mirror of
https://github.com/storytold/effectcraft.git
synced 2026-10-24 10:09:32 -06:00
M9.11: Audio effects (Compressor, Distortion, Gate)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Brandon Thomas
co-authored by
Claude Opus 5.5
Claude Opus 5.5
parent
4bcf1f447c
commit
97cf7e2c02
@@ -1,5 +1,5 @@
|
||||
//! Audio effects (Effect > Audio): Backwards, Bass & Treble, Delay, Flange & Chorus,
|
||||
//! High-Low Pass, Modulator, Parametric EQ, Reverb, Stereo Mixer and Tone.
|
||||
//! Audio effects (Effect > Audio): Backwards, Bass & Treble, Compressor, Delay, Distortion,
|
||||
//! Flange & Chorus, Gate, High-Low Pass, Modulator, Parametric EQ, Reverb, Stereo Mixer and Tone.
|
||||
//!
|
||||
//! They are ordinary effect instances on a layer (so their parameters animate and show in
|
||||
//! Effect Controls), pass video through unchanged, and are applied to the layer's audio by the
|
||||
@@ -12,7 +12,10 @@
|
||||
//! DSP is textbook: second-order sections use the public RBJ "Audio EQ Cookbook" formulas;
|
||||
//! Reverb is a Schroeder/Moorer network (parallel low-pass feedback combs into series
|
||||
//! all-passes, as in the published Freeverb description); chorus/flange/vibrato are modulated
|
||||
//! fractional delay lines.
|
||||
//! fractional delay lines. Compressor and Gate are feed-forward dynamics processors on a
|
||||
//! stereo-linked peak envelope (one-pole attack/release smoothing, the textbook quadratic soft-knee
|
||||
//! gain computer); Distortion is a static waveshaper (soft clip, hard clip, fold-back, bit crush)
|
||||
//! followed by a one-pole tone filter.
|
||||
|
||||
use std::f64::consts::PI;
|
||||
|
||||
@@ -60,6 +63,20 @@ pub fn specs() -> Vec<EffectSpec> {
|
||||
p("treble", "Treble", num(0.0), slider(-100.0, 100.0, -100.0, 100.0, 2)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.compressor",
|
||||
"Compressor",
|
||||
vec![
|
||||
p("threshold", "Threshold (dB)", num(-20.0), slider(-60.0, 0.0, -60.0, 0.0, 2)),
|
||||
p("ratio", "Ratio", num(4.0), slider(1.0, 30.0, 1.0, 20.0, 2)),
|
||||
p("attack", "Attack (ms)", num(10.0), slider(0.0, 500.0, 0.0, 200.0, 2)),
|
||||
p("release", "Release (ms)", num(100.0), slider(1.0, 5000.0, 1.0, 1000.0, 2)),
|
||||
p("knee", "Knee (dB)", num(0.0), slider(0.0, 24.0, 0.0, 24.0, 2)),
|
||||
p("makeupGain", "Makeup Gain (dB)", num(0.0), slider(-24.0, 36.0, 0.0, 24.0, 2)),
|
||||
pp("dryOut", "Dry Out", pct(0.0)),
|
||||
pp("wetOut", "Wet Out", pct(100.0)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.delay",
|
||||
"Delay",
|
||||
@@ -71,6 +88,19 @@ pub fn specs() -> Vec<EffectSpec> {
|
||||
pp("wetOut", "Wet Out", pct(75.0)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.distortion",
|
||||
"Distortion",
|
||||
vec![
|
||||
p("distortionType", "Distortion Type", Value::Enum(0), popup(&["Soft Clip", "Hard Clip", "Fold Back", "Bit Crush"])),
|
||||
p("drive", "Drive (dB)", num(12.0), slider(0.0, 48.0, 0.0, 48.0, 2)),
|
||||
p("bitDepth", "Bit Depth", num(8.0), slider(1.0, 16.0, 1.0, 16.0, 0)),
|
||||
p("tone", "Tone (Hz)", num(8000.0), slider(200.0, 20000.0, 200.0, 20000.0, 1)),
|
||||
p("outputGain", "Output Gain (dB)", num(-6.0), slider(-48.0, 12.0, -24.0, 12.0, 2)),
|
||||
pp("dryOut", "Dry Out", pct(0.0)),
|
||||
pp("wetOut", "Wet Out", pct(100.0)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.flangechorus",
|
||||
"Flange & Chorus",
|
||||
@@ -86,6 +116,17 @@ pub fn specs() -> Vec<EffectSpec> {
|
||||
pp("wetOut", "Wet Out", pct(50.0)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.gate",
|
||||
"Gate",
|
||||
vec![
|
||||
p("threshold", "Threshold (dB)", num(-40.0), slider(-90.0, 0.0, -80.0, 0.0, 2)),
|
||||
p("attack", "Attack (ms)", num(1.0), slider(0.0, 500.0, 0.0, 100.0, 2)),
|
||||
p("hold", "Hold (ms)", num(50.0), slider(0.0, 5000.0, 0.0, 500.0, 2)),
|
||||
p("release", "Release (ms)", num(100.0), slider(1.0, 5000.0, 1.0, 1000.0, 2)),
|
||||
p("range", "Range (dB)", num(-80.0), slider(-120.0, 0.0, -90.0, 0.0, 2)),
|
||||
],
|
||||
),
|
||||
spec(
|
||||
"ec.audio.highlowpass",
|
||||
"High-Low Pass",
|
||||
@@ -167,6 +208,14 @@ pub fn preroll(id: &str, params: &Params) -> f64 {
|
||||
match id {
|
||||
"ec.audio.basstreble" | "ec.audio.highlowpass" | "ec.audio.parametriceq" => 0.05,
|
||||
"ec.audio.flangechorus" | "ec.audio.modulator" => 0.06,
|
||||
"ec.audio.distortion" => 0.01,
|
||||
// The envelope settles within a few attack/release time constants.
|
||||
"ec.audio.compressor" | "ec.audio.gate" => {
|
||||
let rel = params.f("release").max(1.0) / 1000.0;
|
||||
let att = params.f("attack").max(0.0) / 1000.0;
|
||||
let hold = if id == "ec.audio.gate" { params.f("hold").max(0.0) / 1000.0 } else { 0.0 };
|
||||
(9.0 * rel + 9.0 * att + hold + 0.01).min(10.0)
|
||||
}
|
||||
"ec.audio.delay" => {
|
||||
let d = params.f("delayTime").max(1.0) / 1000.0;
|
||||
let fb = (params.f("feedback") / 100.0).clamp(0.0, 0.99);
|
||||
@@ -231,6 +280,9 @@ pub fn process(id: &str, params: &Params, buf: &mut [f32], rate: u32, start: f64
|
||||
}
|
||||
}
|
||||
"ec.audio.delay" => delay(params, buf, sr),
|
||||
"ec.audio.compressor" => compressor(params, buf, sr),
|
||||
"ec.audio.distortion" => distortion(params, buf, sr),
|
||||
"ec.audio.gate" => gate(params, buf, sr),
|
||||
"ec.audio.flangechorus" => flange_chorus(params, buf, sr, start),
|
||||
"ec.audio.modulator" => modulator(params, buf, sr, start),
|
||||
"ec.audio.reverb" => reverb(params, buf, sr),
|
||||
@@ -362,6 +414,126 @@ fn delay(params: &Params, buf: &mut [f32], sr: f64) {
|
||||
}
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn db_to_lin(db: f64) -> f64 {
|
||||
10f64.powf(db / 20.0)
|
||||
}
|
||||
|
||||
#[inline]
|
||||
fn lin_to_db(v: f64) -> f64 {
|
||||
20.0 * v.max(1e-12).log10()
|
||||
}
|
||||
|
||||
/// One-pole smoothing coefficient for a time constant of `ms` milliseconds.
|
||||
fn smoothing(ms: f64, sr: f64) -> f64 {
|
||||
if ms <= 0.0 { 0.0 } else { (-1.0 / (ms / 1000.0 * sr)).exp() }
|
||||
}
|
||||
|
||||
/// Static compressor curve: gain change (dB, ≤ 0) for an input level `x` dB (quadratic soft
|
||||
/// knee of width `knee` around the threshold).
|
||||
pub fn compressor_gain_db(x: f64, threshold: f64, ratio: f64, knee: f64) -> f64 {
|
||||
let r = ratio.max(1.0);
|
||||
let over = x - threshold;
|
||||
let y = if knee > 0.0 && 2.0 * over.abs() <= knee {
|
||||
x + (1.0 / r - 1.0) * (over + knee / 2.0).powi(2) / (2.0 * knee)
|
||||
} else if over > 0.0 {
|
||||
threshold + over / r
|
||||
} else {
|
||||
x
|
||||
};
|
||||
y - x
|
||||
}
|
||||
|
||||
fn compressor(params: &Params, buf: &mut [f32], sr: f64) {
|
||||
let th = params.f("threshold");
|
||||
let ratio = params.f("ratio").max(1.0);
|
||||
let knee = params.f("knee").max(0.0);
|
||||
let att = smoothing(params.f("attack"), sr);
|
||||
let rel = smoothing(params.f("release").max(0.001), sr);
|
||||
let makeup = params.f("makeupGain");
|
||||
let dry = (params.f("dryOut") / 100.0) as f32;
|
||||
let wet = (params.f("wetOut") / 100.0) as f32;
|
||||
// Smoothed gain change in dB (≤ 0): attack while the reduction grows, release as it shrinks.
|
||||
let mut g = 0.0f64;
|
||||
for f in buf.chunks_exact_mut(2) {
|
||||
let peak = f[0].abs().max(f[1].abs()) as f64;
|
||||
let target = compressor_gain_db(lin_to_db(peak), th, ratio, knee);
|
||||
let k = if target < g { att } else { rel };
|
||||
g = target + (g - target) * k;
|
||||
let lin = db_to_lin(g + makeup) as f32;
|
||||
for v in f.iter_mut() {
|
||||
*v = *v * dry + *v * lin * wet;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn gate(params: &Params, buf: &mut [f32], sr: f64) {
|
||||
let th = db_to_lin(params.f("threshold"));
|
||||
let att = smoothing(params.f("attack"), sr);
|
||||
let rel = smoothing(params.f("release").max(0.001), sr);
|
||||
let hold = (params.f("hold").max(0.0) / 1000.0 * sr) as usize;
|
||||
let floor = db_to_lin(params.f("range").min(0.0));
|
||||
// Openness 0..1 (closed..open), mapped to floor..1.
|
||||
let mut g = 0.0f64;
|
||||
let mut held = 0usize;
|
||||
for f in buf.chunks_exact_mut(2) {
|
||||
let peak = f[0].abs().max(f[1].abs()) as f64;
|
||||
let open = if peak >= th {
|
||||
held = hold;
|
||||
true
|
||||
} else if held > 0 {
|
||||
held -= 1;
|
||||
true
|
||||
} else {
|
||||
false
|
||||
};
|
||||
let target = if open { 1.0 } else { 0.0 };
|
||||
let k = if target > g { att } else { rel };
|
||||
g = target + (g - target) * k;
|
||||
let lin = (floor + (1.0 - floor) * g) as f32;
|
||||
f[0] *= lin;
|
||||
f[1] *= lin;
|
||||
}
|
||||
}
|
||||
|
||||
/// The Distortion effect's waveshaper for one sample (`drive` linear gain, `bits` for Bit Crush).
|
||||
pub fn distort_sample(kind: u32, x: f32, drive: f32, bits: f32) -> f32 {
|
||||
let v = x * drive;
|
||||
match kind {
|
||||
1 => v.clamp(-1.0, 1.0),
|
||||
2 => {
|
||||
// Fold back: reflect at ±1 (a triangle function of the input).
|
||||
let t = (v + 1.0).rem_euclid(4.0);
|
||||
if t < 2.0 { t - 1.0 } else { 3.0 - t }
|
||||
}
|
||||
3 => {
|
||||
let q = 2f32.powf(bits.clamp(1.0, 16.0) - 1.0);
|
||||
(v.clamp(-1.0, 1.0) * q).round() / q
|
||||
}
|
||||
_ => v.tanh(),
|
||||
}
|
||||
}
|
||||
|
||||
fn distortion(params: &Params, buf: &mut [f32], sr: f64) {
|
||||
let kind = params.e("distortionType");
|
||||
let drive = db_to_lin(params.f("drive")) as f32;
|
||||
let bits = params.f("bitDepth") as f32;
|
||||
let out = db_to_lin(params.f("outputGain")) as f32;
|
||||
let dry = (params.f("dryOut") / 100.0) as f32;
|
||||
let wet = (params.f("wetOut") / 100.0) as f32;
|
||||
let fc = params.f("tone").clamp(20.0, sr * 0.49);
|
||||
let a = (-2.0 * PI * fc / sr).exp() as f32;
|
||||
let mut lp = [0.0f32; 2];
|
||||
for f in buf.chunks_exact_mut(2) {
|
||||
for ch in 0..2 {
|
||||
let x = f[ch];
|
||||
let y = distort_sample(kind, x, drive, bits);
|
||||
lp[ch] = y + (lp[ch] - y) * a;
|
||||
f[ch] = x * dry + lp[ch] * out * wet;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn lfo(kind: u32, phase: f64) -> f64 {
|
||||
let ph = phase.rem_euclid(1.0);
|
||||
match kind {
|
||||
@@ -546,7 +718,10 @@ mod tests {
|
||||
for id in [
|
||||
"ec.audio.backwards",
|
||||
"ec.audio.basstreble",
|
||||
"ec.audio.compressor",
|
||||
"ec.audio.delay",
|
||||
"ec.audio.distortion",
|
||||
"ec.audio.gate",
|
||||
"ec.audio.flangechorus",
|
||||
"ec.audio.highlowpass",
|
||||
"ec.audio.modulator",
|
||||
@@ -679,4 +854,64 @@ mod tests {
|
||||
assert_eq!(b, vec![2.0, 1.0]);
|
||||
assert!(reverses("ec.audio.backwards"));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn compressor_reduces_gain_above_threshold() {
|
||||
// Static curve: 10 dB over a −20 dB threshold at 4:1 comes out 7.5 dB lower.
|
||||
assert!((compressor_gain_db(-10.0, -20.0, 4.0, 0.0) + 7.5).abs() < 1e-9);
|
||||
assert_eq!(compressor_gain_db(-30.0, -20.0, 4.0, 0.0), 0.0);
|
||||
// The soft knee meets the hard curve at its edges.
|
||||
let k = 6.0;
|
||||
assert!(compressor_gain_db(-23.0, -20.0, 4.0, k).abs() < 1e-9);
|
||||
assert!((compressor_gain_db(-17.0, -20.0, 4.0, k) - compressor_gain_db(-17.0, -20.0, 4.0, 0.0)).abs() < 1e-9);
|
||||
let sr = 48000.0;
|
||||
let mut p = defaults("ec.audio.compressor");
|
||||
p.values.insert("attack".into(), num(1.0));
|
||||
let mut loud = sine(1000.0, sr, 9600);
|
||||
process("ec.audio.compressor", &p, &mut loud, 48000, 0.0);
|
||||
// A full-scale sine (peak 0 dB) is pulled down by ~15 dB once the envelope settles.
|
||||
let peak = loud[18000..].iter().fold(0.0f32, |m, v| m.max(v.abs()));
|
||||
let want = db_to_lin(compressor_gain_db(0.0, -20.0, 4.0, 0.0)) as f32;
|
||||
assert!((peak - want).abs() < 0.05, "{peak} vs {want}");
|
||||
// Quiet input passes untouched.
|
||||
let mut quiet: Vec<f32> = sine(1000.0, sr, 4800).iter().map(|v| v * 0.01).collect();
|
||||
let orig = quiet.clone();
|
||||
process("ec.audio.compressor", &p, &mut quiet, 48000, 0.0);
|
||||
assert!(quiet.iter().zip(&orig).all(|(a, b)| (a - b).abs() < 1e-6));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn gate_mutes_below_threshold() {
|
||||
let sr = 48000.0;
|
||||
let p = defaults("ec.audio.gate");
|
||||
// A −60 dB signal under the −40 dB threshold is attenuated by the −80 dB range.
|
||||
let mut quiet: Vec<f32> = sine(500.0, sr, 9600).iter().map(|v| v * 0.001).collect();
|
||||
process("ec.audio.gate", &p, &mut quiet, 48000, 0.0);
|
||||
assert!(rms(&quiet, 4800) < 1e-6, "{}", rms(&quiet, 4800));
|
||||
// A loud signal opens the gate.
|
||||
let mut loud: Vec<f32> = sine(500.0, sr, 9600).iter().map(|v| v * 0.5).collect();
|
||||
let r0 = rms(&loud, 4800);
|
||||
process("ec.audio.gate", &p, &mut loud, 48000, 0.0);
|
||||
assert!((rms(&loud, 4800) - r0).abs() < 0.01);
|
||||
// Deterministic.
|
||||
let mut a = sine(300.0, sr, 2000);
|
||||
let mut b = a.clone();
|
||||
process("ec.audio.gate", &p, &mut a, 48000, 0.0);
|
||||
process("ec.audio.gate", &p, &mut b, 48000, 0.0);
|
||||
assert_eq!(a, b);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn distortion_shapes_and_bounds() {
|
||||
assert!((distort_sample(0, 0.5, 1.0, 8.0) - 0.5f32.tanh()).abs() < 1e-6);
|
||||
assert_eq!(distort_sample(1, 0.8, 2.0, 8.0), 1.0);
|
||||
assert!((distort_sample(2, 0.7, 2.0, 8.0) - 0.6).abs() < 1e-5);
|
||||
assert_eq!(distort_sample(3, 0.3, 1.0, 2.0), 0.5);
|
||||
let p = defaults("ec.audio.distortion");
|
||||
let mut b = sine(200.0, 48000.0, 4800);
|
||||
process("ec.audio.distortion", &p, &mut b, 48000, 0.0);
|
||||
assert!(b.iter().all(|v| v.abs() <= 1.0));
|
||||
assert!(rms(&b, 100) > 0.1);
|
||||
assert!(preroll("ec.audio.compressor", &defaults("ec.audio.compressor")) > 0.4);
|
||||
}
|
||||
}
|
||||
|
||||
@@ -174,7 +174,17 @@ fn blocks_match_one_long_mix() {
|
||||
let x = ((t * 12345.678).sin() * 43758.5453).fract() as f32;
|
||||
(x, -x)
|
||||
}
|
||||
for id in ["ec.audio.reverb", "ec.audio.basstreble", "ec.audio.flangechorus", "ec.audio.modulator", "ec.audio.delay", "ec.audio.parametriceq"] {
|
||||
for id in [
|
||||
"ec.audio.reverb",
|
||||
"ec.audio.basstreble",
|
||||
"ec.audio.flangechorus",
|
||||
"ec.audio.modulator",
|
||||
"ec.audio.delay",
|
||||
"ec.audio.parametriceq",
|
||||
"ec.audio.compressor",
|
||||
"ec.audio.gate",
|
||||
"ec.audio.distortion",
|
||||
] {
|
||||
let vals: Vec<(&str, Value)> = match id {
|
||||
"ec.audio.basstreble" => vec![("bass", Value::Scalar(50.0))],
|
||||
"ec.audio.parametriceq" => vec![("band1BoostCut", Value::Scalar(9.0))],
|
||||
|
||||
Reference in New Issue
Block a user