diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index 2cc6236..11d82b4 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -96,7 +96,8 @@
                                 size_t frameCountToBeReady = SIZE_MAX,
                                 float speed = 1.0f,
                                 bool isSpatialized = false,
-                                bool isBitPerfect = false);
+                                bool isBitPerfect = false,
+                                float volume = 0.0f);
     ~Track() override;
     status_t initCheck() const final;
     void appendDumpHeader(String8& result) const final;
@@ -222,6 +223,14 @@
 
     bool getInternalMute() const final { return mInternalMute; }
     void setInternalMute(bool muted) final { mInternalMute = muted; }
+
+    // VolumePortInterface implementation
+    void setPortVolume(float volume) override {
+        mVolume = volume;
+        signal();
+    }
+    float getPortVolume() const override { return mVolume; }
+
 protected:
 
     DISALLOW_COPY_AND_ASSIGN(Track);
@@ -403,8 +412,8 @@
     // access these two variables only when holding player thread lock.
     std::unique_ptr<os::PersistableBundle> mMuteEventExtras;
     mute_state_t        mMuteState;
-
     bool                mInternalMute = false;
+    float mVolume = 0.0f;
 };  // end of Track