made Volume filter work on integer samples natively

audio/filter/filter.go

@@ -173,10 +173,10 @@ func (f RealTimeFilter) Process(source audio.Source) audio.Source {
 }
 
 type VolumeFilter struct {
-	adjustment float32
+	adjustment float64
 }
 
-func NewVolumeFilter(adjustment float32) VolumeFilter {
+func NewVolumeFilter(adjustment float64) VolumeFilter {
 	return VolumeFilter{
 		adjustment: adjustment,
 	}
@@ -187,21 +187,54 @@ func (f VolumeFilter) Process(source audio.Source) audio.Source {
 		return source
 	}
 
-	outSource := audio.NewSource[float32](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
-	go func() {
-		defer outSource.Close()
-
-		for block := range source.ToFloat32().GetBlocks() {
-			out := make([]float32, len(block))
-			for i := range block {
-				out[i] = block[i] * f.adjustment
+	if int32Source, ok := source.(audio.TypedSource[int32]); ok {
+		bpsMultiplier := int64((1 << (source.GetBitDepth() - 1)) - 1)
+		adjustment := int64(f.adjustment * float64(bpsMultiplier))
+		outSource := audio.NewSource[int32](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
+		go func() {
+			defer outSource.Close()
+			for block := range int32Source.GetBlocks() {
+				out := make([]int32, len(block))
+				for i := range block {
+					out[i] = int32((int64(block[i]) * adjustment) / bpsMultiplier)
+				}
+				outSource.IngestNative(out, source.GetBitDepth())
 			}
-			outSource.IngestFloat32(out)
-		}
+		}()
+		return outSource
+	} else if int16Source, ok := source.(audio.TypedSource[int16]); ok {
+		bpsMultiplier := int32((1 << (source.GetBitDepth() - 1)) - 1)
+		adjustment := int32(f.adjustment * float64(bpsMultiplier))
+		outSource := audio.NewSource[int16](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
+		go func() {
+			defer outSource.Close()
+			for block := range int16Source.GetBlocks() {
+				out := make([]int16, len(block))
+				for i := range block {
+					out[i] = int16((int32(block[i]) * adjustment) / bpsMultiplier)
+				}
+				outSource.IngestNative(out, source.GetBitDepth())
+			}
+		}()
+		return outSource
+	} else {
+		adjustment := float32(f.adjustment)
+		outSource := audio.NewSource[float32](source.GetBitDepth(), source.GetSampleRate(), source.GetChannels())
+		go func() {
+			defer outSource.Close()
 
-	}()
+			for block := range source.ToFloat32().GetBlocks() {
+				out := make([]float32, len(block))
+				for i := range block {
+					out[i] = block[i] * adjustment
+				}
+				outSource.IngestNative(out, source.GetBitDepth())
+			}
 
-	return outSource
+		}()
+
+		return outSource
+	}
 }
 
 type StereoFilter struct {

audio/filter/filter_test.go

@@ -22,7 +22,7 @@ func TestFilterChainNoResample(t *testing.T) {
 		return
 	}
 
-	result := NewFilterChain(source, MonoFilter{}, StereoFilter{})
+	result := NewFilterChain(source, NewVolumeFilter(0.5), MonoFilter{}, StereoFilter{})
 
 	sink := audio.NewForwardSink(audio.NewNullSink())
 	sink.Process(result)

audio/replaygain/filter.go

@@ -5,11 +5,11 @@ import (
 	"math"
 )
 
-//NewReplayGainFilter Creates a VolumeFilter applying calculated ReplayGain values, pre amplifying by preAmp. Values are in dB
+// NewReplayGainFilter Creates a VolumeFilter applying calculated ReplayGain values, pre amplifying by preAmp. Values are in dB
 func NewReplayGainFilter(gain, peak, preAmp float64) filter.VolumeFilter {
 	volume := math.Pow(10, (gain+preAmp)/20)
 	//prevent clipping
 	volume = math.Min(volume, 1/peak)
 
-	return filter.NewVolumeFilter(float32(volume))
+	return filter.NewVolumeFilter(volume)
 }