0.1.0 - Initial commit

lib/audio/notes.go

@@ -0,0 +1,44 @@
+package audio
+
+import "math"
+
+// Converts note name to frequency in Hz
+func noteToFreq(note string) float64 {
+	noteFreqs := map[string]float64{
+		"C":  16.35,
+		"C#": 17.32,
+		"D":  18.35,
+		"D#": 19.45,
+		"E":  20.60,
+		"F":  21.83,
+		"F#": 23.12,
+		"G":  24.50,
+		"G#": 25.96,
+		"A":  27.50,
+		"A#": 29.14,
+		"B":  30.87,
+	}
+
+	if len(note) < 2 {
+		return 440.0
+	}
+
+	noteName := note[:1]
+	if len(note) > 2 && (note[1] == '#' || note[1] == 'b') {
+		noteName = note[:2]
+	}
+
+	octave := 4
+	if len(note) > 1 {
+		if note[len(note)-1] >= '0' && note[len(note)-1] <= '9' {
+			octave = int(note[len(note)-1] - '0')
+		}
+	}
+
+	baseFreq, exists := noteFreqs[noteName]
+	if !exists {
+		return 440.0
+	}
+
+	return baseFreq * math.Pow(2, float64(octave))
+}