wip: reverb

SoundGen/Fx.fs

@@ -9,14 +9,21 @@ type Saturator = { Gain: float }
 
 let saturate (param: Saturator, x: float) = tanh (param.Gain * x)
 
-let sineWaveShape x  =
-    x + 2.8 * sin (2. * x)
+let sineWaveShape gain factor x  =
+    x + gain * sin (factor * x)
+
+let reverb (buffer:float seq) =
+    let delayMilliseconds = 50.; // 500 is half a second
+    let delaySamples = (delayMilliseconds * 48.0) |> int; // assumes 44100 Hz sample rate
+    let decay = 0.5
+    let mutable newBuffer = Array.ofSeq buffer
+    
+    for i in 0..Seq.length buffer do
+        let smpl = newBuffer.[i] * decay
+        if Array.length newBuffer > (i + delaySamples) then
+            newBuffer.[i + delaySamples] <- smpl
+        else newBuffer <- Array.append newBuffer (smpl |> Array.singleton)
+            
+    newBuffer
+
 
-//
-// let process(effects:Effect list, sound:float seq) =
-//     let mutable output = sound
-//     effects
-//     |> List.iter((fun eff ->
-//         match eff with
-//         |Saturator -> output <- (output |> Seq.map saturate eff)))
-//     

SoundGen/Oscillator.fs

@@ -1,4 +1,5 @@
 module SoundGen.Oscillator
+
 open System
 open Settings
 
@@ -10,6 +11,9 @@ let sineosc hz x =
 let squareosc hz x =
     let sign v : float = if v > 0.0 then 1. else -1.
     x |> sineosc hz |> sign
-let triangleosc (hz:float) (x:float) = 1. - Math.Abs((pos hz x) - 0.5) * 4.
+
+let triangleosc (hz: float) (x: float) = 1. - Math.Abs((pos hz x) - 0.5) * 4.
 let sawosc hz x = (pos hz x) * 2. - 1.
-let sinesquareosc hz x = sawosc (hz / 4.) x + squareosc (hz/2.) x
+
+let sinesquareosc hz x =
+    sawosc (hz / 4.) x + squareosc (hz / 2.) x

SoundGen/Program.fs

@@ -55,8 +55,9 @@ let writeToFile (ms: MemoryStream) =
     ms.WriteTo(fs)
 
 song
-|> Seq.map (fun x ->
-    let x1 = sineWaveShape x
-    saturate ({ Gain = 1.0 }, x1))
+// |> Seq.map (fun x ->
+//     let x1 = sineWaveShape 2.8 2. x
+//     saturate ({ Gain = 1.0 }, x1))
+//|> reverb
 |> createWAV
 |> writeToFile