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fix(tracker): avoid NaNs in volume analyzer better

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vsariola
2021-03-14 18:19:13 +02:00
parent b6283cd13e
commit 5daf81f331
3 changed files with 15 additions and 12 deletions
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21
tracker/vuanalyzer.go
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@ -7,8 +7,8 @@ import (
// Volume represents an average and peak volume measurement, in decibels. 0 dB =
// signal level of +-1.
type Volume struct {
Average [2]float32
Peak [2]float32
Average [2]float64
Peak [2]float64
}
// VuAnalyzer receives stereo from the bc channel and converts these into peak &
@ -28,11 +28,11 @@ type Volume struct {
//
// minVolume is just a hard limit for the vuanalyzer volumes, in decibels, just to
// prevent negative infinities for volumes
func VuAnalyzer(tau float64, attack float64, release float64, minVolume float32, bc <-chan []float32, vc chan<- Volume) {
v := Volume{Average: [2]float32{minVolume, minVolume}, Peak: [2]float32{minVolume, minVolume}}
alpha := 1 - float32(math.Exp(-1.0/(tau*44100))) // from https://en.wikipedia.org/wiki/Exponential_smoothing
alphaAttack := 1 - float32(math.Exp(-1.0/(attack*44100)))
alphaRelease := 1 - float32(math.Exp(-1.0/(release*44100)))
func VuAnalyzer(tau float64, attack float64, release float64, minVolume float64, maxVolume float64, bc <-chan []float32, vc chan<- Volume) {
v := Volume{Average: [2]float64{minVolume, minVolume}, Peak: [2]float64{minVolume, minVolume}}
alpha := 1 - math.Exp(-1.0/(tau*44100)) // from https://en.wikipedia.org/wiki/Exponential_smoothing
alphaAttack := 1 - math.Exp(-1.0/(attack*44100))
alphaRelease := 1 - math.Exp(-1.0/(release*44100))
for buffer := range bc {
for j := 0; j < 2; j++ {
for i := 0; i < len(buffer); i += 2 {
@ -40,10 +40,13 @@ func VuAnalyzer(tau float64, attack float64, release float64, minVolume float32,
if math.IsNaN(sample2) {
sample2 = float64(minVolume)
}
dB := float32(10 * math.Log10(float64(sample2)))
if dB < minVolume {
dB := 10 * math.Log10(float64(sample2))
if dB < minVolume || math.IsNaN(dB) {
dB = minVolume
}
if dB > maxVolume {
dB = maxVolume
}
v.Average[j] += (dB - v.Average[j]) * alpha
alphaPeak := alphaAttack
if dB < v.Peak[j] {