From de59c932190c84c22461ba552f9d31f245d331cb Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Mon, 8 Jun 2015 00:04:21 +0900
Subject: [PATCH] audio: Change API to accept raw PCM data

---
 example/audio/main.go | 22 +++++++++++++++++++---
 example/piano/main.go | 36 +++++++++++++++++++++++++-----------
 exp/audio/audio.go    | 30 ++++++++++++++++++++++++++++--
 3 files changed, 72 insertions(+), 16 deletions(-)

diff --git a/example/audio/main.go b/example/audio/main.go
index b3a82fcee..523b361fc 100644
--- a/example/audio/main.go
+++ b/example/audio/main.go
@@ -15,12 +15,15 @@
 package main
 
 import (
+	"bytes"
+	"encoding/binary"
 	"fmt"
+	"log"
+	"math"
+
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"
 	"github.com/hajimehoshi/ebiten/exp/audio"
-	"log"
-	"math"
 )
 
 const (
@@ -69,6 +72,19 @@ func square(out []int16, volume float64, freq float64, sequence float64) {
 	}
 }
 
+func toBytes(l, r []int16) []byte {
+	if len(l) != len(r) {
+		panic("len(l) must equal to len(r)")
+	}
+	b := &bytes.Buffer{}
+	for i := 0; i < len(l); i++ {
+		if err := binary.Write(b, binary.LittleEndian, []int16{l[i], r[i]}); err != nil {
+			panic(err)
+		}
+	}
+	return b.Bytes()
+}
+
 func addNote() {
 	size := audio.SampleRate() / 60
 	notes := []float64{freqC, freqD, freqE, freqF, freqG, freqA * 2, freqB * 2}
@@ -97,7 +113,7 @@ func addNote() {
 	vol := 1.0 / 16.0
 	square(l, vol, freq, 0.25)
 	square(r, vol, freq, 0.25)
-	audio.Play(0, l, r)
+	audio.Play(0, toBytes(l, r))
 }
 
 func update(screen *ebiten.Image) error {
diff --git a/example/piano/main.go b/example/piano/main.go
index bcb34879c..5c3a8a8dc 100644
--- a/example/piano/main.go
+++ b/example/piano/main.go
@@ -15,14 +15,17 @@
 package main
 
 import (
+	"bytes"
+	"encoding/binary"
 	"fmt"
+	"image/color"
+	"log"
+	"math"
+
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"
 	"github.com/hajimehoshi/ebiten/example/common"
 	"github.com/hajimehoshi/ebiten/exp/audio"
-	"image/color"
-	"log"
-	"math"
 )
 
 const (
@@ -50,15 +53,26 @@ func init() {
 }
 
 var (
-	noteLCache = map[int][]int16{}
-	noteRCache = map[int][]int16{}
+	noteCache = map[int][]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 := 0; i < len(l); i++ {
+		if err := binary.Write(b, binary.LittleEndian, []int16{l[i], r[i]}); err != nil {
+			panic(err)
+		}
+	}
+	return b.Bytes()
+}
+
 func addNote(freq float64, vol float64) {
 	f := int(freq)
-	if l, ok := noteLCache[f]; ok {
-		r := noteRCache[f]
-		audio.Play(-1, l, r)
+	if n, ok := noteCache[f]; ok {
+		audio.Play(-1, n)
 		return
 	}
 	length := len(pcm) * baseFreq / f
@@ -73,9 +87,9 @@ func addNote(freq float64, vol float64) {
 		jj += f
 		j = jj / baseFreq
 	}
-	noteLCache[f] = l
-	noteRCache[f] = r
-	audio.Play(-1, l, r)
+	n := toBytes(l, r)
+	noteCache[f] = n
+	audio.Play(-1, n)
 }
 
 var keys = []ebiten.Key{
diff --git a/exp/audio/audio.go b/exp/audio/audio.go
index 750b57b09..a7b3f0f36 100644
--- a/exp/audio/audio.go
+++ b/exp/audio/audio.go
@@ -15,6 +15,9 @@
 package audio
 
 import (
+	"bytes"
+	"encoding/binary"
+
 	"github.com/hajimehoshi/ebiten/exp/audio/internal"
 )
 
@@ -26,13 +29,32 @@ func SampleRate() int {
 // MaxChannel is a max number of channels.
 var MaxChannel = internal.MaxChannel
 
+func toLR(data []byte) ([]int16, []int16) {
+	buf := bytes.NewReader(data)
+	b := make([]int16, len(data)/2)
+	if err := binary.Read(buf, binary.LittleEndian, b); err != nil {
+		panic(err)
+	}
+	l := make([]int16, len(data)/4)
+	r := make([]int16, len(data)/4)
+	for i := 0; i < len(data)/4; i++ {
+		l[i] = b[2*i]
+		r[i] = b[2*i+1]
+	}
+	return l, r
+}
+
 // Play appends the given data to the given channel.
 //
 // channel must be -1 or a channel index. If channel is -1, an empty channel is automatically selected.
 // If the channel is not empty, this function does nothing and returns false. This returns true otherwise.
 //
+// data's format must be linear PCM (44100Hz, stereo, 16bit little endian).
+//
 // This function is useful to play SE or a note of PCM synthesis immediately.
-func Play(channel int, l []int16, r []int16) bool {
+func Play(channel int, data []byte) bool {
+	l, r := toLR(data)
+	// TODO: Pass data directly.
 	return internal.Play(channel, l, r)
 }
 
@@ -41,8 +63,12 @@ func Play(channel int, l []int16, r []int16) bool {
 //
 // channel must be a channel index. You can't give -1 to channel.
 //
+// data's format must be linear PCM (44100Hz, stereo, 16bit little endian).
+//
 // This function is useful to play streaming data.
-func Queue(channel int, l []int16, r []int16) {
+func Queue(channel int, data []byte) {
+	l, r := toLR(data)
+	// TODO: Pass data directly.
 	internal.Queue(channel, l, r)
 }