feat: stable note tracking, NOTE pitch source and unsure fallback

Producers found the tracked plugins jumpy: the shared tracker switched notes
after 10 ms and retuned every 5 ms, so growls and formant basses flickered
and every tracked plugin acted on wrong notes.

Shared tracker (common-dsp):
- A new note needs a steady read for 40 ms; an octave down 80 ms, an octave
  up 200 ms (an octave-up read still fits the note's period and counts as
  agreeing). Inside a note the tuning only moves past a 0.25 semitone
  deadband. Follow bends keeps the old fast behaviour as an option.
- A trust score turns the note unsure while reads disagree; Tracker::active
  and NoteState report it, and Fallback latches "step back" across note ends.
- Notes end when the window start stays below the gate's release level for
  20 ms, so short gaps between notes are seen without waiting for the gate.
- PitchSource replaces the old (midi, gate, glide) arguments: Audio, MIDI or
  Note mode (a set note, no detection), plus a key lock (minor, major, root
  only) that snaps reads to the key.
- stems.rs: synthetic stems (growls, wobble, reese, formant, 808 slide,
  layered drop, noise riser) and a score; examples/tracker_report scores the
  corpus or real WAV stems. On the corpus the old behaviour makes up to 28
  extra note starts per second; the stable default makes none.

Plugins:
- Anvil, Lathe, Temper, Knurl, Planish, Braze and Forge gain the NOTE pitch
  source, the key lock and Follow bends (shared common-params crate and a
  shared header switch in common-ui).
- Unsure tracking: Anvil brings the original sub back in place of the sine,
  Lathe passes the audio through, Knurl fades its texture out; Temper,
  Planish and Braze hold their last sure tuning. Readouts show the note only
  when it is sure.
- Anvil gains Mode: Replace or Enhance (keeps the original sub and adds the
  sine under it).
- Planish slides its band edges over 6 ms on a new note instead of snapping.
- Ballast defaults to Grid parts, which need no tracking.

plugins/planish/core/src/lib.rs

@@ -34,6 +34,8 @@ pub const ATTACK_MS: [f32; BANDS] = [30., 15., 8., 4.];
 pub const RELEASE_MS: [f32; BANDS] = [200., 160., 120., 90.];
 /// Filter coefficients are recomputed this often, in samples.
 const RETUNE: usize = 16;
+/// A new note slides the band edges over about this long instead of snapping them.
+const EDGE_MS: f32 = 6.;
 const Q: f32 = std::f32::consts::FRAC_1_SQRT_2;
 const SILENT: f32 = -120.;
 
@@ -176,6 +178,9 @@ pub struct Engine {
     pitch: PitchFollower,
     hz: f32,
     hz_coef: f32,
+    edge_coef: f32,
+    /// The edges are sliding to a new note.
+    sliding: bool,
     countdown: usize,
     edges: [f32; BANDS - 1],
     coefs: Coefs,
@@ -226,6 +231,8 @@ impl Engine {
             pitch: PitchFollower::default(),
             hz: 0.,
             hz_coef: 1.,
+            edge_coef: coefficient(rate, EDGE_MS / 3.),
+            sliding: false,
             countdown: 0,
             edges: [0.; BANDS - 1],
             coefs: Coefs {
@@ -264,7 +271,7 @@ impl Engine {
     pub fn set_settings(&mut self, s: Settings) -> Result<(), &'static str> {
         s.validate()?;
         self.tracker
-            .set(s.source == Source::Midi, s.gate, s.smooth > 0.);
+            .set(s.pitch.source(s.source.mode(), s.gate, s.smooth > 0.));
         self.hz_coef = coefficient(self.rate, s.smooth / 3.);
         if s.time != self.settings.time || self.fresh {
             let scale = s.time * 0.01;
@@ -296,6 +303,7 @@ impl Engine {
         self.levels = [SILENT; BANDS];
         self.gains = [0.; BANDS];
         self.countdown = 0;
+        self.sliding = false;
         self.fresh = true;
     }
     pub fn note_on(&mut self, note: u8) {
@@ -346,9 +354,23 @@ impl Engine {
         self.delay_at = (self.delay_at + 1) % len;
         let y = self.delay[self.delay_at];
 
+        // Unsure tracking sends no events, so the edges hold the last sure note. A new note
+        // slides them instead of snapping, so the bands do not pump on note changes.
         let (hz, jump) = self.pitch.step(self.hz_coef);
-        self.hz = hz;
-        if jump || self.countdown == 0 {
+        let first = self.hz == 0.;
+        if jump && !first {
+            self.sliding = true;
+        }
+        if self.sliding {
+            self.hz += (hz - self.hz) * self.edge_coef;
+            if (hz - self.hz).abs() < 1e-3 * hz {
+                self.hz = hz;
+                self.sliding = false;
+            }
+        } else {
+            self.hz = hz;
+        }
+        if (jump && first) || self.countdown == 0 {
             self.retune();
             self.countdown = RETUNE;
         }
@@ -404,7 +426,7 @@ impl Engine {
             sample_rate: self.rate,
             ..AnalyzerFrame::default()
         };
-        if self.tracker.sounding() && self.hz > 0. {
+        if self.tracker.active() && self.hz > 0. {
             f.note = Some(hz_to_midi(self.hz).round().clamp(0., 127.) as u8);
         }
         f

plugins/planish/core/src/settings.rs

@@ -1,4 +1,5 @@
 //! Host-independent controls. Levels in dB, times in milliseconds, amounts in percent.
+use common_dsp::tracker::{Pitch, PitchMode};
 use serde::{Deserialize, Serialize};
 
 /// Bands: the fundamental, low harmonics, mid harmonics and the top.
@@ -15,12 +16,33 @@ pub enum Source {
     Audio,
     /// Notes come from MIDI note input.
     Midi,
+    /// Note starts are detected, the pitch is the set note: nothing is guessed.
+    Note,
+}
+impl Source {
+    pub fn mode(self) -> PitchMode {
+        match self {
+            Source::Audio => PitchMode::Audio,
+            Source::Midi => PitchMode::Midi,
+            Source::Note => PitchMode::Note,
+        }
+    }
+    pub fn from_mode(mode: PitchMode) -> Self {
+        match mode {
+            PitchMode::Audio => Source::Audio,
+            PitchMode::Midi => Source::Midi,
+            PitchMode::Note => Source::Note,
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq)]
 #[serde(deny_unknown_fields)]
 pub struct Settings {
     pub source: Source,
+    /// Note mode's note, the key lock and Follow bends.
+    #[serde(default)]
+    pub pitch: Pitch,
     /// Highest harmonic in the bottom band. 1 keeps the fundamental on its own.
     pub low: u32,
     /// Highest harmonic in the second band.
@@ -54,6 +76,7 @@ impl Default for Settings {
     fn default() -> Self {
         Self {
             source: Source::Audio,
+            pitch: Pitch::default(),
             low: 1,
             mid: 4,
             high: 16,
@@ -73,6 +96,7 @@ impl Default for Settings {
 }
 impl Settings {
     pub fn validate(&self) -> Result<(), &'static str> {
+        self.pitch.validate()?;
         let finite = [
             self.depth,
             self.time,

plugins/planish/plugin/Cargo.lock

@@ -309,11 +309,23 @@ dependencies = [
 [[package]]
 name = "common-dsp"
 version = "0.1.0"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "common-params"
+version = "0.1.0"
+dependencies = [
+ "common-dsp",
+ "nih_plug",
+]
 
 [[package]]
 name = "common-ui"
 version = "0.1.0"
 dependencies = [
+ "common-dsp",
  "egui",
 ]
 
@@ -1443,6 +1455,7 @@ name = "planish"
 version = "0.1.0"
 dependencies = [
  "clap-sys",
+ "common-params",
  "crossbeam-queue",
  "nih_plug",
  "nih_plug_egui",

plugins/planish/plugin/Cargo.toml

@@ -13,6 +13,7 @@ crate-type = ["cdylib", "rlib"]
 nih_plug = { git = "https://github.com/robbert-vdh/nih-plug.git", rev = "de421011f41a6d10fc8c7a6084e4f4dee0143683", default-features = false }
 nih_plug_egui = { git = "https://github.com/robbert-vdh/nih-plug.git", rev = "de421011f41a6d10fc8c7a6084e4f4dee0143683" }
 planish-core = { path = "../core" }
+common-params = { path = "../../common/params" }
 planish-ui = { path = "../ui" }
 crossbeam-queue = "0.3"
 

plugins/planish/plugin/src/params.rs

@@ -1,3 +1,4 @@
+use common_params::PitchParams;
 use nih_plug::prelude::*;
 use nih_plug_egui::EguiState;
 use planish_core::{Settings, Source, BANDS, GAIN_MAX, GAIN_MIN, TOP_MAX};
@@ -10,6 +11,26 @@ pub enum SourceParam {
     #[id = "midi"]
     #[name = "MIDI"]
     Midi,
+    #[id = "note"]
+    Note,
+}
+impl From<SourceParam> for Source {
+    fn from(s: SourceParam) -> Self {
+        match s {
+            SourceParam::Audio => Source::Audio,
+            SourceParam::Midi => Source::Midi,
+            SourceParam::Note => Source::Note,
+        }
+    }
+}
+impl From<Source> for SourceParam {
+    fn from(s: Source) -> Self {
+        match s {
+            Source::Audio => SourceParam::Audio,
+            Source::Midi => SourceParam::Midi,
+            Source::Note => SourceParam::Note,
+        }
+    }
 }
 fn linear(name: &str, v: f32, min: f32, max: f32, unit: &'static str) -> FloatParam {
     FloatParam::new(name, v, FloatRange::Linear { min, max }).with_unit(unit)
@@ -26,6 +47,8 @@ pub struct PlanishParams {
     pub editor: Arc<EguiState>,
     #[id = "source"]
     pub source: EnumParam<SourceParam>,
+    #[nested(group = "Pitch")]
+    pub pitch: PitchParams,
     #[id = "depth"]
     pub depth: FloatParam,
     #[id = "time"]
@@ -68,6 +91,7 @@ impl Default for PlanishParams {
         Self {
             editor: EguiState::from_size(planish_ui::WIDTH, planish_ui::HEIGHT),
             source: EnumParam::new("Pitch source", SourceParam::Audio),
+            pitch: PitchParams::default(),
             depth: linear("Depth", d.depth, 0., 100., " %"),
             time: linear("Time", d.time, 10., 1000., " %"),
             upward: linear("Upward", d.upward, 0., 100., " %"),
@@ -92,10 +116,8 @@ impl PlanishParams {
     pub fn settings(&self) -> Settings {
         let gains = [&self.gain_1, &self.gain_2, &self.gain_3, &self.gain_4];
         Settings {
-            source: match self.source.value() {
-                SourceParam::Audio => Source::Audio,
-                SourceParam::Midi => Source::Midi,
-            },
+            source: self.source.value().into(),
+            pitch: self.pitch.pitch(),
             low: self.low.value() as u32,
             mid: self.mid.value() as u32,
             high: self.high.value() as u32,
@@ -180,13 +202,10 @@ impl PlanishParams {
             }
         }
         if new.source != old.source {
-            let v = match new.source {
-                Source::Audio => SourceParam::Audio,
-                Source::Midi => SourceParam::Midi,
-            };
             setter.begin_set_parameter(&self.source);
-            setter.set_parameter(&self.source, v);
+            setter.set_parameter(&self.source, new.source.into());
             setter.end_set_parameter(&self.source);
         }
+        self.pitch.apply(setter, &old.pitch, &new.pitch);
     }
 }

plugins/planish/ui/src/lib.rs

@@ -358,13 +358,9 @@ pub fn show(ui: &mut egui::Ui, settings: &mut Settings, state: &mut State) {
             settings.bypass = !settings.bypass;
         }
         ui.separator();
-        for (source, label) in [(Source::Midi, "MIDI"), (Source::Audio, "AUDIO")] {
-            let r = ui.selectable_label(settings.source == source, RichText::new(label).size(13.));
-            if r.clicked() {
-                settings.source = source;
-            }
-        }
-        caption(ui, "PITCH FROM");
+        let mut mode = settings.source.mode();
+        pitch_from(ui, &mut mode, &mut settings.pitch);
+        settings.source = Source::from_mode(mode);
     });
     ui.add_space(6.);
     let frame = state.analyzer;
@@ -418,10 +414,7 @@ fn note_panel(
         RichText::new(format!(
             "{:.0} ms lookahead · {}",
             frame.latency as f32 / frame.sample_rate * 1000.,
-            match settings.source {
-                Source::Audio => "detecting pitch",
-                Source::Midi => "following MIDI",
-            }
+            pitch_status(settings.source.mode(), &settings.pitch)
         ))
         .size(12.)
         .color(MUTED),