Initial noise suppression added.

noise/suppression.go

@@ -0,0 +1,112 @@
+package noise
+
+import (
+	"math"
+)
+
+// Ensure Suppressor implements the NoiseProcessor interface
+var _ interface {
+	ProcessSamples(samples []int16)
+	IsEnabled() bool
+} = (*Suppressor)(nil)
+
+// Suppressor handles noise suppression for audio samples
+type Suppressor struct {
+	enabled    bool
+	threshold  float32
+	gainFactor float32
+	
+	// Simple high-pass filter state for DC removal
+	prevInput  float32
+	prevOutput float32
+	alpha      float32
+}
+
+// NewSuppressor creates a new noise suppressor
+func NewSuppressor() *Suppressor {
+	return &Suppressor{
+		enabled:    false,
+		threshold:  0.02,     // Noise threshold level
+		gainFactor: 0.8,      // Gain reduction for noise
+		alpha:      0.95,     // High-pass filter coefficient
+	}
+}
+
+// SetEnabled enables or disables noise suppression
+func (s *Suppressor) SetEnabled(enabled bool) {
+	s.enabled = enabled
+}
+
+// IsEnabled returns whether noise suppression is enabled
+func (s *Suppressor) IsEnabled() bool {
+	return s.enabled
+}
+
+// SetThreshold sets the noise threshold (0.0 to 1.0)
+func (s *Suppressor) SetThreshold(threshold float32) {
+	if threshold >= 0.0 && threshold <= 1.0 {
+		s.threshold = threshold
+	}
+}
+
+// GetThreshold returns the current noise threshold
+func (s *Suppressor) GetThreshold() float32 {
+	return s.threshold
+}
+
+// ProcessSamples applies noise suppression to audio samples
+func (s *Suppressor) ProcessSamples(samples []int16) {
+	if !s.enabled || len(samples) == 0 {
+		return
+	}
+
+	// Simple noise suppression algorithm
+	for i, sample := range samples {
+		// Convert to float for processing
+		floatSample := float32(sample) / 32767.0
+		
+		// Apply high-pass filter for DC removal
+		filtered := s.highPassFilter(floatSample)
+		
+		// Calculate signal strength
+		strength := float32(math.Abs(float64(filtered)))
+		
+		// Apply noise gate
+		if strength < s.threshold {
+			// Below threshold - reduce gain
+			filtered *= s.gainFactor
+		}
+		
+		// Apply simple spectral subtraction-like effect
+		// If signal is weak, reduce it further
+		if strength < s.threshold * 2 {
+			filtered *= (strength / (s.threshold * 2))
+		}
+		
+		// Convert back to int16
+		processed := filtered * 32767.0
+		if processed > 32767 {
+			processed = 32767
+		} else if processed < -32767 {
+			processed = -32767
+		}
+		
+		samples[i] = int16(processed)
+	}
+}
+
+// highPassFilter applies a simple high-pass filter to remove DC component
+func (s *Suppressor) highPassFilter(input float32) float32 {
+	// Simple high-pass filter: y[n] = alpha * (y[n-1] + x[n] - x[n-1])
+	output := s.alpha * (s.prevOutput + input - s.prevInput)
+	s.prevInput = input
+	s.prevOutput = output
+	return output
+}
+
+// ProcessSamplesAdvanced applies more sophisticated noise suppression
+// This is a placeholder for future RNNoise integration
+func (s *Suppressor) ProcessSamplesAdvanced(samples []int16) {
+	// TODO: Integrate RNNoise or other advanced algorithms
+	s.ProcessSamples(samples)
+}