playback: minor replaygain fixes

Fix issues with the new replaygain system in the ducking system and
when there is no metadata to parse.

app/src/main/java/org/oxycblt/auxio/playback/system/AudioReactor.kt

@@ -46,6 +46,8 @@ class AudioReactor(
         .setOnAudioFocusChangeListener(this)
         .build()
 
+    private var previousVolume = player.volume
+
     private var pauseWasTransient = false
 
     /**
@@ -105,19 +107,17 @@ class AudioReactor(
     }
 
     private fun onDuck() {
-        logD("Ducking, lowering volume")
-
+        previousVolume = player.volume
         player.volume = VOLUME_DUCK
+        logD("Ducked volume to ${player.volume} [previous: $previousVolume]")
     }
 
     private fun unduck() {
-        logD("Unducking, raising volume")
-
-        player.volume = VOLUME_FULL
+        player.volume = previousVolume
+        logD("Unducked volume to ${player.volume}")
     }
 
     companion object {
         private const val VOLUME_DUCK = 0.2f
-        private const val VOLUME_FULL = 1.0f
     }
 }

app/src/main/java/org/oxycblt/auxio/playback/system/PlaybackService.kt

@@ -238,6 +238,8 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
     override fun onTracksInfoChanged(tracksInfo: TracksInfo) {
         super.onTracksInfoChanged(tracksInfo)
 
+        var consumed = false
+
         for (info in tracksInfo.trackGroupInfos) {
             if (info.isSelected) {
                 for (i in 0 until info.trackGroup.length) {
@@ -245,6 +247,7 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
                         val metadata = info.trackGroup.getFormat(i).metadata
 
                         if (metadata != null) {
+                            consumed = true
                             player.volume = calculateReplayGain(metadata)
                             logD("Applied ReplayGain adjustment: ${player.volume}")
                         }
@@ -256,6 +259,12 @@ class PlaybackService : Service(), Player.Listener, PlaybackStateManager.Callbac
                 break
             }
         }
+
+        if (!consumed) {
+            // Sadly we couldn't parse any ReplayGain tags. Revert to normal volume.
+            player.volume = 1f
+            logD("No parsable ReplayGain tags, returning volume to 1.")
+        }
     }
 
     // --- PLAYBACK STATE CALLBACK OVERRIDES ---