Move Crossover biquads to their own module
This commit is contained in:
Robbert van der Helm
parent
89afa8bf00
commit
694996dcf4
196
plugins/crossover/src/biquad.rs
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196
plugins/crossover/src/biquad.rs
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@ -0,0 +1,196 @@
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// Crossover: clean crossovers as a multi-out plugin
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// Copyright (C) 2022 Robbert van der Helm
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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use nih_plug::debug::*;
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use std::f32::consts;
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use std::ops::{Add, Mul, Sub};
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use std::simd::f32x2;
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/// A simple biquad filter with functions for generating coefficients for second order low-pass and
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/// high-pass filters. Since these filters have 3 dB of attenuation at the center frequency, we'll
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/// two of them in series to get 6 dB of attenutation at the crossover point for the LR24
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/// crossovers.
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///
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/// Based on <https://en.wikipedia.org/wiki/Digital_biquad_filter#Transposed_direct_forms>.
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///
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/// The type parameter T should be either an `f32` or a SIMD type.
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#[derive(Clone, Copy, Debug)]
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pub struct Biquad<T> {
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pub coefficients: BiquadCoefficients<T>,
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s1: T,
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s2: T,
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}
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/// The coefficients `[b0, b1, b2, a1, a2]` for [`Biquad`]. These coefficients are all
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/// prenormalized, i.e. they have been divided by `a0`.
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///
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/// The type parameter T should be either an `f32` or a SIMD type.
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#[derive(Clone, Copy, Debug)]
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pub struct BiquadCoefficients<T> {
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b0: T,
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b1: T,
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b2: T,
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a1: T,
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a2: T,
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}
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/// Either an `f32` or some SIMD vector type of `f32`s that can be used with our biquads.
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pub trait SimdType:
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Mul<Output = Self> + Sub<Output = Self> + Add<Output = Self> + Copy + Sized
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{
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fn from_f32(value: f32) -> Self;
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}
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impl<T: SimdType> Default for Biquad<T> {
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/// Before setting constants the filter should just act as an identity function.
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fn default() -> Self {
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Self {
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coefficients: BiquadCoefficients::identity(),
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s1: T::from_f32(0.0),
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s2: T::from_f32(0.0),
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}
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}
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}
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impl<T: SimdType> Biquad<T> {
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/// Process a single sample.
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pub fn process(&mut self, sample: T) -> T {
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let result = self.coefficients.b0 * sample + self.s1;
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self.s1 = self.coefficients.b1 * sample - self.coefficients.a1 * result + self.s2;
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self.s2 = self.coefficients.b2 * sample - self.coefficients.a2 * result;
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result
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}
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/// Reset the state to zero, useful after making making large, non-interpolatable changes to the
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/// filter coefficients.
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pub fn reset(&mut self) {
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self.s1 = T::from_f32(0.0);
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self.s2 = T::from_f32(0.0);
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}
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}
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impl<T: SimdType> BiquadCoefficients<T> {
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/// Convert scalar coefficients into the correct vector type.
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pub fn from_f32s(scalar: BiquadCoefficients<f32>) -> Self {
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Self {
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b0: T::from_f32(scalar.b0),
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b1: T::from_f32(scalar.b1),
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b2: T::from_f32(scalar.b2),
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a1: T::from_f32(scalar.a1),
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a2: T::from_f32(scalar.a2),
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}
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}
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/// Filter coefficients that would cause the sound to be passed through as is.
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pub fn identity() -> Self {
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Self::from_f32s(BiquadCoefficients {
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b0: 1.0,
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b1: 0.0,
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b2: 0.0,
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a1: 0.0,
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a2: 0.0,
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})
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}
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/// Compute the coefficients for a low-pass filter.
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///
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/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
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pub fn lowpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
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nih_debug_assert!(sample_rate > 0.0);
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nih_debug_assert!(frequency > 0.0);
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nih_debug_assert!(frequency < sample_rate / 2.0);
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nih_debug_assert!(q > 0.0);
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let omega0 = consts::TAU * (frequency / sample_rate);
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let cos_omega0 = omega0.cos();
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let alpha = omega0.sin() / (2.0 * q);
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// We'll prenormalize everything with a0
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let a0 = 1.0 + alpha;
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let b0 = ((1.0 - cos_omega0) / 2.0) / a0;
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let b1 = (1.0 - cos_omega0) / a0;
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let b2 = ((1.0 - cos_omega0) / 2.0) / a0;
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let a1 = (-2.0 * cos_omega0) / a0;
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let a2 = (1.0 - alpha) / a0;
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Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
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}
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/// Compute the coefficients for a high-pass filter.
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///
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/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
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pub fn highpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
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nih_debug_assert!(sample_rate > 0.0);
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nih_debug_assert!(frequency > 0.0);
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nih_debug_assert!(frequency < sample_rate / 2.0);
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nih_debug_assert!(q > 0.0);
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let omega0 = consts::TAU * (frequency / sample_rate);
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let cos_omega0 = omega0.cos();
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let alpha = omega0.sin() / (2.0 * q);
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// We'll prenormalize everything with a0
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let a0 = 1.0 + alpha;
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let b0 = ((1.0 + cos_omega0) / 2.0) / a0;
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let b1 = -(1.0 + cos_omega0) / a0;
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let b2 = ((1.0 + cos_omega0) / 2.0) / a0;
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let a1 = (-2.0 * cos_omega0) / a0;
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let a2 = (1.0 - alpha) / a0;
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Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
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}
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/// Compute the coefficients for an all-pass filter.
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///
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/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
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pub fn allpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
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nih_debug_assert!(sample_rate > 0.0);
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nih_debug_assert!(frequency > 0.0);
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nih_debug_assert!(frequency < sample_rate / 2.0);
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nih_debug_assert!(q > 0.0);
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let omega0 = consts::TAU * (frequency / sample_rate);
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let cos_omega0 = omega0.cos();
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let alpha = omega0.sin() / (2.0 * q);
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// We'll prenormalize everything with a0
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let a0 = 1.0 + alpha;
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let b0 = (1.0 - alpha) / a0;
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let b1 = (-2.0 * cos_omega0) / a0;
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let b2 = (1.0 + alpha) / a0;
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let a1 = (-2.0 * cos_omega0) / a0;
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let a2 = (1.0 - alpha) / a0;
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Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
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}
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}
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impl SimdType for f32 {
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#[inline(always)]
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fn from_f32(value: f32) -> Self {
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value
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}
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}
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impl SimdType for f32x2 {
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#[inline(always)]
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fn from_f32(value: f32) -> Self {
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f32x2::splat(value)
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}
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}
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@ -16,10 +16,9 @@
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use nih_plug::buffer::ChannelSamples;
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use nih_plug::buffer::ChannelSamples;
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use nih_plug::debug::*;
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use nih_plug::debug::*;
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use std::f32::consts;
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use std::ops::{Add, Mul, Sub};
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use std::simd::f32x2;
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use std::simd::f32x2;
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use crate::biquad::{Biquad, BiquadCoefficients};
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use crate::NUM_BANDS;
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use crate::NUM_BANDS;
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const NEUTRAL_Q: f32 = std::f32::consts::FRAC_1_SQRT_2;
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const NEUTRAL_Q: f32 = std::f32::consts::FRAC_1_SQRT_2;
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@ -273,178 +272,3 @@ impl AllPassCascade {
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}
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}
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}
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}
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}
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}
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/// A simple biquad filter with functions for generating coefficients for second order low-pass and
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/// high-pass filters. Since these filters have 3 dB of attenuation at the center frequency, we'll
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/// two of them in series to get 6 dB of attenutation at the crossover point for the LR24
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/// crossovers.
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///
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/// Based on <https://en.wikipedia.org/wiki/Digital_biquad_filter#Transposed_direct_forms>.
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///
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/// The type parameter T should be either an `f32` or a SIMD type.
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#[derive(Clone, Copy, Debug)]
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pub struct Biquad<T> {
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pub coefficients: BiquadCoefficients<T>,
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s1: T,
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s2: T,
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}
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/// The coefficients `[b0, b1, b2, a1, a2]` for [`Biquad`]. These coefficients are all
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/// prenormalized, i.e. they have been divided by `a0`.
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///
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/// The type parameter T should be either an `f32` or a SIMD type.
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#[derive(Clone, Copy, Debug)]
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pub struct BiquadCoefficients<T> {
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b0: T,
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b1: T,
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b2: T,
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a1: T,
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a2: T,
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}
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/// Either an `f32` or some SIMD vector type of `f32`s that can be used with our biquads.
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pub trait SimdType:
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Mul<Output = Self> + Sub<Output = Self> + Add<Output = Self> + Copy + Sized
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{
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fn from_f32(value: f32) -> Self;
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}
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impl<T: SimdType> Default for Biquad<T> {
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/// Before setting constants the filter should just act as an identity function.
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fn default() -> Self {
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Self {
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coefficients: BiquadCoefficients::identity(),
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s1: T::from_f32(0.0),
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s2: T::from_f32(0.0),
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}
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}
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}
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impl<T: SimdType> Biquad<T> {
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/// Process a single sample.
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pub fn process(&mut self, sample: T) -> T {
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let result = self.coefficients.b0 * sample + self.s1;
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self.s1 = self.coefficients.b1 * sample - self.coefficients.a1 * result + self.s2;
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self.s2 = self.coefficients.b2 * sample - self.coefficients.a2 * result;
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result
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}
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/// Reset the state to zero, useful after making making large, non-interpolatable changes to the
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/// filter coefficients.
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pub fn reset(&mut self) {
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self.s1 = T::from_f32(0.0);
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self.s2 = T::from_f32(0.0);
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}
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}
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impl<T: SimdType> BiquadCoefficients<T> {
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/// Convert scalar coefficients into the correct vector type.
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pub fn from_f32s(scalar: BiquadCoefficients<f32>) -> Self {
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Self {
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b0: T::from_f32(scalar.b0),
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b1: T::from_f32(scalar.b1),
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b2: T::from_f32(scalar.b2),
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a1: T::from_f32(scalar.a1),
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a2: T::from_f32(scalar.a2),
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}
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}
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/// Filter coefficients that would cause the sound to be passed through as is.
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pub fn identity() -> Self {
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Self::from_f32s(BiquadCoefficients {
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b0: 1.0,
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b1: 0.0,
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b2: 0.0,
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a1: 0.0,
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a2: 0.0,
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})
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}
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/// Compute the coefficients for a low-pass filter.
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///
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/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
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pub fn lowpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
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nih_debug_assert!(sample_rate > 0.0);
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nih_debug_assert!(frequency > 0.0);
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nih_debug_assert!(frequency < sample_rate / 2.0);
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nih_debug_assert!(q > 0.0);
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let omega0 = consts::TAU * (frequency / sample_rate);
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let cos_omega0 = omega0.cos();
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let alpha = omega0.sin() / (2.0 * q);
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// We'll prenormalize everything with a0
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let a0 = 1.0 + alpha;
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let b0 = ((1.0 - cos_omega0) / 2.0) / a0;
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let b1 = (1.0 - cos_omega0) / a0;
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let b2 = ((1.0 - cos_omega0) / 2.0) / a0;
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let a1 = (-2.0 * cos_omega0) / a0;
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let a2 = (1.0 - alpha) / a0;
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Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
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}
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/// Compute the coefficients for a high-pass filter.
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///
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/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
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pub fn highpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
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nih_debug_assert!(sample_rate > 0.0);
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nih_debug_assert!(frequency > 0.0);
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nih_debug_assert!(frequency < sample_rate / 2.0);
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nih_debug_assert!(q > 0.0);
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let omega0 = consts::TAU * (frequency / sample_rate);
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let cos_omega0 = omega0.cos();
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let alpha = omega0.sin() / (2.0 * q);
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// We'll prenormalize everything with a0
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let a0 = 1.0 + alpha;
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let b0 = ((1.0 + cos_omega0) / 2.0) / a0;
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let b1 = -(1.0 + cos_omega0) / a0;
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let b2 = ((1.0 + cos_omega0) / 2.0) / a0;
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let a1 = (-2.0 * cos_omega0) / a0;
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let a2 = (1.0 - alpha) / a0;
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Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
|
|
||||||
}
|
|
||||||
|
|
||||||
/// Compute the coefficients for an all-pass filter.
|
|
||||||
///
|
|
||||||
/// Based on <http://shepazu.github.io/Audio-EQ-Cookbook/audio-eq-cookbook.html>.
|
|
||||||
pub fn allpass(sample_rate: f32, frequency: f32, q: f32) -> Self {
|
|
||||||
nih_debug_assert!(sample_rate > 0.0);
|
|
||||||
nih_debug_assert!(frequency > 0.0);
|
|
||||||
nih_debug_assert!(frequency < sample_rate / 2.0);
|
|
||||||
nih_debug_assert!(q > 0.0);
|
|
||||||
|
|
||||||
let omega0 = consts::TAU * (frequency / sample_rate);
|
|
||||||
let cos_omega0 = omega0.cos();
|
|
||||||
let alpha = omega0.sin() / (2.0 * q);
|
|
||||||
|
|
||||||
// We'll prenormalize everything with a0
|
|
||||||
let a0 = 1.0 + alpha;
|
|
||||||
let b0 = (1.0 - alpha) / a0;
|
|
||||||
let b1 = (-2.0 * cos_omega0) / a0;
|
|
||||||
let b2 = (1.0 + alpha) / a0;
|
|
||||||
let a1 = (-2.0 * cos_omega0) / a0;
|
|
||||||
let a2 = (1.0 - alpha) / a0;
|
|
||||||
|
|
||||||
Self::from_f32s(BiquadCoefficients { b0, b1, b2, a1, a2 })
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
impl SimdType for f32 {
|
|
||||||
#[inline(always)]
|
|
||||||
fn from_f32(value: f32) -> Self {
|
|
||||||
value
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
impl SimdType for f32x2 {
|
|
||||||
#[inline(always)]
|
|
||||||
fn from_f32(value: f32) -> Self {
|
|
||||||
f32x2::splat(value)
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
|
||||||
|
|
@ -24,6 +24,7 @@ use nih_plug::prelude::*;
|
||||||
use std::sync::atomic::{AtomicBool, Ordering};
|
use std::sync::atomic::{AtomicBool, Ordering};
|
||||||
use std::sync::Arc;
|
use std::sync::Arc;
|
||||||
|
|
||||||
|
mod biquad;
|
||||||
mod crossover;
|
mod crossover;
|
||||||
|
|
||||||
/// The number of bands. Not used directly here, but this avoids hardcoding some constants in the
|
/// The number of bands. Not used directly here, but this avoids hardcoding some constants in the
|
||||||
|
|
|
||||||
Loading…
Reference in a new issue