audio: Change API: accept []int16 instead of []float32

example/audio/main.go

@@ -20,6 +20,7 @@ import (
 	"github.com/hajimehoshi/ebiten/ebitenutil"
 	"github.com/hajimehoshi/ebiten/exp/audio"
 	"log"
+	"math"
 )
 
 const (
@@ -48,7 +49,7 @@ const score = `CCGGAAGR FFEEDDCR GGFFEEDR GGFFEEDR CCGGAAGR FFEEDDCR`
 
 var scoreIndex = 0
 
-func square(out []float32, volume float64, freq float64, sequence float64) {
+func square(out []int16, volume float64, freq float64, sequence float64) {
 	if freq == 0 {
 		for i := 0; i < len(out); i++ {
 			out[i] = 0
@@ -60,7 +61,7 @@ func square(out []float32, volume float64, freq float64, sequence float64) {
 		panic("invalid freq")
 	}
 	for i := 0; i < len(out); i++ {
-		a := float32(volume)
+		a := int16(volume * math.MaxInt16)
 		if i%length < int(float64(length)*sequence) {
 			a = -a
 		}
@@ -76,8 +77,8 @@ func addNote() {
 		scoreIndex++
 		scoreIndex %= len(score)
 	}()
-	l := make([]float32, size*30)
+	l := make([]int16, size*30)
-	r := make([]float32, size*30)
+	r := make([]int16, size*30)
 	note := score[scoreIndex]
 	for note == ' ' {
 		scoreIndex++

exp/audio/audio.go

@@ -32,7 +32,7 @@ var MaxChannel = audio.MaxChannel
 // If the channel is not empty, this function does nothing and returns false. This returns true otherwise.
 //
 // This function is useful to play SE or a note of PCM synthesis immediately.
-func Play(channel int, l []float32, r []float32) bool {
+func Play(channel int, l []int16, r []int16) bool {
 	return audio.Play(channel, l, r)
 }
 
@@ -42,7 +42,7 @@ func Play(channel int, l []float32, r []float32) bool {
 // channel must be a channel index. You can't give -1 to channel.
 //
 // This function is useful to play streaming data.
-func Queue(channel int, l []float32, r []float32) {
+func Queue(channel int, l []int16, r []int16) {
 	audio.Queue(channel, l, r)
 }
 

internal/audio/audio.go

@@ -27,8 +27,8 @@ var nextInsertionPosition = 0
 var currentPosition = 0
 
 type channel struct {
-	l []float32
+	l []int16
-	r []float32
+	r []int16
 }
 
 var MaxChannel = 32
@@ -39,8 +39,8 @@ var channelsLock sync.Mutex
 func init() {
 	for i, _ := range channels {
 		channels[i] = &channel{
-			l: []float32{},
+			l: []int16{},
-			r: []float32{},
+			r: []int16{},
 		}
 	}
 }
@@ -73,7 +73,7 @@ func channelAt(i int) *channel {
 	return nil
 }
 
-func Play(channel int, l []float32, r []float32) bool {
+func Play(channel int, l []int16, r []int16) bool {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
@@ -88,14 +88,14 @@ func Play(channel int, l []float32, r []float32) bool {
 	if ch == nil {
 		return false
 	}
-	ch.l = append(ch.l, make([]float32, nextInsertionPosition-len(ch.l))...)
+	ch.l = append(ch.l, make([]int16, nextInsertionPosition-len(ch.l))...)
-	ch.r = append(ch.r, make([]float32, nextInsertionPosition-len(ch.r))...)
+	ch.r = append(ch.r, make([]int16, nextInsertionPosition-len(ch.r))...)
 	ch.l = append(ch.l, l...)
 	ch.r = append(ch.r, r...)
 	return true
 }
 
-func Queue(channel int, l []float32, r []float32) {
+func Queue(channel int, l []int16, r []int16) {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
@@ -138,7 +138,7 @@ func isChannelsEmpty() bool {
 	return true
 }
 
-func loadChannelBuffers() (l, r []float32) {
+func loadChannelBuffers() (l, r []int16) {
 	channelsLock.Lock()
 	defer channelsLock.Unlock()
 
@@ -146,8 +146,8 @@ func loadChannelBuffers() (l, r []float32) {
 		return nil, nil
 	}
 
-	inputL := make([]float32, bufferSize)
+	inputL := make([]int16, bufferSize)
-	inputR := make([]float32, bufferSize)
+	inputR := make([]int16, bufferSize)
 	for _, ch := range channels {
 		if len(ch.l) == 0 {
 			continue

internal/audio/audio_js.go

@@ -38,6 +38,7 @@ func initialize() {
 		r := e.Get("outputBuffer").Call("getChannelData", 1)
 		inputL, inputR := loadChannelBuffers()
 		nextInsertionPosition -= min(bufferSize, nextInsertionPosition)
+		const max = 1 << 16
 		for i := 0; i < bufferSize; i++ {
 			// TODO: Use copyFromChannel?
 			if len(inputL) <= i {
@@ -45,8 +46,8 @@ func initialize() {
 				r.SetIndex(i, 0)
 				continue
 			}
-			l.SetIndex(i, inputL[i])
+			l.SetIndex(i, float64(inputL[i])/max)
-			r.SetIndex(i, inputR[i])
+			r.SetIndex(i, float64(inputR[i])/max)
 		}
 	})
 	audioEnabled = true

internal/audio/audio_openal.go

@@ -22,20 +22,17 @@ import (
 	"fmt"
 	"github.com/timshannon/go-openal/openal"
 	"log"
-	"math"
 	"runtime"
 	"time"
 )
 
-func toBytes(l, r []float32) []byte {
+func toBytes(l, r []int16) []byte {
 	if len(l) != len(r) {
 		panic("len(l) must equal to len(r)")
 	}
 	b := &bytes.Buffer{}
 	for i, _ := range l {
-		l := int16(l[i] * math.MaxInt16)
+		if err := binary.Write(b, binary.LittleEndian, []int16{l[i], r[i]}); err != nil {
-		r := int16(r[i] * math.MaxInt16)
-		if err := binary.Write(b, binary.LittleEndian, []int16{l, r}); err != nil {
 			panic(err)
 		}
 	}