67 lines
2.0 KiB
Forth
67 lines
2.0 KiB
Forth
module SoundGen.Synth
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open Settings
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open Oscillator
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let private getHzBySemitones semi =
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pitchStandard * (2. ** (1. / 12.)) ** semi
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let private getSemitoneShiftInternal (rootNote: string) (targetNote: string) : int =
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// Define arrays to map pitch classes to numeric values and vice versa
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let pitchClasses =
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[| "C"; "C#"; "D"; "D#"; "E"; "F"; "F#"; "G"; "G#"; "A"; "A#"; "B" |]
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// Extract the note number and pitch class for the root note
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let rootNoteNum = int (rootNote.Substring(rootNote.Length - 1))
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let rootPitchClass =
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Array.findIndex ((=) (rootNote.Substring(0, rootNote.Length - 1))) pitchClasses
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// Extract the note number and pitch class for the target note
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let targetNoteNum = int (targetNote.Substring(targetNote.Length - 1))
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let targetPitchClass =
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Array.findIndex ((=) (targetNote.Substring(0, targetNote.Length - 1))) pitchClasses
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// Calculate the semitone shift using the formula
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(targetNoteNum - rootNoteNum) * 12 + (targetPitchClass - rootPitchClass)
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let private freq hz duration (osc: OscillatorParameter list) =
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let samples = seq { 0.0 .. (duration * sampleRate) }
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let attack =
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let samplesToRise = (sampleRate * (0.001 * attackMs))
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let risingDelta = 1. / samplesToRise
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let mutable i = 0.
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seq {
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while true do
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i <- i + risingDelta
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yield min i 1.
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}
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let output =
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Seq.map (fun x -> multiosc { Oscillators = osc; Sample = x } |> (*) volume) samples
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let adsrLength = Seq.length output
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let attackArray = attack |> Seq.take adsrLength
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let release = Seq.rev attackArray
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Seq.zip3 release attackArray output |> Seq.map (fun (x, y, z) -> (x * y * z))
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let getSemitoneShift (targetNote: string) : int =
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getSemitoneShiftInternal "A4" targetNote
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let note semitone beats =
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let hz = getHzBySemitones (semitone)
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freq
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hz
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(beats * beatDuration)
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[ { Osc = Saw; Freq = hz / 4. }
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{ Osc = Saw; Freq = hz + 0.5 }
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{ Osc = Saw; Freq = hz - 1. } ]
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