diff --git a/automotive/evs/aidl/impl/default/include/EvsCamera.h b/automotive/evs/aidl/impl/default/include/EvsCamera.h
index 5774db5..539d5f6 100644
--- a/automotive/evs/aidl/impl/default/include/EvsCamera.h
+++ b/automotive/evs/aidl/impl/default/include/EvsCamera.h
@@ -85,7 +85,7 @@
 
     void closeAllBuffers_unsafe();
 
-    // Returns (ID, handle) if succeeds. (static_cast<size_t>(-1), nullptr) otherwise.
+    // Returns (ID, handle) if succeeds. (kInvalidBufferID, nullptr) otherwise.
     [[nodiscard]] std::pair<std::size_t, buffer_handle_t> useBuffer_unsafe();
 
     void returnBuffer_unsafe(const std::size_t id);
@@ -133,6 +133,12 @@
 
     std::size_t mAvailableFrames{0};
     std::size_t mFramesInUse{0};
+
+    // We use all 1's as a reserved invalid buffer ID.
+    static constexpr std::size_t kInvalidBufferID = ~static_cast<std::size_t>(0);
+
+  public:
+    static bool IsBufferIDValid(const std::size_t bufferId) { return ~bufferId; }
 };
 
 }  // namespace aidl::android::hardware::automotive::evs::implementation
diff --git a/automotive/evs/aidl/impl/default/include/EvsMockCamera.h b/automotive/evs/aidl/impl/default/include/EvsMockCamera.h
index c7b9e0f..cd68532 100644
--- a/automotive/evs/aidl/impl/default/include/EvsMockCamera.h
+++ b/automotive/evs/aidl/impl/default/include/EvsMockCamera.h
@@ -17,29 +17,36 @@
 #pragma once
 
 #include "ConfigManager.h"
-#include "EvsCameraBase.h"
+#include "EvsCamera.h"
 
-#include <aidl/android/hardware/automotive/evs/BufferDesc.h>
 #include <aidl/android/hardware/automotive/evs/CameraDesc.h>
 #include <aidl/android/hardware/automotive/evs/CameraParam.h>
-#include <aidl/android/hardware/automotive/evs/EvsResult.h>
 #include <aidl/android/hardware/automotive/evs/IEvsCameraStream.h>
 #include <aidl/android/hardware/automotive/evs/IEvsDisplay.h>
 #include <aidl/android/hardware/automotive/evs/ParameterRange.h>
 #include <aidl/android/hardware/automotive/evs/Stream.h>
-// #include <android-base/result.h>
 #include <android/hardware_buffer.h>
 #include <ui/GraphicBuffer.h>
 
-#include <functional>
+#include <cstdint>
+#include <memory>
 #include <thread>
+#include <unordered_map>
+#include <vector>
 
 namespace aidl::android::hardware::automotive::evs::implementation {
 
-class EvsMockCamera : public EvsCameraBase {
+class EvsMockCamera : public EvsCamera {
+  private:
+    using Base = EvsCamera;
+
   public:
+    EvsMockCamera(Sigil sigil, const char* deviceName,
+                  std::unique_ptr<ConfigManager::CameraInfo>& camInfo);
+    EvsMockCamera(const EvsMockCamera&) = delete;
+    EvsMockCamera& operator=(const EvsMockCamera&) = delete;
+
     // Methods from ::android::hardware::automotive::evs::IEvsCamera follow.
-    ndk::ScopedAStatus doneWithFrame(const std::vector<evs::BufferDesc>& buffers) override;
     ndk::ScopedAStatus forcePrimaryClient(
             const std::shared_ptr<evs::IEvsDisplay>& display) override;
     ndk::ScopedAStatus getCameraInfo(evs::CameraDesc* _aidl_return) override;
@@ -51,49 +58,37 @@
     ndk::ScopedAStatus getParameterList(std::vector<evs::CameraParam>* _aidl_return) override;
     ndk::ScopedAStatus getPhysicalCameraInfo(const std::string& deviceId,
                                              evs::CameraDesc* _aidl_return) override;
-    ndk::ScopedAStatus importExternalBuffers(const std::vector<evs::BufferDesc>& buffers,
-                                             int32_t* _aidl_return) override;
-    ndk::ScopedAStatus pauseVideoStream() override;
-    ndk::ScopedAStatus resumeVideoStream() override;
     ndk::ScopedAStatus setExtendedInfo(int32_t opaqueIdentifier,
                                        const std::vector<uint8_t>& opaqueValue) override;
     ndk::ScopedAStatus setIntParameter(evs::CameraParam id, int32_t value,
                                        std::vector<int32_t>* effectiveValue) override;
     ndk::ScopedAStatus setPrimaryClient() override;
-    ndk::ScopedAStatus setMaxFramesInFlight(int32_t bufferCount) override;
-    ndk::ScopedAStatus startVideoStream(
-            const std::shared_ptr<evs::IEvsCameraStream>& receiver) override;
-    ndk::ScopedAStatus stopVideoStream() override;
     ndk::ScopedAStatus unsetPrimaryClient() override;
 
+    const evs::CameraDesc& getDesc() { return mDescription; }
+
     static std::shared_ptr<EvsMockCamera> Create(const char* deviceName);
     static std::shared_ptr<EvsMockCamera> Create(
             const char* deviceName, std::unique_ptr<ConfigManager::CameraInfo>& camInfo,
             const evs::Stream* streamCfg = nullptr);
-    EvsMockCamera(const EvsMockCamera&) = delete;
-    EvsMockCamera& operator=(const EvsMockCamera&) = delete;
-
-    virtual ~EvsMockCamera() override;
-
-    // Methods from EvsCameraBase follow.
-    void shutdown() override;
-
-    const evs::CameraDesc& getDesc() { return mDescription; }
-
-    // Constructors
-    EvsMockCamera(Sigil sigil, const char* deviceName,
-                  std::unique_ptr<ConfigManager::CameraInfo>& camInfo);
 
   private:
-    // These three functions are expected to be called while mAccessLock is held
-    bool setAvailableFrames_Locked(unsigned bufferCount);
-    unsigned increaseAvailableFrames_Locked(unsigned numToAdd);
-    unsigned decreaseAvailableFrames_Locked(unsigned numToRemove);
-
     void generateFrames();
     void fillMockFrame(buffer_handle_t handle, const AHardwareBuffer_Desc* pDesc);
-    void returnBufferLocked(const uint32_t bufferId);
-    ndk::ScopedAStatus stopVideoStream_impl();
+
+    ::android::status_t allocateOneFrame(buffer_handle_t* handle) override;
+
+    bool startVideoStreamImpl_locked(const std::shared_ptr<evs::IEvsCameraStream>& receiver,
+                                     ndk::ScopedAStatus& status,
+                                     std::unique_lock<std::mutex>& lck) override;
+
+    bool stopVideoStreamImpl_locked(ndk::ScopedAStatus& status,
+                                    std::unique_lock<std::mutex>& lck) override;
+
+    bool postVideoStreamStop_locked(ndk::ScopedAStatus& status,
+                                    std::unique_lock<std::mutex>& lck) override;
+
+    void initializeParameters();
 
     CameraDesc mDescription = {};  // The properties of this camera
 
@@ -114,28 +109,6 @@
     // Bytes per line in the buffers
     uint32_t mStride = 0;
 
-    struct BufferRecord {
-        buffer_handle_t handle;
-        bool inUse;
-
-        explicit BufferRecord(buffer_handle_t h) : handle(h), inUse(false){};
-    };
-
-    std::vector<BufferRecord> mBuffers;  // Graphics buffers to transfer images
-    unsigned mFramesAllowed;             // How many buffers are we currently using
-    unsigned mFramesInUse;               // How many buffers are currently outstanding
-
-    enum StreamStateValues {
-        STOPPED,
-        RUNNING,
-        STOPPING,
-        DEAD,
-    };
-    StreamStateValues mStreamState;
-
-    // Synchronization necessary to deconflict mCaptureThread from the main service thread
-    std::mutex mAccessLock;
-
     // Static camera module information
     std::unique_ptr<ConfigManager::CameraInfo>& mCameraInfo;
 
@@ -155,7 +128,6 @@
         int32_t value;
     };
     std::unordered_map<CameraParam, std::shared_ptr<CameraParameterDesc>> mParams;
-    void initializeParameters();
 };
 
 }  // namespace aidl::android::hardware::automotive::evs::implementation
diff --git a/automotive/evs/aidl/impl/default/src/EvsCamera.cpp b/automotive/evs/aidl/impl/default/src/EvsCamera.cpp
index 208a1a4..bc3bfdd 100644
--- a/automotive/evs/aidl/impl/default/src/EvsCamera.cpp
+++ b/automotive/evs/aidl/impl/default/src/EvsCamera.cpp
@@ -292,7 +292,7 @@
 std::pair<std::size_t, buffer_handle_t> EvsCamera::useBuffer_unsafe() {
     if (mFramesInUse >= mAvailableFrames) {
         DCHECK_EQ(mFramesInUse, mAvailableFrames);
-        return {static_cast<std::size_t>(-1), nullptr};
+        return {kInvalidBufferID, nullptr};
     }
     const std::size_t pos = mFramesInUse++;
     auto& buffer = mBuffers[pos];
diff --git a/automotive/evs/aidl/impl/default/src/EvsMockCamera.cpp b/automotive/evs/aidl/impl/default/src/EvsMockCamera.cpp
index 797b221..ef43925 100644
--- a/automotive/evs/aidl/impl/default/src/EvsMockCamera.cpp
+++ b/automotive/evs/aidl/impl/default/src/EvsMockCamera.cpp
@@ -15,28 +15,25 @@
  */
 
 #include "EvsMockCamera.h"
-#include "ConfigManager.h"
-#include "EvsEnumerator.h"
+
+#include <aidl/android/hardware/automotive/evs/EvsResult.h>
 
 #include <aidlcommonsupport/NativeHandle.h>
+#include <android-base/logging.h>
 #include <ui/GraphicBufferAllocator.h>
 #include <ui/GraphicBufferMapper.h>
 #include <utils/SystemClock.h>
 
+#include <cstddef>
+#include <cstdint>
 #include <memory>
+#include <tuple>
 
 namespace {
 
 using ::aidl::android::hardware::graphics::common::BufferUsage;
 using ::ndk::ScopedAStatus;
 
-// Arbitrary limit on number of graphics buffers allowed to be allocated
-// Safeguards against unreasonable resource consumption and provides a testable limit
-constexpr unsigned kMaxBuffersInFlight = 100;
-
-// Minimum number of buffers to run a video stream
-constexpr int kMinimumBuffersInFlight = 1;
-
 // Colors for the colorbar test pattern in ABGR format
 constexpr uint32_t kColors[] = {
         0xFFFFFFFF,  // white
@@ -56,7 +53,7 @@
 
 EvsMockCamera::EvsMockCamera([[maybe_unused]] Sigil sigil, const char* id,
                              std::unique_ptr<ConfigManager::CameraInfo>& camInfo)
-    : mFramesAllowed(0), mFramesInUse(0), mStreamState(STOPPED), mCameraInfo(camInfo) {
+    : mCameraInfo(camInfo) {
     LOG(DEBUG) << __FUNCTION__;
 
     /* set a camera id */
@@ -73,11 +70,6 @@
     initializeParameters();
 }
 
-EvsMockCamera::~EvsMockCamera() {
-    LOG(DEBUG) << __FUNCTION__;
-    shutdown();
-}
-
 void EvsMockCamera::initializeParameters() {
     mParams.emplace(
             CameraParam::BRIGHTNESS,
@@ -90,35 +82,6 @@
             new CameraParameterDesc(/* min= */ 0, /* max= */ 255, /* step= */ 1, /* value= */ 255));
 }
 
-// This gets called if another caller "steals" ownership of the camera
-void EvsMockCamera::shutdown() {
-    LOG(DEBUG) << __FUNCTION__;
-
-    // Make sure our output stream is cleaned up
-    // (It really should be already)
-    stopVideoStream_impl();
-
-    // Claim the lock while we work on internal state
-    std::lock_guard lock(mAccessLock);
-
-    // Drop all the graphics buffers we've been using
-    if (mBuffers.size() > 0) {
-        ::android::GraphicBufferAllocator& alloc(::android::GraphicBufferAllocator::get());
-        for (auto&& rec : mBuffers) {
-            if (rec.inUse) {
-                LOG(WARNING) << "WARNING: releasing a buffer remotely owned.";
-            }
-            alloc.free(rec.handle);
-            rec.handle = nullptr;
-        }
-        mBuffers.clear();
-    }
-
-    // Put this object into an unrecoverable error state since somebody else
-    // is going to own the underlying camera now
-    mStreamState = DEAD;
-}
-
 // Methods from ::aidl::android::hardware::automotive::evs::IEvsCamera follow.
 ScopedAStatus EvsMockCamera::getCameraInfo(CameraDesc* _aidl_return) {
     LOG(DEBUG) << __FUNCTION__;
@@ -128,115 +91,6 @@
     return ScopedAStatus::ok();
 }
 
-ScopedAStatus EvsMockCamera::setMaxFramesInFlight(int32_t bufferCount) {
-    LOG(DEBUG) << __FUNCTION__ << ", bufferCount = " << bufferCount;
-    ;
-
-    std::lock_guard lock(mAccessLock);
-
-    // If we've been displaced by another owner of the camera, then we can't do anything else
-    if (mStreamState == DEAD) {
-        LOG(ERROR) << "Ignoring setMaxFramesInFlight call when camera has been lost.";
-        return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::OWNERSHIP_LOST));
-    }
-
-    // We cannot function without at least one video buffer to send data
-    if (bufferCount < 1) {
-        LOG(ERROR) << "Ignoring setMaxFramesInFlight with less than one buffer requested.";
-        return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::INVALID_ARG));
-    }
-
-    // Update our internal state
-    if (!setAvailableFrames_Locked(bufferCount)) {
-        LOG(ERROR) << "Failed to adjust the maximum number of frames in flight.";
-        return ScopedAStatus::fromServiceSpecificError(
-                static_cast<int>(EvsResult::BUFFER_NOT_AVAILABLE));
-    }
-
-    return ScopedAStatus::ok();
-}
-
-ScopedAStatus EvsMockCamera::startVideoStream(const std::shared_ptr<IEvsCameraStream>& cb) {
-    LOG(DEBUG) << __FUNCTION__;
-
-    if (!cb) {
-        LOG(ERROR) << "A given stream callback is invalid.";
-        return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::INVALID_ARG));
-    }
-
-    std::lock_guard lock(mAccessLock);
-
-    // If we've been displaced by another owner of the camera, then we can't do anything else
-    if (mStreamState == DEAD) {
-        LOG(ERROR) << "Ignoring startVideoStream call when camera has been lost.";
-        return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::OWNERSHIP_LOST));
-    }
-
-    if (mStreamState != STOPPED) {
-        LOG(ERROR) << "Ignoring startVideoStream call when a stream is already running.";
-        return ScopedAStatus::fromServiceSpecificError(
-                static_cast<int>(EvsResult::STREAM_ALREADY_RUNNING));
-    }
-
-    // If the client never indicated otherwise, configure ourselves for a single streaming buffer
-    if (mFramesAllowed < kMinimumBuffersInFlight &&
-        !setAvailableFrames_Locked(kMinimumBuffersInFlight)) {
-        LOG(ERROR) << "Failed to start stream because we couldn't get a graphics buffer";
-        return ScopedAStatus::fromServiceSpecificError(
-                static_cast<int>(EvsResult::BUFFER_NOT_AVAILABLE));
-    }
-
-    // Record the user's callback for use when we have a frame ready
-    mStream = cb;
-
-    // Start the frame generation thread
-    mStreamState = RUNNING;
-    mCaptureThread = std::thread([this]() { generateFrames(); });
-
-    return ScopedAStatus::ok();
-}
-
-ScopedAStatus EvsMockCamera::doneWithFrame(const std::vector<BufferDesc>& list) {
-    std::lock_guard lock(mAccessLock);
-    for (const auto& desc : list) {
-        returnBufferLocked(desc.bufferId);
-    }
-
-    return ScopedAStatus::ok();
-}
-
-ScopedAStatus EvsMockCamera::stopVideoStream() {
-    LOG(DEBUG) << __FUNCTION__;
-    return stopVideoStream_impl();
-}
-
-ScopedAStatus EvsMockCamera::stopVideoStream_impl() {
-    std::unique_lock lock(mAccessLock);
-
-    if (mStreamState != RUNNING) {
-        // Safely return here because a stream is not running.
-        return ScopedAStatus::ok();
-    }
-
-    // Tell the GenerateFrames loop we want it to stop
-    mStreamState = STOPPING;
-
-    // Block outside the mutex until the "stop" flag has been acknowledged
-    // We won't send any more frames, but the client might still get some already in flight
-    LOG(DEBUG) << "Waiting for stream thread to end...";
-    lock.unlock();
-    if (mCaptureThread.joinable()) {
-        mCaptureThread.join();
-    }
-    lock.lock();
-
-    mStreamState = STOPPED;
-    mStream = nullptr;
-    LOG(DEBUG) << "Stream marked STOPPED.";
-
-    return ScopedAStatus::ok();
-}
-
 ScopedAStatus EvsMockCamera::getExtendedInfo(int32_t opaqueIdentifier,
                                              std::vector<uint8_t>* opaqueValue) {
     const auto it = mExtInfo.find(opaqueIdentifier);
@@ -264,14 +118,6 @@
     return ScopedAStatus::ok();
 }
 
-ScopedAStatus EvsMockCamera::pauseVideoStream() {
-    return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::NOT_SUPPORTED));
-}
-
-ScopedAStatus EvsMockCamera::resumeVideoStream() {
-    return ScopedAStatus::fromServiceSpecificError(static_cast<int>(EvsResult::NOT_SUPPORTED));
-}
-
 ScopedAStatus EvsMockCamera::setPrimaryClient() {
     /* Because EVS HW module reference implementation expects a single client at
      * a time, this returns a success code always.
@@ -346,232 +192,27 @@
     return ScopedAStatus::ok();
 }
 
-ScopedAStatus EvsMockCamera::importExternalBuffers(const std::vector<BufferDesc>& buffers,
-                                                   int32_t* _aidl_return) {
-    size_t numBuffersToAdd = buffers.size();
-    if (numBuffersToAdd < 1) {
-        LOG(DEBUG) << "Ignoring a request to import external buffers with an empty list.";
-        return ScopedAStatus::ok();
-    }
-
-    std::lock_guard lock(mAccessLock);
-    if (numBuffersToAdd > (kMaxBuffersInFlight - mFramesAllowed)) {
-        numBuffersToAdd -= (kMaxBuffersInFlight - mFramesAllowed);
-        LOG(WARNING) << "Exceed the limit on the number of buffers. " << numBuffersToAdd
-                     << " buffers will be imported only.";
-    }
-
-    ::android::GraphicBufferMapper& mapper = ::android::GraphicBufferMapper::get();
-    const size_t before = mFramesAllowed;
-    for (size_t i = 0; i < numBuffersToAdd; ++i) {
-        auto& b = buffers[i];
-        const AHardwareBuffer_Desc* pDesc =
-                reinterpret_cast<const AHardwareBuffer_Desc*>(&b.buffer.description);
-
-        buffer_handle_t handleToImport = ::android::dupFromAidl(b.buffer.handle);
-        buffer_handle_t handleToStore = nullptr;
-        if (handleToImport == nullptr) {
-            LOG(WARNING) << "Failed to duplicate a memory handle. Ignoring a buffer " << b.bufferId;
-            continue;
-        }
-
-        ::android::status_t result =
-                mapper.importBuffer(handleToImport, pDesc->width, pDesc->height, pDesc->layers,
-                                    pDesc->format, pDesc->usage, pDesc->stride, &handleToStore);
-        if (result != ::android::NO_ERROR || handleToStore == nullptr) {
-            LOG(WARNING) << "Failed to import a buffer " << b.bufferId;
-            continue;
-        }
-
-        bool stored = false;
-        for (auto&& rec : mBuffers) {
-            if (rec.handle != nullptr) {
-                continue;
-            }
-
-            // Use this existing entry.
-            rec.handle = handleToStore;
-            rec.inUse = false;
-            stored = true;
-            break;
-        }
-
-        if (!stored) {
-            // Add a BufferRecord wrapping this handle to our set of available buffers.
-            mBuffers.push_back(BufferRecord(handleToStore));
-        }
-        ++mFramesAllowed;
-    }
-
-    *_aidl_return = mFramesAllowed - before;
-    return ScopedAStatus::ok();
-}
-
-bool EvsMockCamera::setAvailableFrames_Locked(unsigned bufferCount) {
-    if (bufferCount < 1) {
-        LOG(ERROR) << "Ignoring request to set buffer count to zero";
-        return false;
-    }
-    if (bufferCount > kMaxBuffersInFlight) {
-        LOG(ERROR) << "Rejecting buffer request in excess of internal limit";
-        return false;
-    }
-
-    // Is an increase required?
-    if (mFramesAllowed < bufferCount) {
-        // An increase is required
-        auto needed = bufferCount - mFramesAllowed;
-        LOG(INFO) << "Allocating " << needed << " buffers for camera frames";
-
-        auto added = increaseAvailableFrames_Locked(needed);
-        if (added != needed) {
-            // If we didn't add all the frames we needed, then roll back to the previous state
-            LOG(ERROR) << "Rolling back to previous frame queue size";
-            decreaseAvailableFrames_Locked(added);
-            return false;
-        }
-    } else if (mFramesAllowed > bufferCount) {
-        // A decrease is required
-        auto framesToRelease = mFramesAllowed - bufferCount;
-        LOG(INFO) << "Returning " << framesToRelease << " camera frame buffers";
-
-        auto released = decreaseAvailableFrames_Locked(framesToRelease);
-        if (released != framesToRelease) {
-            // This shouldn't happen with a properly behaving client because the client
-            // should only make this call after returning sufficient outstanding buffers
-            // to allow a clean resize.
-            LOG(ERROR) << "Buffer queue shrink failed -- too many buffers currently in use?";
-        }
-    }
-
-    return true;
-}
-
-unsigned EvsMockCamera::increaseAvailableFrames_Locked(unsigned numToAdd) {
-    // Acquire the graphics buffer allocator
-    ::android::GraphicBufferAllocator& alloc(::android::GraphicBufferAllocator::get());
-
-    unsigned added = 0;
-    while (added < numToAdd) {
-        unsigned pixelsPerLine = 0;
-        buffer_handle_t memHandle = nullptr;
-        auto result = alloc.allocate(mWidth, mHeight, mFormat, 1, mUsage, &memHandle,
-                                     &pixelsPerLine, 0, "EvsMockCamera");
-        if (result != ::android::NO_ERROR) {
-            LOG(ERROR) << "Error " << result << " allocating " << mWidth << " x " << mHeight
-                       << " graphics buffer";
-            break;
-        }
-        if (memHandle == nullptr) {
-            LOG(ERROR) << "We didn't get a buffer handle back from the allocator";
-            break;
-        }
-        if (mStride > 0) {
-            if (mStride != pixelsPerLine) {
-                LOG(ERROR) << "We did not expect to get buffers with different strides!";
-            }
-        } else {
-            // Gralloc defines stride in terms of pixels per line
-            mStride = pixelsPerLine;
-        }
-
-        // Find a place to store the new buffer
-        auto stored = false;
-        for (auto&& rec : mBuffers) {
-            if (rec.handle == nullptr) {
-                // Use this existing entry
-                rec.handle = memHandle;
-                rec.inUse = false;
-                stored = true;
-                break;
-            }
-        }
-        if (!stored) {
-            // Add a BufferRecord wrapping this handle to our set of available buffers
-            mBuffers.push_back(BufferRecord(memHandle));
-        }
-
-        ++mFramesAllowed;
-        ++added;
-    }
-
-    return added;
-}
-
-unsigned EvsMockCamera::decreaseAvailableFrames_Locked(unsigned numToRemove) {
-    // Acquire the graphics buffer allocator
-    ::android::GraphicBufferAllocator& alloc(::android::GraphicBufferAllocator::get());
-
-    unsigned removed = 0;
-    for (auto&& rec : mBuffers) {
-        // Is this record not in use, but holding a buffer that we can free?
-        if ((rec.inUse == false) && (rec.handle != nullptr)) {
-            // Release buffer and update the record so we can recognize it as "empty"
-            alloc.free(rec.handle);
-            rec.handle = nullptr;
-
-            --mFramesAllowed;
-            ++removed;
-
-            if (removed == numToRemove) {
-                break;
-            }
-        }
-    }
-
-    return removed;
-}
-
 // This is the asynchronous frame generation thread that runs in parallel with the
 // main serving thread.  There is one for each active camera instance.
 void EvsMockCamera::generateFrames() {
     LOG(DEBUG) << "Frame generation loop started.";
 
-    unsigned idx = 0;
     while (true) {
-        bool timeForFrame = false;
         const nsecs_t startTime = systemTime(SYSTEM_TIME_MONOTONIC);
-
-        // Lock scope for updating shared state
+        std::size_t bufferId = kInvalidBufferID;
+        buffer_handle_t bufferHandle = nullptr;
         {
-            std::lock_guard lock(mAccessLock);
-
-            if (mStreamState != RUNNING) {
-                // Break out of our main thread loop
+            std::lock_guard lock(mMutex);
+            if (mStreamState != StreamState::RUNNING) {
                 break;
             }
-
-            // Are we allowed to issue another buffer?
-            if (mFramesInUse >= mFramesAllowed) {
-                // Can't do anything right now -- skip this frame
-                LOG(WARNING) << "Skipped a frame because too many are in flight.";
-            } else {
-                // Identify an available buffer to fill
-                for (idx = 0; idx < mBuffers.size(); idx++) {
-                    if (!mBuffers[idx].inUse) {
-                        if (mBuffers[idx].handle != nullptr) {
-                            // Found an available record, so stop looking
-                            break;
-                        }
-                    }
-                }
-                if (idx >= mBuffers.size()) {
-                    // This shouldn't happen since we already checked mFramesInUse vs mFramesAllowed
-                    ALOGE("Failed to find an available buffer slot\n");
-                } else {
-                    // We're going to make the frame busy
-                    mBuffers[idx].inUse = true;
-                    mFramesInUse++;
-                    timeForFrame = true;
-                }
-            }
+            std::tie(bufferId, bufferHandle) = useBuffer_unsafe();
         }
 
-        if (timeForFrame) {
+        if (bufferHandle != nullptr) {
             using AidlPixelFormat = ::aidl::android::hardware::graphics::common::PixelFormat;
 
             // Assemble the buffer description we'll transmit below
-            buffer_handle_t memHandle = mBuffers[idx].handle;
             BufferDesc newBuffer = {
                     .buffer =
                             {
@@ -584,39 +225,31 @@
                                                     .usage = static_cast<BufferUsage>(mUsage),
                                                     .stride = static_cast<int32_t>(mStride),
                                             },
-                                    .handle = ::android::dupToAidl(memHandle),
+                                    .handle = ::android::dupToAidl(bufferHandle),
                             },
-                    .bufferId = static_cast<int32_t>(idx),
+                    .bufferId = static_cast<int32_t>(bufferId),
                     .deviceId = mDescription.id,
                     .timestamp = static_cast<int64_t>(::android::elapsedRealtimeNano() *
                                                       1e+3),  // timestamps is in microseconds
             };
 
             // Write test data into the image buffer
-            fillMockFrame(memHandle, reinterpret_cast<const AHardwareBuffer_Desc*>(
-                                             &newBuffer.buffer.description));
+            fillMockFrame(bufferHandle, reinterpret_cast<const AHardwareBuffer_Desc*>(
+                                                &newBuffer.buffer.description));
+
+            std::vector<BufferDesc> frames;
+            frames.push_back(std::move(newBuffer));
 
             // Issue the (asynchronous) callback to the client -- can't be holding the lock
-            auto flag = false;
-            if (mStream) {
-                std::vector<BufferDesc> frames;
-                frames.push_back(std::move(newBuffer));
-                flag = mStream->deliverFrame(frames).isOk();
-            }
-
-            if (flag) {
-                LOG(DEBUG) << "Delivered " << memHandle << ", id = " << mBuffers[idx].handle;
+            if (mStream && mStream->deliverFrame(frames).isOk()) {
+                LOG(DEBUG) << "Delivered " << bufferHandle << ", id = " << bufferId;
             } else {
                 // This can happen if the client dies and is likely unrecoverable.
                 // To avoid consuming resources generating failing calls, we stop sending
                 // frames.  Note, however, that the stream remains in the "STREAMING" state
                 // until cleaned up on the main thread.
                 LOG(ERROR) << "Frame delivery call failed in the transport layer.";
-
-                // Since we didn't actually deliver it, mark the frame as available
-                std::lock_guard<std::mutex> lock(mAccessLock);
-                mBuffers[idx].inUse = false;
-                mFramesInUse--;
+                doneWithFrame(frames);
             }
         }
 
@@ -671,34 +304,45 @@
     mapper.unlock(handle);
 }
 
-void EvsMockCamera::returnBufferLocked(const uint32_t bufferId) {
-    if (bufferId >= mBuffers.size()) {
-        ALOGE("ignoring doneWithFrame called with invalid bufferId %d (max is %zu)", bufferId,
-              mBuffers.size() - 1);
-        return;
+::android::status_t EvsMockCamera::allocateOneFrame(buffer_handle_t* handle) {
+    static auto& alloc = ::android::GraphicBufferAllocator::get();
+    unsigned pixelsPerLine = 0;
+    const auto result = alloc.allocate(mWidth, mHeight, mFormat, 1, mUsage, handle, &pixelsPerLine,
+                                       0, "EvsMockCamera");
+    if (mStride < mWidth) {
+        // Gralloc defines stride in terms of pixels per line
+        mStride = pixelsPerLine;
+    } else if (mStride != pixelsPerLine) {
+        LOG(ERROR) << "We did not expect to get buffers with different strides!";
     }
+    return result;
+}
 
-    if (!mBuffers[bufferId].inUse) {
-        ALOGE("ignoring doneWithFrame called on frame %d which is already free", bufferId);
-        return;
+bool EvsMockCamera::startVideoStreamImpl_locked(
+        const std::shared_ptr<evs::IEvsCameraStream>& receiver, ndk::ScopedAStatus& /* status */,
+        std::unique_lock<std::mutex>& /* lck */) {
+    mStream = receiver;
+    mCaptureThread = std::thread([this]() { generateFrames(); });
+    return true;
+}
+
+bool EvsMockCamera::stopVideoStreamImpl_locked(ndk::ScopedAStatus& /* status */,
+                                               std::unique_lock<std::mutex>& lck) {
+    lck.unlock();
+    if (mCaptureThread.joinable()) {
+        mCaptureThread.join();
     }
+    lck.lock();
+    return true;
+}
 
-    // Mark the frame as available
-    mBuffers[bufferId].inUse = false;
-    mFramesInUse--;
-
-    // If this frame's index is high in the array, try to move it down
-    // to improve locality after mFramesAllowed has been reduced.
-    if (bufferId >= mFramesAllowed) {
-        // Find an empty slot lower in the array (which should always exist in this case)
-        for (auto&& rec : mBuffers) {
-            if (rec.handle == nullptr) {
-                rec.handle = mBuffers[bufferId].handle;
-                mBuffers[bufferId].handle = nullptr;
-                break;
-            }
-        }
+bool EvsMockCamera::postVideoStreamStop_locked(ndk::ScopedAStatus& status,
+                                               std::unique_lock<std::mutex>& lck) {
+    if (!Base::postVideoStreamStop_locked(status, lck)) {
+        return false;
     }
+    mStream = nullptr;
+    return true;
 }
 
 std::shared_ptr<EvsMockCamera> EvsMockCamera::Create(const char* deviceName) {
diff --git a/automotive/evs/aidl/impl/default/tests/EvsCameraBufferTest.cpp b/automotive/evs/aidl/impl/default/tests/EvsCameraBufferTest.cpp
index 3cbc04a..8b4676e 100644
--- a/automotive/evs/aidl/impl/default/tests/EvsCameraBufferTest.cpp
+++ b/automotive/evs/aidl/impl/default/tests/EvsCameraBufferTest.cpp
@@ -134,6 +134,7 @@
         for (std::size_t i = 0; i < kNumOfHandles; ++i) {
             const auto [id, handle] = evsCam->useBuffer_unsafe();
             const std::size_t handleInt = reinterpret_cast<std::size_t>(handle);
+            EXPECT_TRUE(EvsCamera::IsBufferIDValid(id));
             EXPECT_NE(handle, nullptr);
             EXPECT_LT(id, kNumOfHandles);
 
@@ -160,6 +161,7 @@
         for (std::size_t i = 0; i < kNumOfHandles; ++i) {
             const auto [id, handle] = evsCam->useBuffer_unsafe();
             const std::size_t handleInt = reinterpret_cast<std::size_t>(handle);
+            EXPECT_TRUE(EvsCamera::IsBufferIDValid(id));
             EXPECT_NE(handle, nullptr);
             EXPECT_LT(id, kNumOfHandles);
 
@@ -189,6 +191,7 @@
         for (std::size_t i = 0; i < kNumOfHandles; ++i) {
             const auto [id, handle] = evsCam->useBuffer_unsafe();
             const std::size_t handleInt = reinterpret_cast<std::size_t>(handle);
+            EXPECT_TRUE(EvsCamera::IsBufferIDValid(id));
             EXPECT_NE(handle, nullptr);
             EXPECT_LT(id, kNumOfHandles);