Added normalization filter

audio/filter.go

@@ -89,12 +89,12 @@ func (f RealTimeFilter) Process(source Source) Source {
 }
 
 type VolumeFilter struct {
-	adjustement float32
+	adjustment float32
 }
 
-func NewVolumeFilter(adjustement float32) VolumeFilter {
+func NewVolumeFilter(adjustment float32) VolumeFilter {
 	return VolumeFilter{
-		adjustement: adjustement,
+		adjustment: adjustment,
 	}
 }
 
@@ -106,7 +106,7 @@ func (f VolumeFilter) Process(source Source) Source {
 		for block := range source.Blocks {
 			out := make([]float32, len(block))
 			for i := range block {
-				out[i] = block[i] * f.adjustement
+				out[i] = block[i] * f.adjustment
 			}
 			outBlocks <- out
 		}

audio/replaygain/filter.go

@@ -2,6 +2,7 @@ package replaygain
 
 import (
 	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
+	libebur128 "git.gammaspectra.live/S.O.N.G/go-ebur128"
 	"math"
 )
 
@@ -13,3 +14,55 @@ func NewReplayGainFilter(gain, peak, preAmp float64) audio.VolumeFilter {
 
 	return audio.NewVolumeFilter(float32(volume))
 }
+
+// NormalizationFilter Normalizes running audio source
+type NormalizationFilter struct {
+}
+
+func (f NormalizationFilter) Process(source audio.Source) audio.Source {
+	outBlocks := make(chan []float32)
+	go func() {
+		defer close(outBlocks)
+
+		state := libebur128.NewState(source.Channels, source.SampleRate, libebur128.LoudnessShortTerm|libebur128.SamplePeak)
+		if state == nil {
+			return
+		}
+		defer state.Close()
+
+		for block := range source.Blocks {
+			if state.AddFloat(block) != nil {
+				return
+			}
+
+			loudness, _ := state.GetLoudnessShortTerm()
+			peakSlice, _ := state.GetPreviousSamplePeak()
+
+			var peak float64
+			for _, p := range peakSlice {
+				if p > peak {
+					peak = p
+				}
+			}
+
+			volume := math.Pow(10, (referenceLevel-loudness)/20)
+			//prevent clipping
+			volume = math.Min(volume, 1/peak)
+
+			adjustment := float32(volume)
+
+			out := make([]float32, len(block))
+			for i := range block {
+				out[i] = block[i] * adjustment
+			}
+			outBlocks <- out
+		}
+
+	}()
+
+	return audio.Source{
+		Channels:   source.Channels,
+		SampleRate: source.SampleRate,
+		Blocks:     outBlocks,
+	}
+}