74 lines
2.1 KiB
Forth
74 lines
2.1 KiB
Forth
module SoundGen.Synth
|
|
|
|
open Settings
|
|
open Oscillator
|
|
open SoundGen.Oscillator
|
|
|
|
let private getHzBySemitones semi =
|
|
pitchStandard * (2. ** (1. / 12.)) ** semi
|
|
|
|
let getSemitoneShift (rootNote : string) (targetNote : string) : int =
|
|
// Define arrays to map pitch classes to numeric values and vice versa
|
|
let pitchClasses = [| "C"; "C#"; "D"; "D#"; "E"; "F"; "F#"; "G"; "G#"; "A"; "A#"; "B" |]
|
|
let pitchClassValues = [| 0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11 |]
|
|
|
|
// Extract the note number and pitch class for the root note
|
|
let rootNoteNum = int (rootNote.Substring(rootNote.Length - 1))
|
|
let rootPitchClass = Array.findIndex ((=) (rootNote.Substring(0, rootNote.Length - 1))) pitchClasses
|
|
|
|
// Extract the note number and pitch class for the target note
|
|
let targetNoteNum = int (targetNote.Substring(targetNote.Length - 1))
|
|
let targetPitchClass = Array.findIndex ((=) (targetNote.Substring(0, targetNote.Length - 1))) pitchClasses
|
|
|
|
// Calculate the semitone shift using the formula
|
|
(targetNoteNum - rootNoteNum) * 12 + (targetPitchClass - rootPitchClass)
|
|
|
|
|
|
|
|
|
|
|
|
let private freq hz duration (osc: OscillatorParameter list) =
|
|
let samples =
|
|
seq { 0.0 .. (duration * sampleRate) }
|
|
|
|
let attack =
|
|
let samplesToRise =
|
|
(sampleRate * (0.001 * attackMs))
|
|
|
|
let risingDelta = 1. / samplesToRise
|
|
let mutable i = 0.
|
|
|
|
seq {
|
|
while true do
|
|
i <- i + risingDelta
|
|
yield min i 1.
|
|
}
|
|
|
|
let output =
|
|
Seq.map
|
|
(fun x ->
|
|
multiosc { Oscillators = osc; Sample = x }
|
|
|> (*) volume)
|
|
samples
|
|
|
|
let adsrLength = Seq.length output
|
|
|
|
let attackArray =
|
|
attack |> Seq.take adsrLength
|
|
|
|
let release = Seq.rev attackArray
|
|
|
|
Seq.zip3 release attackArray output
|
|
|> Seq.map (fun (x, y, z) -> (x * y * z))
|
|
|
|
|
|
let note semitone beats =
|
|
let hz = getHzBySemitones (semitone)
|
|
|
|
freq
|
|
hz
|
|
(beats * beatDuration)
|
|
[ { Osc = Saw; Freq = hz / 4. };
|
|
{ Osc = Saw; Freq = hz+0.5 };
|
|
{ Osc = Saw; Freq = hz-1. } ]
|