Initial Air Freshener plugin implementation

ebu-dsp/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "ebu-dsp"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+nih_plug = { git = "https://github.com/robbert-vdh/nih-plug", version = "0.0.0", default-features = false }

ebu-dsp/src/amplitude.rs

@@ -0,0 +1,74 @@
+use std::fmt::{Debug, Display};
+
+use crate::{decibel::Decibel, math_ops_impl};
+
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Amplitude(pub f64);
+impl From<Amplitude> for Decibel {
+    fn from(value: Amplitude) -> Self {
+        Decibel::from(20.0 * value.0.abs().log10())
+    }
+}
+impl Amplitude {
+    pub fn value(&self) -> f64 {
+        self.0
+    }
+}
+
+impl Display for Amplitude {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&format!("{:.2}", self.0))
+    }
+}
+impl Debug for Amplitude {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&format!("{}", self.0))
+    }
+}
+
+math_ops_impl!(Amplitude);
+
+impl std::ops::Add for Amplitude {
+    type Output = Amplitude;
+    fn add(self, rhs: Amplitude) -> Self::Output {
+        Self(self.0 + rhs.0)
+    }
+}
+impl std::ops::Sub for Amplitude {
+    type Output = Amplitude;
+    fn sub(self, rhs: Amplitude) -> Self::Output {
+        Self(self.0 - rhs.0)
+    }
+}
+impl std::ops::Mul for Amplitude {
+    type Output = Amplitude;
+    fn mul(self, rhs: Amplitude) -> Self::Output {
+        Self(self.0 * rhs.0)
+    }
+}
+impl std::ops::Div for Amplitude {
+    type Output = Amplitude;
+    fn div(self, rhs: Amplitude) -> Self::Output {
+        Self(self.0 / rhs.0)
+    }
+}
+impl std::ops::AddAssign for Amplitude {
+    fn add_assign(&mut self, rhs: Amplitude) {
+        self.0 += rhs.0;
+    }
+}
+impl std::ops::SubAssign for Amplitude {
+    fn sub_assign(&mut self, rhs: Amplitude) {
+        self.0 -= rhs.0;
+    }
+}
+impl std::ops::MulAssign for Amplitude {
+    fn mul_assign(&mut self, rhs: Amplitude) {
+        self.0 *= rhs.0;
+    }
+}
+impl std::ops::DivAssign for Amplitude {
+    fn div_assign(&mut self, rhs: Amplitude) {
+        self.0 /= rhs.0;
+    }
+}

ebu-dsp/src/biquad.rs

@@ -0,0 +1,348 @@
+use std::{
+    f64::{self, consts::SQRT_2},
+    fmt::Display,
+    sync::Arc,
+};
+
+use crate::{
+    decibel::Decibel, SampleRate,
+    traits::{IntFormatter, Processor},
+};
+
+#[derive(Default, Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Slope {
+    #[default]
+    DB12,
+    DB24,
+    DB36,
+    DB48,
+}
+
+#[derive(Default, Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum FilterMode {
+    Peak,
+    HighPass,
+    HighShelf,
+    LowPass,
+    LowShelf,
+    AllPass,
+    BandPass,
+    BandReject,
+    #[default]
+    None,
+}
+impl TryFrom<i32> for FilterMode {
+    type Error = ();
+    fn try_from(value: i32) -> Result<Self, Self::Error> {
+        match value {
+            0 => Ok(FilterMode::Peak),
+            1 => Ok(FilterMode::HighPass),
+            2 => Ok(FilterMode::HighShelf),
+            3 => Ok(FilterMode::LowPass),
+            4 => Ok(FilterMode::LowShelf),
+            5 => Ok(FilterMode::AllPass),
+            6 => Ok(FilterMode::BandPass),
+            7 => Ok(FilterMode::BandReject),
+            _ => Err(()),
+        }
+    }
+}
+impl From<FilterMode> for i32 {
+    fn from(value: FilterMode) -> Self {
+        match value {
+            FilterMode::Peak => 0,
+            FilterMode::HighPass => 1,
+            FilterMode::HighShelf => 2,
+            FilterMode::LowPass => 3,
+            FilterMode::LowShelf => 4,
+            FilterMode::AllPass => 5,
+            FilterMode::BandPass => 6,
+            FilterMode::BandReject => 7,
+            FilterMode::None => 8,
+        }
+    }
+}
+impl TryFrom<&str> for FilterMode {
+    type Error = ();
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "Peak" => Ok(FilterMode::Peak),
+            "Highpass" => Ok(FilterMode::HighPass),
+            "High Shelf" => Ok(FilterMode::HighShelf),
+            "Lowpass" => Ok(FilterMode::LowPass),
+            "Low Shelf" => Ok(FilterMode::LowShelf),
+            "Allpass" => Ok(FilterMode::AllPass),
+            "Bandpass" => Ok(FilterMode::BandPass),
+            "Notch" => Ok(FilterMode::BandReject),
+            _ => Err(()),
+        }
+    }
+}
+impl Display for FilterMode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            FilterMode::Peak => "Peak",
+            FilterMode::HighPass => "Highpass",
+            FilterMode::HighShelf => "High Shelf",
+            FilterMode::LowPass => "Lowpass",
+            FilterMode::LowShelf => "Low Shelf",
+            FilterMode::AllPass => "Allpass",
+            FilterMode::BandPass => "Bandpass",
+            FilterMode::BandReject => "Notch",
+            FilterMode::None => "None",
+        })
+    }
+}
+
+impl IntFormatter for FilterMode {
+    fn v2s() -> Arc<dyn Fn(i32) -> String + Send + Sync>
+    where
+        Self: Sized,
+    {
+        Arc::new(move |value| FilterMode::try_from(value).unwrap_or_default().to_string())
+    }
+
+    fn s2v() -> Arc<dyn Fn(&str) -> Option<i32> + Send + Sync>
+    where
+        Self: Sized,
+    {
+        Arc::new(move |value| FilterMode::try_from(value).map(i32::from).ok())
+    }
+}
+
+#[derive(Default, Debug, Clone, Copy)]
+struct FilterCoefficients {
+    a1: f64,
+    a2: f64,
+    b0: f64,
+    b1: f64,
+    b2: f64,
+}
+impl FilterCoefficients {
+    fn calculate(
+        &mut self,
+        mode: FilterMode,
+        sample_rate: SampleRate,
+        freq: f64,
+        q: f64,
+        gain_db: Decibel,
+    ) {
+        let v = 10f64.powf(gain_db.value().abs() / 20.0);
+        let k = (f64::consts::PI * freq / sample_rate.0).tan();
+
+        match mode {
+            FilterMode::Peak => {
+                if gain_db.value() >= 0.0 {
+                    let norm = 1.0 / (1.0 + 1.0 / q * k + k * k);
+                    self.b0 = (1.0 + v / q * k + k * k) * norm;
+                    self.b1 = 2.0 * (k * k - 1.0) * norm;
+                    self.b2 = (1.0 - v / q * k + k * k) * norm;
+                    self.a1 = self.b1;
+                    self.a2 = (1.0 - 1.0 / q * k + k * k) * norm;
+                } else {
+                    let norm = 1.0 / (1.0 + v / q * k + k * k);
+                    self.b0 = (1.0 + 1.0 / q * k + k * k) * norm;
+                    self.b1 = 2.0 * (k * k - 1.0) * norm;
+                    self.b2 = (1.0 - 1.0 / q * k + k * k) * norm;
+                    self.a1 = self.b1;
+                    self.a2 = (1.0 - v / q * k + k * k) * norm;
+                }
+            }
+            FilterMode::HighPass => {
+                let norm = 1.0 / (1.0 + k / q + k * k);
+                self.b0 = 1.0 * norm;
+                self.b1 = -2.0 * self.b0;
+                self.b2 = self.b0;
+                self.a1 = 2.0 * (k * k - 1.0) * norm;
+                self.a2 = (1.0 - k / q + k * k) * norm;
+            }
+            FilterMode::HighShelf => {
+                if gain_db.value() >= 0.0 {
+                    let norm = 1.0 / (1.0 + SQRT_2 * k + k * k);
+                    self.b0 = (v + (2.0 * v).sqrt() * k + k * k) * norm;
+                    self.b1 = 2.0 * (k * k - v) * norm;
+                    self.b2 = (v - (2.0 * v).sqrt() * k + k * k) * norm;
+                    self.a1 = 2.0 * (k * k - 1.0) * norm;
+                    self.a2 = (1.0 - SQRT_2 * k + k * k) * norm;
+                } else {
+                    let norm = 1.0 / (v + (2.0 * v).sqrt() * k + k * k);
+                    self.b0 = (1.0 + SQRT_2 * k + k * k) * norm;
+                    self.b1 = 2.0 * (k * k - 1.0) * norm;
+                    self.b2 = (1.0 - SQRT_2 * k + k * k) * norm;
+                    self.a1 = 2.0 * (k * k - v) * norm;
+                    self.a2 = (v - (2.0 * v).sqrt() * k + k * k) * norm;
+                }
+            }
+            FilterMode::LowPass => {
+                let norm = 1.0 / (1.0 + k / q + k * k);
+                self.b0 = k * k * norm;
+                self.b1 = 2.0 * self.b0;
+                self.b2 = self.b0;
+                self.a1 = 2.0 * (k * k - 1.0) * norm;
+                self.a2 = (1.0 - k / q + k * k) * norm;
+            }
+            FilterMode::LowShelf => {
+                if gain_db.value() >= 0.0 {
+                    let norm = 1.0 / (1.0 + SQRT_2 * k + k * k);
+                    self.b0 = (1.0 + (2.0 * v).sqrt() * k + v * k * k) * norm;
+                    self.b1 = 2.0 * (v * k * k - 1.0) * norm;
+                    self.b2 = (1.0 - (2.0 * v).sqrt() * k + v * k * k) * norm;
+                    self.a1 = 2.0 * (k * k - 1.0) * norm;
+                    self.a2 = (1.0 - SQRT_2 * k + k * k) * norm;
+                } else {
+                    let norm = 1.0 / (1.0 + (2.0 * v).sqrt() * k + v * k * k);
+                    self.b0 = (1.0 + SQRT_2 * k + k * k) * norm;
+                    self.b1 = 2.0 * (k * k - 1.0) * norm;
+                    self.b2 = (1.0 - SQRT_2 * k + k * k) * norm;
+                    self.a1 = 2.0 * (v * k * k - 1.0) * norm;
+                    self.a2 = (1.0 - (2.0 * v).sqrt() * k + v * k * k) * norm;
+                }
+            }
+            FilterMode::AllPass => {
+                let norm = 1.0 / (1.0 + k / q + k * k);
+                self.b0 = (1.0 - k / q + k * k) * norm;
+                self.b1 = 2.0 * (k * k - 1.0) * norm;
+                self.b2 = 1.0;
+                self.a1 = self.b1;
+                self.a2 = self.b0;
+            }
+            FilterMode::BandPass => {
+                let norm = 1.0 / (1.0 + k / q + k * k);
+                self.b0 = k / q * norm;
+                self.b1 = 0.0;
+                self.b2 = -self.b0;
+                self.a1 = 2.0 * (k * k - 1.0) * norm;
+                self.a2 = (1.0 - k / q + k * k) * norm;
+            }
+            FilterMode::BandReject => {
+                let norm = 1.0 / (1.0 + k / q + k * k);
+                self.b0 = (1.0 + k * k) * norm;
+                self.b1 = 2.0 * (k * k - 1.0) * norm;
+                self.b2 = self.b0;
+                self.a1 = self.b1;
+                self.a2 = (1.0 - k / q + k * k) * norm;
+            }
+            FilterMode::None => {}
+        }
+    }
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+struct State {
+    s1: f64,
+    s2: f64,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct BiquadFilterState {
+    pub mode: FilterMode,
+    pub cutoff: f64,
+    pub q: f64,
+    pub gain_db: Decibel,
+    pub slope: Slope,
+}
+impl Default for BiquadFilterState {
+    fn default() -> Self {
+        Self {
+            mode: FilterMode::None,
+            cutoff: 2000.0,
+            q: 0.707,
+            gain_db: Decibel::from(0.0),
+            slope: Slope::DB12,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct BiquadFilter {
+    pub state: BiquadFilterState,
+    sample_rate: SampleRate,
+    coefficients: FilterCoefficients,
+    slope_states: [State; 4],
+    dirty: bool,
+}
+
+impl BiquadFilter {
+    pub fn new(sample_rate: SampleRate) -> Self {
+        Self::from_state(sample_rate, BiquadFilterState::default())
+    }
+    pub fn from_state(sample_rate: SampleRate, state: BiquadFilterState) -> Self {
+        Self {
+            sample_rate,
+            coefficients: FilterCoefficients::default(),
+            slope_states: [State::default(); 4],
+            dirty: true,
+            state
+        }
+    }
+    pub fn set_mode(&mut self, mode: FilterMode) {
+        self.dirty = true;
+        self.state.mode = mode;
+    }
+    pub fn set_cutoff(&mut self, cutoff: f64) {
+        self.dirty = true;
+        self.state.cutoff = cutoff;
+    }
+    pub fn set_slope(&mut self, slope: Slope) {
+        self.dirty = true;
+        self.state.slope = slope;
+    }
+    pub fn set_q(&mut self, q: f64) {
+        self.dirty = true;
+        self.state.q = q;
+    }
+    pub fn set_gain<T>(&mut self, gain_db: T)
+    where
+        T: Into<Decibel>,
+    {
+        self.dirty = true;
+        self.state.gain_db = gain_db.into();
+    }
+
+    fn update_coefficients(&mut self) {
+        if !self.dirty {
+            return;
+        }
+        self.dirty = false;
+
+        self.coefficients.calculate(
+            self.state.mode,
+            self.sample_rate,
+            self.state.cutoff,
+            self.state.q,
+            self.state.gain_db,
+        );
+    }
+}
+
+impl Processor for BiquadFilter {
+    fn process(&mut self, sample: f64) -> f64 {
+        self.update_coefficients();
+
+        let iterations = match self.state.slope {
+            Slope::DB12 => 1,
+            Slope::DB24 => 2,
+            Slope::DB36 => 3,
+            Slope::DB48 => 4,
+        };
+        let mut current = sample;
+
+        for i in 0..iterations {
+            let result = self.coefficients.b0 * current + self.slope_states[i].s1;
+            let s1 = self.coefficients.b1 * current - self.coefficients.a1 * result
+                + self.slope_states[i].s2;
+            let s2 = self.coefficients.b2 * current - self.coefficients.a2 * result;
+
+            self.slope_states[i].s1 = s1;
+            self.slope_states[i].s2 = s2;
+            current = result;
+        }
+
+        if current.is_nan() || current.is_infinite() {
+            0.0
+        } else {
+            current
+        }
+    }
+}

ebu-dsp/src/comp.rs

@@ -0,0 +1,127 @@
+use crate::{
+    Ratio, SampleRate, amplitude::Amplitude, decibel::Decibel, ring_buffer::RingBuffer, rms, smoother::Smoother, traits::Processor
+};
+use std::time::Duration;
+
+#[derive(Debug, Default, Clone, Copy)]
+pub enum CompressorPeakMode {
+    #[default]
+    Sample,
+    RMS,
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+pub struct CompressorState {
+    pub peak_mode: CompressorPeakMode,
+    pub threshold: Decibel,
+    pub ratio: Ratio,
+    pub gain: Decibel,
+    pub attack: Duration,
+    pub release: Duration,
+    pub last_rms: f64,
+    pub input_db: Decibel,
+    pub output_static_db: Decibel,
+    pub gain_db: Decibel,
+    pub gain_smoothed_db: Decibel,
+    pub final_gain_db: Decibel,
+}
+impl CompressorState {
+    pub fn new() -> Self {
+        Self {
+            peak_mode: CompressorPeakMode::Sample,
+            threshold: Decibel::from(-24.0),
+            ratio: Ratio(1.0, 3.0),
+            gain: Decibel::from(0.0),
+            attack: Duration::from_millis(25),
+            release: Duration::from_millis(100),
+            last_rms: 0.0,
+            input_db: Decibel::from(0.0),
+            output_static_db: Decibel::from(0.0),
+            gain_db: Decibel::from(0.0),
+            gain_smoothed_db: Decibel::from(0.0),
+            final_gain_db: Decibel::from(0.0),
+        }
+    }
+}
+
+pub struct Compressor {
+    pub state: CompressorState,
+    sample_buffer: RingBuffer<f64, 2048>,
+    smoother: Smoother,
+}
+
+impl Compressor {
+    pub fn new(sample_rate: SampleRate) -> Self {
+        Self::from_state(sample_rate, CompressorState::default())
+    }
+    pub fn from_state(sample_rate: SampleRate, state: CompressorState) -> Self {
+        Self {
+            sample_buffer: RingBuffer::new(0.0),
+            smoother: Smoother::new(sample_rate),
+            state,
+        }
+    }
+    pub fn set_threshold<T>(&mut self, threshold: T)
+    where
+        T: Into<Decibel>,
+    {
+        self.state.threshold = threshold.into();
+    }
+    pub fn set_attack<T>(&mut self, attack: T)
+    where
+        T: Into<Duration>,
+    {
+        self.smoother.set_attack(attack);
+    }
+    pub fn set_release<T>(&mut self, release: T)
+    where
+        T: Into<Duration>,
+    {
+        self.smoother.set_release(release);
+    }
+    pub fn set_ratio<R>(&mut self, ratio: R)
+    where
+        R: Into<Ratio>,
+    {
+        self.state.ratio = ratio.into();
+    }
+    pub fn set_gain<T>(&mut self, gain: T)
+    where
+        T: Into<Decibel>,
+    {
+        self.state.gain = gain.into();
+    }
+}
+
+impl Processor for Compressor {
+    fn process(&mut self, sample: f64) -> f64 {
+        self.sample_buffer[0] = sample;
+
+        self.state.input_db = Decibel::from(Amplitude(match self.state.peak_mode {
+            CompressorPeakMode::Sample => sample.abs() + f64::EPSILON,
+            CompressorPeakMode::RMS => {
+                self.state.last_rms = rms(&self.sample_buffer, self.state.last_rms);
+                self.state.last_rms.abs().sqrt() + f64::EPSILON
+            }
+        }));
+
+        self.state.output_static_db = if self.state.input_db < self.state.threshold {
+            self.state.input_db
+        } else {
+            self.state.threshold
+                + (self.state.input_db - self.state.threshold) * self.state.ratio.multiplier()
+        };
+        self.state.gain_db = self.state.output_static_db - self.state.input_db;
+
+        self.state.gain_smoothed_db = if self.state.gain_db < self.state.gain_smoothed_db {
+            self.smoother.attack(self.state.gain_db)
+        } else {
+            self.smoother.release(self.state.gain_db)
+        };
+
+        self.state.final_gain_db = self.state.gain_smoothed_db + self.state.gain;
+        self.sample_buffer.shift();
+
+        sample * self.state.final_gain_db
+    }
+}

ebu-dsp/src/decibel.rs

@@ -0,0 +1,141 @@
+use std::fmt::{Debug, Display};
+
+use crate::{amplitude::Amplitude, math_ops_impl};
+
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Decibel(f64);
+impl Decibel {
+    pub fn value(&self) -> f64 {
+        self.0
+    }
+}
+impl From<Decibel> for Amplitude {
+    fn from(value: Decibel) -> Self {
+        Amplitude(10f64.powf(value.0 / 20.0))
+    }
+}
+
+impl Display for Decibel {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.0 >= 0.0 {
+            f.write_str(&format!("+{:.2}dB", self.0))
+        } else {
+            f.write_str(&format!("{:.2}dB", self.0))
+        }
+    }
+}
+impl Debug for Decibel {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.0 >= 0.0 {
+            f.write_str(&format!("+{}dB", self.0))
+        } else {
+            f.write_str(&format!("{}dB", self.0))
+        }
+    }
+}
+
+impl From<f32> for Decibel {
+    fn from(value: f32) -> Self {
+        Decibel(value as f64)
+    }
+}
+impl From<Decibel> for f32 {
+    fn from(value: Decibel) -> Self {
+        value.0 as f32
+    }
+}
+
+impl From<f64> for Decibel {
+    fn from(value: f64) -> Self {
+        let mut value = value;
+        #[cfg(debug_assertions)]
+        {
+            use nih_plug::nih_warn;
+            if value.is_nan() {
+                nih_warn!("Tried making dB from NaN");
+                value = 0.0;
+            } else if value.is_infinite() {
+                nih_warn!("Tried making dB from Inf");
+                value = 0.0;
+            } else if value >= 120.0 {
+                nih_warn!("Impossibly large dB {value}");
+            }
+        }
+        Decibel(value)
+    }
+}
+impl From<Decibel> for f64 {
+    fn from(value: Decibel) -> Self {
+        value.0
+    }
+}
+
+math_ops_impl!(Decibel);
+
+impl std::ops::Add for Decibel {
+    type Output = Decibel;
+    fn add(self, rhs: Decibel) -> Self::Output {
+        Self(self.0 + rhs.0)
+    }
+}
+impl std::ops::Sub for Decibel {
+    type Output = Decibel;
+    fn sub(self, rhs: Decibel) -> Self::Output {
+        Self(self.0 - rhs.0)
+    }
+}
+impl std::ops::AddAssign for Decibel {
+    fn add_assign(&mut self, rhs: Decibel) {
+        self.0 += rhs.0;
+    }
+}
+impl std::ops::SubAssign for Decibel {
+    fn sub_assign(&mut self, rhs: Decibel) {
+        self.0 -= rhs.0;
+    }
+}
+
+impl std::ops::Mul<Decibel> for f32 {
+    type Output = f32;
+    fn mul(self, rhs: Decibel) -> Self::Output {
+        ((self as f64) * rhs) as f32
+    }
+}
+impl std::ops::Mul<Decibel> for f64 {
+    type Output = f64;
+    fn mul(self, rhs: Decibel) -> Self::Output {
+        self * Amplitude::from(rhs).0
+    }
+}
+impl std::ops::Div<Decibel> for f32 {
+    type Output = f32;
+    fn div(self, rhs: Decibel) -> Self::Output {
+        ((self as f64) / rhs) as f32
+    }
+}
+impl std::ops::Div<Decibel> for f64 {
+    type Output = f64;
+    fn div(self, rhs: Decibel) -> Self::Output {
+        self / Amplitude::from(rhs).0
+    }
+}
+impl std::ops::MulAssign<Decibel> for f32 {
+    fn mul_assign(&mut self, rhs: Decibel) {
+        *self = ((*self as f64) * rhs) as f32
+    }
+}
+impl std::ops::MulAssign<Decibel> for f64 {
+    fn mul_assign(&mut self, rhs: Decibel) {
+        *self *= Amplitude::from(rhs).0
+    }
+}
+impl std::ops::DivAssign<Decibel> for f32 {
+    fn div_assign(&mut self, rhs: Decibel) {
+        *self = ((*self as f64) / rhs) as f32
+    }
+}
+impl std::ops::DivAssign<Decibel> for f64 {
+    fn div_assign(&mut self, rhs: Decibel) {
+        *self /= Amplitude::from(rhs).0
+    }
+}

ebu-dsp/src/eq.rs

@@ -0,0 +1,31 @@
+use crate::{BiquadFilter, BiquadFilterState, Processor};
+
+#[derive(Debug, Default, Clone)]
+pub struct EqualizerState {
+    pub nodes: [Option<BiquadFilter>; 6],
+}
+
+pub struct Equalizer {
+    pub state: EqualizerState,
+}
+
+impl Equalizer {
+    pub fn new() -> Self {
+        Self::from_state(EqualizerState::default())
+    }
+    pub fn from_state(state: EqualizerState) -> Self {
+        Self { state }
+    }
+}
+
+impl Processor for Equalizer {
+    fn process(&mut self, sample: f64) -> f64 {
+        let mut sample = sample;
+        for node in &mut self.state.nodes {
+            if let Some(filter) = node {
+                sample = filter.process(sample);
+            }
+        }
+        sample
+    }
+}

ebu-dsp/src/freq_split.rs

@@ -0,0 +1,56 @@
+use crate::{BiquadFilter, FilterMode, SampleRate, biquad::Slope, traits::Processor};
+
+pub struct FreqSplitterState {
+    pub split_frequency: f64,
+    pub slope: Slope,
+}
+impl Default for FreqSplitterState {
+    fn default() -> Self {
+        Self {
+            split_frequency: 2000.0,
+            slope: Slope::DB24,
+        }
+    }
+}
+
+pub struct FreqSplitter {
+    pub state: FreqSplitterState,
+    low_band: BiquadFilter,
+    high_band: BiquadFilter,
+}
+
+impl FreqSplitter {
+    pub fn new(sample_rate: SampleRate) -> Self {
+        Self::from_state(sample_rate, FreqSplitterState::default())
+    }
+    pub fn from_state(sample_rate: SampleRate, state: FreqSplitterState) -> Self {
+        let mut this = Self {
+            state,
+            low_band: BiquadFilter::new(sample_rate),
+            high_band: BiquadFilter::new(sample_rate),
+        };
+        this.low_band.set_mode(FilterMode::LowPass);
+        this.high_band.set_mode(FilterMode::HighPass);
+        this
+    }
+}
+
+impl Processor<f64, (f64, f64)> for FreqSplitter {
+    fn process(&mut self, sample: f64) -> (f64, f64) {
+        self.low_band.set_cutoff(self.state.split_frequency);
+        self.low_band.set_slope(self.state.slope);
+        self.high_band.set_cutoff(self.state.split_frequency);
+        self.high_band.set_slope(self.state.slope);
+        (
+            self.low_band.process(sample),
+            self.high_band.process(sample),
+        )
+    }
+}
+
+impl Processor<f32, (f32, f32)> for FreqSplitter {
+    fn process(&mut self, sample: f32) -> (f32, f32) {
+        let (low, high) = self.process(sample as f64);
+        (low as f32, high as f32)
+    }
+}

ebu-dsp/src/lib.rs

@@ -0,0 +1,198 @@
+mod amplitude;
+mod biquad;
+mod comp;
+mod decibel;
+mod freq_split;
+mod meter;
+mod ring_buffer;
+mod smoother;
+mod traits;
+mod eq;
+
+use std::{
+    fmt::Debug,
+    ops::Add,
+    time::Duration,
+};
+
+pub use biquad::{BiquadFilter, BiquadFilterState, FilterMode, Slope};
+pub use comp::{Compressor, CompressorState};
+pub use freq_split::{FreqSplitter, FreqSplitterState};
+pub use traits::{FloatFormatter, IntFormatter, Lerp, Processor};
+pub use decibel::Decibel;
+pub use amplitude::Amplitude;
+pub use eq::{Equalizer, EqualizerState};
+
+pub struct Rect<T> {
+    pub x: T,
+    pub y: T,
+    pub width: T,
+    pub height: T,
+}
+impl<T: Debug> Debug for Rect<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Rect")
+            .field("x", &self.x)
+            .field("y", &self.y)
+            .field("width", &self.width)
+            .field("height", &self.height)
+            .finish()
+    }
+}
+impl<T: PartialOrd + Add<Output = T> + Copy> Rect<T> {
+    pub fn contains(&self, value: (T, T)) -> bool {
+        value.0 >= self.x
+            && value.1 >= self.y
+            && value.0 < self.x + self.width
+            && value.1 < self.y + self.height
+    }
+}
+impl<T> Default for Rect<T>
+where
+    T: Default,
+{
+    fn default() -> Self {
+        Self {
+            x: Default::default(),
+            y: Default::default(),
+            width: Default::default(),
+            height: Default::default(),
+        }
+    }
+}
+
+use crate::ring_buffer::RingBuffer;
+use std::fmt::Display;
+
+#[macro_export]
+macro_rules! math_ops_impl {
+    ($T:ty) => {
+        /* impls for f32 */
+        impl std::ops::Add<f32> for $T {
+            type Output = $T;
+            fn add(self, rhs: f32) -> Self::Output {
+                Self(self.0 + rhs as f64)
+            }
+        }
+        impl std::ops::Sub<f32> for $T {
+            type Output = $T;
+            fn sub(self, rhs: f32) -> Self::Output {
+                Self(self.0 - rhs as f64)
+            }
+        }
+        impl std::ops::Mul<f32> for $T {
+            type Output = $T;
+            fn mul(self, rhs: f32) -> Self::Output {
+                Self(self.0 * rhs as f64)
+            }
+        }
+        impl std::ops::Div<f32> for $T {
+            type Output = $T;
+            fn div(self, rhs: f32) -> Self::Output {
+                Self(self.0 / rhs as f64)
+            }
+        }
+        impl std::ops::AddAssign<f32> for $T {
+            fn add_assign(&mut self, rhs: f32) {
+                self.0 += rhs as f64;
+            }
+        }
+        impl std::ops::SubAssign<f32> for $T {
+            fn sub_assign(&mut self, rhs: f32) {
+                self.0 -= rhs as f64;
+            }
+        }
+        impl std::ops::MulAssign<f32> for $T {
+            fn mul_assign(&mut self, rhs: f32) {
+                self.0 *= rhs as f64;
+            }
+        }
+        impl std::ops::DivAssign<f32> for $T {
+            fn div_assign(&mut self, rhs: f32) {
+                self.0 /= rhs as f64;
+            }
+        }
+
+        /* impls for f64 */
+        impl std::ops::Add<f64> for $T {
+            type Output = $T;
+            fn add(self, rhs: f64) -> Self::Output {
+                Self(self.0 + rhs)
+            }
+        }
+        impl std::ops::Sub<f64> for $T {
+            type Output = $T;
+            fn sub(self, rhs: f64) -> Self::Output {
+                Self(self.0 - rhs)
+            }
+        }
+        impl std::ops::Mul<f64> for $T {
+            type Output = $T;
+            fn mul(self, rhs: f64) -> Self::Output {
+                Self(self.0 * rhs)
+            }
+        }
+        impl std::ops::Div<f64> for $T {
+            type Output = $T;
+            fn div(self, rhs: f64) -> Self::Output {
+                Self(self.0 / rhs)
+            }
+        }
+        impl std::ops::AddAssign<f64> for $T {
+            fn add_assign(&mut self, rhs: f64) {
+                self.0 += rhs;
+            }
+        }
+        impl std::ops::SubAssign<f64> for $T {
+            fn sub_assign(&mut self, rhs: f64) {
+                self.0 -= rhs;
+            }
+        }
+        impl std::ops::MulAssign<f64> for $T {
+            fn mul_assign(&mut self, rhs: f64) {
+                self.0 *= rhs;
+            }
+        }
+        impl std::ops::DivAssign<f64> for $T {
+            fn div_assign(&mut self, rhs: f64) {
+                self.0 /= rhs;
+            }
+        }
+    };
+}
+
+#[derive(Default, Debug, Copy, Clone, PartialEq, PartialOrd)]
+pub struct SampleRate(pub f64);
+impl SampleRate {
+    pub fn as_samples<D>(&self, time: D) -> f64
+    where
+        D: Into<Duration>,
+    {
+        self.0 * time.into().as_secs_f64()
+    }
+}
+
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Ratio(pub f64, pub f64);
+impl Ratio {
+    pub fn multiplier(&self) -> f64 {
+        self.0 / self.1
+    }
+}
+impl Display for Ratio {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&format!("{}:{} ({})", self.0, self.1, self.multiplier()))
+    }
+}
+impl Debug for Ratio {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&format!("{}:{} ({})", self.0, self.1, self.multiplier()))
+    }
+}
+
+pub fn rms<const N: usize>(sample_buffer: &RingBuffer<f64, N>, last_rms: f64) -> f64 {
+    // RMS_0  = sqrt((1/n) * (x0^2 + x1^2 + x2^2 + ... + xN^2))
+    // RMS_-1 = sqrt((1/n) * (       x1^2 + x2^2 + ... + xN^2 + x(N+1)^2))
+    last_rms.powf(2.0)
+        + (1.0 / N as f64) * (sample_buffer[0].powf(2.0) - sample_buffer[N - 1].powf(2.0))
+}

ebu-dsp/src/ring_buffer.rs

@@ -0,0 +1,38 @@
+use std::ops::{Index, IndexMut};
+
+pub struct RingBuffer<T, const N: usize> {
+    buffer: [T; N],
+    index: usize,
+}
+
+impl<T, const N: usize> RingBuffer<T, N>
+where
+    T: Copy,
+{
+    pub const fn new(value: T) -> Self {
+        Self {
+            buffer: [value; N],
+            index: 0,
+        }
+    }
+    pub const fn len(&self) -> usize {
+        N
+    }
+    pub fn shift(&mut self) {
+        self.index = (self.index + 1) % N;
+    }
+
+}
+impl<T, const N: usize> Index<usize> for RingBuffer<T, N> {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.buffer[(self.index + index) % N]
+    }
+}
+
+impl<T, const N: usize> IndexMut<usize> for RingBuffer<T, N> {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        &mut self.buffer[(self.index + index) % N]
+    }
+}

ebu-dsp/src/smoother.rs

@@ -0,0 +1,50 @@
+use std::time::Duration;
+
+use crate::SampleRate;
+
+pub struct Smoother {
+    sample_rate: SampleRate,
+    attack: Duration,
+    release: Duration,
+    last_value: f64,
+}
+impl Smoother {
+    pub const fn new(sample_rate: SampleRate) -> Self {
+        Self {
+            sample_rate,
+            attack: Duration::ZERO,
+            release: Duration::ZERO,
+            last_value: 0.0,
+        }
+    }
+    pub fn set_attack<D>(&mut self, duration: D)
+    where
+        D: Into<Duration>,
+    {
+        self.attack = duration.into();
+    }
+    pub fn attack<T>(&mut self, value: T) -> T
+    where
+        T: From<f64>,
+        T: Into<f64>,
+    {
+        let a = (-2.2 / (self.attack.as_secs_f64() * self.sample_rate.0) + f64::EPSILON).exp();
+        self.last_value = a * self.last_value + (1.0 - a) * value.into();
+        (self.last_value + f64::EPSILON).into()
+    }
+    pub fn set_release<D>(&mut self, duration: D)
+    where
+        D: Into<Duration>,
+    {
+        self.release = duration.into();
+    }
+    pub fn release<T>(&mut self, value: T) -> T
+    where
+        T: From<f64>,
+        T: Into<f64>,
+    {
+        let a = (-2.2 / (self.release.as_secs_f64() * self.sample_rate.0) + f64::EPSILON).exp();
+        self.last_value = a * self.last_value + (1.0 - a) * value.into();
+        (self.last_value + f64::EPSILON).into()
+    }
+}

ebu-dsp/src/traits.rs

@@ -0,0 +1,68 @@
+use std::{
+    ops::{Add, Mul},
+    sync::Arc,
+};
+
+pub trait FloatFormatter {
+    fn v2s(digits: usize) -> Arc<dyn Fn(f32) -> String + Send + Sync>
+    where
+        Self: Sized;
+    fn s2v() -> Arc<dyn Fn(&str) -> Option<f32> + Send + Sync>
+    where
+        Self: Sized;
+}
+pub trait IntFormatter {
+    fn v2s() -> Arc<dyn Fn(i32) -> String + Send + Sync>
+    where
+        Self: Sized;
+    fn s2v() -> Arc<dyn Fn(&str) -> Option<i32> + Send + Sync>
+    where
+        Self: Sized;
+}
+
+pub trait Processor<I = f64, O = f64> {
+    fn process(&mut self, sample: I) -> O;
+}
+
+impl<I> Processor<f32, f32> for I
+where
+    I: Processor<f64, f64>,
+{
+    fn process(&mut self, sample: f32) -> f32 {
+        self.process(sample as f64) as f32
+    }
+}
+
+pub trait Lerp<F> {
+    type Output;
+    fn lerp(&self, to: Self, t: F) -> Self::Output;
+    fn lerp_unbounded(&self, to: Self, t: F) -> Self::Output;
+}
+impl<T> Lerp<f64> for T
+where
+    T: Mul<f64, Output = T>,
+    <T as Mul<f64>>::Output: Add,
+    Self: Copy,
+{
+    type Output = <T as Add<Self>>::Output;
+    fn lerp(&self, to: Self, t: f64) -> Self::Output {
+        self.lerp_unbounded(to, t.clamp(0.0, 1.0))
+    }
+    fn lerp_unbounded(&self, to: Self, t: f64) -> Self::Output {
+        *self * (1.0 - t) + to * t
+    }
+}
+impl<T> Lerp<f32> for T
+where
+    T: Mul<f32, Output = T>,
+    <T as Mul<f32>>::Output: Add,
+    Self: Copy,
+{
+    type Output = <T as Add<Self>>::Output;
+    fn lerp(&self, to: Self, t: f32) -> Self::Output {
+        self.lerp_unbounded(to, t.clamp(0.0, 1.0))
+    }
+    fn lerp_unbounded(&self, to: Self, t: f32) -> Self::Output {
+        *self * (1.0 - t) + to * t
+    }
+}