0.1.0 - Initial commit

lib/audio/oscillator.go

@@ -0,0 +1,80 @@
+package audio
+
+import "math"
+
+// Generates audio samples for a given waveform type
+func (g *Generator) generateOscillator(waveType string, freq, duration, amplitude, phase float64) []float64 {
+	samples := int(duration * g.sampleRate)
+	if samples <= 0 {
+		return nil
+	}
+	output := make([]float64, samples)
+	
+	sampleRateInv := 1.0 / g.sampleRate
+	twoPiFreq := 2 * math.Pi * freq
+	fadeSamples := int(math.Min(0.005*g.sampleRate, float64(samples)*0.1))
+	fadeSamplesInv := 1.0 / float64(fadeSamples)
+	switch waveType {
+	case "sine":
+		for i := 0; i < samples; i++ {
+			t := float64(i)*sampleRateInv + phase
+			sample := math.Sin(twoPiFreq*t) * amplitude
+			
+			if i < fadeSamples {
+				sample *= float64(i) * fadeSamplesInv
+			} else if i >= samples-fadeSamples {
+				sample *= float64(samples-i) * fadeSamplesInv
+			}
+			
+			output[i] = sample
+		}
+	case "square":
+		for i := 0; i < samples; i++ {
+			t := float64(i)*sampleRateInv + phase
+			var sample float64
+			if math.Sin(twoPiFreq*t) > 0 {
+				sample = amplitude
+			} else {
+				sample = -amplitude
+			}
+			
+			if i < fadeSamples {
+				sample *= float64(i) * fadeSamplesInv
+			} else if i >= samples-fadeSamples {
+				sample *= float64(samples-i) * fadeSamplesInv
+			}
+			
+			output[i] = sample
+		}
+	case "saw":
+		for i := 0; i < samples; i++ {
+			t := float64(i)*sampleRateInv + phase
+			sample := (2*(t*freq-math.Floor(0.5+t*freq))) * amplitude
+			
+			if i < fadeSamples {
+				sample *= float64(i) * fadeSamplesInv
+			} else if i >= samples-fadeSamples {
+				sample *= float64(samples-i) * fadeSamplesInv
+			}
+			
+			output[i] = sample
+		}
+	case "triangle":
+		for i := 0; i < samples; i++ {
+			t := float64(i)*sampleRateInv + phase
+			sample := (math.Abs(2*(t*freq-math.Floor(t*freq+0.5)))*2 - 1) * amplitude
+			
+			if i < fadeSamples {
+				sample *= float64(i) * fadeSamplesInv
+			} else if i >= samples-fadeSamples {
+				sample *= float64(samples-i) * fadeSamplesInv
+			}
+			
+			output[i] = sample
+		}
+	default:
+		return output
+	}
+
+	return output
+}