audio: Bug fix: Do not create players every call of IsReady

Close #1709

audio/audio.go

@@ -71,6 +71,7 @@ type Context struct {
 	sampleRate int
 	err        error
 	ready      bool
+	readyOnce  sync.Once
 
 	players map[playerImpl]struct{}
 
@@ -255,7 +256,9 @@ func (c *Context) IsReady() bool {
 		return r
 	}
 
+	c.readyOnce.Do(func() {
 		// Create another goroutine since (*Player).Play can lock the context's mutex.
+		// TODO: Is this needed for reader players?
 		go func() {
 			// The audio context is never ready unless there is a player. This is
 			// problematic when a user tries to play audio after the context is ready.
@@ -264,6 +267,7 @@ func (c *Context) IsReady() bool {
 			p := NewPlayerFromBytes(c, make([]byte, bufferSize()*2))
 			p.Play()
 		}()
+	})
 
 	return r
 }