67 lines
1.5 KiB
Rust
67 lines
1.5 KiB
Rust
pub const MINUS_INFINITY_DB: f32 = -100.0;
|
|
|
|
/// Convert decibels to a voltage gain ratio, treating anything below -100 dB as minus infinity.
|
|
pub fn db_to_gain(dbs: f32) -> f32 {
|
|
if dbs > MINUS_INFINITY_DB {
|
|
10.0f32.powf(dbs * 0.05)
|
|
} else {
|
|
0.0
|
|
}
|
|
}
|
|
|
|
/// Convert a voltage gain ratio to decibels. Gain ratios that aren't positive will be treated as
|
|
/// [MINUS_INFINITY_DB].
|
|
pub fn gain_to_db(gain: f32) -> f32 {
|
|
if gain > 0.0 {
|
|
gain.log10() * 20.0
|
|
} else {
|
|
MINUS_INFINITY_DB
|
|
}
|
|
}
|
|
|
|
/// Convert a MIDI note ID to a frequency at A4 = 440 Hz equal temperament and middle C = note 60 =
|
|
/// C4.
|
|
pub fn midi_note_to_freq(pitch: u8) -> f32 {
|
|
2.0f32.powf((pitch as f32 - 69.0) / 12.0) * 440.0
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn test_db_to_gain_positive() {
|
|
assert_eq!(db_to_gain(3.0), 1.4125376);
|
|
}
|
|
|
|
#[test]
|
|
fn test_db_to_gain_negative() {
|
|
assert_eq!(db_to_gain(-3.0), 1.4125376f32.recip());
|
|
}
|
|
|
|
#[test]
|
|
fn test_db_to_gain_minus_infinity() {
|
|
assert_eq!(db_to_gain(-100.0), 0.0);
|
|
}
|
|
|
|
#[test]
|
|
fn test_gain_to_db_positive() {
|
|
assert_eq!(gain_to_db(4.0), 12.041201);
|
|
}
|
|
|
|
#[test]
|
|
fn test_gain_to_db_negative() {
|
|
assert_eq!(gain_to_db(0.25), -12.041201);
|
|
}
|
|
|
|
#[test]
|
|
fn test_gain_to_db_minus_infinity_zero() {
|
|
assert_eq!(gain_to_db(0.0), MINUS_INFINITY_DB);
|
|
}
|
|
|
|
#[test]
|
|
fn test_gain_to_db_minus_infinity_negative() {
|
|
assert_eq!(gain_to_db(-2.0), MINUS_INFINITY_DB);
|
|
}
|
|
}
|