higher Order Bell
• Higher Order Band Pass
• Asymmetrical
• Tilt
• Flat Tilt

Filter Features

• Bode Plot (phase & amplitude)
• 1st and 2nd order filter primitives
• Higher orders via cascading
• Virtual analog (VA) State Variable Filters (SVF) for both 1st & 2nd order IIR.
• Linkwitz-Riley filters
• Elliptic filters
• Phase aligned crossovers
• Decramping near nyquist
• Minimum Phase IIR Mode
• Linear Phase Mode

let sample_rate_hz = 48000.0;
let cutoff_hz = 1000.0;
let gain_db = 6.0;
let width_oct = 1.0;
let order = 4.0;

let coeffs = FilterBandCoefficients::highshelf(cutoff_hz, gain_db, width_oct, order, sample_rate_hz);

let mut filter_left = FilterBand::from(&coeffs);
let mut filter_right = FilterBand::from(&coeffs);

for i in 0..1000 {
    left[i] = (filter_left.process)(&mut filter_left, left[i]);
    right[i] = (filter_right.process)(&mut filter_right, right[i]);
}