bass-foundry/plugins/anvil/core/tests/dsp.rs

use anvil_core::{Engine, Monitor, Settings, Source};
use common_dsp::Saw;

const RATE: f32 = 48000.;

/// Saw notes (start s, end s, Hz, peak) with 1 ms fades.
fn notes(list: &[(f32, f32, f32, f32)], total: f32) -> Vec<f32> {
    let mut x = vec![0.; (total * RATE) as usize];
    for &(a, b, hz, amp) in list {
        let (a, b) = ((a * RATE) as usize, (b * RATE) as usize);
        let mut saw = Saw::new(RATE, hz);
        let fade = (0.001 * RATE) as usize;
        for i in a..b.min(x.len()) {
            let edge = ((i - a).min(b - 1 - i) as f32 / fade as f32).min(1.);
            x[i] += saw.sample() * amp * edge;
        }
    }
    x
}
fn render(e: &mut Engine, x: &[f32], solo: bool) -> Vec<f32> {
    x.iter()
        .map(|&s| {
            e.process_sample(
                [s, s],
                Monitor {
                    solo,
                    ..Monitor::default()
                },
            )[0]
        })
        .collect()
}
fn rms(x: &[f32]) -> f32 {
    (x.iter().map(|v| v * v).sum::<f32>() / x.len() as f32).sqrt()
}
fn db(x: f32) -> f32 {
    20. * x.max(1e-9).log10()
}
/// Frequency from interpolated rising zero crossings.
fn frequency(x: &[f32]) -> f32 {
    let mut first = None;
    let mut last = 0.;
    let mut count = 0;
    for i in 1..x.len() {
        if x[i - 1] < 0. && x[i] >= 0. {
            let t = (i - 1) as f32 + x[i - 1] / (x[i - 1] - x[i]);
            if first.is_none() {
                first = Some(t);
            } else {
                count += 1;
            }
            last = t;
        }
    }
    count as f32 * RATE / (last - first.unwrap())
}
fn seconds(t: f32) -> usize {
    (t * RATE) as usize
}
fn engine(s: Settings) -> (Engine, usize) {
    let mut e = Engine::new(RATE, 2).unwrap();
    e.set_settings(s).unwrap();
    let l = e.latency_samples() as usize;
    (e, l)
}

#[test]
fn every_note_gets_the_same_sub_level() {
    let (mut e, l) = engine(Settings::default());
    let x = notes(&[(0.1, 0.6, 55., 0.5), (0.8, 1.3, 55., 0.1)], 1.6);
    let y = render(&mut e, &x, true);
    let loud = rms(&y[seconds(0.3) + l..seconds(0.5) + l]);
    let quiet = rms(&y[seconds(1.0) + l..seconds(1.2) + l]);
    assert!(
        (db(loud) - db(quiet)).abs() < 0.5,
        "{} vs {}",
        db(loud),
        db(quiet)
    );
    // −9 dBFS peak sine.
    assert!((db(loud * 2f32.sqrt()) + 9.).abs() < 0.5, "{}", db(loud));
}

#[test]
fn sub_follows_the_detected_pitch_and_octave() {
    for (octave, expect) in [(0, 43.654), (-1, 21.827)] {
        let (mut e, l) = engine(Settings {
            octave,
            ..Settings::default()
        });
        let x = notes(&[(0.1, 1.1, 43.65, 0.5)], 1.3);
        let y = render(&mut e, &x, true);
        let f = frequency(&y[seconds(0.3) + l..seconds(1.0) + l]);
        assert!((f / expect - 1.).abs() < 0.005, "octave {octave}: {f}");
    }
}

#[test]
fn a_pitch_change_without_a_gap_is_a_new_note() {
    let (mut e, l) = engine(Settings::default());
    let x = notes(&[(0.1, 0.6, 55., 0.5), (0.6, 1.1, 82.41, 0.5)], 1.3);
    let y = render(&mut e, &x, true);
    let f = frequency(&y[seconds(0.75) + l..seconds(1.05) + l]);
    assert!((f / 82.41 - 1.).abs() < 0.005, "{f}");
}

#[test]
fn every_note_restarts_at_the_start_phase() {
    let (mut e, l) = engine(Settings {
        phase: 90.,
        ..Settings::default()
    });
    let x = notes(&[(0.1, 0.4, 55., 0.5), (0.6, 0.9, 55., 0.3)], 1.1);
    let y = render(&mut e, &x, true);
    let period = (RATE / 55.) as usize;
    let a = &y[seconds(0.1) + l..seconds(0.1) + l + 2 * period];
    let b = &y[seconds(0.6) + l..seconds(0.6) + l + 2 * period];
    let peak = y.iter().fold(0f32, |m, v| m.max(v.abs()));
    let worst = a.iter().zip(b).fold(0f32, |m, (p, q)| m.max((p - q).abs()));
    assert!(worst < 0.1 * peak, "{worst} of {peak}");
    // Fit the phase over the second period, after the 2 ms attack.
    let w = std::f32::consts::TAU * 55. / RATE;
    let (mut s, mut c) = (0., 0.);
    for (k, v) in a.iter().enumerate().skip(period) {
        s += v * (w * k as f32).sin();
        c += v * (w * k as f32).cos();
    }
    let phase = c.atan2(s).to_degrees();
    assert!((phase - 90.).abs() < 20., "{phase}");
}

#[test]
fn midi_notes_set_pitch_and_are_delayed_by_the_latency() {
    let (mut e, l) = engine(Settings {
        source: Source::Midi,
        ..Settings::default()
    });
    let mut y = Vec::new();
    for i in 0..seconds(0.8) {
        if i == 1000 {
            e.note_on(33);
        }
        if i == seconds(0.6) {
            e.note_off(33);
        }
        y.push(
            e.process_sample(
                [0.; 2],
                Monitor {
                    solo: true,
                    ..Monitor::default()
                },
            )[0],
        );
    }
    assert!(y[..1000 + l].iter().all(|v| *v == 0.));
    assert!(y[1000 + l + 50].abs() > 0.);
    let f = frequency(&y[seconds(0.2) + l..seconds(0.5)]);
    assert!((f / 55. - 1.).abs() < 0.001, "{f}");
    assert!(y[seconds(0.6) + l + seconds(0.05)..]
        .iter()
        .all(|v| v.abs() < 1e-6));
}

#[test]
fn note_changes_do_not_click() {
    let (mut e, _) = engine(Settings::default());
    let x = notes(
        &[
            (0.1, 0.4, 55., 0.5),
            (0.4, 0.7, 73.42, 0.5),
            (0.7, 1.0, 41.2, 0.5),
        ],
        1.3,
    );
    let y = render(&mut e, &x, true);
    let step = y.windows(2).fold(0f32, |m, w| m.max((w[1] - w[0]).abs()));
    // A −9 dBFS sine at 73 Hz moves at most 0.0034 per sample.
    assert!(step < 0.012, "{step}");
}

#[test]
fn keep_without_notes_is_an_allpass() {
    let (mut e, _) = engine(Settings {
        source: Source::Midi,
        keep: 100.,
        ..Settings::default()
    });
    for hz in [40., 90., 300., 3000.] {
        e.reset();
        let x: Vec<f32> = (0..seconds(1.))
            .map(|i| 0.3 * (std::f32::consts::TAU * hz * i as f32 / RATE).sin())
            .collect();
        let y = render(&mut e, &x, false);
        let d = db(rms(&y[seconds(0.5)..])) - db(rms(&x[seconds(0.5)..]));
        assert!(d.abs() < 0.1, "{hz}: {d}");
    }
}

#[test]
fn split_removes_original_sub_and_keeps_mids() {
    let (mut e, l) = engine(Settings {
        source: Source::Midi,
        ..Settings::default()
    });
    let x: Vec<f32> = (0..seconds(1.))
        .map(|i| 0.3 * (std::f32::consts::TAU * 40. * i as f32 / RATE).sin())
        .collect();
    let y = render(&mut e, &x, false);
    assert!(db(rms(&y[seconds(0.5) + l..])) < db(0.3) - 18.);
}

#[test]
fn settings_are_validated_and_serialise() {
    let mut e = Engine::new(RATE, 1).unwrap();
    assert!(e
        .set_settings(Settings {
            level: 3.,
            ..Settings::default()
        })
        .is_err());
    let json = serde_json::to_string(&Settings::default()).unwrap();
    assert_eq!(
        serde_json::from_str::<Settings>(&json).unwrap(),
        Settings::default()
    );
    assert!(Engine::new(1000., 2).is_err());
    assert!(Engine::new(48000., 3).is_err());
}

/// Peak amplitude of the component at `hz`, over a window of whole cycles.
fn amplitude(x: &[f32], hz: f32) -> f32 {
    let w = std::f32::consts::TAU * hz / RATE;
    let (re, im) = x.iter().enumerate().fold((0., 0.), |(re, im), (n, v)| {
        (re + v * (w * n as f32).cos(), im - v * (w * n as f32).sin())
    });
    2. * (re * re + im * im).sqrt() / x.len() as f32
}
/// Sines (Hz, peak) from 0.1 s to `total` − 0.1 s, with 1 ms fades.
fn tones(list: &[(f32, f32)], total: f32) -> Vec<f32> {
    let n = (total * RATE) as usize;
    let (a, b, fade) = (seconds(0.1), n - seconds(0.1), seconds(0.001));
    (0..n)
        .map(|i| {
            if i < a || i >= b {
                return 0.;
            }
            let edge = ((i - a).min(b - 1 - i) as f32 / fade as f32).min(1.);
            let t = (i - a) as f32 / RATE;
            edge * list
                .iter()
                .map(|&(hz, amp)| amp * (std::f32::consts::TAU * hz * t).sin())
                .sum::<f32>()
        })
        .collect()
}
fn ghost(amount: f32) -> Settings {
    Settings {
        ghost: amount,
        ghost_from: 300.,
        ..Settings::default()
    }
}

#[test]
fn ghost_fills_the_harmonics_a_clean_sub_lacks() {
    let (mut e, l) = engine(ghost(100.));
    let x = tones(&[(55., 0.5)], 1.);
    let y = render(&mut e, &x, true);
    // 0.2 s holds exactly 11 cycles of 55 Hz.
    let w = &y[seconds(0.5) + l..seconds(0.7) + l];
    let sub = amplitude(w, 55.);
    assert!((db(sub) + 9.).abs() < 0.5, "{}", db(sub));
    for k in 2..=5 {
        // Below Ghost from: nothing added, so the sub stays a clean sine there.
        let a = amplitude(w, 55. * k as f32);
        assert!(db(a / sub) < -60., "harmonic {k}: {}", db(a / sub));
    }
    for k in 8..=10 {
        let a = amplitude(w, 55. * k as f32);
        let expect = 20. * (2. / k as f32).log10();
        assert!(
            (db(a / sub) - expect).abs() < 1.,
            "harmonic {k}: {}",
            db(a / sub)
        );
    }
    // Harmonic 6 (330 Hz) sits in the fade above 300 Hz: present, but quieter.
    let six = db(amplitude(w, 330.) / sub);
    assert!(six < 20. * (2f32 / 6.).log10() - 3. && six > -40., "{six}");
}

#[test]
fn ghost_leaves_harmonics_the_patch_already_has() {
    let (mut e, l) = engine(ghost(100.));
    // The patch carries its 8th harmonic (440 Hz) louder than Ghost would add it.
    let x = tones(&[(55., 0.5), (440., 0.2)], 1.);
    let y = render(&mut e, &x, false);
    let w = &y[seconds(0.5) + l..seconds(0.7) + l];
    let eighth = amplitude(w, 440.);
    assert!((db(eighth) - db(0.2)).abs() < 0.5, "{}", db(eighth));
    // The 9th is missing from the patch, so Ghost fills it.
    let ninth = amplitude(w, 495.) / amplitude(w, 55.);
    assert!(
        (db(ninth) - 20. * (2f32 / 9.).log10()).abs() < 1.,
        "{}",
        db(ninth)
    );
}

#[test]
fn ghost_off_adds_nothing_and_phone_listen_drops_the_sub() {
    let x = tones(&[(55., 0.5)], 1.);
    let (mut e, l) = engine(ghost(0.));
    let y = render(&mut e, &x, true);
    let w = &y[seconds(0.5) + l..seconds(0.7) + l];
    for k in 2..=10 {
        assert!(amplitude(w, 55. * k as f32) < 1e-4, "harmonic {k}");
    }
    let phone = |amount: f32| {
        let (mut e, l) = engine(ghost(amount));
        let y: Vec<f32> = x
            .iter()
            .map(|&s| {
                e.process_sample(
                    [s, s],
                    Monitor {
                        solo: true,
                        phone: true,
                        audition: false,
                    },
                )[0]
            })
            .collect();
        rms(&y[seconds(0.5) + l..seconds(0.7) + l])
    };
    // A clean 55 Hz sub all but vanishes on a phone; Ghost makes the note heard.
    let (plain, ghosted) = (phone(0.), phone(100.));
    assert!(db(plain) < -50., "{}", db(plain));
    assert!(
        db(ghosted) - db(plain) > 25.,
        "{} vs {}",
        db(ghosted),
        db(plain)
    );
}

/// A kick-like burst: a 55 Hz sine starting at phase 0 with a 60 ms decay, at each time.
fn kicks(times: &[f32], total: f32) -> Vec<f32> {
    let mut k = vec![0.; seconds(total)];
    for &t in times {
        for i in 0..seconds(0.2) {
            let n = seconds(t) + i;
            if n < k.len() {
                let t = i as f32 / RATE;
                k[n] += 0.8 * (std::f32::consts::TAU * 55. * t).sin() * (-t / 0.06).exp();
            }
        }
    }
    k
}
fn render_kick(e: &mut Engine, x: &[f32], k: &[f32], monitor: Monitor) -> Vec<f32> {
    x.iter()
        .zip(k)
        .map(|(&s, &k)| e.process_with_kick([s, s], k, monitor)[0])
        .collect()
}
/// Normalised correlation of `y[a..b]` with a sine of `hz` at phase 0 at sample `zero`.
fn sine_match(y: &[f32], a: usize, b: usize, hz: f32, zero: f32) -> f32 {
    let w = std::f32::consts::TAU * hz / RATE;
    let (mut xy, mut xx, mut yy) = (0., 0., 0.);
    for (i, &v) in y.iter().enumerate().take(b).skip(a) {
        let r = (w * (i as f32 - zero)).sin();
        xy += v * r;
        xx += r * r;
        yy += v * v;
    }
    xy / (xx * yy).sqrt()
}
const SOLO: Monitor = Monitor {
    solo: true,
    phone: false,
    audition: false,
};
fn kick_lock(offset: f32) -> Settings {
    Settings {
        kick_lock: true,
        kick_offset: offset,
        ..Settings::default()
    }
}

#[test]
fn a_kick_restarts_the_sub_at_the_start_phase_and_ducks_it() {
    // A bass note that started off the kick: before the hit, the sub runs at its own phase.
    let x = tones(&[(55., 0.5)], 1.4);
    let k = kicks(&[0.613], 1.4);
    let (mut e, l) = engine(kick_lock(0.));
    let y = render_kick(&mut e, &x, &k, SOLO);
    let hit = seconds(0.613) + l;
    let after = sine_match(
        &y,
        hit + seconds(0.004),
        hit + seconds(0.04),
        55.,
        hit as f32,
    );
    assert!(after > 0.99, "{after}");
    let before = rms(&y[hit - seconds(0.1)..hit - seconds(0.01)]);
    let ducked = rms(&y[hit + seconds(0.004)..hit + seconds(0.022)]);
    let back = rms(&y[hit + seconds(0.4)..hit + seconds(0.5)]);
    assert!(
        db(before) - db(ducked) > 2.,
        "{} vs {}",
        db(before),
        db(ducked)
    );
    assert!(
        (db(back) - db(before)).abs() < 0.3,
        "{} vs {}",
        db(back),
        db(before)
    );
    assert_eq!(e.take_analyzer().kick_hits, 1);
}

#[test]
fn the_offset_restarts_the_sub_before_or_after_the_kick() {
    let x = tones(&[(55., 0.5)], 1.2);
    let k = kicks(&[0.613], 1.2);
    for offset in [-10., 7.] {
        // No duck: only the phase is checked here.
        let (mut e, l) = engine(Settings {
            kick_duck: 0.,
            ..kick_lock(offset)
        });
        let y = render_kick(&mut e, &x, &k, SOLO);
        let start = (seconds(0.613) + l) as f32 + offset * 0.001 * RATE;
        let a = start as usize + seconds(0.004);
        let m = sine_match(&y, a, a + seconds(0.03), 55., start);
        assert!(m > 0.99, "{offset}: {m}");
    }
}

#[test]
fn without_kick_lock_the_sidechain_changes_nothing() {
    let x = tones(&[(55., 0.5)], 1.);
    let k = kicks(&[0.3, 0.6], 1.);
    let (mut a, _) = engine(Settings::default());
    let (mut b, _) = engine(Settings::default());
    let with = render_kick(&mut a, &x, &k, SOLO);
    let without = render(&mut b, &x, true);
    assert_eq!(with, without);
}

#[test]
fn the_audition_finds_where_kick_and_sub_sum() {
    use anvil_core::{AUDITION, AUDITION_HITS};
    let hits = AUDITION.len() * AUDITION_HITS as usize;
    let total = 0.5 + hits as f32 * 0.2 + 0.4;
    let x = tones(&[(55., 0.5)], total);
    let times: Vec<f32> = (0..hits).map(|i| 0.5 + i as f32 * 0.2).collect();
    let k = kicks(&times, total);
    let (mut e, _) = engine(kick_lock(0.));
    let monitor = Monitor {
        audition: true,
        ..SOLO
    };
    render_kick(&mut e, &x, &k, monitor);
    let f = e.take_analyzer();
    assert_eq!(f.kick_hits as usize, hits);
    let sums = f.audition_sums;
    assert!(sums.iter().all(|v| v.is_finite()), "{sums:?}");
    // The kick is a 55 Hz burst at phase 0, like the sub: they sum fully at 0 ms and
    // cancel half a period (9 ms) away.
    let best = (0..sums.len())
        .max_by(|&a, &b| sums[a].total_cmp(&sums[b]))
        .unwrap();
    assert_eq!(AUDITION[best], 0., "{sums:?}");
    let zero = sums[6];
    assert!(zero > 2., "{zero}");
    for i in [4, 8] {
        assert!(
            zero - sums[i] > 4.,
            "{} ms: {} vs {zero}",
            AUDITION[i],
            sums[i]
        );
    }
}