refactor: remove LowPassFilter implementation from filter.go

shazam/filter.go

@@ -1,36 +0,0 @@
-package shazam
-
-import (
-	"math"
-)
-
-// LowPassFilter is a first-order low-pass filter using H(p) = 1 / (1 + pRC)
-type LowPassFilter struct {
-	alpha float64 // Filter coefficient
-	yPrev float64 // Previous output value
-}
-
-// NewLowPassFilter creates a new low-pass filter
-func NewLowPassFilter(cutoffFrequency, sampleRate float64) *LowPassFilter {
-	rc := 1.0 / (2 * math.Pi * cutoffFrequency)
-	dt := 1.0 / sampleRate
-	alpha := dt / (rc + dt)
-	return &LowPassFilter{
-		alpha: alpha,
-		yPrev: 0,
-	}
-}
-
-// Filter processes the input signal through the low-pass filter
-func (lpf *LowPassFilter) Filter(input []float64) []float64 {
-	filtered := make([]float64, len(input))
-	for i, x := range input {
-		if i == 0 {
-			filtered[i] = x * lpf.alpha
-		} else {
-			filtered[i] = lpf.alpha*x + (1-lpf.alpha)*lpf.yPrev
-		}
-		lpf.yPrev = filtered[i]
-	}
-	return filtered
-}