From 5daf81f33151b553eff1d2e15c9fcf8f9c30b1d9 Mon Sep 17 00:00:00 2001
From: vsariola <5684185+vsariola@users.noreply.github.com>
Date: Sun, 14 Mar 2021 18:19:13 +0200
Subject: [PATCH] fix(tracker): avoid NaNs in volume analyzer better

---
 tracker/gioui/tracker.go |  2 +-
 tracker/gioui/vumeter.go |  4 ++--
 tracker/vuanalyzer.go    | 21 ++++++++++++---------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/tracker/gioui/tracker.go b/tracker/gioui/tracker.go
index 1a7e8ee..2195065 100644
--- a/tracker/gioui/tracker.go
+++ b/tracker/gioui/tracker.go
@@ -149,7 +149,7 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService, syn
 	}
 	t.Model = tracker.NewModel()
 	vuBufferObserver := make(chan []float32)
-	go tracker.VuAnalyzer(0.3, 1e-4, 1, -100, vuBufferObserver, t.volumeChan)
+	go tracker.VuAnalyzer(0.3, 1e-4, 1, -100, 20, vuBufferObserver, t.volumeChan)
 	t.Theme.Palette.Fg = primaryColor
 	t.Theme.Palette.ContrastFg = black
 	t.SetEditMode(tracker.EditTracks)
diff --git a/tracker/gioui/vumeter.go b/tracker/gioui/vumeter.go
index dee5166..714db4d 100644
--- a/tracker/gioui/vumeter.go
+++ b/tracker/gioui/vumeter.go
@@ -21,7 +21,7 @@ func (v VuMeter) Layout(gtx C) D {
 	gtx.Constraints.Max.Y = gtx.Px(unit.Dp(12))
 	height := gtx.Px(unit.Dp(6))
 	for j := 0; j < 2; j++ {
-		value := v.Volume.Average[j] + v.Range
+		value := float32(v.Volume.Average[j]) + v.Range
 		if value > 0 {
 			x := int(value/v.Range*float32(gtx.Constraints.Max.X) + 0.5)
 			if x > gtx.Constraints.Max.X {
@@ -29,7 +29,7 @@ func (v VuMeter) Layout(gtx C) D {
 			}
 			paint.FillShape(gtx.Ops, mediumEmphasisTextColor, clip.Rect(image.Rect(0, 0, x, height)).Op())
 		}
-		valueMax := v.Volume.Peak[j] + v.Range
+		valueMax := float32(v.Volume.Peak[j]) + v.Range
 		if valueMax > 0 {
 			color := white
 			if valueMax >= v.Range {
diff --git a/tracker/vuanalyzer.go b/tracker/vuanalyzer.go
index 198634c..9168ca6 100644
--- a/tracker/vuanalyzer.go
+++ b/tracker/vuanalyzer.go
@@ -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] {