audio: an inner player should be in the context

exp/audio/audio.go

@@ -94,6 +94,7 @@ type Context struct {
 	sampleRate  int
 	stream      *mixedPlayersStream
 	players     map[*Player]struct{}
+	innerPlayer *player
 	sync.Mutex
 }
 
@@ -104,9 +105,11 @@ func NewContext(sampleRate int) *Context {
 		players:    map[*Player]struct{}{},
 	}
 	c.stream = &mixedPlayersStream{c}
-	if err := startPlaying(c.stream, c.sampleRate); err != nil {
+	p, err := startPlaying(c.stream, c.sampleRate)
+	if err != nil {
 		panic(fmt.Sprintf("audio: NewContext error: %v", err))
 	}
+	c.innerPlayer = p
 	return c
 }
 

exp/audio/audio_js.go

@@ -31,17 +31,12 @@ type player struct {
 	bufferSource *js.Object
 }
 
-var currentPlayer *player
-
-func startPlaying(src io.Reader, sampleRate int) error {
+func startPlaying(src io.Reader, sampleRate int) (*player, error) {
 	// Do nothing in node.js.
 	if js.Global.Get("require") != js.Undefined {
-		return nil
+		return nil, nil
 	}
 
-	if currentPlayer != nil {
-		panic("audio: currentPlayer already exists")
-	}
 	class := js.Global.Get("AudioContext")
 	if class == js.Undefined {
 		class = js.Global.Get("webkitAudioContext")
@@ -49,17 +44,17 @@ func startPlaying(src io.Reader, sampleRate int) error {
 	if class == js.Undefined {
 		panic("audio: audio couldn't be initialized")
 	}
-	currentPlayer = &player{
+	p := &player{
 		src:          src,
 		sampleRate:   sampleRate,
 		bufferSource: nil,
 		context:      class.New(),
 	}
-	currentPlayer.position = currentPlayer.context.Get("currentTime").Float()
-	if err := currentPlayer.start(); err != nil {
-		return err
+	p.position = p.context.Get("currentTime").Float()
+	if err := p.start(); err != nil {
+		return nil, err
 	}
-	return nil
+	return p, nil
 }
 
 func toLR(data []byte) ([]int16, []int16) {

exp/audio/audio_openal.go

@@ -39,30 +39,25 @@ type player struct {
 	isClosed   bool
 }
 
-var currentPlayer *player
-
-func startPlaying(src io.Reader, sampleRate int) error {
-	if currentPlayer != nil {
-		panic("audio: currentPlayer already exists")
-	}
+func startPlaying(src io.Reader, sampleRate int) (*player, error) {
 	if e := al.OpenDevice(); e != nil {
-		return fmt.Errorf("audio: OpenAL initialization failed: %v", e)
+		return nil, fmt.Errorf("audio: OpenAL initialization failed: %v", e)
 	}
 	s := al.GenSources(1)
 	if err := al.Error(); err != 0 {
 		panic(fmt.Sprintf("audio: al.GenSources error: %d", err))
 	}
-	currentPlayer = &player{
+	p := &player{
 		alSource:   s[0],
 		alBuffers:  []al.Buffer{},
 		source:     src,
 		sampleRate: sampleRate,
 	}
-	runtime.SetFinalizer(currentPlayer, (*player).close)
-	if err := currentPlayer.start(); err != nil {
-		return err
+	runtime.SetFinalizer(p, (*player).close)
+	if err := p.start(); err != nil {
+		return nil, err
 	}
-	return nil
+	return p, nil
 }
 
 const bufferSize = 1024