audio/internal/readerderiver: Bug fix: Reduce noises on Android

Closes #1632

audio/internal/oboe/binding_android.cpp

@@ -57,6 +57,11 @@ public:
       std::lock_guard<std::mutex> lock(GetPlayersMutex());
       GetPlayers().insert(this);
     }
+    // Fill zeros with 1/60[s] as the first part to avoid noises (#1632).
+    // 1/60[s] is an arbitrary duration and might need to be adjusted.
+    size_t mul = channel_num_ * bit_depth_in_bytes_;
+    size_t size = (sample_rate_ * channel_num_ * bit_depth_in_bytes_) / 60 / mul * mul;
+    buf_.resize(size);
   }
 
   void SetVolume(double volume) {

audio/internal/readerdriver/driver_android.go

@@ -93,17 +93,30 @@ func (p *player) Play() {
 		return
 	}
 	defer p.cond.Signal()
+	var runLoop bool
 	if p.p == nil {
 		p.p = oboe.NewPlayer(p.context.sampleRate, p.context.channelNum, p.context.bitDepthInBytes, p.volume, func() {
 			p.cond.Signal()
 		})
-		go p.loop()
+		runLoop = true
+
+		// Fill the first part before playing to reduce noises (#1632).
+		buf := make([]byte, p.context.oneBufferSize())
+		n, err := p.src.Read(buf)
+		if err != nil && err != io.EOF {
+			p.setErrorImpl(err)
+			return
+		}
+		p.p.AppendBuffer(buf[:n])
 	}
 	if err := p.p.Play(); err != nil {
 		p.setErrorImpl(err)
 		return
 	}
 	p.state = playerPlay
+	if runLoop {
+		go p.loop()
+	}
 }
 
 func (p *player) IsPlaying() bool {