117 lines
2.4 KiB
Go
117 lines
2.4 KiB
Go
//go:build cgo
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package replaygain
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import (
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"git.gammaspectra.live/S.O.N.G/Kirika/audio"
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libebur128 "git.gammaspectra.live/S.O.N.G/go-ebur128"
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"math"
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"time"
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)
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// NormalizationFilter Normalizes running audio source
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type NormalizationFilter struct {
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delay int
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}
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func NewNormalizationFilter(delayInSeconds int) NormalizationFilter {
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return NormalizationFilter{
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delay: delayInSeconds,
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}
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}
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func (f NormalizationFilter) Process(source audio.Source) audio.Source {
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outBlocks := make(chan []float32)
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go func() {
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defer close(outBlocks)
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state := libebur128.NewState(source.Channels, source.SampleRate, libebur128.LoudnessShortTerm|libebur128.SamplePeak)
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if state == nil {
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return
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}
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defer state.Close()
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if state.SetMaxWindow(time.Second*time.Duration(f.delay)) != nil {
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return
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}
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var sampleBuffer []float32
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var adjustment float32 = 1.0
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for block := range source.Blocks {
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if state.AddFloat(block) != nil {
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return
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}
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sampleBuffer = append(sampleBuffer, block...)
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loudness, _ := state.GetLoudnessWindow(time.Second * time.Duration(f.delay))
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peakSlice, _ := state.GetPreviousSamplePeak()
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var peak float64
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for _, p := range peakSlice {
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if p > peak {
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peak = p
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}
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}
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gain := referenceLevel - loudness
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if gain > 52 {
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gain = 52
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} else if gain < -52 {
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gain = -52
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}
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volume := math.Pow(10, (gain)/20)
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nsamples := source.SampleRate * source.Channels * f.delay
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ratio := float32(math.Min(1, float64(len(block))/float64(nsamples)))
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adjustment = adjustment*(1-ratio) + float32(volume)*ratio
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if adjustment > float32(1/peak) {
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adjustment = float32(1 / peak)
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}
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if len(sampleBuffer) > nsamples {
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adjustment = adjustment*(1-ratio) + float32(volume)*ratio
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if adjustment > float32(1/peak) {
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adjustment = float32(1 / peak)
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}
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size := len(sampleBuffer) - nsamples
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out := make([]float32, size)
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for i, e := range sampleBuffer[:size] {
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out[i] = e * adjustment
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}
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outBlocks <- out
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sampleBuffer = sampleBuffer[size:]
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} else {
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adjustment = float32(volume)
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if adjustment > float32(1/peak) {
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adjustment = float32(1 / peak)
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}
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}
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}
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//flush
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if len(sampleBuffer) > 0 {
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out := make([]float32, len(sampleBuffer))
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for i := range sampleBuffer {
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out[i] = sampleBuffer[i] * adjustment
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}
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outBlocks <- out
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}
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}()
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return audio.Source{
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Channels: source.Channels,
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SampleRate: source.SampleRate,
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Blocks: outBlocks,
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}
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}
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