diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index ac7f6cf..9f2bd3a 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -446,7 +446,7 @@
      */
             status_t dump(int fd, const Vector<String16>& args) const;
 
-private:
+protected:
     /* copying audio tracks is not allowed */
                         AudioTrack(const AudioTrack& other);
             AudioTrack& operator = (const AudioTrack& other);
@@ -518,10 +518,33 @@
     int                     mAuxEffectId;
     mutable Mutex           mLock;
     status_t                mRestoreStatus;
+    bool                    mIsTimed;
     int                     mPreviousPriority;          // before start()
     int                     mPreviousSchedulingGroup;
 };
 
+class TimedAudioTrack : public AudioTrack
+{
+public:
+    TimedAudioTrack();
+
+    /* allocate a shared memory buffer that can be passed to queueTimedBuffer */
+    status_t allocateTimedBuffer(size_t size, sp<IMemory>* buffer);
+
+    /* queue a buffer obtained via allocateTimedBuffer for playback at the
+       given timestamp.  PTS units a microseconds on the media time timeline.
+       The media time transform (set with setMediaTimeTransform) set by the
+       audio producer will handle converting from media time to local time
+       (perhaps going through the common time timeline in the case of
+       synchronized multiroom audio case) */
+    status_t queueTimedBuffer(const sp<IMemory>& buffer, int64_t pts);
+
+    /* define a transform between media time and either common time or
+       local time */
+    enum TargetTimeline {LOCAL_TIME, COMMON_TIME};
+    status_t setMediaTimeTransform(const LinearTransform& xform,
+                                   TargetTimeline target);
+};
 
 }; // namespace android