Added support for audio ducking (not just loss of focus).

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/playback/PlayerWrapper.java

@@ -9,6 +9,8 @@ import io.casey.musikcube.remote.util.Preconditions;
 
 public abstract class PlayerWrapper {
     private static final String TAG = "MediaPlayerWrapper";
+    private static final float DUCK_COEF = 0.2f; /* volume = 20% when ducked */
+    private static final float DUCK_NONE = -1.0f;
 
     public enum State {
         Stopped,
@@ -29,19 +31,52 @@ public abstract class PlayerWrapper {
     private static Set<PlayerWrapper> activePlayers = new HashSet<>();
     private static float globalVolume = 1.0f;
     private static boolean globalMuted = false;
+    private static float preDuckGlobalVolume = DUCK_NONE;
 
-    public static void setGlobalVolume(final float volume) {
+    public static void duck() {
         Preconditions.throwIfNotOnMainThread();
 
-        globalVolume = volume;
+        if (preDuckGlobalVolume == DUCK_NONE) {
-        for (final PlayerWrapper w : activePlayers) {
+            final float lastVolume = globalVolume;
-            w.updateVolume();
+            setGlobalVolume(globalVolume * DUCK_COEF);
+            preDuckGlobalVolume = lastVolume;
+        }
+    }
+
+    public static void unduck() {
+        Preconditions.throwIfNotOnMainThread();
+
+        if (preDuckGlobalVolume != DUCK_NONE) {
+            final float temp = preDuckGlobalVolume;
+            preDuckGlobalVolume = DUCK_NONE;
+            setGlobalVolume(temp);
+        }
+    }
+
+    public static void setGlobalVolume(float volume) {
+        Preconditions.throwIfNotOnMainThread();
+
+        if (preDuckGlobalVolume != DUCK_NONE) {
+            preDuckGlobalVolume = volume;
+            volume = volume * DUCK_COEF;
+        }
+
+        if (volume != globalVolume) {
+            globalVolume = volume;
+            for (final PlayerWrapper w : activePlayers) {
+                w.updateVolume();
+            }
         }
     }
 
     public static float getGlobalVolume() {
         Preconditions.throwIfNotOnMainThread();
-        return globalMuted ? 0 : globalVolume;
+
+        if (globalMuted) {
+            return 0;
+        }
+
+        return (preDuckGlobalVolume == DUCK_NONE) ? globalVolume : preDuckGlobalVolume;
     }
 
     public static void setGlobalMute(final boolean muted) {

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/playback/StreamingPlaybackService.java

@@ -858,23 +858,23 @@ public class StreamingPlaybackService implements PlaybackService {
 
     private Runnable pauseServiceShutdownRunnable = () -> SystemService.shutdown();
 
-    private AudioManager.OnAudioFocusChangeListener audioFocusChangeListener
+    private AudioManager.OnAudioFocusChangeListener audioFocusChangeListener = (flag) -> {
-        = new AudioManager.OnAudioFocusChangeListener() {
+        switch (flag) {
-        @Override
+            case AudioManager.AUDIOFOCUS_GAIN:
-        public void onAudioFocusChange(int flag) {
+            case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT:
-            switch (flag) {
+            case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE:
-                case AudioManager.AUDIOFOCUS_GAIN:
+            case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK:
-                case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT:
+                PlayerWrapper.unduck();
-                case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE:
+                break;
-                case AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK:
-                    break;
 
-                case AudioManager.AUDIOFOCUS_LOSS:
+            case AudioManager.AUDIOFOCUS_LOSS:
-                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
+            case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
-                case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
+                killAudioFocus();
-                    killAudioFocus();
+                break;
-                    break;
+
-            }
+            case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
+                PlayerWrapper.duck();
+                break;
         }
     };
 

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/playback/SystemService.java

@@ -77,10 +77,6 @@ public class SystemService extends Service {
     public static void shutdown() {
         final Context c = Application.getInstance();
         c.startService(new Intent(c, SystemService.class).setAction(ACTION_SHUT_DOWN));
-
-        final Exception ex = new Exception();
-        ex.fillInStackTrace();
-        ex.printStackTrace();
     }
 
     @Override
@@ -266,8 +262,8 @@ public class SystemService extends Service {
             }
             else if (albumArtModel.is(artist, album)) {
                 if (image == null && Strings.notEmpty(albumArtModel.getUrl())) {
-                /* lookup may have failed -- try again. if the fetch is already in
+                    /* lookup may have failed -- try again. if the fetch is already in
-                progress this will be a no-op */
+                    progress this will be a no-op */
                     albumArtModel.fetch();
                 }
 

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/websocket/Prefs.java

@@ -16,6 +16,7 @@ public interface Prefs {
         String CERT_VALIDATION_DISABLED = "cert_validation_disabled";
         String TRANSCODER_BITRATE_INDEX = "transcoder_bitrate_index";
         String DISK_CACHE_SIZE_INDEX = "disk_cache_size_index";
+        String SYSTEM_SERVICE_FOR_REMOTE = "system_service_for_remote";
     }
 
     interface Default {
@@ -31,5 +32,6 @@ public interface Prefs {
         boolean CERT_VALIDATION_DISABLED = false;
         int TRANSCODER_BITRATE_INDEX = 0;
         int DISK_CACHE_SIZE_INDEX = 0;
+        boolean SYSTEM_SERVICE_FOR_REMOTE = false;
     }
 }

src/musikdroid/app/src/main/res/values/strings.xml

@@ -67,6 +67,7 @@
     <string name="settings_ssl_dialog_message">the musikcube server doesn\'t support ssl by default. it does, however, work very well with nginx and ssl termination. press \'learn more\' for configuration information.</string>
     <string name="settings_disable_cert_validation_title">certificate verification</string>
     <string name="settings_disable_cert_validation_message">there is really no reason to enable this setting. ssl without certificate validation opens you up to man-in-the-middle attacks, and only adds a false sense of security.\n\nare you sure you want to enable this setting?</string>
+    <string name="settings_enable_notification_for_remote_playback">enable lock screen integration for remote playback</string>
     <string name="unknown_artist">[unknown artist]</string>
     <string name="unknown_album">[unknown album]</string>
     <string name="unknown_title">[unknown title]</string>