diff --git a/audio/aidl/default/Stream.cpp b/audio/aidl/default/Stream.cpp
index 77b0601..73f1293 100644
--- a/audio/aidl/default/Stream.cpp
+++ b/audio/aidl/default/Stream.cpp
@@ -152,6 +152,7 @@
         case Tag::halReservedExit:
             if (const int32_t cookie = command.get<Tag::halReservedExit>();
                 cookie == mInternalCommandCookie) {
+                mDriver->shutdown();
                 setClosed();
                 // This is an internal command, no need to reply.
                 return Status::EXIT;
@@ -364,6 +365,7 @@
         case Tag::halReservedExit:
             if (const int32_t cookie = command.get<Tag::halReservedExit>();
                 cookie == mInternalCommandCookie) {
+                mDriver->shutdown();
                 setClosed();
                 // This is an internal command, no need to reply.
                 return Status::EXIT;
@@ -567,8 +569,7 @@
     return !fatal;
 }
 
-template <class Metadata>
-StreamCommonImpl<Metadata>::~StreamCommonImpl() {
+StreamCommonImpl::~StreamCommonImpl() {
     if (!isClosed()) {
         LOG(ERROR) << __func__ << ": stream was not closed prior to destruction, resource leak";
         stopWorker();
@@ -576,19 +577,16 @@
     }
 }
 
-template <class Metadata>
-void StreamCommonImpl<Metadata>::createStreamCommon(
+ndk::ScopedAStatus StreamCommonImpl::initInstance(
         const std::shared_ptr<StreamCommonInterface>& delegate) {
-    if (mCommon != nullptr) {
-        LOG(FATAL) << __func__ << ": attempting to create the common interface twice";
-    }
-    mCommon = ndk::SharedRefBase::make<StreamCommon>(delegate);
+    mCommon = ndk::SharedRefBase::make<StreamCommonDelegator>(delegate);
     mCommonBinder = mCommon->asBinder();
     AIBinder_setMinSchedulerPolicy(mCommonBinder.get(), SCHED_NORMAL, ANDROID_PRIORITY_AUDIO);
+    return mWorker->start() ? ndk::ScopedAStatus::ok()
+                            : ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_STATE);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::getStreamCommon(
+ndk::ScopedAStatus StreamCommonImpl::getStreamCommonCommon(
         std::shared_ptr<IStreamCommon>* _aidl_return) {
     if (mCommon == nullptr) {
         LOG(FATAL) << __func__ << ": the common interface was not created";
@@ -598,30 +596,26 @@
     return ndk::ScopedAStatus::ok();
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::updateHwAvSyncId(int32_t in_hwAvSyncId) {
+ndk::ScopedAStatus StreamCommonImpl::updateHwAvSyncId(int32_t in_hwAvSyncId) {
     LOG(DEBUG) << __func__ << ": id " << in_hwAvSyncId;
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::getVendorParameters(
+ndk::ScopedAStatus StreamCommonImpl::getVendorParameters(
         const std::vector<std::string>& in_ids, std::vector<VendorParameter>* _aidl_return) {
     LOG(DEBUG) << __func__ << ": id count: " << in_ids.size();
     (void)_aidl_return;
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::setVendorParameters(
+ndk::ScopedAStatus StreamCommonImpl::setVendorParameters(
         const std::vector<VendorParameter>& in_parameters, bool in_async) {
     LOG(DEBUG) << __func__ << ": parameters count " << in_parameters.size()
                << ", async: " << in_async;
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::addEffect(
+ndk::ScopedAStatus StreamCommonImpl::addEffect(
         const std::shared_ptr<::aidl::android::hardware::audio::effect::IEffect>& in_effect) {
     if (in_effect == nullptr) {
         LOG(DEBUG) << __func__ << ": null effect";
@@ -631,8 +625,7 @@
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::removeEffect(
+ndk::ScopedAStatus StreamCommonImpl::removeEffect(
         const std::shared_ptr<::aidl::android::hardware::audio::effect::IEffect>& in_effect) {
     if (in_effect == nullptr) {
         LOG(DEBUG) << __func__ << ": null effect";
@@ -642,8 +635,7 @@
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::close() {
+ndk::ScopedAStatus StreamCommonImpl::close() {
     LOG(DEBUG) << __func__;
     if (!isClosed()) {
         stopWorker();
@@ -659,8 +651,7 @@
     }
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::prepareToClose() {
+ndk::ScopedAStatus StreamCommonImpl::prepareToClose() {
     LOG(DEBUG) << __func__;
     if (!isClosed()) {
         return ndk::ScopedAStatus::ok();
@@ -669,8 +660,7 @@
     return ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_STATE);
 }
 
-template <class Metadata>
-void StreamCommonImpl<Metadata>::stopWorker() {
+void StreamCommonImpl::stopWorker() {
     if (auto commandMQ = mContext.getCommandMQ(); commandMQ != nullptr) {
         LOG(DEBUG) << __func__ << ": asking the worker to exit...";
         auto cmd = StreamDescriptor::Command::make<StreamDescriptor::Command::Tag::halReservedExit>(
@@ -686,10 +676,12 @@
     }
 }
 
-template <class Metadata>
-ndk::ScopedAStatus StreamCommonImpl<Metadata>::updateMetadata(const Metadata& metadata) {
+ndk::ScopedAStatus StreamCommonImpl::updateMetadataCommon(const Metadata& metadata) {
     LOG(DEBUG) << __func__;
     if (!isClosed()) {
+        if (metadata.index() != mMetadata.index()) {
+            LOG(FATAL) << __func__ << ": changing metadata variant is not allowed";
+        }
         mMetadata = metadata;
         return ndk::ScopedAStatus::ok();
     }
@@ -697,12 +689,10 @@
     return ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_STATE);
 }
 
-// static
-ndk::ScopedAStatus StreamIn::initInstance(const std::shared_ptr<StreamIn>& stream) {
-    if (auto status = stream->init(); !status.isOk()) {
-        return status;
-    }
-    stream->createStreamCommon(stream);
+ndk::ScopedAStatus StreamCommonImpl::setConnectedDevices(
+        const std::vector<::aidl::android::media::audio::common::AudioDevice>& devices) {
+    mWorker->setIsConnected(!devices.empty());
+    mConnectedDevices = devices;
     return ndk::ScopedAStatus::ok();
 }
 
@@ -716,12 +706,8 @@
 }
 }  // namespace
 
-StreamIn::StreamIn(const SinkMetadata& sinkMetadata, StreamContext&& context,
-                   const DriverInterface::CreateInstance& createDriver,
-                   const StreamWorkerInterface::CreateInstance& createWorker,
-                   const std::vector<MicrophoneInfo>& microphones)
-    : StreamCommonImpl<SinkMetadata>(sinkMetadata, std::move(context), createDriver, createWorker),
-      mMicrophones(transformMicrophones(microphones)) {
+StreamIn::StreamIn(const std::vector<MicrophoneInfo>& microphones)
+    : mMicrophones(transformMicrophones(microphones)) {
     LOG(DEBUG) << __func__;
 }
 
@@ -729,9 +715,9 @@
         std::vector<MicrophoneDynamicInfo>* _aidl_return) {
     std::vector<MicrophoneDynamicInfo> result;
     std::vector<MicrophoneDynamicInfo::ChannelMapping> channelMapping{
-            getChannelCount(mContext.getChannelLayout()),
+            getChannelCount(getContext().getChannelLayout()),
             MicrophoneDynamicInfo::ChannelMapping::DIRECT};
-    for (auto it = mConnectedDevices.begin(); it != mConnectedDevices.end(); ++it) {
+    for (auto it = getConnectedDevices().begin(); it != getConnectedDevices().end(); ++it) {
         if (auto micIt = mMicrophones.find(*it); micIt != mMicrophones.end()) {
             MicrophoneDynamicInfo dynMic;
             dynMic.id = micIt->second;
@@ -777,22 +763,8 @@
     return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
-// static
-ndk::ScopedAStatus StreamOut::initInstance(const std::shared_ptr<StreamOut>& stream) {
-    if (auto status = stream->init(); !status.isOk()) {
-        return status;
-    }
-    stream->createStreamCommon(stream);
-    return ndk::ScopedAStatus::ok();
-}
-
-StreamOut::StreamOut(const SourceMetadata& sourceMetadata, StreamContext&& context,
-                     const DriverInterface::CreateInstance& createDriver,
-                     const StreamWorkerInterface::CreateInstance& createWorker,
-                     const std::optional<AudioOffloadInfo>& offloadInfo)
-    : StreamCommonImpl<SourceMetadata>(sourceMetadata, std::move(context), createDriver,
-                                       createWorker),
-      mOffloadInfo(offloadInfo) {
+StreamOut::StreamOut(const std::optional<AudioOffloadInfo>& offloadInfo)
+    : mOffloadInfo(offloadInfo) {
     LOG(DEBUG) << __func__;
 }
 
diff --git a/audio/aidl/default/StreamStub.cpp b/audio/aidl/default/StreamStub.cpp
index 2467320..289afa1 100644
--- a/audio/aidl/default/StreamStub.cpp
+++ b/audio/aidl/default/StreamStub.cpp
@@ -31,33 +31,34 @@
 
 namespace aidl::android::hardware::audio::core {
 
-DriverStub::DriverStub(const StreamContext& context, bool isInput)
-    : mFrameSizeBytes(context.getFrameSize()),
+StreamStub::StreamStub(const Metadata& metadata, StreamContext&& context)
+    : StreamCommonImpl(metadata, std::move(context)),
+      mFrameSizeBytes(context.getFrameSize()),
       mSampleRate(context.getSampleRate()),
       mIsAsynchronous(!!context.getAsyncCallback()),
-      mIsInput(isInput) {}
+      mIsInput(isInput(metadata)) {}
 
-::android::status_t DriverStub::init() {
+::android::status_t StreamStub::init() {
     usleep(500);
     return ::android::OK;
 }
 
-::android::status_t DriverStub::drain(StreamDescriptor::DrainMode) {
+::android::status_t StreamStub::drain(StreamDescriptor::DrainMode) {
     usleep(500);
     return ::android::OK;
 }
 
-::android::status_t DriverStub::flush() {
+::android::status_t StreamStub::flush() {
     usleep(500);
     return ::android::OK;
 }
 
-::android::status_t DriverStub::pause() {
+::android::status_t StreamStub::pause() {
     usleep(500);
     return ::android::OK;
 }
 
-::android::status_t DriverStub::transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
+::android::status_t StreamStub::transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
                                          int32_t* latencyMs) {
     static constexpr float kMicrosPerSecond = MICROS_PER_SECOND;
     static constexpr float kScaleFactor = .8f;
@@ -79,16 +80,12 @@
     return ::android::OK;
 }
 
-::android::status_t DriverStub::standby() {
+::android::status_t StreamStub::standby() {
     usleep(500);
     return ::android::OK;
 }
 
-::android::status_t DriverStub::setConnectedDevices(
-        const std::vector<AudioDevice>& connectedDevices __unused) {
-    usleep(500);
-    return ::android::OK;
-}
+void StreamStub::shutdown() {}
 
 // static
 ndk::ScopedAStatus StreamInStub::createInstance(const SinkMetadata& sinkMetadata,
@@ -97,7 +94,7 @@
                                                 std::shared_ptr<StreamIn>* result) {
     std::shared_ptr<StreamIn> stream =
             ndk::SharedRefBase::make<StreamInStub>(sinkMetadata, std::move(context), microphones);
-    if (auto status = initInstance(stream); !status.isOk()) {
+    if (auto status = stream->initInstance(stream); !status.isOk()) {
         return status;
     }
     *result = std::move(stream);
@@ -106,16 +103,7 @@
 
 StreamInStub::StreamInStub(const SinkMetadata& sinkMetadata, StreamContext&& context,
                            const std::vector<MicrophoneInfo>& microphones)
-    : StreamIn(
-              sinkMetadata, std::move(context),
-              [](const StreamContext& ctx) -> DriverInterface* {
-                  return new DriverStub(ctx, true /*isInput*/);
-              },
-              [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
-                  // The default worker implementation is used.
-                  return new StreamInWorker(ctx, driver);
-              },
-              microphones) {}
+    : StreamStub(sinkMetadata, std::move(context)), StreamIn(microphones) {}
 
 // static
 ndk::ScopedAStatus StreamOutStub::createInstance(const SourceMetadata& sourceMetadata,
@@ -124,7 +112,7 @@
                                                  std::shared_ptr<StreamOut>* result) {
     std::shared_ptr<StreamOut> stream = ndk::SharedRefBase::make<StreamOutStub>(
             sourceMetadata, std::move(context), offloadInfo);
-    if (auto status = initInstance(stream); !status.isOk()) {
+    if (auto status = stream->initInstance(stream); !status.isOk()) {
         return status;
     }
     *result = std::move(stream);
@@ -133,15 +121,6 @@
 
 StreamOutStub::StreamOutStub(const SourceMetadata& sourceMetadata, StreamContext&& context,
                              const std::optional<AudioOffloadInfo>& offloadInfo)
-    : StreamOut(
-              sourceMetadata, std::move(context),
-              [](const StreamContext& ctx) -> DriverInterface* {
-                  return new DriverStub(ctx, false /*isInput*/);
-              },
-              [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
-                  // The default worker implementation is used.
-                  return new StreamOutWorker(ctx, driver);
-              },
-              offloadInfo) {}
+    : StreamStub(sourceMetadata, std::move(context)), StreamOut(offloadInfo) {}
 
 }  // namespace aidl::android::hardware::audio::core
diff --git a/audio/aidl/default/include/core-impl/Stream.h b/audio/aidl/default/include/core-impl/Stream.h
index 826b0f1ec..ff5b5a0 100644
--- a/audio/aidl/default/include/core-impl/Stream.h
+++ b/audio/aidl/default/include/core-impl/Stream.h
@@ -164,8 +164,8 @@
     DebugParameters mDebugParameters;
 };
 
+// This interface provides operations of the stream which are executed on the worker thread.
 struct DriverInterface {
-    using CreateInstance = std::function<DriverInterface*(const StreamContext&)>;
     virtual ~DriverInterface() = default;
     // All the methods below are called on the worker thread.
     virtual ::android::status_t init() = 0;  // This function is only called once.
@@ -175,11 +175,7 @@
     virtual ::android::status_t transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
                                          int32_t* latencyMs) = 0;
     virtual ::android::status_t standby() = 0;
-    // The method below is called from a thread of the Binder pool. Access to data shared with other
-    // methods of this interface must be done in a thread-safe manner.
-    virtual ::android::status_t setConnectedDevices(
-            const std::vector<::aidl::android::media::audio::common::AudioDevice>&
-                    connectedDevices) = 0;
+    virtual void shutdown() = 0;  // This function is only called once.
 };
 
 class StreamWorkerCommonLogic : public ::android::hardware::audio::common::StreamLogic {
@@ -296,14 +292,20 @@
 };
 using StreamOutWorker = StreamWorkerImpl<StreamOutWorkerLogic>;
 
-// This provides a C++ interface with methods of the IStreamCommon Binder interface,
-// but intentionally does not inherit from it. This is needed to avoid inheriting
-// StreamIn and StreamOut from two Binder interface classes, as these parts of the class
-// will be reference counted separately.
-//
-// The implementation of these common methods is in the StreamCommonImpl template class.
+// This interface provides operations of the stream which are executed on a Binder pool thread.
+// These methods originate both from the AIDL interface and its implementation.
 struct StreamCommonInterface {
+    using ConnectedDevices = std::vector<::aidl::android::media::audio::common::AudioDevice>;
+    using Metadata =
+            std::variant<::aidl::android::hardware::audio::common::SinkMetadata /*IStreamIn*/,
+                         ::aidl::android::hardware::audio::common::SourceMetadata /*IStreamOut*/>;
+
+    static constexpr bool isInput(const Metadata& metadata) { return metadata.index() == 0; }
+
     virtual ~StreamCommonInterface() = default;
+    // Methods below originate from the 'IStreamCommon' interface.
+    // This is semantically equivalent to inheriting from 'IStreamCommon' with a benefit
+    // that concrete stream implementations can inherit both from this interface and IStreamIn/Out.
     virtual ndk::ScopedAStatus close() = 0;
     virtual ndk::ScopedAStatus prepareToClose() = 0;
     virtual ndk::ScopedAStatus updateHwAvSyncId(int32_t in_hwAvSyncId) = 0;
@@ -317,11 +319,30 @@
     virtual ndk::ScopedAStatus removeEffect(
             const std::shared_ptr<::aidl::android::hardware::audio::effect::IEffect>&
                     in_effect) = 0;
+    // Methods below are common for both 'IStreamIn' and 'IStreamOut'. Note that
+    // 'updateMetadata' in them uses an individual structure which is wrapped here.
+    // The 'Common' suffix is added to distinguish them from the methods from 'IStreamIn/Out'.
+    virtual ndk::ScopedAStatus getStreamCommonCommon(
+            std::shared_ptr<IStreamCommon>* _aidl_return) = 0;
+    virtual ndk::ScopedAStatus updateMetadataCommon(const Metadata& metadata) = 0;
+    // Methods below are called by implementation of 'IModule', 'IStreamIn' and 'IStreamOut'.
+    virtual ndk::ScopedAStatus initInstance(
+            const std::shared_ptr<StreamCommonInterface>& delegate) = 0;
+    virtual const StreamContext& getContext() const = 0;
+    virtual bool isClosed() const = 0;
+    virtual const ConnectedDevices& getConnectedDevices() const = 0;
+    virtual ndk::ScopedAStatus setConnectedDevices(
+            const std::vector<::aidl::android::media::audio::common::AudioDevice>& devices) = 0;
 };
 
-class StreamCommon : public BnStreamCommon {
+// This is equivalent to automatically generated 'IStreamCommonDelegator' but uses
+// a weak pointer to avoid creating a reference loop. The loop will occur because
+// 'IStreamIn/Out.getStreamCommon' must return the same instance every time, thus
+// the stream implementation must hold a strong pointer to an instance of 'IStreamCommon'.
+// Also, we use 'StreamCommonInterface' here instead of 'IStreamCommon'.
+class StreamCommonDelegator : public BnStreamCommon {
   public:
-    explicit StreamCommon(const std::shared_ptr<StreamCommonInterface>& delegate)
+    explicit StreamCommonDelegator(const std::shared_ptr<StreamCommonInterface>& delegate)
         : mDelegate(delegate) {}
 
   private:
@@ -372,9 +393,20 @@
     std::weak_ptr<StreamCommonInterface> mDelegate;
 };
 
-template <class Metadata>
-class StreamCommonImpl : public StreamCommonInterface {
+// The implementation of DriverInterface must be provided by each concrete stream implementation.
+class StreamCommonImpl : virtual public StreamCommonInterface, virtual public DriverInterface {
   public:
+    StreamCommonImpl(const Metadata& metadata, StreamContext&& context,
+                     const StreamWorkerInterface::CreateInstance& createWorker)
+        : mMetadata(metadata),
+          mContext(std::move(context)),
+          mWorker(createWorker(mContext, this)) {}
+    StreamCommonImpl(const Metadata& metadata, StreamContext&& context)
+        : StreamCommonImpl(
+                  metadata, std::move(context),
+                  isInput(metadata) ? getDefaultInWorkerCreator() : getDefaultOutWorkerCreator()) {}
+    ~StreamCommonImpl();
+
     ndk::ScopedAStatus close() override;
     ndk::ScopedAStatus prepareToClose() override;
     ndk::ScopedAStatus updateHwAvSyncId(int32_t in_hwAvSyncId) override;
@@ -389,46 +421,50 @@
             const std::shared_ptr<::aidl::android::hardware::audio::effect::IEffect>& in_effect)
             override;
 
-    ndk::ScopedAStatus getStreamCommon(std::shared_ptr<IStreamCommon>* _aidl_return);
-    ndk::ScopedAStatus init() {
-        return mWorker->start() ? ndk::ScopedAStatus::ok()
-                                : ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_STATE);
-    }
-    bool isClosed() const { return mWorker->isClosed(); }
+    ndk::ScopedAStatus getStreamCommonCommon(std::shared_ptr<IStreamCommon>* _aidl_return) override;
+    ndk::ScopedAStatus updateMetadataCommon(const Metadata& metadata) override;
+
+    ndk::ScopedAStatus initInstance(
+            const std::shared_ptr<StreamCommonInterface>& delegate) override;
+    const StreamContext& getContext() const override { return mContext; }
+    bool isClosed() const override { return mWorker->isClosed(); }
+    const ConnectedDevices& getConnectedDevices() const override { return mConnectedDevices; }
     ndk::ScopedAStatus setConnectedDevices(
-            const std::vector<::aidl::android::media::audio::common::AudioDevice>& devices) {
-        mWorker->setIsConnected(!devices.empty());
-        mConnectedDevices = devices;
-        return ndk::ScopedAStatus::fromStatus(mDriver->setConnectedDevices(devices));
-    }
-    ndk::ScopedAStatus updateMetadata(const Metadata& metadata);
+            const std::vector<::aidl::android::media::audio::common::AudioDevice>& devices)
+            override;
 
   protected:
-    StreamCommonImpl(const Metadata& metadata, StreamContext&& context,
-                     const DriverInterface::CreateInstance& createDriver,
-                     const StreamWorkerInterface::CreateInstance& createWorker)
-        : mMetadata(metadata),
-          mContext(std::move(context)),
-          mDriver(createDriver(mContext)),
-          mWorker(createWorker(mContext, mDriver.get())) {}
-    ~StreamCommonImpl();
-    void stopWorker();
-    void createStreamCommon(const std::shared_ptr<StreamCommonInterface>& delegate);
+    static StreamWorkerInterface::CreateInstance getDefaultInWorkerCreator() {
+        return [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
+            return new StreamInWorker(ctx, driver);
+        };
+    }
+    static StreamWorkerInterface::CreateInstance getDefaultOutWorkerCreator() {
+        return [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
+            return new StreamOutWorker(ctx, driver);
+        };
+    }
 
-    std::shared_ptr<StreamCommon> mCommon;
-    ndk::SpAIBinder mCommonBinder;
+    void stopWorker();
+
     Metadata mMetadata;
     StreamContext mContext;
-    std::unique_ptr<DriverInterface> mDriver;
     std::unique_ptr<StreamWorkerInterface> mWorker;
-    std::vector<::aidl::android::media::audio::common::AudioDevice> mConnectedDevices;
+    std::shared_ptr<StreamCommonDelegator> mCommon;
+    ndk::SpAIBinder mCommonBinder;
+    ConnectedDevices mConnectedDevices;
 };
 
-class StreamIn : public StreamCommonImpl<::aidl::android::hardware::audio::common::SinkMetadata>,
-                 public BnStreamIn {
+// Note: 'StreamIn/Out' can not be used on their own. Instead, they must be used for defining
+// concrete input/output stream implementations.
+class StreamIn : virtual public StreamCommonInterface, public BnStreamIn {
+  protected:
     ndk::ScopedAStatus getStreamCommon(std::shared_ptr<IStreamCommon>* _aidl_return) override {
-        return StreamCommonImpl<::aidl::android::hardware::audio::common::SinkMetadata>::
-                getStreamCommon(_aidl_return);
+        return getStreamCommonCommon(_aidl_return);
+    }
+    ndk::ScopedAStatus updateMetadata(const ::aidl::android::hardware::audio::common::SinkMetadata&
+                                              in_sinkMetadata) override {
+        return updateMetadataCommon(in_sinkMetadata);
     }
     ndk::ScopedAStatus getActiveMicrophones(
             std::vector<::aidl::android::media::audio::common::MicrophoneDynamicInfo>* _aidl_return)
@@ -437,27 +473,13 @@
     ndk::ScopedAStatus setMicrophoneDirection(MicrophoneDirection in_direction) override;
     ndk::ScopedAStatus getMicrophoneFieldDimension(float* _aidl_return) override;
     ndk::ScopedAStatus setMicrophoneFieldDimension(float in_zoom) override;
-    ndk::ScopedAStatus updateMetadata(const ::aidl::android::hardware::audio::common::SinkMetadata&
-                                              in_sinkMetadata) override {
-        return StreamCommonImpl<::aidl::android::hardware::audio::common::SinkMetadata>::
-                updateMetadata(in_sinkMetadata);
-    }
     ndk::ScopedAStatus getHwGain(std::vector<float>* _aidl_return) override;
     ndk::ScopedAStatus setHwGain(const std::vector<float>& in_channelGains) override;
 
-  protected:
     friend class ndk::SharedRefBase;
 
-    static ndk::ScopedAStatus initInstance(const std::shared_ptr<StreamIn>& stream);
-
-    StreamIn(const ::aidl::android::hardware::audio::common::SinkMetadata& sinkMetadata,
-             StreamContext&& context, const DriverInterface::CreateInstance& createDriver,
-             const StreamWorkerInterface::CreateInstance& createWorker,
-             const std::vector<::aidl::android::media::audio::common::MicrophoneInfo>& microphones);
-    void createStreamCommon(const std::shared_ptr<StreamIn>& myPtr) {
-        StreamCommonImpl<
-                ::aidl::android::hardware::audio::common::SinkMetadata>::createStreamCommon(myPtr);
-    }
+    explicit StreamIn(
+            const std::vector<::aidl::android::media::audio::common::MicrophoneInfo>& microphones);
 
     const std::map<::aidl::android::media::audio::common::AudioDevice, std::string> mMicrophones;
 
@@ -469,17 +491,15 @@
             std::shared_ptr<StreamIn>* result)>;
 };
 
-class StreamOut : public StreamCommonImpl<::aidl::android::hardware::audio::common::SourceMetadata>,
-                  public BnStreamOut {
+class StreamOut : virtual public StreamCommonInterface, public BnStreamOut {
+  protected:
     ndk::ScopedAStatus getStreamCommon(std::shared_ptr<IStreamCommon>* _aidl_return) override {
-        return StreamCommonImpl<::aidl::android::hardware::audio::common::SourceMetadata>::
-                getStreamCommon(_aidl_return);
+        return getStreamCommonCommon(_aidl_return);
     }
     ndk::ScopedAStatus updateMetadata(
             const ::aidl::android::hardware::audio::common::SourceMetadata& in_sourceMetadata)
             override {
-        return StreamCommonImpl<::aidl::android::hardware::audio::common::SourceMetadata>::
-                updateMetadata(in_sourceMetadata);
+        return updateMetadataCommon(in_sourceMetadata);
     }
     ndk::ScopedAStatus updateOffloadMetadata(
             const ::aidl::android::hardware::audio::common::AudioOffloadMetadata&
@@ -504,21 +524,10 @@
             override;
     ndk::ScopedAStatus selectPresentation(int32_t in_presentationId, int32_t in_programId) override;
 
-    void createStreamCommon(const std::shared_ptr<StreamOut>& myPtr) {
-        StreamCommonImpl<::aidl::android::hardware::audio::common::SourceMetadata>::
-                createStreamCommon(myPtr);
-    }
-
-  protected:
     friend class ndk::SharedRefBase;
 
-    static ndk::ScopedAStatus initInstance(const std::shared_ptr<StreamOut>& stream);
-
-    StreamOut(const ::aidl::android::hardware::audio::common::SourceMetadata& sourceMetadata,
-              StreamContext&& context, const DriverInterface::CreateInstance& createDriver,
-              const StreamWorkerInterface::CreateInstance& createWorker,
-              const std::optional<::aidl::android::media::audio::common::AudioOffloadInfo>&
-                      offloadInfo);
+    explicit StreamOut(const std::optional<::aidl::android::media::audio::common::AudioOffloadInfo>&
+                               offloadInfo);
 
     std::optional<::aidl::android::media::audio::common::AudioOffloadInfo> mOffloadInfo;
     std::optional<::aidl::android::hardware::audio::common::AudioOffloadMetadata> mOffloadMetadata;
@@ -540,26 +549,18 @@
         : mStream(streamOut), mStreamBinder(streamOut->asBinder()) {}
     ndk::SpAIBinder getBinder() const { return mStreamBinder; }
     bool isStreamOpen() const {
-        return std::visit(
-                [](auto&& ws) -> bool {
-                    auto s = ws.lock();
-                    return s && !s->isClosed();
-                },
-                mStream);
+        auto s = mStream.lock();
+        return s && !s->isClosed();
     }
     ndk::ScopedAStatus setConnectedDevices(
             const std::vector<::aidl::android::media::audio::common::AudioDevice>& devices) {
-        return std::visit(
-                [&](auto&& ws) {
-                    auto s = ws.lock();
-                    if (s) return s->setConnectedDevices(devices);
-                    return ndk::ScopedAStatus::ok();
-                },
-                mStream);
+        auto s = mStream.lock();
+        if (s) return s->setConnectedDevices(devices);
+        return ndk::ScopedAStatus::ok();
     }
 
   private:
-    std::variant<std::weak_ptr<StreamIn>, std::weak_ptr<StreamOut>> mStream;
+    std::weak_ptr<StreamCommonInterface> mStream;
     ndk::SpAIBinder mStreamBinder;
 };
 
diff --git a/audio/aidl/default/include/core-impl/StreamStub.h b/audio/aidl/default/include/core-impl/StreamStub.h
index 436e610..def98b7 100644
--- a/audio/aidl/default/include/core-impl/StreamStub.h
+++ b/audio/aidl/default/include/core-impl/StreamStub.h
@@ -20,9 +20,10 @@
 
 namespace aidl::android::hardware::audio::core {
 
-class DriverStub : public DriverInterface {
+class StreamStub : public StreamCommonImpl {
   public:
-    DriverStub(const StreamContext& context, bool isInput);
+    StreamStub(const Metadata& metadata, StreamContext&& context);
+    // Methods of 'DriverInterface'.
     ::android::status_t init() override;
     ::android::status_t drain(StreamDescriptor::DrainMode) override;
     ::android::status_t flush() override;
@@ -30,10 +31,7 @@
     ::android::status_t transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
                                  int32_t* latencyMs) override;
     ::android::status_t standby() override;
-    // Note: called on a different thread.
-    ::android::status_t setConnectedDevices(
-            const std::vector<::aidl::android::media::audio::common::AudioDevice>& connectedDevices)
-            override;
+    void shutdown() override;
 
   private:
     const size_t mFrameSizeBytes;
@@ -42,7 +40,7 @@
     const bool mIsInput;
 };
 
-class StreamInStub final : public StreamIn {
+class StreamInStub final : public StreamStub, public StreamIn {
   public:
     static ndk::ScopedAStatus createInstance(
             const ::aidl::android::hardware::audio::common::SinkMetadata& sinkMetadata,
@@ -58,7 +56,7 @@
             const std::vector<::aidl::android::media::audio::common::MicrophoneInfo>& microphones);
 };
 
-class StreamOutStub final : public StreamOut {
+class StreamOutStub final : public StreamStub, public StreamOut {
   public:
     static ndk::ScopedAStatus createInstance(
             const ::aidl::android::hardware::audio::common::SourceMetadata& sourceMetadata,
diff --git a/audio/aidl/default/include/core-impl/StreamUsb.h b/audio/aidl/default/include/core-impl/StreamUsb.h
index 05d889a..24ea8be 100644
--- a/audio/aidl/default/include/core-impl/StreamUsb.h
+++ b/audio/aidl/default/include/core-impl/StreamUsb.h
@@ -30,9 +30,10 @@
 
 namespace aidl::android::hardware::audio::core {
 
-class DriverUsb : public DriverInterface {
+class StreamUsb : public StreamCommonImpl {
   public:
-    DriverUsb(const StreamContext& context, bool isInput);
+    StreamUsb(const Metadata& metadata, StreamContext&& context);
+    // Methods of 'DriverInterface'.
     ::android::status_t init() override;
     ::android::status_t drain(StreamDescriptor::DrainMode) override;
     ::android::status_t flush() override;
@@ -40,27 +41,25 @@
     ::android::status_t transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
                                  int32_t* latencyMs) override;
     ::android::status_t standby() override;
-    // Note: called on a different thread.
-    ::android::status_t setConnectedDevices(
-            const std::vector<::aidl::android::media::audio::common::AudioDevice>& connectedDevices)
-            override;
+    void shutdown() override;
+
+    // Overridden methods of 'StreamCommonImpl', called on a Binder thread.
+    const ConnectedDevices& getConnectedDevices() const override;
+    ndk::ScopedAStatus setConnectedDevices(const ConnectedDevices& devices) override;
 
   private:
     ::android::status_t exitStandby();
 
-    std::mutex mLock;
+    mutable std::mutex mLock;
 
     const size_t mFrameSizeBytes;
     std::optional<struct pcm_config> mConfig;
     const bool mIsInput;
-    // Cached device addresses for connected devices.
-    std::vector<::aidl::android::media::audio::common::AudioDeviceAddress> mConnectedDevices
-            GUARDED_BY(mLock);
     std::vector<std::shared_ptr<alsa_device_proxy>> mAlsaDeviceProxies GUARDED_BY(mLock);
     bool mIsStandby = true;
 };
 
-class StreamInUsb final : public StreamIn {
+class StreamInUsb final : public StreamUsb, public StreamIn {
     ndk::ScopedAStatus getActiveMicrophones(
             std::vector<::aidl::android::media::audio::common::MicrophoneDynamicInfo>* _aidl_return)
             override;
@@ -80,7 +79,7 @@
             const std::vector<::aidl::android::media::audio::common::MicrophoneInfo>& microphones);
 };
 
-class StreamOutUsb final : public StreamOut {
+class StreamOutUsb final : public StreamUsb, public StreamOut {
   public:
     static ndk::ScopedAStatus createInstance(
             const ::aidl::android::hardware::audio::common::SourceMetadata& sourceMetadata,
diff --git a/audio/aidl/default/usb/StreamUsb.cpp b/audio/aidl/default/usb/StreamUsb.cpp
index d2ee484..fcac5df 100644
--- a/audio/aidl/default/usb/StreamUsb.cpp
+++ b/audio/aidl/default/usb/StreamUsb.cpp
@@ -18,6 +18,7 @@
 #include <android-base/logging.h>
 
 #include <Utils.h>
+#include <error/expected_utils.h>
 
 #include "UsbAlsaMixerControl.h"
 #include "UsbAlsaUtils.h"
@@ -42,10 +43,12 @@
 
 namespace aidl::android::hardware::audio::core {
 
-DriverUsb::DriverUsb(const StreamContext& context, bool isInput)
-    : mFrameSizeBytes(context.getFrameSize()), mIsInput(isInput) {
+StreamUsb::StreamUsb(const Metadata& metadata, StreamContext&& context)
+    : StreamCommonImpl(metadata, std::move(context)),
+      mFrameSizeBytes(context.getFrameSize()),
+      mIsInput(isInput(metadata)) {
     struct pcm_config config;
-    config.channels = usb::getChannelCountFromChannelMask(context.getChannelLayout(), isInput);
+    config.channels = usb::getChannelCountFromChannelMask(context.getChannelLayout(), mIsInput);
     if (config.channels == 0) {
         LOG(ERROR) << __func__ << ": invalid channel=" << context.getChannelLayout().toString();
         return;
@@ -63,48 +66,50 @@
     mConfig = config;
 }
 
-::android::status_t DriverUsb::init() {
+::android::status_t StreamUsb::init() {
     return mConfig.has_value() ? ::android::OK : ::android::NO_INIT;
 }
 
-::android::status_t DriverUsb::setConnectedDevices(
+const StreamCommonInterface::ConnectedDevices& StreamUsb::getConnectedDevices() const {
+    std::lock_guard guard(mLock);
+    return mConnectedDevices;
+}
+
+ndk::ScopedAStatus StreamUsb::setConnectedDevices(
         const std::vector<AudioDevice>& connectedDevices) {
     if (mIsInput && connectedDevices.size() > 1) {
         LOG(ERROR) << __func__ << ": wrong device size(" << connectedDevices.size()
                    << ") for input stream";
-        return ::android::INVALID_OPERATION;
+        return ndk::ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
     }
     for (const auto& connectedDevice : connectedDevices) {
         if (connectedDevice.address.getTag() != AudioDeviceAddress::alsa) {
             LOG(ERROR) << __func__ << ": bad device address" << connectedDevice.address.toString();
-            return ::android::BAD_VALUE;
+            return ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_ARGUMENT);
         }
     }
     std::lock_guard guard(mLock);
     mAlsaDeviceProxies.clear();
-    mConnectedDevices.clear();
-    for (const auto& connectedDevice : connectedDevices) {
-        mConnectedDevices.push_back(connectedDevice.address);
-    }
-    return ::android::OK;
+    RETURN_STATUS_IF_ERROR(StreamCommonImpl::setConnectedDevices(connectedDevices));
+    return ndk::ScopedAStatus::ok();
 }
 
-::android::status_t DriverUsb::drain(StreamDescriptor::DrainMode) {
+::android::status_t StreamUsb::drain(StreamDescriptor::DrainMode) {
     usleep(1000);
     return ::android::OK;
 }
 
-::android::status_t DriverUsb::flush() {
+::android::status_t StreamUsb::flush() {
     usleep(1000);
     return ::android::OK;
 }
 
-::android::status_t DriverUsb::pause() {
+::android::status_t StreamUsb::pause() {
     usleep(1000);
     return ::android::OK;
 }
 
-::android::status_t DriverUsb::transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
+::android::status_t StreamUsb::transfer(void* buffer, size_t frameCount, size_t* actualFrameCount,
                                         int32_t* latencyMs) {
     {
         std::lock_guard guard(mLock);
@@ -139,7 +144,7 @@
     return ::android::OK;
 }
 
-::android::status_t DriverUsb::standby() {
+::android::status_t StreamUsb::standby() {
     if (!mIsStandby) {
         std::lock_guard guard(mLock);
         mAlsaDeviceProxies.clear();
@@ -148,11 +153,15 @@
     return ::android::OK;
 }
 
-::android::status_t DriverUsb::exitStandby() {
+void StreamUsb::shutdown() {}
+
+::android::status_t StreamUsb::exitStandby() {
     std::vector<AudioDeviceAddress> connectedDevices;
     {
         std::lock_guard guard(mLock);
-        connectedDevices = mConnectedDevices;
+        std::transform(mConnectedDevices.begin(), mConnectedDevices.end(),
+                       std::back_inserter(connectedDevices),
+                       [](const auto& device) { return device.address; });
     }
     std::vector<std::shared_ptr<alsa_device_proxy>> alsaDeviceProxies;
     for (const auto& device : connectedDevices) {
@@ -203,7 +212,7 @@
                                                std::shared_ptr<StreamIn>* result) {
     std::shared_ptr<StreamIn> stream =
             ndk::SharedRefBase::make<StreamInUsb>(sinkMetadata, std::move(context), microphones);
-    if (auto status = initInstance(stream); !status.isOk()) {
+    if (auto status = stream->initInstance(stream); !status.isOk()) {
         return status;
     }
     *result = std::move(stream);
@@ -212,16 +221,7 @@
 
 StreamInUsb::StreamInUsb(const SinkMetadata& sinkMetadata, StreamContext&& context,
                          const std::vector<MicrophoneInfo>& microphones)
-    : StreamIn(
-              sinkMetadata, std::move(context),
-              [](const StreamContext& ctx) -> DriverInterface* {
-                  return new DriverUsb(ctx, true /*isInput*/);
-              },
-              [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
-                  // The default worker implementation is used.
-                  return new StreamInWorker(ctx, driver);
-              },
-              microphones) {}
+    : StreamUsb(sinkMetadata, std::move(context)), StreamIn(microphones) {}
 
 ndk::ScopedAStatus StreamInUsb::getActiveMicrophones(
         std::vector<MicrophoneDynamicInfo>* _aidl_return __unused) {
@@ -240,7 +240,7 @@
     }
     std::shared_ptr<StreamOut> stream =
             ndk::SharedRefBase::make<StreamOutUsb>(sourceMetadata, std::move(context), offloadInfo);
-    if (auto status = initInstance(stream); !status.isOk()) {
+    if (auto status = stream->initInstance(stream); !status.isOk()) {
         return status;
     }
     *result = std::move(stream);
@@ -249,17 +249,8 @@
 
 StreamOutUsb::StreamOutUsb(const SourceMetadata& sourceMetadata, StreamContext&& context,
                            const std::optional<AudioOffloadInfo>& offloadInfo)
-    : StreamOut(
-              sourceMetadata, std::move(context),
-              [](const StreamContext& ctx) -> DriverInterface* {
-                  return new DriverUsb(ctx, false /*isInput*/);
-              },
-              [](const StreamContext& ctx, DriverInterface* driver) -> StreamWorkerInterface* {
-                  // The default worker implementation is used.
-                  return new StreamOutWorker(ctx, driver);
-              },
-              offloadInfo) {
-    mChannelCount = getChannelCount(mContext.getChannelLayout());
+    : StreamUsb(sourceMetadata, std::move(context)), StreamOut(offloadInfo) {
+    mChannelCount = getChannelCount(getContext().getChannelLayout());
 }
 
 ndk::ScopedAStatus StreamOutUsb::getHwVolume(std::vector<float>* _aidl_return) {
@@ -268,7 +259,7 @@
 }
 
 ndk::ScopedAStatus StreamOutUsb::setHwVolume(const std::vector<float>& in_channelVolumes) {
-    for (const auto& device : mConnectedDevices) {
+    for (const auto& device : getConnectedDevices()) {
         if (device.address.getTag() != AudioDeviceAddress::alsa) {
             LOG(DEBUG) << __func__ << ": skip as the device address is not alsa";
             continue;