Struct PolyIIRHalfbandFilter

pub struct PolyIIRHalfbandFilter { /* private fields */ }

This is a polyphase iir halfband filter (cutoff at fs/4) consisting of cascades of allpasses. translated from the freely available source code at https://www.musicdsp.org/en/latest/Filters/39-polyphase-filters.html

Usage:

 #![feature(portable_simd)]
 use std::simd::f32x4;

 use synfx_dsp::PolyIIRHalfbandFilter;

 struct MyNiceDistort {
     upsampler: PolyIIRHalfbandFilter,
     downsampler: PolyIIRHalfbandFilter,
 }

 impl MyNiceDistort {
     fn new() -> Self {
         Self {
             upsampler: PolyIIRHalfbandFilter::new(8, true),
             downsampler: PolyIIRHalfbandFilter::new(8, true),
         }
     }

     fn process(&mut self, in_l: f32, in_r: f32) -> (f32, f32) {
         let frame = f32x4::from_array([in_l, in_r, 0.0, 0.0]);
         // Zero stuffing:
         let input = [frame, f32x4::splat(0.)];
         // Prepare the output:
         let mut output = f32x4::splat(0.);
         for i in 0..2 {
             // Upsampling:
             let frame = self.upsampler.process(f32x4::splat(2.) * input[i]);

             // Apply some non linear stuff:
             let out = synfx_dsp::tanh_levien(frame * f32x4::splat(10.0));

             // Downsampling:
             output = self.downsampler.process(out);
         }

         let output = output.as_array();
         (output[0], output[1])
     }
 }

Implementations

impl PolyIIRHalfbandFilter

pub fn new(order: usize, steep: bool) -> PolyIIRHalfbandFilter

Create a new PolyIIRHalfbandFilter with the given order.

• order can be 2, 4, 6, 8, 10 or 12
• if steep is true, it gives rejection of 69dB at order=8. Transition band is 0.01. if steep is false, it gives rejection of 106dB at order=8. Transition band is 0.05.

pub fn process(&mut self, input: f32x4) -> f32x4

Trait Implementations

impl Clone for PolyIIRHalfbandFilter

fn clone(&self) -> PolyIIRHalfbandFilter

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PolyIIRHalfbandFilter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PolyIIRHalfbandFilter

fn default() -> PolyIIRHalfbandFilter

Returns the “default value” for a type.

impl Copy for PolyIIRHalfbandFilter