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Move frequency to note number conversion to utils

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This commit is contained in:
Robbert van der Helm 2022-11-18 16:09:18 +01:00
parent e5211ced4c
commit 6d0c1eebbe
2 changed files with 8 additions and 1 deletions
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2
src/formatters.rs
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@ -143,7 +143,7 @@ pub fn v2s_f32_hz_then_khz_with_note_name(
) -> Arc<dyn Fn(f32) -> String + Send + Sync> {
Arc::new(move |value| {
// This is the inverse of the formula in `f32_midi_note_to_freq`
let fractional_note = ((value / 440.0).log2() * 12.0) + 69.0;
let fractional_note = util::freq_to_midi_note(value);
let note = fractional_note.round();
let cents = ((fractional_note - note) * 100.0) as i32;

7
src/util.rs
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@ -57,6 +57,13 @@ pub fn f32_midi_note_to_freq(note: f32) -> f32 {
2.0f32.powf((note - 69.0) / 12.0) * 440.0
}
/// The inverse of [`f32_midi_note_to_freq()`]. This returns a fractional note number. Round to a
/// whole number, subtract that from the result, and multiply the fractional part by 100 to get the
/// number of cents.
pub fn freq_to_midi_note(freq: f32) -> f32 {
((freq / 440.0).log2() * 12.0) + 69.0
}
#[cfg(test)]
mod tests {
use super::*;