Improved normalization filter

audio/replaygain/filter.go

@@ -4,6 +4,7 @@ import (
 	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
 	libebur128 "git.gammaspectra.live/S.O.N.G/go-ebur128"
 	"math"
+	"time"
 )
 
 //NewReplayGainFilter Creates a VolumeFilter applying calculated ReplayGain values, pre amplifying by preAmp. Values are in dB
@@ -17,6 +18,13 @@ func NewReplayGainFilter(gain, peak, preAmp float64) audio.VolumeFilter {
 
 // NormalizationFilter Normalizes running audio source
 type NormalizationFilter struct {
+	delay int
+}
+
+func NewNormalizationFilter(delayInSeconds int) NormalizationFilter {
+	return NormalizationFilter{
+		delay: delayInSeconds,
+	}
 }
 
 func (f NormalizationFilter) Process(source audio.Source) audio.Source {
@@ -30,12 +38,21 @@ func (f NormalizationFilter) Process(source audio.Source) audio.Source {
 		}
 		defer state.Close()
 
+		if state.SetMaxWindow(time.Second*time.Duration(f.delay)) != nil {
+			return
+		}
+
+		var sampleBuffer []float32
+		var adjustment float32 = 1.0
+
 		for block := range source.Blocks {
 			if state.AddFloat(block) != nil {
 				return
 			}
 
-			loudness, _ := state.GetLoudnessShortTerm()
+			sampleBuffer = append(sampleBuffer, block...)
+
+			loudness, _ := state.GetLoudnessWindow(time.Second * time.Duration(f.delay))
 			peakSlice, _ := state.GetPreviousSamplePeak()
 
 			var peak float64
@@ -45,15 +62,37 @@ func (f NormalizationFilter) Process(source audio.Source) audio.Source {
 				}
 			}
 
-			volume := math.Pow(10, (referenceLevel-loudness)/20)
+			gain := referenceLevel - loudness
+			if gain > 52 {
+				gain = 52
+			} else if gain < -52 {
+				gain = -52
+			}
+
+			volume := math.Pow(10, (gain)/20)
 			//prevent clipping
 			volume = math.Min(volume, 1/peak)
 
-			adjustment := float32(volume)
+			adjustment = float32(volume)
 
-			out := make([]float32, len(block))
-			for i := range block {
-				out[i] = block[i] * adjustment
+			nsamples := source.SampleRate * source.Channels * f.delay
+
+			if len(sampleBuffer) > nsamples {
+				size := len(sampleBuffer) - nsamples
+				out := make([]float32, size)
+				for i, e := range sampleBuffer[:size] {
+					out[i] = e * adjustment
+				}
+				outBlocks <- out
+				sampleBuffer = sampleBuffer[size:]
+			}
+		}
+
+		//flush
+		if len(sampleBuffer) > 0 {
+			out := make([]float32, len(sampleBuffer))
+			for i := range sampleBuffer {
+				out[i] = sampleBuffer[i] * adjustment
 			}
 			outBlocks <- out
 		}

go.mod

@@ -3,7 +3,7 @@ module git.gammaspectra.live/S.O.N.G/Kirika
 go 1.18
 
 require (
-	git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308105126-3299585e6a9a
+	git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308113719-afad5c6e5c28
 	git.gammaspectra.live/S.O.N.G/go-fdkaac v0.0.0-20220228131722-e9cb84c52f48
 	git.gammaspectra.live/S.O.N.G/go-pus v0.0.0-20220227175608-6cc027f24dba
 	git.gammaspectra.live/S.O.N.G/go-tta v0.2.1-0.20220226150007-096de1072bd6

go.sum

@@ -1,5 +1,5 @@
-git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308105126-3299585e6a9a h1:cEkgIB5RSBFcyeB/VhpHiuYof2V/nMU5js46UroYs4c=
-git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308105126-3299585e6a9a/go.mod h1:5H4eVW9uknpn8REFr+C3ejhvXdncgm/pbGqKGC43gFY=
+git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308113719-afad5c6e5c28 h1:7YLU2eyGBX8juV445KlBxW71NjFAzbRvfotZBUP16Bs=
+git.gammaspectra.live/S.O.N.G/go-ebur128 v0.0.0-20220308113719-afad5c6e5c28/go.mod h1:5H4eVW9uknpn8REFr+C3ejhvXdncgm/pbGqKGC43gFY=
 git.gammaspectra.live/S.O.N.G/go-fdkaac v0.0.0-20220228131722-e9cb84c52f48 h1:MaKiBfXQl0keyfdCi1PxGOKRTiWhIs8PqCal5GhKDi0=
 git.gammaspectra.live/S.O.N.G/go-fdkaac v0.0.0-20220228131722-e9cb84c52f48/go.mod h1:pkWt//S9hLVEQaJDPu/cHHPk8vPpo/0+zHy0me4LIP4=
 git.gammaspectra.live/S.O.N.G/go-pus v0.0.0-20220227175608-6cc027f24dba h1:JEaxCVgdr3XXAuDCPAx7ttLFZaaHzTEzG+oRnVUtUKU=