audio: Use bigger buffers for mobiles

audio/audio.go

@@ -234,9 +234,7 @@ func (c *Context) loop() {
 	// e.g. a variable for JVM on Android might not be set.
 	<-initCh
 
-	// On most desktop environments, 4096 [bytes] is enough
-	// but there are some known environment that is too short (e.g. Windows on Parallels, iOS).
-	p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, 8192)
+	p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, bufferSize())
 	if err != nil {
 		c.err = err
 		return

audio/buffersize_mobile.go

@@ -0,0 +1,23 @@
+// Copyright 2018 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build android ios
+
+package audio
+
+func bufferSize() int {
+	// From the experience of Daigo's games (e.g. Clock of Atonement),
+	// 8192 is not enough on mobile devices. Use x1.5 value.
+	return 12288
+}

audio/buffersize_notmobile.go

@@ -0,0 +1,24 @@
+// Copyright 2018 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !android
+// +build !ios
+
+package audio
+
+func bufferSize() int {
+	// On most desktop environments, 4096 [bytes] is enough
+	// but there are some known environment that is too short (e.g. Windows on Parallels).
+	return 8192
+}