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/braze/core/src/lib.rs

@@ -181,7 +181,9 @@ impl Engine {
     }
     pub fn set_settings(&mut self, s: Settings) -> Result<(), &'static str> {
         s.validate()?;
-        self.tracker.set(s.source == Source::Midi, s.gate, true);
+        // Unsure tracking sends no events, so the beating holds its last sure note.
+        self.tracker
+            .set(s.pitch.source(s.source.mode(), s.gate, true));
         if s.low_cut != self.settings.low_cut || self.fresh {
             let q = std::f32::consts::FRAC_1_SQRT_2;
             let hz = s.low_cut.min(0.45 * self.rate);
@@ -340,7 +342,7 @@ impl Engine {
             let beat_hz = self.tempo / 60. / s.rate.quarters();
             f.ratio = 1. + (beat_hz / (s.harmonic as f64 * hz as f64)) as f32;
         }
-        if self.tracker.sounding() && hz > 0. {
+        if self.tracker.active() && hz > 0. {
             f.note = Some(hz_to_midi(hz).round().clamp(0., 127.) as u8);
         }
         f

plugins/braze/core/src/settings.rs

@@ -1,4 +1,5 @@
 //! Host-independent controls. Levels in dB, amounts in percent, angles in degrees.
+use common_dsp::tracker::{Pitch, PitchMode};
 use serde::{Deserialize, Serialize};
 
 /// Highest harmonic the beat rate can be set on.
@@ -14,6 +15,24 @@ 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,
+        }
+    }
 }
 
 /// One beat cycle lasts this note value.
@@ -75,6 +94,9 @@ impl Rate {
 #[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,
     /// How long one beat cycle of `harmonic` lasts.
     pub rate: Rate,
     /// The harmonic that beats exactly at `rate`. Harmonic n beats n/harmonic times as fast.
@@ -100,6 +122,7 @@ impl Default for Settings {
     fn default() -> Self {
         Self {
             source: Source::Audio,
+            pitch: Pitch::default(),
             rate: Rate::Eighth,
             // Harmonic 4 sits above the low cut on every bass note, and on F1 it asks for
             // about 45 cents of detune, a usual reese spread.
@@ -117,6 +140,7 @@ impl Default for Settings {
 }
 impl Settings {
     pub fn validate(&self) -> Result<(), &'static str> {
+        self.pitch.validate()?;
         let finite = [
             self.depth,
             self.low_cut,

plugins/braze/plugin/Cargo.lock

@@ -189,6 +189,7 @@ dependencies = [
  "braze-core",
  "braze-ui",
  "clap-sys",
+ "common-params",
  "crossbeam-queue",
  "nih_plug",
  "nih_plug_egui",
@@ -340,11 +341,23 @@ 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",
 ]
 

plugins/braze/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" }
 braze-core = { path = "../core" }
+common-params = { path = "../../common/params" }
 braze-ui = { path = "../ui" }
 crossbeam-queue = "0.3"
 

plugins/braze/plugin/src/params.rs

@@ -1,4 +1,5 @@
 use braze_core::{Rate, Settings, Source, HARMONIC_MAX, LOW_CUT_MAX};
+use common_params::PitchParams;
 use nih_plug::prelude::*;
 use nih_plug_egui::EguiState;
 use std::sync::Arc;
@@ -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,
+        }
+    }
 }
 #[derive(Enum, Debug, PartialEq, Eq, Clone, Copy)]
 pub enum RateParam {
@@ -70,6 +91,8 @@ pub struct BrazeParams {
     pub editor: Arc<EguiState>,
     #[id = "source"]
     pub source: EnumParam<SourceParam>,
+    #[nested(group = "Pitch")]
+    pub pitch: PitchParams,
     #[id = "rate"]
     pub rate: EnumParam<RateParam>,
     #[id = "harmonic"]
@@ -97,6 +120,7 @@ impl Default for BrazeParams {
         Self {
             editor: EguiState::from_size(braze_ui::WIDTH, braze_ui::HEIGHT),
             source: EnumParam::new("Pitch source", SourceParam::Audio),
+            pitch: PitchParams::default(),
             rate: EnumParam::new("Rate", to_param(d.rate)),
             harmonic: IntParam::new(
                 "Harmonic",
@@ -130,10 +154,8 @@ impl BrazeParams {
     pub fn settings(&self) -> Settings {
         let rate = self.rate.value();
         Settings {
-            source: match self.source.value() {
-                SourceParam::Audio => Source::Audio,
-                SourceParam::Midi => Source::Midi,
-            },
+            source: self.source.value().into(),
+            pitch: self.pitch.pitch(),
             rate: RATES
                 .iter()
                 .find(|(p, _)| *p == rate)
@@ -207,13 +229,10 @@ impl BrazeParams {
             }
         }
         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/braze/ui/src/lib.rs

@@ -202,13 +202,9 @@ 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;
@@ -279,10 +275,7 @@ fn note_panel(ui: &mut egui::Ui, settings: &Settings, frame: &AnalyzerFrame) {
         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 notes",
-            }
+            pitch_status(settings.source.mode(), &settings.pitch)
         ))
         .size(12.)
         .color(MUTED),