diff --git a/libs/vr/libdvr/dvr_tracking.cpp b/libs/vr/libdvr/dvr_tracking.cpp
index 77a9438..73addc9 100644
--- a/libs/vr/libdvr/dvr_tracking.cpp
+++ b/libs/vr/libdvr/dvr_tracking.cpp
@@ -29,6 +29,34 @@
   return -ENOSYS;
 }
 
+int dvrTrackingFeatureExtractorCreate(DvrTrackingFeatureExtractor**) {
+  ALOGE("dvrTrackingFeatureExtractorCreate is not implemented.");
+  return -ENOSYS;
+}
+
+void dvrTrackingFeatureExtractorDestroy(DvrTrackingFeatureExtractor*) {
+  ALOGE("dvrTrackingFeatureExtractorDestroy is not implemented.");
+}
+
+int dvrTrackingFeatureExtractorStart(DvrTrackingFeatureExtractor*,
+                                     DvrTrackingFeatureCallback, void*) {
+  ALOGE("dvrTrackingFeatureExtractorCreate is not implemented.");
+  return -ENOSYS;
+}
+
+int dvrTrackingFeatureExtractorStop(DvrTrackingFeatureExtractor*) {
+  ALOGE("dvrTrackingFeatureExtractorCreate is not implemented.");
+  return -ENOSYS;
+}
+
+int dvrTrackingFeatureExtractorProcessBuffer(DvrTrackingFeatureExtractor*,
+                                             DvrReadBuffer*,
+                                             const DvrTrackingBufferMetadata*,
+                                             bool*) {
+  ALOGE("dvrTrackingFeatureExtractorProcessBuffer is not implemented.");
+  return -ENOSYS;
+}
+
 int dvrTrackingSensorsCreate(DvrTrackingSensors**, const char*) {
   ALOGE("dvrTrackingSensorsCreate is not implemented.");
   return -ENOSYS;
diff --git a/libs/vr/libdvr/include/dvr/dvr_api.h b/libs/vr/libdvr/include/dvr/dvr_api.h
index 1e532a6..024cae9 100644
--- a/libs/vr/libdvr/include/dvr/dvr_api.h
+++ b/libs/vr/libdvr/include/dvr/dvr_api.h
@@ -375,6 +375,19 @@
                                          DvrWriteBufferQueue* write_queue);
 typedef int (*DvrTrackingCameraStopPtr)(DvrTrackingCamera* camera);
 
+typedef int (*DvrTrackingFeatureExtractorCreatePtr)(
+    DvrTrackingFeatureExtractor** out_extractor);
+typedef void (*DvrTrackingFeatureExtractorDestroyPtr)(
+    DvrTrackingFeatureExtractor* extractor);
+typedef int (*DvrTrackingFeatureExtractorStartPtr)(
+    DvrTrackingFeatureExtractor* extractor,
+    DvrTrackingFeatureCallback callback, void* context);
+typedef int (*DvrTrackingFeatureExtractorStopPtr)(
+    DvrTrackingFeatureExtractor* extractor);
+typedef int (*DvrTrackingFeatureExtractorProcessBufferPtr)(
+    DvrTrackingFeatureExtractor* extractor, DvrReadBuffer* buffer,
+    const DvrTrackingBufferMetadata* metadata, bool* out_skipped);
+
 typedef int (*DvrTrackingSensorsCreatePtr)(DvrTrackingSensors** out_sensors,
                                            const char* mode);
 typedef void (*DvrTrackingSensorsDestroyPtr)(DvrTrackingSensors* sensors);
diff --git a/libs/vr/libdvr/include/dvr/dvr_api_entries.h b/libs/vr/libdvr/include/dvr/dvr_api_entries.h
index 989980e..6620a37 100644
--- a/libs/vr/libdvr/include/dvr/dvr_api_entries.h
+++ b/libs/vr/libdvr/include/dvr/dvr_api_entries.h
@@ -187,6 +187,13 @@
 DVR_V1_API_ENTRY(TrackingCameraDestroy);
 DVR_V1_API_ENTRY(TrackingCameraStart);
 DVR_V1_API_ENTRY(TrackingCameraStop);
+
+DVR_V1_API_ENTRY(TrackingFeatureExtractorCreate);
+DVR_V1_API_ENTRY(TrackingFeatureExtractorDestroy);
+DVR_V1_API_ENTRY(TrackingFeatureExtractorStart);
+DVR_V1_API_ENTRY(TrackingFeatureExtractorStop);
+DVR_V1_API_ENTRY(TrackingFeatureExtractorProcessBuffer);
+
 DVR_V1_API_ENTRY(TrackingSensorsCreate);
 DVR_V1_API_ENTRY(TrackingSensorsDestroy);
 DVR_V1_API_ENTRY(TrackingSensorsStart);
diff --git a/libs/vr/libdvr/include/dvr/dvr_tracking.h b/libs/vr/libdvr/include/dvr/dvr_tracking.h
index ca97345..b5591a0 100644
--- a/libs/vr/libdvr/include/dvr/dvr_tracking.h
+++ b/libs/vr/libdvr/include/dvr/dvr_tracking.h
@@ -4,30 +4,21 @@
 #include <stdint.h>
 #include <sys/cdefs.h>
 
+#include <dvr/dvr_tracking_types.h>
+
 __BEGIN_DECLS
 
-// Represents a sensor event.
-typedef struct DvrTrackingSensorEvent {
-  // The sensor type.
-  int32_t sensor;
-
-  // Event type.
-  int32_t type;
-
-  // This is the timestamp recorded from the device. Taken in the middle
-  // of the integration interval and adjusted for any low pass filtering.
-  int64_t timestamp_ns;
-
-  // The event data.
-  float x;
-  float y;
-  float z;
-} DvrTrackingSensorEvent;
-
-typedef struct DvrTrackingSensors DvrTrackingSensors;
+typedef struct DvrReadBuffer DvrReadBuffer;
 typedef struct DvrTrackingCamera DvrTrackingCamera;
+typedef struct DvrTrackingFeatureExtractor DvrTrackingFeatureExtractor;
+typedef struct DvrTrackingSensors DvrTrackingSensors;
 typedef struct DvrWriteBufferQueue DvrWriteBufferQueue;
 
+// The callback for DvrTrackingFeatureExtractor that will deliver the feature
+// events. This callback is passed to dvrTrackingFeatureExtractorStart.
+typedef void (*DvrTrackingFeatureCallback)(void* context,
+                                           const DvrTrackingFeatures* event);
+
 // The callback for DvrTrackingSensors session that will deliver the events.
 // This callback is passed to dvrTrackingSensorsStart.
 typedef void (*DvrTrackingSensorEventCallback)(void* context,
@@ -67,7 +58,8 @@
 // @param write_queue A DvrWriteBufferQueue that the camera stack can use to
 //     populate the buffer into. The queue must be empty and the camera stack
 //     will request buffer allocation with proper buffer dimension, format, and
-//     usage.
+//     usage. Note that the write queue must be created with user_metadata_size
+//     set to sizeof(DvrTrackingBufferMetadata).
 // @return Zero on success, or negative error code.
 int dvrTrackingCameraStart(DvrTrackingCamera* camera,
                            DvrWriteBufferQueue* write_queue);
@@ -96,12 +88,12 @@
 int dvrTrackingSensorsCreate(DvrTrackingSensors** out_sensors,
                              const char* mode);
 
-// Destroy a DvrTrackingSensors session.
+// Destroys a DvrTrackingSensors session.
 //
 // @param sensors The DvrTrackingSensors struct to destroy.
 void dvrTrackingSensorsDestroy(DvrTrackingSensors* sensors);
 
-// Start the tracking.
+// Starts the tracking sensor session.
 //
 // This will start the device sensors and start pumping the feature and sensor
 // events as they arrive.
@@ -115,7 +107,7 @@
                             DvrTrackingSensorEventCallback callback,
                             void* context);
 
-// Stop the tracking.
+// Stops a DvrTrackingSensors session.
 //
 // This will stop the device sensors. dvrTrackingSensorsStart can be called to
 // restart them again.
@@ -124,6 +116,67 @@
 // @return Zero on success, or negative error code.
 int dvrTrackingSensorsStop(DvrTrackingSensors* sensors);
 
+// Creates a tracking feature extractor.
+//
+// This will initialize but not start the feature extraction session. Upon
+// successful creation, the client can call dvrTrackingFeatureExtractorStart to
+// start receiving features.
+//
+// @param out_extractor The pointer of a DvrTrackingFeatureExtractor will be
+//     filled here if the method call succeeds.
+int dvrTrackingFeatureExtractorCreate(
+    DvrTrackingFeatureExtractor** out_extractor);
+
+// Destroys a tracking feature extractor.
+//
+// @param extractor The DvrTrackingFeatureExtractor to destroy.
+void dvrTrackingFeatureExtractorDestroy(DvrTrackingFeatureExtractor* extractor);
+
+// Starts the tracking feature extractor.
+//
+// This will start the extractor and start pumping the output feature events to
+// the registered callback. Note that this method will create one or more
+// threads to handle feature processing.
+//
+// @param extractor The DvrTrackingFeatureExtractor to destroy.
+int dvrTrackingFeatureExtractorStart(DvrTrackingFeatureExtractor* extractor,
+                                     DvrTrackingFeatureCallback callback,
+                                     void* context);
+
+// Stops the tracking feature extractor.
+//
+// This will stop the extractor session and clean up all internal resourcse
+// related to this extractor. On succssful return, all internal therad started
+// by dvrTrackingFeatureExtractorStart should be stopped.
+//
+// @param extractor The DvrTrackingFeatureExtractor to destroy.
+int dvrTrackingFeatureExtractorStop(DvrTrackingFeatureExtractor* extractor);
+
+// Processes one buffer to extract features from.
+//
+// The buffer will be sent over to DSP for feature extraction. Once the process
+// is done, the processing thread will invoke DvrTrackingFeatureCallback with
+// newly extracted features. Note that not all buffers will be processed, as the
+// underlying DSP can only process buffers at a certain framerate. If a buffer
+// needs to be skipped, out_skipped filed will be set to true. Also note that
+// for successfully processed stereo buffer, two callbacks (one for each eye)
+// will be fired.
+//
+// @param extractor The DvrTrackingFeatureExtractor to destroy.
+// @param buffer The buffer to extract features from. Note that the buffer must
+//     be in acquired state for the buffer to be processed. Also note that the
+//     buffer will be released back to its producer on successful return of the
+//     method.
+// @param metadata The metadata associated with the buffer. Should be populated
+//     by DvrTrackingCamera session as user defined metadata.
+// @param out_skipped On successful return, the field will be set to true iff
+//     the buffer was skipped; and false iff the buffer was processed. This
+//     field is optional and nullptr can be passed here to ignore the field.
+// @return Zero on success, or negative error code.
+int dvrTrackingFeatureExtractorProcessBuffer(
+    DvrTrackingFeatureExtractor* extractor, DvrReadBuffer* buffer,
+    const DvrTrackingBufferMetadata* metadata, bool* out_skipped);
+
 __END_DECLS
 
 #endif  // ANDROID_DVR_TRACKING_H_
diff --git a/libs/vr/libdvr/include/dvr/dvr_tracking_types.h b/libs/vr/libdvr/include/dvr/dvr_tracking_types.h
new file mode 100644
index 0000000..81310d2
--- /dev/null
+++ b/libs/vr/libdvr/include/dvr/dvr_tracking_types.h
@@ -0,0 +1,104 @@
+#ifndef ANDROID_DVR_TRACKING_TYPES_H_
+#define ANDROID_DVR_TRACKING_TYPES_H_
+
+#include <stdint.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+typedef struct DvrTrackingBufferMetadata {
+  // Specifies the source of this image.
+  uint32_t camera_mask;
+  // Specifies the memory format of this image.
+  uint32_t format;
+  /// The width of the image data.
+  uint32_t width;
+  /// The height of the image data.
+  uint32_t height;
+  /// The number of bytes per scanline of image data.
+  uint32_t stride;
+  /// The frame number of this image.
+  int32_t frame_number;
+  /// The timestamp of this image in nanoseconds. Taken in the middle of the
+  /// exposure interval.
+  int64_t timestamp_ns;
+  // This is the timestamp for recording when the system using the HAL
+  // received the callback.  It will not be populated by the HAL.
+  int64_t callback_timestamp_ns;
+  /// The exposure duration of this image in nanoseconds.
+  int64_t exposure_duration_ns;
+} DvrTrackingBufferMetadata;
+
+// Represents a set of features extracted from a camera frame. Note that this
+// should be in sync with TangoHalCallbacks defined in tango-hal.h.
+typedef struct DvrTrackingFeatures {
+  // Specifies the source of the features.
+  uint32_t camera_mask;
+
+  // This is unused.
+  uint32_t unused;
+
+  // The timestamp in nanoseconds from the image that generated the features.
+  // Taken in the middle of the exposure interval.
+  int64_t timestamp_ns;
+
+  // This is the timestamp for recording when the system using the HAL
+  // received the callback.  It will not be populated by the HAL.
+  int64_t callback_timestamp_ns;
+
+  // The frame number from the image that generated the features.
+  int64_t frame_number;
+
+  // The number of features.
+  int count;
+
+  // An array of 2D image points for each feature in the current image.
+  // This is sub-pixel refined extremum location at the fine resolution.
+  float (*positions)[2];
+
+  // The id of these measurements.
+  int32_t* ids;
+
+  // The feature descriptors.
+  uint64_t (*descriptors)[8];
+
+  // Laplacian scores for each feature.
+  float* scores;
+
+  // Is this feature a minimum or maximum in the Laplacian image.
+  // 0 if the feature is a maximum, 1 if it is a minimum.
+  int32_t* is_minimum;
+
+  // This corresponds to the sub-pixel index of the laplacian image
+  // that the extremum was found.
+  float* scales;
+
+  // Computed orientation of keypoint as part of FREAK extraction, except
+  // it's represented in radians and measured anti-clockwise.
+  float* angles;
+
+  // Edge scores for each feature.
+  float* edge_scores;
+} DvrTrackingFeatures;
+
+// Represents a sensor event.
+typedef struct DvrTrackingSensorEvent {
+  // The sensor type.
+  int32_t sensor;
+
+  // Event type.
+  int32_t type;
+
+  // This is the timestamp recorded from the device. Taken in the middle
+  // of the integration interval and adjusted for any low pass filtering.
+  int64_t timestamp_ns;
+
+  // The event data.
+  float x;
+  float y;
+  float z;
+} DvrTrackingSensorEvent;
+
+__END_DECLS
+
+#endif  // ANDROID_DVR_TRACKING_TYPES_H_
diff --git a/libs/vr/libdvr/tests/dvr_tracking-test.cpp b/libs/vr/libdvr/tests/dvr_tracking-test.cpp
index 6a52801..3b6d6e1 100644
--- a/libs/vr/libdvr/tests/dvr_tracking-test.cpp
+++ b/libs/vr/libdvr/tests/dvr_tracking-test.cpp
@@ -13,9 +13,15 @@
   ASSERT_TRUE(api_.TrackingCameraCreate != nullptr);
   ASSERT_TRUE(api_.TrackingCameraStart != nullptr);
   ASSERT_TRUE(api_.TrackingCameraStop != nullptr);
+
+  ASSERT_TRUE(api_.TrackingFeatureExtractorCreate != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorDestroy != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorStart != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorStop != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorProcessBuffer != nullptr);
 }
 
-TEST_F(DvrTrackingTest, CreateFailsForInvalidInput) {
+TEST_F(DvrTrackingTest, CameraCreateFailsForInvalidInput) {
   int ret;
   ret = api_.TrackingCameraCreate(nullptr);
   EXPECT_EQ(ret, -EINVAL);
@@ -25,7 +31,7 @@
   EXPECT_EQ(ret, -EINVAL);
 }
 
-TEST_F(DvrTrackingTest, CreateDestroy) {
+TEST_F(DvrTrackingTest, CameraCreateDestroy) {
   DvrTrackingCamera* camera = nullptr;
   int ret = api_.TrackingCameraCreate(&camera);
 
@@ -35,6 +41,27 @@
   api_.TrackingCameraDestroy(camera);
 }
 
+TEST_F(DvrTrackingTest, FeatureExtractorCreateFailsForInvalidInput) {
+  int ret;
+  ret = api_.TrackingFeatureExtractorCreate(nullptr);
+  EXPECT_EQ(ret, -EINVAL);
+
+  DvrTrackingFeatureExtractor* camera =
+      reinterpret_cast<DvrTrackingFeatureExtractor*>(42);
+  ret = api_.TrackingFeatureExtractorCreate(&camera);
+  EXPECT_EQ(ret, -EINVAL);
+}
+
+TEST_F(DvrTrackingTest, FeatureExtractorCreateDestroy) {
+  DvrTrackingFeatureExtractor* camera = nullptr;
+  int ret = api_.TrackingFeatureExtractorCreate(&camera);
+
+  EXPECT_EQ(ret, 0);
+  ASSERT_TRUE(camera != nullptr);
+
+  api_.TrackingFeatureExtractorDestroy(camera);
+}
+
 #else  // !DVR_TRACKING_IMPLEMENTED
 
 TEST_F(DvrTrackingTest, NotImplemented) {
@@ -47,6 +74,20 @@
   EXPECT_EQ(api_.TrackingCameraStart(nullptr, nullptr), -ENOSYS);
   EXPECT_EQ(api_.TrackingCameraStop(nullptr), -ENOSYS);
 
+  ASSERT_TRUE(api_.TrackingFeatureExtractorCreate != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorDestroy != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorStart != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorStop != nullptr);
+  ASSERT_TRUE(api_.TrackingFeatureExtractorProcessBuffer != nullptr);
+
+  EXPECT_EQ(api_.TrackingFeatureExtractorCreate(nullptr), -ENOSYS);
+  EXPECT_EQ(api_.TrackingFeatureExtractorStart(nullptr, nullptr, nullptr),
+            -ENOSYS);
+  EXPECT_EQ(api_.TrackingFeatureExtractorStop(nullptr), -ENOSYS);
+  EXPECT_EQ(api_.TrackingFeatureExtractorProcessBuffer(nullptr, nullptr,
+                                                       nullptr, nullptr),
+            -ENOSYS);
+
   ASSERT_TRUE(api_.TrackingSensorsCreate != nullptr);
   ASSERT_TRUE(api_.TrackingSensorsDestroy != nullptr);
   ASSERT_TRUE(api_.TrackingSensorsStart != nullptr);