From f0d7a811e1bd31eccde8b5045a1207534b5616c5 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 12 Feb 2016 03:06:04 +0900
Subject: [PATCH] audio: Enable to play inifinite stream

---
 exp/audio/audio.go        |   6 +-
 exp/audio/audio_openal.go | 119 ++++++++++++++++++++++++++++++++++----
 2 files changed, 110 insertions(+), 15 deletions(-)

diff --git a/exp/audio/audio.go b/exp/audio/audio.go
index 54d862d95..32bd420fa 100644
--- a/exp/audio/audio.go
+++ b/exp/audio/audio.go
@@ -19,7 +19,7 @@ import (
 )
 
 type Player struct {
-	*player
+	player *player
 }
 
 // NewPlayer creates a new player with the given data to the given channel.
@@ -35,9 +35,9 @@ func NewPlayer(src io.ReadSeeker, sampleRate int) *Player {
 }
 
 func (p *Player) Play() error {
-	return p.play()
+	return p.player.play()
 }
 
 func (p *Player) Close() error {
-	return p.close()
+	return p.player.close()
 }
diff --git a/exp/audio/audio_openal.go b/exp/audio/audio_openal.go
index 572d4c418..338e8539e 100644
--- a/exp/audio/audio_openal.go
+++ b/exp/audio/audio_openal.go
@@ -17,9 +17,13 @@
 package audio
 
 import (
+	"fmt"
 	"io"
+	"runtime"
+	"sync"
+	"time"
 
-	"golang.org/x/mobile/exp/audio"
+	"golang.org/x/mobile/exp/audio/al"
 )
 
 type readSeekCloser struct {
@@ -31,27 +35,118 @@ func (r *readSeekCloser) Close() error {
 }
 
 type player struct {
-	*audio.Player
+	alSource   al.Source
+	alBuffers  []al.Buffer
+	source     io.ReadSeeker
+	sampleRate int
 }
 
+var m sync.Mutex
+
+var sn = 0
+
 func newPlayer(src io.ReadSeeker, sampleRate int) *Player {
-	p, err := audio.NewPlayer(&readSeekCloser{src}, audio.Stereo16, int64(sampleRate))
-	if err != nil {
-		// TODO: Should we return errors for this method?
-		panic(err)
+	m.Lock()
+	if err := al.OpenDevice(); err != nil {
+		panic(fmt.Sprintf("audio: OpenAL initialization failed: %v", err))
 	}
-	pp := &player{p}
-	return &Player{pp}
+	// TODO: Too many generating sources may cause error. Limit the number of sources.
+	s := al.GenSources(1)
+	if err := al.Error(); err != 0 {
+		panic(fmt.Sprintf("audio: al.GenSources error: %d", err))
+	}
+	m.Unlock()
+	p := &player{
+		alSource:   s[0],
+		alBuffers:  []al.Buffer{},
+		source:     src,
+		sampleRate: sampleRate,
+	}
+	runtime.SetFinalizer(p, (*player).close)
+	return &Player{p}
+}
+
+const bufferSize = 1024
+
+func (p *player) proceed() error {
+	m.Lock()
+	processedNum := p.alSource.BuffersProcessed()
+	if 0 < processedNum {
+		bufs := make([]al.Buffer, processedNum)
+		p.alSource.UnqueueBuffers(bufs...)
+		p.alBuffers = append(p.alBuffers, bufs...)
+	}
+	m.Unlock()
+	for 0 < len(p.alBuffers) {
+		b := make([]byte, bufferSize)
+		n, err := p.source.Read(b)
+		if 0 < n {
+			m.Lock()
+			buf := p.alBuffers[0]
+			p.alBuffers = p.alBuffers[1:]
+			buf.BufferData(al.FormatStereo16, b[:n], int32(p.sampleRate))
+			p.alSource.QueueBuffers(buf)
+			m.Unlock()
+		}
+		if err != nil {
+			return err
+		}
+	}
+	m.Lock()
+	if p.alSource.State() == al.Stopped {
+		al.RewindSources(p.alSource)
+		al.PlaySources(p.alSource)
+	}
+	m.Unlock()
+
+	return nil
 }
 
 func (p *player) play() error {
-	// TODO: audio.NewPlayer interprets WAV header, which we don't want.
-	// Use OpenAL or native API instead.
-	return p.Play()
+	// TODO: What if play is already called?
+	emptyBytes := make([]byte, bufferSize)
+	m.Lock()
+	bufs := al.GenBuffers(8)
+	for _, buf := range bufs {
+		// Note that the third argument of only the first buffer is used.
+		buf.BufferData(al.FormatStereo16, emptyBytes, int32(p.sampleRate))
+		p.alSource.QueueBuffers(buf)
+	}
+	al.PlaySources(p.alSource)
+	m.Unlock()
+	go func() {
+		defer p.close()
+		for {
+			err := p.proceed()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				// TODO: Record the last error
+				panic(err)
+			}
+			time.Sleep(1)
+		}
+	}()
+	return nil
 }
 
 func (p *player) close() error {
-	return p.Close()
+	m.Lock()
+	if p.alSource != 0 {
+		al.DeleteSources(p.alSource)
+		p.alSource = 0
+	}
+	if 0 < len(p.alBuffers) {
+		al.DeleteBuffers(p.alBuffers...)
+		p.alBuffers = []al.Buffer{}
+	}
+	if err := al.Error(); err != 0 {
+		panic(fmt.Sprintf("audio: close error: %d", err))
+	}
+	m.Unlock()
+	runtime.SetFinalizer(p, nil)
+	return nil
 }
 
 // TODO: Implement Close method