audio: Add channel.nextInsertion

example/audio/main.go

@@ -48,6 +48,12 @@ const score = `CCGGAAGR FFEEDDCR GGFFEEDR GGFFEEDR CCGGAAGR FFEEDDCR`
 var scoreIndex = 0
 
 func square(out []float32, volume float64, freq float64, sequence float64) {
+	if freq == 0 {
+		for i := 0; i < len(out); i++ {
+			out[i] = 0
+		}
+		return
+	}
 	length := int(float64(ebiten.AudioSampleRate()) / freq)
 	if length == 0 {
 		panic("invalid freq")
@@ -69,8 +75,8 @@ func addNote() {
 		scoreIndex++
 		scoreIndex %= len(score)
 	}()
-	l := make([]float32, size*30*2)
+	l := make([]float32, size*30)
-	r := make([]float32, size*30*2)
+	r := make([]float32, size*30)
 	note := score[scoreIndex]
 	for note == ' ' {
 		scoreIndex++
@@ -80,7 +86,7 @@ func addNote() {
 	freq := 0.0
 	switch {
 	case note == 'R':
-		return
+		freq = 0
 	case note <= 'B':
 		freq = notes[int(note)+len(notes)-int('C')]
 	default:
@@ -89,7 +95,7 @@ func addNote() {
 	vol := 1.0 / 32.0
 	square(l, vol, freq, 0.5)
 	square(r, vol, freq, 0.5)
-	ebiten.AppendToAudioBuffer(-1, l, r)
+	ebiten.AppendToAudioBuffer(0, l, r)
 }
 
 func update(screen *ebiten.Image) error {

internal/audio/audio.go

@@ -35,3 +35,7 @@ func CurrentBytes() int {
 	// TODO: Implement
 	return 0
 }
+
+func Update() {
+	// TODO: Implement
+}

internal/audio/audio_js.go

@@ -30,6 +30,7 @@ const SampleRate = 44100
 type channel struct {
 	l             []float32
 	r             []float32
+	nextInsertion int
 }
 
 var channels = make([]*channel, 16)
@@ -83,6 +84,7 @@ func Init() {
 			usedLen := min(bufferSize, len(ch.l))
 			ch.l = ch.l[usedLen:]
 			ch.r = ch.r[usedLen:]
+			ch.nextInsertion -= min(bufferSize, ch.nextInsertion)
 		}
 		for i := 0; i < bufferSize; i++ {
 			// TODO: Use copyFromChannel?
@@ -97,6 +99,15 @@ func Init() {
 	})
 }
 
+func Update() {
+	for _, ch := range channels {
+		if len(ch.l) == 0 {
+			continue
+		}
+		ch.nextInsertion += SampleRate / 60
+	}
+}
+
 func Start() {
 	// TODO: For iOS, node should be connected with a buffer node.
 	node.Call("connect", context.Get("destination"))
@@ -105,20 +116,18 @@ func Start() {
 func channelAt(i int) *channel {
 	if i == -1 {
 		for _, ch := range channels {
-			if 0 < len(ch.l) {
+			if len(ch.l) <= ch.nextInsertion {
-				continue
-			}
 				return ch
 			}
+		}
 		return nil
 	}
 	ch := channels[i]
-	// TODO: Can we append even though all data is not consumed? Need game timer?
+	if len(ch.l) <= ch.nextInsertion {
-	if 0 < len(ch.l) {
-		return nil
-	}
 		return ch
 	}
+	return nil
+}
 
 func Append(i int, l []float32, r []float32) bool {
 	// TODO: Mutex (especially for OpenAL)
@@ -129,6 +138,9 @@ func Append(i int, l []float32, r []float32) bool {
 	if ch == nil {
 		return false
 	}
+	print(ch.nextInsertion)
+	ch.l = append(ch.l, make([]float32, ch.nextInsertion-len(ch.l))...)
+	ch.r = append(ch.r, make([]float32, ch.nextInsertion-len(ch.r))...)
 	ch.l = append(ch.l, l...)
 	ch.r = append(ch.r, r...)
 	return true

run.go

@@ -15,6 +15,7 @@
 package ebiten
 
 import (
+	"github.com/hajimehoshi/ebiten/internal/audio"
 	"github.com/hajimehoshi/ebiten/internal/opengl"
 	"github.com/hajimehoshi/ebiten/internal/ui"
 	"time"
@@ -69,6 +70,8 @@ func Run(f func(*Image) error, width, height, scale int, title string) error {
 		if err := graphicsContext.postUpdate(); err != nil {
 			return err
 		}
+		// TODO: I'm not sure this is 'Update'. Is 'Tick' better?
+		audio.Update()
 		ui.SwapBuffers()
 		if err != nil {
 			return err