Android audio playout now supports non-call media streams

webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java

Index: webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java
diff --git a/webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java b/webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java
index c2874316a5ddac0e6a0c03a78f810a918f420a38..825f627d038742d8c5ef6ec72a2bdd62e09fa7f2 100644
--- a/webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java
+++ b/webrtc/modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java
@@ -188,6 +188,17 @@ public class WebRtcAudioTrack {
       Logging.e(TAG, "AudioTrack.getMinBufferSize returns an invalid value.");
       return false;
     }
+    // The default (preferred) stream type is STREAM_VOICE_CALL since the
+    // WebRTC stack is mainly intended for VoIP calls.
+    int streamType = AudioManager.STREAM_VOICE_CALL;
+    if (audioManager.getMode() != AudioManager.MODE_IN_COMMUNICATION) {
+      // But if the user wants to run in another mode than COMM mode, we
+      // accept it and change the stream type to STREAM_MUSIC instead. It can
+      // e.g. be suitable for applications that do not record audio or if a
+      // call shall be casted to a Chromecast device.
+      streamType = AudioManager.STREAM_MUSIC;
+      Logging.w(TAG, "Using AudioManager.STREAM_MUSIC as stream type.");
+    }
 
     // Ensure that prevision audio session was stopped correctly before trying
     // to create a new AudioTrack.
@@ -199,9 +210,8 @@ public class WebRtcAudioTrack {
       // Create an AudioTrack object and initialize its associated audio buffer.
       // The size of this buffer determines how long an AudioTrack can play
       // before running out of data.
-      audioTrack =
-          new AudioTrack(AudioManager.STREAM_VOICE_CALL, sampleRate, AudioFormat.CHANNEL_OUT_MONO,
-              AudioFormat.ENCODING_PCM_16BIT, minBufferSizeInBytes, AudioTrack.MODE_STREAM);
+      audioTrack = new AudioTrack(streamType, sampleRate, AudioFormat.CHANNEL_OUT_MONO,
+          AudioFormat.ENCODING_PCM_16BIT, minBufferSizeInBytes, AudioTrack.MODE_STREAM);
     } catch (IllegalArgumentException e) {
       Logging.d(TAG, e.getMessage());
       return false;