feat(crucible): name slices only by a sure note, spelled for the song key

A slice gets a note name only when at least 60 % of up to twelve reads
across its body sit on one note; growls, pitch drops and noise get no name
rather than a wrong one. An optional song key spells names with flats in
flat keys (Eb2, not D#2).

plugins/common/dsp/src/lib.rs

@@ -218,10 +218,18 @@ pub fn hz_to_midi(hz: f32) -> f32 {
 }
 /// Scientific note name: MIDI 60 = C4, 43.65 Hz = F1. FL Studio labels MIDI 60 as C5.
 pub fn note_name(note: u8) -> String {
-    const NAMES: [&str; 12] = [
+    note_name_spelled(note, false)
+}
+/// Note name with sharps, or with flats (Db, Eb, Gb, Ab, Bb) for keys written in flats.
+pub fn note_name_spelled(note: u8, flats: bool) -> String {
+    const SHARPS: [&str; 12] = [
         "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B",
     ];
-    format!("{}{}", NAMES[note as usize % 12], note as i32 / 12 - 1)
+    const FLATS: [&str; 12] = [
+        "C", "Db", "D", "Eb", "E", "F", "Gb", "G", "Ab", "A", "Bb", "B",
+    ];
+    let names = if flats { FLATS } else { SHARPS };
+    format!("{}{}", names[note as usize % 12], note as i32 / 12 - 1)
 }
 /// Reads a scientific note name such as "F1" or "c#2", the inverse of [`note_name`].
 pub fn parse_note(text: &str) -> Option<u8> {
@@ -231,7 +239,14 @@ pub fn parse_note(text: &str) -> Option<u8> {
     let text = text.trim();
     let split = text.find(|c: char| c.is_ascii_digit() || c == '-')?;
     let (pitch, octave) = text.split_at(split);
-    let class = NAMES.iter().position(|n| n.eq_ignore_ascii_case(pitch))? as i32;
+    const FLATS: [&str; 12] = [
+        "C", "Db", "D", "Eb", "E", "F", "Gb", "G", "Ab", "A", "Bb", "B",
+    ];
+    let class = NAMES
+        .iter()
+        .position(|n| n.eq_ignore_ascii_case(pitch))
+        .or_else(|| FLATS.iter().position(|n| n.eq_ignore_ascii_case(pitch)))?
+        as i32;
     let octave: i32 = octave.parse().ok()?;
     u8::try_from((octave + 1) * 12 + class)
         .ok()

plugins/common/dsp/tests/blocks.rs

@@ -374,5 +374,7 @@ fn note_names_parse_back() {
         assert_eq!(common_dsp::parse_note(&common_dsp::note_name(n)), Some(n));
     }
     assert_eq!(common_dsp::parse_note(" f1 "), Some(29));
+    assert_eq!(common_dsp::note_name_spelled(30, true), "Gb1");
+    assert_eq!(common_dsp::parse_note("Gb1"), Some(30));
     assert_eq!(common_dsp::parse_note("H2"), None);
 }