audio: Replace 'for' with 'if' as preparation to avoid goroutine

exp/audio/audio_openal.go

@@ -100,7 +100,7 @@ func (p *player) proceed() error {
 		p.alBuffers = append(p.alBuffers, bufs...)
 	}
 
-	for 0 < len(p.alBuffers) {
+	if 0 < len(p.alBuffers) {
 		n, err := p.source.Read(tmpBuffer)
 		if 0 < n {
 			buf := p.alBuffers[0]
@@ -130,7 +130,6 @@ func (p *player) proceed() error {
 	return nil
 }
 
-// TODO: When is this called? Can we remove this?
 func (p *player) close() error {
 	if err := al.Error(); err != 0 {
 		return fmt.Errorf("audio: error before closing: %d", err)

exp/audio/audio_windows.go

@@ -116,6 +116,7 @@ func newPlayer(src io.Reader, sampleRate int) (*player, error) {
 }
 
 func (p *player) proceed() error {
+	// TODO: Read should be called only when there are buffers available?
 	b := make([]byte, bufferSize)
 	n, err := p.src.Read(b)
 	if 0 < n {