diff --git a/camera/device/default/ExternalCameraDeviceSession.h b/camera/device/default/ExternalCameraDeviceSession.h
new file mode 100644
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--- /dev/null
+++ b/camera/device/default/ExternalCameraDeviceSession.h
@@ -0,0 +1,399 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef HARDWARE_INTERFACES_CAMERA_DEVICE_DEFAULT_EXTERNALCAMERADEVICESESSION_H_
+#define HARDWARE_INTERFACES_CAMERA_DEVICE_DEFAULT_EXTERNALCAMERADEVICESESSION_H_
+
+#include <ExternalCameraUtils.h>
+#include <SimpleThread.h>
+#include <aidl/android/hardware/camera/common/Status.h>
+#include <aidl/android/hardware/camera/device/BnCameraDeviceSession.h>
+#include <aidl/android/hardware/camera/device/BufferRequest.h>
+#include <aidl/android/hardware/camera/device/Stream.h>
+#include <android-base/unique_fd.h>
+#include <fmq/AidlMessageQueue.h>
+#include <utils/Thread.h>
+#include <deque>
+#include <list>
+
+namespace android {
+namespace hardware {
+namespace camera {
+namespace device {
+namespace implementation {
+
+using ::aidl::android::hardware::camera::common::Status;
+using ::aidl::android::hardware::camera::device::BnCameraDeviceSession;
+using ::aidl::android::hardware::camera::device::BufferCache;
+using ::aidl::android::hardware::camera::device::BufferRequest;
+using ::aidl::android::hardware::camera::device::CameraMetadata;
+using ::aidl::android::hardware::camera::device::CameraOfflineSessionInfo;
+using ::aidl::android::hardware::camera::device::CaptureRequest;
+using ::aidl::android::hardware::camera::device::HalStream;
+using ::aidl::android::hardware::camera::device::ICameraDeviceCallback;
+using ::aidl::android::hardware::camera::device::ICameraOfflineSession;
+using ::aidl::android::hardware::camera::device::RequestTemplate;
+using ::aidl::android::hardware::camera::device::Stream;
+using ::aidl::android::hardware::camera::device::StreamConfiguration;
+using ::aidl::android::hardware::common::fmq::MQDescriptor;
+using ::aidl::android::hardware::common::fmq::SynchronizedReadWrite;
+using ::android::AidlMessageQueue;
+using ::android::base::unique_fd;
+using ::android::hardware::camera::common::helper::SimpleThread;
+using ::android::hardware::camera::external::common::ExternalCameraConfig;
+using ::android::hardware::camera::external::common::SizeHasher;
+using ::ndk::ScopedAStatus;
+
+class ExternalCameraDeviceSession : public BnCameraDeviceSession, public OutputThreadInterface {
+  public:
+    ExternalCameraDeviceSession(const std::shared_ptr<ICameraDeviceCallback>&,
+                                const ExternalCameraConfig& cfg,
+                                const std::vector<SupportedV4L2Format>& sortedFormats,
+                                const CroppingType& croppingType,
+                                const common::V1_0::helper::CameraMetadata& chars,
+                                const std::string& cameraId, unique_fd v4l2Fd);
+    ~ExternalCameraDeviceSession() override;
+
+    // Caller must use this method to check if CameraDeviceSession ctor failed
+    bool isInitFailed();
+    bool isClosed();
+
+    ScopedAStatus close() override;
+
+    ScopedAStatus configureStreams(const StreamConfiguration& in_requestedConfiguration,
+                                   std::vector<HalStream>* _aidl_return) override;
+    ScopedAStatus constructDefaultRequestSettings(RequestTemplate in_type,
+                                                  CameraMetadata* _aidl_return) override;
+    ScopedAStatus flush() override;
+    ScopedAStatus getCaptureRequestMetadataQueue(
+            MQDescriptor<int8_t, SynchronizedReadWrite>* _aidl_return) override;
+    ScopedAStatus getCaptureResultMetadataQueue(
+            MQDescriptor<int8_t, SynchronizedReadWrite>* _aidl_return) override;
+    ScopedAStatus isReconfigurationRequired(const CameraMetadata& in_oldSessionParams,
+                                            const CameraMetadata& in_newSessionParams,
+                                            bool* _aidl_return) override;
+    ScopedAStatus processCaptureRequest(const std::vector<CaptureRequest>& in_requests,
+                                        const std::vector<BufferCache>& in_cachesToRemove,
+                                        int32_t* _aidl_return) override;
+    ScopedAStatus signalStreamFlush(const std::vector<int32_t>& in_streamIds,
+                                    int32_t in_streamConfigCounter) override;
+    ScopedAStatus switchToOffline(const std::vector<int32_t>& in_streamsToKeep,
+                                  CameraOfflineSessionInfo* out_offlineSessionInfo,
+                                  std::shared_ptr<ICameraOfflineSession>* _aidl_return) override;
+    ScopedAStatus repeatingRequestEnd(int32_t in_frameNumber,
+                                      const std::vector<int32_t>& in_streamIds) override;
+
+    Status importBuffer(int32_t streamId, uint64_t bufId, buffer_handle_t buf,
+                        buffer_handle_t** outBufPtr) override;
+
+    void notifyError(int32_t frameNumber, int32_t streamId, ErrorCode ec) override;
+
+    Status processCaptureRequestError(const std::shared_ptr<HalRequest>& ptr,
+                                      std::vector<NotifyMsg>* msgs,
+                                      std::vector<CaptureResult>* results) override;
+
+    Status processCaptureResult(std::shared_ptr<HalRequest>& ptr) override;
+    ssize_t getJpegBufferSize(int32_t width, int32_t height) const override;
+
+    // Called by CameraDevice to dump active device states
+    binder_status_t dump(int fd, const char** args, uint32_t numArgs) override;
+
+    static Status isStreamCombinationSupported(
+            const StreamConfiguration& config,
+            const std::vector<SupportedV4L2Format>& supportedFormats,
+            const ExternalCameraConfig& devCfg);
+
+    static const int kMaxProcessedStream = 2;
+    static const int kMaxStallStream = 1;
+    static const uint32_t kMaxBytesPerPixel = 2;
+
+    class BufferRequestThread : public SimpleThread {
+      public:
+        BufferRequestThread(std::weak_ptr<OutputThreadInterface> parent,
+                            std::shared_ptr<ICameraDeviceCallback> callbacks);
+
+        int requestBufferStart(const std::vector<HalStreamBuffer>&);
+        int waitForBufferRequestDone(
+                /*out*/ std::vector<HalStreamBuffer>*);
+
+        bool threadLoop() override;
+
+      private:
+        void waitForNextRequest();
+
+        const std::weak_ptr<OutputThreadInterface> mParent;
+        const std::shared_ptr<ICameraDeviceCallback> mCallbacks;
+
+        std::mutex mLock;
+        bool mRequestingBuffer = false;
+
+        std::vector<HalStreamBuffer> mBufferReqs;
+        std::vector<HalStreamBuffer> mPendingReturnBufferReqs;
+        // mHalBufferReqs is not under mLock protection during the HIDL transaction
+        std::vector<BufferRequest> mHalBufferReqs;
+
+        // request buffers takes much less time in steady state, but can take much longer
+        // when requesting 1st buffer from a stream.
+        // TODO: consider a separate timeout for new vs. steady state?
+        // TODO: or make sure framework is warming up the pipeline during configure new stream?
+        static const int kReqProcTimeoutMs = 66;
+
+        static const int kReqWaitTimeoutMs = 33;
+        static const int kReqWaitTimesWarn = 90;   // 33ms * 90 ~= 3 sec
+        std::condition_variable mRequestCond;      // signaled when a new buffer request incoming
+        std::condition_variable mRequestDoneCond;  // signaled when a request is done
+    };
+
+    class OutputThread : public SimpleThread {
+      public:
+        OutputThread(std::weak_ptr<OutputThreadInterface> parent, CroppingType,
+                     const common::V1_0::helper::CameraMetadata&,
+                     std::shared_ptr<BufferRequestThread> bufReqThread);
+        ~OutputThread();
+
+        Status allocateIntermediateBuffers(const Size& v4lSize, const Size& thumbSize,
+                                           const std::vector<Stream>& streams,
+                                           uint32_t blobBufferSize);
+        Status submitRequest(const std::shared_ptr<HalRequest>&);
+        void flush();
+        void dump(int fd);
+        bool threadLoop() override;
+
+        void setExifMakeModel(const std::string& make, const std::string& model);
+
+        // The remaining request list is returned for offline processing
+        std::list<std::shared_ptr<HalRequest>> switchToOffline();
+
+      protected:
+        static const int kFlushWaitTimeoutSec = 3;  // 3 sec
+        static const int kReqWaitTimeoutMs = 33;    // 33ms
+        static const int kReqWaitTimesMax = 90;     // 33ms * 90 ~= 3 sec
+
+        // Methods to request output buffer in parallel
+        int requestBufferStart(const std::vector<HalStreamBuffer>&);
+        int waitForBufferRequestDone(
+                /*out*/ std::vector<HalStreamBuffer>*);
+
+        void waitForNextRequest(std::shared_ptr<HalRequest>* out);
+        void signalRequestDone();
+
+        int cropAndScaleLocked(std::shared_ptr<AllocatedFrame>& in, const Size& outSize,
+                               YCbCrLayout* out);
+
+        int cropAndScaleThumbLocked(std::shared_ptr<AllocatedFrame>& in, const Size& outSize,
+                                    YCbCrLayout* out);
+
+        int createJpegLocked(HalStreamBuffer& halBuf,
+                             const common::V1_0::helper::CameraMetadata& settings);
+
+        void clearIntermediateBuffers();
+
+        const std::weak_ptr<OutputThreadInterface> mParent;
+        const CroppingType mCroppingType;
+        const common::V1_0::helper::CameraMetadata mCameraCharacteristics;
+
+        mutable std::mutex mRequestListLock;       // Protect access to mRequestList,
+                                                   // mProcessingRequest and mProcessingFrameNumber
+        std::condition_variable mRequestCond;      // signaled when a new request is submitted
+        std::condition_variable mRequestDoneCond;  // signaled when a request is done processing
+        std::list<std::shared_ptr<HalRequest>> mRequestList;
+        bool mProcessingRequest = false;
+        uint32_t mProcessingFrameNumber = 0;
+
+        // V4L2 frameIn
+        // (MJPG decode)-> mYu12Frame
+        // (Scale)-> mScaledYu12Frames
+        // (Format convert) -> output gralloc frames
+        mutable std::mutex mBufferLock;  // Protect access to intermediate buffers
+        std::shared_ptr<AllocatedFrame> mYu12Frame;
+        std::shared_ptr<AllocatedFrame> mYu12ThumbFrame;
+        std::unordered_map<Size, std::shared_ptr<AllocatedFrame>, SizeHasher> mIntermediateBuffers;
+        std::unordered_map<Size, std::shared_ptr<AllocatedFrame>, SizeHasher> mScaledYu12Frames;
+        YCbCrLayout mYu12FrameLayout;
+        YCbCrLayout mYu12ThumbFrameLayout;
+        std::vector<uint8_t> mMuteTestPatternFrame;
+        uint32_t mTestPatternData[4] = {0, 0, 0, 0};
+        bool mCameraMuted = false;
+        uint32_t mBlobBufferSize = 0;  // 0 -> HAL derive buffer size, else: use given size
+
+        std::string mExifMake;
+        std::string mExifModel;
+
+        const std::shared_ptr<BufferRequestThread> mBufferRequestThread;
+    };
+
+  private:
+    bool initialize();
+    // To init/close different version of output thread
+    void initOutputThread();
+    void closeOutputThread();
+    void closeOutputThreadImpl();
+
+    void close(bool callerIsDtor);
+    Status initStatus() const;
+    status_t initDefaultRequests();
+
+    status_t fillCaptureResult(common::V1_0::helper::CameraMetadata& md, nsecs_t timestamp);
+    int configureV4l2StreamLocked(const SupportedV4L2Format& fmt, double fps = 0.0);
+    int v4l2StreamOffLocked();
+
+    int setV4l2FpsLocked(double fps);
+
+    std::unique_ptr<V4L2Frame> dequeueV4l2FrameLocked(
+            /*out*/ nsecs_t* shutterTs);  // Called with mLock held
+
+    void enqueueV4l2Frame(const std::shared_ptr<V4L2Frame>&);
+
+    // Check if input Stream is one of supported stream setting on this device
+    static bool isSupported(const Stream& stream,
+                            const std::vector<SupportedV4L2Format>& supportedFormats,
+                            const ExternalCameraConfig& cfg);
+
+    // Validate and import request's output buffers and acquire fence
+    Status importRequestLocked(const CaptureRequest& request,
+                               std::vector<buffer_handle_t*>& allBufPtrs,
+                               std::vector<int>& allFences);
+
+    Status importRequestLockedImpl(const CaptureRequest& request,
+                                   std::vector<buffer_handle_t*>& allBufPtrs,
+                                   std::vector<int>& allFences);
+
+    Status importBufferLocked(int32_t streamId, uint64_t bufId, buffer_handle_t buf,
+                              /*out*/ buffer_handle_t** outBufPtr);
+    static void cleanupInflightFences(std::vector<int>& allFences, size_t numFences);
+    void cleanupBuffersLocked(int id);
+
+    void updateBufferCaches(const std::vector<BufferCache>& cachesToRemove);
+
+    Status processOneCaptureRequest(const CaptureRequest& request);
+    void notifyShutter(int32_t frameNumber, nsecs_t shutterTs);
+
+    void invokeProcessCaptureResultCallback(std::vector<CaptureResult>& results, bool tryWriteFmq);
+    Size getMaxJpegResolution() const;
+
+    Size getMaxThumbResolution() const;
+
+    int waitForV4L2BufferReturnLocked(std::unique_lock<std::mutex>& lk);
+
+    // Main body of switchToOffline. This method does not invoke any callbacks
+    // but instead returns the necessary callbacks in output arguments so callers
+    // can callback later without holding any locks
+    Status switchToOffline(const std::vector<int32_t>& offlineStreams,
+                           /*out*/ std::vector<NotifyMsg>* msgs,
+                           /*out*/ std::vector<CaptureResult>* results,
+                           /*out*/ CameraOfflineSessionInfo* info,
+                           /*out*/ std::shared_ptr<ICameraOfflineSession>* session);
+
+    bool supportOfflineLocked(int32_t streamId);
+
+    // Whether a request can be completely dropped when switching to offline
+    bool canDropRequest(const std::vector<int32_t>& offlineStreams,
+                        std::shared_ptr<HalRequest> halReq);
+
+    void fillOfflineSessionInfo(const std::vector<int32_t>& offlineStreams,
+                                std::deque<std::shared_ptr<HalRequest>>& offlineReqs,
+                                const std::map<int, CirculatingBuffers>& circulatingBuffers,
+                                /*out*/ CameraOfflineSessionInfo* info);
+
+    // Protect (most of) HIDL interface methods from synchronized-entering
+    mutable Mutex mInterfaceLock;
+
+    mutable Mutex mLock;  // Protect all private members except otherwise noted
+    const std::shared_ptr<ICameraDeviceCallback> mCallback;
+    const ExternalCameraConfig& mCfg;
+    const common::V1_0::helper::CameraMetadata mCameraCharacteristics;
+    const std::vector<SupportedV4L2Format> mSupportedFormats;
+    const CroppingType mCroppingType;
+    const std::string mCameraId;
+
+    // Not protected by mLock, this is almost a const.
+    // Setup in constructor, reset in close() after OutputThread is joined
+    unique_fd mV4l2Fd;
+
+    // device is closed either
+    //    - closed by user
+    //    - init failed
+    //    - camera disconnected
+    bool mClosed = false;
+    bool mInitialized = false;
+    bool mInitFail = false;
+    bool mFirstRequest = false;
+    common::V1_0::helper::CameraMetadata mLatestReqSetting;
+
+    bool mV4l2Streaming = false;
+    SupportedV4L2Format mV4l2StreamingFmt;
+    double mV4l2StreamingFps = 0.0;
+    size_t mV4L2BufferCount = 0;
+
+    static const int kBufferWaitTimeoutSec = 3;  // TODO: handle long exposure (or not allowing)
+    std::mutex mV4l2BufferLock;                  // protect the buffer count and condition below
+    std::condition_variable mV4L2BufferReturned;
+    size_t mNumDequeuedV4l2Buffers = 0;
+    uint32_t mMaxV4L2BufferSize = 0;
+
+    // Not protected by mLock (but might be used when mLock is locked)
+    std::shared_ptr<OutputThread> mOutputThread;
+
+    // Stream ID -> Stream cache
+    std::unordered_map<int, Stream> mStreamMap;
+
+    std::mutex mInflightFramesLock;  // protect mInflightFrames
+    std::unordered_set<uint32_t> mInflightFrames;
+
+    // Stream ID -> circulating buffers map
+    std::map<int, CirculatingBuffers> mCirculatingBuffers;
+    // Protect mCirculatingBuffers, must not lock mLock after acquiring this lock
+    mutable Mutex mCbsLock;
+
+    std::mutex mAfTriggerLock;  // protect mAfTrigger
+    bool mAfTrigger = false;
+
+    uint32_t mBlobBufferSize = 0;
+
+    static HandleImporter sHandleImporter;
+
+    bool mSupportBufMgr;
+    std::shared_ptr<BufferRequestThread> mBufferRequestThread;
+
+    /* Beginning of members not changed after initialize() */
+    using RequestMetadataQueue = AidlMessageQueue<int8_t, SynchronizedReadWrite>;
+    std::unique_ptr<RequestMetadataQueue> mRequestMetadataQueue;
+    using ResultMetadataQueue = AidlMessageQueue<int8_t, SynchronizedReadWrite>;
+    std::shared_ptr<ResultMetadataQueue> mResultMetadataQueue;
+
+    // Protect against invokeProcessCaptureResultCallback()
+    Mutex mProcessCaptureResultLock;
+
+    // tracks last seen stream config counter
+    int32_t mLastStreamConfigCounter = -1;
+
+    std::unordered_map<RequestTemplate, CameraMetadata> mDefaultRequests;
+
+    const Size mMaxThumbResolution;
+    const Size mMaxJpegResolution;
+
+    std::string mExifMake;
+    std::string mExifModel;
+    /* End of members not changed after initialize() */
+};
+
+}  // namespace implementation
+}  // namespace device
+}  // namespace camera
+}  // namespace hardware
+}  // namespace android
+
+#endif  // HARDWARE_INTERFACES_CAMERA_DEVICE_DEFAULT_EXTERNALCAMERADEVICESESSION_H_