diff --git a/media/libmediaplayer2/JAudioTrack.cpp b/media/libmediaplayer2/JAudioTrack.cpp
index 6d9605a..ac0cc57 100644
--- a/media/libmediaplayer2/JAudioTrack.cpp
+++ b/media/libmediaplayer2/JAudioTrack.cpp
@@ -32,6 +32,8 @@
         uint32_t sampleRate,                          // AudioFormat && bufferSizeInBytes
         audio_format_t format,                        // AudioFormat && bufferSizeInBytes
         audio_channel_mask_t channelMask,             // AudioFormat && bufferSizeInBytes
+        callback_t cbf,                               // Offload
+        void* user,                                   // Offload
         size_t frameCount,                            // bufferSizeInBytes
         audio_session_t sessionId,                    // AudioTrack
         const audio_attributes_t* pAttributes,        // AudioAttributes
@@ -90,8 +92,27 @@
         jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetSessionId, sessionId);
     }
 
+    if (cbf != NULL) {
+        jmethodID jSetOffloadedPlayback = env->GetMethodID(jBuilderCls, "setOffloadedPlayback",
+                "(Z)Landroid/media/AudioTrack$Builder;");
+        jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetOffloadedPlayback, true);
+        mFlags = AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD;
+    }
+
     jmethodID jBuild = env->GetMethodID(jBuilderCls, "build", "()Landroid/media/AudioTrack;");
     mAudioTrackObj = env->CallObjectMethod(jBuilderObj, jBuild);
+
+    if (cbf != NULL) {
+        // Set offload mode callback
+        jobject jStreamEventCallbackObj = createStreamEventCallback(cbf, user);
+        jobject jExecutorObj = createCallbackExecutor();
+        jmethodID jSetStreamEventCallback = env->GetMethodID(
+                jAudioTrackCls,
+                "setStreamEventCallback",
+                "(Ljava/util/concurrent/Executor;Landroid/media/AudioTrack$StreamEventCallback;)V");
+        env->CallVoidMethod(
+                mAudioTrackObj, jSetStreamEventCallback, jExecutorObj, jStreamEventCallbackObj);
+    }
 }
 
 JAudioTrack::~JAudioTrack() {
@@ -160,6 +181,11 @@
     return true;
 }
 
+status_t JAudioTrack::getTimestamp(ExtendedTimestamp *timestamp __unused) {
+    // TODO: Implement this after appropriate Java AudioTrack method is available.
+    return NO_ERROR;
+}
+
 status_t JAudioTrack::setPlaybackRate(const AudioPlaybackRate &playbackRate) {
     // TODO: existing native AudioTrack returns INVALID_OPERATION on offload/direct/fast tracks.
     // Should we do the same thing?
@@ -442,6 +468,80 @@
     return routedDeviceId;
 }
 
+audio_session_t JAudioTrack::getAudioSessionId() {
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jmethodID jGetAudioSessionId = env->GetMethodID(mAudioTrackCls, "getAudioSessionId", "()I");
+    jint sessionId = env->CallIntMethod(mAudioTrackObj, jGetAudioSessionId);
+    return (audio_session_t) sessionId;
+}
+
+status_t JAudioTrack::setOutputDevice(audio_port_handle_t deviceId) {
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jclass jMP2ImplCls = env->FindClass("android/media/MediaPlayer2Impl");
+    jmethodID jSetAudioOutputDeviceById = env->GetMethodID(
+            jMP2ImplCls, "setAudioOutputDeviceById", "(Landroid/media/AudioTrack;I)Z");
+    jboolean result = env->CallStaticBooleanMethod(
+            jMP2ImplCls, jSetAudioOutputDeviceById, mAudioTrackObj, deviceId);
+    return result == true ? NO_ERROR : BAD_VALUE;
+}
+
+status_t JAudioTrack::pendingDuration(int32_t *msec) {
+    if (msec == nullptr) {
+        return BAD_VALUE;
+    }
+
+    bool isPurePcmData = audio_is_linear_pcm(format()) && (getFlags() & AUDIO_FLAG_HW_AV_SYNC) == 0;
+    if (!isPurePcmData) {
+        return INVALID_OPERATION;
+    }
+
+    // TODO: Need to know the difference btw. client and server time.
+    // If getTimestamp(ExtendedTimestamp) is ready, and un-comment below and modify appropriately.
+    // (copied from AudioTrack.cpp)
+
+//    ExtendedTimestamp ets;
+//    ExtendedTimestamp::LOCATION location = ExtendedTimestamp::LOCATION_SERVER;
+//    if (getTimestamp_l(&ets) == OK && ets.mTimeNs[location] > 0) {
+//        int64_t diff = ets.mPosition[ExtendedTimestamp::LOCATION_CLIENT]
+//                - ets.mPosition[location];
+//        if (diff < 0) {
+//            *msec = 0;
+//        } else {
+//            // ms is the playback time by frames
+//            int64_t ms = (int64_t)((double)diff * 1000 /
+//                    ((double)mSampleRate * mPlaybackRate.mSpeed));
+//            // clockdiff is the timestamp age (negative)
+//            int64_t clockdiff = (mState != STATE_ACTIVE) ? 0 :
+//                    ets.mTimeNs[location]
+//                    + ets.mTimebaseOffset[ExtendedTimestamp::TIMEBASE_MONOTONIC]
+//                    - systemTime(SYSTEM_TIME_MONOTONIC);
+//
+//            //ALOGV("ms: %lld  clockdiff: %lld", (long long)ms, (long long)clockdiff);
+//            static const int NANOS_PER_MILLIS = 1000000;
+//            *msec = (int32_t)(ms + clockdiff / NANOS_PER_MILLIS);
+//        }
+//        return NO_ERROR;
+//    }
+
+    return NO_ERROR;
+}
+
+status_t JAudioTrack::addAudioDeviceCallback(
+        const sp<AudioSystem::AudioDeviceCallback>& callback __unused) {
+    // TODO: Implement this after appropriate Java AudioTrack method is available.
+    return NO_ERROR;
+}
+
+status_t JAudioTrack::removeAudioDeviceCallback(
+        const sp<AudioSystem::AudioDeviceCallback>& callback __unused) {
+    // TODO: Implement this after appropriate Java AudioTrack method is available.
+    return NO_ERROR;
+}
+
+/////////////////////////////////////////////////////////////
+///                Private method begins                  ///
+/////////////////////////////////////////////////////////////
+
 jobject JAudioTrack::createVolumeShaperConfigurationObj(
         const sp<media::VolumeShaper::Configuration>& config) {
 
@@ -546,6 +646,24 @@
     return env->CallObjectMethod(jBuilderObj, jBuild);
 }
 
+jobject JAudioTrack::createStreamEventCallback(callback_t cbf, void* user) {
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jclass jCallbackCls = env->FindClass("android/media/MediaPlayer2Impl$StreamEventCallback");
+    jmethodID jCallbackCtor = env->GetMethodID(jCallbackCls, "<init>", "(JJJ)V");
+    jobject jCallbackObj = env->NewObject(jCallbackCls, jCallbackCtor, this, cbf, user);
+    return jCallbackObj;
+}
+
+jobject JAudioTrack::createCallbackExecutor() {
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jclass jExecutorsCls = env->FindClass("java/util/concurrent/Executors");
+    jmethodID jNewSingleThreadExecutor = env->GetStaticMethodID(jExecutorsCls,
+            "newSingleThreadExecutor", "()Ljava/util/concurrent/ExecutorService;");
+    jobject jSingleThreadExecutorObj =
+            env->CallStaticObjectMethod(jExecutorsCls, jNewSingleThreadExecutor);
+    return jSingleThreadExecutorObj;
+}
+
 status_t JAudioTrack::javaToNativeStatus(int javaStatus) {
     switch (javaStatus) {
     case AUDIO_JAVA_SUCCESS:
diff --git a/media/libmediaplayer2/include/mediaplayer2/JAudioTrack.h b/media/libmediaplayer2/include/mediaplayer2/JAudioTrack.h
index 10fa5e8..301825b 100644
--- a/media/libmediaplayer2/include/mediaplayer2/JAudioTrack.h
+++ b/media/libmediaplayer2/include/mediaplayer2/JAudioTrack.h
@@ -19,6 +19,7 @@
 
 #include <jni.h>
 #include <media/AudioResamplerPublic.h>
+#include <media/AudioSystem.h>
 #include <media/VolumeShaper.h>
 #include <system/audio.h>
 #include <utils/Errors.h>
@@ -31,6 +32,42 @@
 class JAudioTrack {
 public:
 
+    /* Events used by AudioTrack callback function (callback_t).
+     * Keep in sync with frameworks/base/media/java/android/media/AudioTrack.java NATIVE_EVENT_*.
+     */
+    enum event_type {
+        EVENT_MORE_DATA = 0,        // Request to write more data to buffer.
+        EVENT_NEW_IAUDIOTRACK = 6,  // IAudioTrack was re-created, either due to re-routing and
+                                    // voluntary invalidation by mediaserver, or mediaserver crash.
+        EVENT_STREAM_END = 7,       // Sent after all the buffers queued in AF and HW are played
+                                    // back (after stop is called) for an offloaded track.
+    };
+
+    class Buffer
+    {
+    public:
+        size_t      mSize;        // input/output in bytes.
+        void*       mData;        // pointer to the audio data.
+    };
+
+    /* As a convenience, if a callback is supplied, a handler thread
+     * is automatically created with the appropriate priority. This thread
+     * invokes the callback when a new buffer becomes available or various conditions occur.
+     *
+     * Parameters:
+     *
+     * event:   type of event notified (see enum AudioTrack::event_type).
+     * user:    Pointer to context for use by the callback receiver.
+     * info:    Pointer to optional parameter according to event type:
+     *          - EVENT_MORE_DATA: pointer to JAudioTrack::Buffer struct. The callback must not
+     *            write more bytes than indicated by 'size' field and update 'size' if fewer bytes
+     *            are written.
+     *          - EVENT_NEW_IAUDIOTRACK: unused.
+     *          - EVENT_STREAM_END: unused.
+     */
+
+    typedef void (*callback_t)(int event, void* user, void *info);
+
     /* Creates an JAudioTrack object for non-offload mode.
      * Once created, the track needs to be started before it can be used.
      * Unspecified values are set to appropriate default values.
@@ -49,6 +86,9 @@
      *                     output sink.
      *                     (TODO: How can we check whether a format is supported?)
      * channelMask:        Channel mask, such that audio_is_output_channel(channelMask) is true.
+     * cbf:                Callback function. If not null, this function is called periodically
+     *                     to provide new data and inform of marker, position updates, etc.
+     * user:               Context for use by the callback receiver.
      * frameCount:         Minimum size of track PCM buffer in frames. This defines the
      *                     application's contribution to the latency of the track.
      *                     The actual size selected by the JAudioTrack could be larger if the
@@ -68,35 +108,20 @@
                 uint32_t sampleRate,
                 audio_format_t format,
                 audio_channel_mask_t channelMask,
+                callback_t cbf,
+                void* user,
                 size_t frameCount = 0,
                 audio_session_t sessionId  = AUDIO_SESSION_ALLOCATE,
                 const audio_attributes_t* pAttributes = NULL,
                 float maxRequiredSpeed = 1.0f);
 
     /*
-       Temporarily removed constructor arguments:
-
-       // Q. Values are in audio-base.h, but where can we find explanation for them?
-       audio_output_flags_t flags,
-
        // Q. May be used in AudioTrack.setPreferredDevice(AudioDeviceInfo)?
        audio_port_handle_t selectedDeviceId,
 
-       // Should be deleted, since we don't use Binder anymore.
-       bool doNotReconnect,
-
-       // Do we need UID and PID?
-       uid_t uid,
-       pid_t pid,
-
-       // TODO: Uses these values when Java AudioTrack supports the offload mode.
-       callback_t cbf,
-       void* user,
+       // TODO: No place to use these values.
        int32_t notificationFrames,
        const audio_offload_info_t *offloadInfo,
-
-       // Fixed to false, but what is this?
-       threadCanCallJava
     */
 
     virtual ~JAudioTrack();
@@ -138,6 +163,46 @@
      */
     bool getTimestamp(AudioTimestamp& timestamp);
 
+    // TODO: This doc is just copied from AudioTrack.h. Revise it after implemenation.
+    /* Return the extended timestamp, with additional timebase info and improved drain behavior.
+     *
+     * This is similar to the AudioTrack.java API:
+     * getTimestamp(@NonNull AudioTimestamp timestamp, @AudioTimestamp.Timebase int timebase)
+     *
+     * Some differences between this method and the getTimestamp(AudioTimestamp& timestamp) method
+     *
+     *   1. stop() by itself does not reset the frame position.
+     *      A following start() resets the frame position to 0.
+     *   2. flush() by itself does not reset the frame position.
+     *      The frame position advances by the number of frames flushed,
+     *      when the first frame after flush reaches the audio sink.
+     *   3. BOOTTIME clock offsets are provided to help synchronize with
+     *      non-audio streams, e.g. sensor data.
+     *   4. Position is returned with 64 bits of resolution.
+     *
+     * Parameters:
+     *  timestamp: A pointer to the caller allocated ExtendedTimestamp.
+     *
+     * Returns NO_ERROR    on success; timestamp is filled with valid data.
+     *         BAD_VALUE   if timestamp is NULL.
+     *         WOULD_BLOCK if called immediately after start() when the number
+     *                     of frames consumed is less than the
+     *                     overall hardware latency to physical output. In WOULD_BLOCK cases,
+     *                     one might poll again, or use getPosition(), or use 0 position and
+     *                     current time for the timestamp.
+     *                     If WOULD_BLOCK is returned, the timestamp is still
+     *                     modified with the LOCATION_CLIENT portion filled.
+     *         DEAD_OBJECT if AudioFlinger dies or the output device changes and
+     *                     the track cannot be automatically restored.
+     *                     The application needs to recreate the AudioTrack
+     *                     because the audio device changed or AudioFlinger died.
+     *                     This typically occurs for direct or offloaded tracks
+     *                     or if mDoNotReconnect is true.
+     *         INVALID_OPERATION  if called on a offloaded or direct track.
+     *                     Use getTimestamp(AudioTimestamp& timestamp) instead.
+     */
+    status_t getTimestamp(ExtendedTimestamp *timestamp);
+
     /* Set source playback rate for timestretch
      * 1.0 is normal speed: < 1.0 is slower, > 1.0 is faster
      * 1.0 is normal pitch: < 1.0 is lower pitch, > 1.0 is higher pitch
@@ -270,7 +335,65 @@
      */
     audio_port_handle_t getRoutedDeviceId();
 
+    /* Returns the ID of the audio session this AudioTrack belongs to. */
+    audio_session_t getAudioSessionId();
+
+    /* Selects the audio device to use for output of this AudioTrack. A value of
+     * AUDIO_PORT_HANDLE_NONE indicates default routing.
+     *
+     * Parameters:
+     *  The device ID of the selected device (as returned by the AudioDevicesManager API).
+     *
+     * Returned value:
+     *  - NO_ERROR: successful operation
+     *  - BAD_VALUE: failed to find the valid output device with given device Id.
+     */
+    status_t setOutputDevice(audio_port_handle_t deviceId);
+
+    // TODO: Add AUDIO_OUTPUT_FLAG_DIRECT when it is possible to check.
+    // TODO: Add AUDIO_FLAG_HW_AV_SYNC when it is possible to check.
+    /* Returns the flags */
+    audio_output_flags_t getFlags() const { return mFlags; }
+
+    /* Obtain the pending duration in milliseconds for playback of pure PCM data remaining in
+     * AudioTrack.
+     *
+     * Returns NO_ERROR if successful.
+     *         INVALID_OPERATION if the AudioTrack does not contain pure PCM data.
+     *         BAD_VALUE if msec is nullptr.
+     */
+    status_t pendingDuration(int32_t *msec);
+
+    /* Adds an AudioDeviceCallback. The caller will be notified when the audio device to which this
+     * AudioTrack is routed is updated.
+     * Replaces any previously installed callback.
+     *
+     * Parameters:
+     *
+     * callback: The callback interface
+     *
+     * Returns NO_ERROR if successful.
+     *         INVALID_OPERATION if the same callback is already installed.
+     *         NO_INIT or PREMISSION_DENIED if AudioFlinger service is not reachable
+     *         BAD_VALUE if the callback is NULL
+     */
+    status_t addAudioDeviceCallback(const sp<AudioSystem::AudioDeviceCallback>& callback);
+
+    /* Removes an AudioDeviceCallback.
+     *
+     * Parameters:
+     *
+     * callback: The callback interface
+     *
+     * Returns NO_ERROR if successful.
+     *         INVALID_OPERATION if the callback is not installed
+     *         BAD_VALUE if the callback is NULL
+     */
+    status_t removeAudioDeviceCallback(const sp<AudioSystem::AudioDeviceCallback>& callback);
+
 private:
+    audio_output_flags_t mFlags;
+
     jclass mAudioTrackCls;
     jobject mAudioTrackObj;
 
@@ -282,6 +405,12 @@
     jobject createVolumeShaperOperationObj(
             const sp<media::VolumeShaper::Operation>& operation);
 
+    /* Creates a Java StreamEventCallback object */
+    jobject createStreamEventCallback(callback_t cbf, void* user);
+
+    /* Creates a Java Executor object for running a callback */
+    jobject createCallbackExecutor();
+
     status_t javaToNativeStatus(int javaStatus);
 };