diff --git a/CMakeLists.txt b/CMakeLists.txt
index c95899660ef..367e28beaea 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -414,12 +414,14 @@ add_library(mixxx-lib STATIC EXCLUDE_FROM_ALL
   src/controllers/dlgprefcontrollerdlg.ui
   src/controllers/dlgprefcontrollers.cpp
   src/controllers/dlgprefcontrollersdlg.ui
-  src/controllers/engine/controllerengine.cpp
-  src/controllers/engine/controllerenginejsproxy.cpp
-  src/controllers/engine/colormapper.cpp
-  src/controllers/engine/colormapperjsproxy.cpp
-  src/controllers/engine/scriptconnection.cpp
-  src/controllers/engine/scriptconnectionjsproxy.cpp
+  src/controllers/scripting/controllerscriptenginebase.cpp
+  src/controllers/scripting/controllerscriptmoduleengine.cpp
+  src/controllers/scripting/colormapper.cpp
+  src/controllers/scripting/colormapperjsproxy.cpp
+  src/controllers/scripting/legacy/controllerscriptenginelegacy.cpp
+  src/controllers/scripting/legacy/controllerscriptinterfacelegacy.cpp
+  src/controllers/scripting/legacy/scriptconnection.cpp
+  src/controllers/scripting/legacy/scriptconnectionjsproxy.cpp
   src/controllers/keyboard/keyboardeventfilter.cpp
   src/controllers/learningutils.cpp
   src/controllers/midi/midicontroller.cpp
@@ -1388,7 +1390,7 @@ add_executable(mixxx-test
   src/test/compatibility_test.cpp
   src/test/configobject_test.cpp
   src/test/controller_preset_validation_test.cpp
-  src/test/controllerengine_test.cpp
+  src/test/controllerscriptenginelegacy_test.cpp
   src/test/controlobjecttest.cpp
   src/test/coverartcache_test.cpp
   src/test/coverartutils_test.cpp
diff --git a/src/control/controlobjectscript.cpp b/src/control/controlobjectscript.cpp
index db11155d580..3c6a6495732 100644
--- a/src/control/controlobjectscript.cpp
+++ b/src/control/controlobjectscript.cpp
@@ -2,10 +2,11 @@
 
 #include <QtDebug>
 
+#include "controllers/controllerdebug.h"
 #include "moc_controlobjectscript.cpp"
 
 ControlObjectScript::ControlObjectScript(const ConfigKey& key, QObject* pParent)
-        : ControlProxy(key, pParent, ControlFlag::NoAssertIfMissing) {
+        : ControlProxy(key, pParent, ControllerDebug::controlFlags()) {
 }
 
 bool ControlObjectScript::addScriptConnection(const ScriptConnection& conn) {
diff --git a/src/control/controlobjectscript.h b/src/control/controlobjectscript.h
index 90dce136552..219a4b0a991 100644
--- a/src/control/controlobjectscript.h
+++ b/src/control/controlobjectscript.h
@@ -3,8 +3,7 @@
 #include <QVector>
 
 #include "control/controlproxy.h"
-#include "controllers/controllerdebug.h"
-#include "controllers/engine/scriptconnection.h"
+#include "controllers/scripting/legacy/scriptconnection.h"
 
 // this is used for communicate with controller scripts
 class ControlObjectScript : public ControlProxy {
diff --git a/src/controllers/bulk/bulkcontroller.cpp b/src/controllers/bulk/bulkcontroller.cpp
index 5cb65ee93de..7b62d843d9e 100644
--- a/src/controllers/bulk/bulkcontroller.cpp
+++ b/src/controllers/bulk/bulkcontroller.cpp
@@ -47,8 +47,8 @@ void BulkReader::run() {
         if (result >= 0) {
             Trace process("BulkReader process packet");
             //qDebug() << "Read" << result << "bytes, pointer:" << data;
-            QByteArray outData((char*)data, transferred);
-            emit incomingData(outData, mixxx::Time::elapsed());
+            QByteArray byteArray(reinterpret_cast<char*>(data), transferred);
+            emit incomingData(byteArray, mixxx::Time::elapsed());
         }
     }
     qDebug() << "Stopped Reader";
diff --git a/src/controllers/controller.cpp b/src/controllers/controller.cpp
index 0f6a25defc4..6753260c95a 100644
--- a/src/controllers/controller.cpp
+++ b/src/controllers/controller.cpp
@@ -9,7 +9,7 @@
 #include "util/screensaver.h"
 
 Controller::Controller()
-        : m_pEngine(nullptr),
+        : m_pScriptEngineLegacy(nullptr),
           m_bIsOutputDevice(false),
           m_bIsInputDevice(false),
           m_bIsOpen(false),
@@ -29,31 +29,30 @@ ControllerJSProxy* Controller::jsProxy() {
 void Controller::startEngine()
 {
     controllerDebug("  Starting engine");
-    if (m_pEngine != nullptr) {
+    if (m_pScriptEngineLegacy) {
         qWarning() << "Controller: Engine already exists! Restarting:";
         stopEngine();
     }
-    m_pEngine = new ControllerEngine(this);
+    m_pScriptEngineLegacy = new ControllerScriptEngineLegacy(this);
 }
 
 void Controller::stopEngine() {
     controllerDebug("  Shutting down engine");
-    if (m_pEngine == nullptr) {
+    if (!m_pScriptEngineLegacy) {
         qWarning() << "Controller::stopEngine(): No engine exists!";
         return;
     }
-    m_pEngine->gracefulShutdown();
-    delete m_pEngine;
-    m_pEngine = nullptr;
+    delete m_pScriptEngineLegacy;
+    m_pScriptEngineLegacy = nullptr;
 }
 
-bool Controller::applyPreset(bool initializeScripts) {
+bool Controller::applyPreset() {
     qDebug() << "Applying controller preset...";
 
     const ControllerPreset* pPreset = preset();
 
     // Load the script code into the engine
-    if (m_pEngine == nullptr) {
+    if (!m_pScriptEngineLegacy) {
         qWarning() << "Controller::applyPreset(): No engine exists!";
         return false;
     }
@@ -64,19 +63,8 @@ bool Controller::applyPreset(bool initializeScripts) {
         return true;
     }
 
-    bool success = m_pEngine->loadScriptFiles(scriptFiles);
-    if (success && initializeScripts) {
-        m_pEngine->initializeScripts(scriptFiles);
-    }
-
-    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
-    // actually contains a reference, so we check if the filePath is empty as a
-    // workaround.
-    // See https://stackoverflow.com/a/45652741/1455128 for details.
-    if (initializeScripts && !pPreset->moduleFileInfo().filePath().isEmpty()) {
-        m_pEngine->loadModule(pPreset->moduleFileInfo());
-    }
-    return success;
+    m_pScriptEngineLegacy->setScriptFiles(scriptFiles);
+    return m_pScriptEngineLegacy->initialize();
 }
 
 void Controller::startLearning() {
@@ -113,7 +101,7 @@ void Controller::triggerActivity()
     }
 }
 void Controller::receive(const QByteArray& data, mixxx::Duration timestamp) {
-    if (m_pEngine == nullptr) {
+    if (!m_pScriptEngineLegacy) {
         //qWarning() << "Controller::receive called with no active engine!";
         // Don't complain, since this will always show after closing a device as
         //  queued signals flush out
@@ -122,7 +110,7 @@ void Controller::receive(const QByteArray& data, mixxx::Duration timestamp) {
     triggerActivity();
 
     int length = data.size();
-    if (ControllerDebug::enabled()) {
+    if (ControllerDebug::isEnabled()) {
         // Formatted packet display
         QString message = QString("%1: t:%2, %3 bytes:\n")
                                   .arg(m_sDeviceName,
@@ -145,14 +133,5 @@ void Controller::receive(const QByteArray& data, mixxx::Duration timestamp) {
         controllerDebug(message);
     }
 
-    foreach (QString function, m_pEngine->getScriptFunctionPrefixes()) {
-        if (function == "") {
-            continue;
-        }
-        function.append(".incomingData");
-        QJSValue incomingDataFunction = m_pEngine->wrapFunctionCode(function, 2);
-        m_pEngine->executeFunction(incomingDataFunction, data);
-    }
-
-    m_pEngine->handleInput(data, timestamp);
+    m_pScriptEngineLegacy->handleIncomingData(data);
 }
diff --git a/src/controllers/controller.h b/src/controllers/controller.h
index 67df67fad6a..095e49fb0c9 100644
--- a/src/controllers/controller.h
+++ b/src/controllers/controller.h
@@ -1,19 +1,18 @@
 #pragma once
 
 #include <QElapsedTimer>
+#include <QTimerEvent>
 
 #include "controllers/controllerpreset.h"
 #include "controllers/controllerpresetfilehandler.h"
 #include "controllers/controllerpresetinfo.h"
 #include "controllers/controllerpresetvisitor.h"
 #include "controllers/controllervisitor.h"
-#include "controllers/engine/controllerengine.h"
+#include "controllers/scripting/legacy/controllerscriptenginelegacy.h"
 #include "util/duration.h"
 
 class ControllerJSProxy;
 
-/// Base class representing a physical (or software) controller.
-///
 /// This is a base class representing a physical (or software) controller.  It
 /// must be inherited by a class that implements it on some API. Note that the
 /// subclass' destructor should call close() at a minimum.
@@ -85,13 +84,7 @@ class Controller : public QObject, ConstControllerPresetVisitor {
     // this if they have an alternate way of handling such data.)
     virtual void receive(const QByteArray& data, mixxx::Duration timestamp);
 
-    /// Apply the preset to the controller.
-    /// Initializes both controller engine and static output mappings.
-    ///
-    /// @param initializeScripts Can be set to false to skip script
-    /// initialization for unit tests.
-    /// @return Returns whether it was successful.
-    virtual bool applyPreset(bool initializeScripts = true);
+    virtual bool applyPreset();
 
     // Puts the controller in and out of learning mode.
     void startLearning();
@@ -108,17 +101,17 @@ class Controller : public QObject, ConstControllerPresetVisitor {
 
     // To be called in sub-class' open() functions after opening the device but
     // before starting any input polling/processing.
-    void startEngine();
+    virtual void startEngine();
 
     // To be called in sub-class' close() functions after stopping any input
     // polling/processing but before closing the device.
-    void stopEngine();
+    virtual void stopEngine();
 
     // To be called when receiving events
     void triggerActivity();
 
-    inline ControllerEngine* getEngine() const {
-        return m_pEngine;
+    inline ControllerScriptEngineLegacy* getScriptEngine() const {
+        return m_pScriptEngineLegacy;
     }
     inline void setDeviceName(const QString& deviceName) {
         m_sDeviceName = deviceName;
@@ -155,7 +148,7 @@ class Controller : public QObject, ConstControllerPresetVisitor {
     // Returns a pointer to the currently loaded controller preset. For internal
     // use only.
     virtual ControllerPreset* preset() = 0;
-    ControllerEngine* m_pEngine;
+    ControllerScriptEngineLegacy* m_pScriptEngineLegacy;
 
     // Verbose and unique device name suitable for display.
     QString m_sDeviceName;
diff --git a/src/controllers/controllerdebug.cpp b/src/controllers/controllerdebug.cpp
index ac1c3f39ef4..ce71d4381cf 100644
--- a/src/controllers/controllerdebug.cpp
+++ b/src/controllers/controllerdebug.cpp
@@ -5,8 +5,9 @@
 
 //static
 bool ControllerDebug::s_enabled = false;
+bool ControllerDebug::s_testing = false;
 
 //static
-bool ControllerDebug::enabled() {
+bool ControllerDebug::isEnabled() {
     return s_enabled || CmdlineArgs::Instance().getMidiDebug();
 }
diff --git a/src/controllers/controllerdebug.h b/src/controllers/controllerdebug.h
index d99eaf146dc..16fe5918c76 100644
--- a/src/controllers/controllerdebug.h
+++ b/src/controllers/controllerdebug.h
@@ -2,6 +2,8 @@
 
 #include <QDebug>
 
+#include "control/control.h"
+
 // Specifies whether or not we should dump incoming data to the console at
 // runtime. This is useful for end-user debugging and script-writing.
 class ControllerDebug {
@@ -11,22 +13,36 @@ class ControllerDebug {
     static constexpr const char kLogMessagePrefix[] = "CDBG";
     static constexpr int kLogMessagePrefixLength = sizeof(kLogMessagePrefix) - 1;
 
-    static bool enabled();
+    static bool isEnabled();
 
     /// Override the command-line argument (for testing)
-    static void enable() {
-        s_enabled = true;
+    static void setEnabled(bool enabled) {
+        s_enabled = enabled;
     }
 
-    /// Override the command-line argument (for testing)
-    static void disable() {
-        s_enabled = false;
+    static void setTesting(bool isTesting) {
+        s_testing = isTesting;
+    }
+
+    /// Return the appropriate flag for ControlProxies in mappings.
+    ///
+    /// Normally, accessing an invalid control from a mapping should *not*
+    /// throw a debug assertion because controller mappings are considered
+    /// user data. If we're testing or controller debugging is enabled, we *do*
+    /// want assertions to prevent overlooking bugs in controller mappings.
+    static ControlFlags controlFlags() {
+        if (s_enabled || s_testing) {
+            return ControlFlag::None;
+        }
+
+        return ControlFlag::AllowMissingOrInvalid;
     }
 
   private:
     ControllerDebug() = delete;
 
     static bool s_enabled;
+    static bool s_testing;
 };
 
 // Usage: controllerDebug("hello" << "world");
@@ -39,7 +55,7 @@ class ControllerDebug {
 // output for mixxx.log with .noquote(), because in qt5 QDebug() is quoted by default.
 #define controllerDebug(stream)                                                           \
     {                                                                                     \
-        if (ControllerDebug::enabled()) {                                                 \
+        if (ControllerDebug::isEnabled()) {                                               \
             QDebug(QtDebugMsg).noquote() << ControllerDebug::kLogMessagePrefix << stream; \
         }                                                                                 \
     }
diff --git a/src/controllers/controllerpreset.h b/src/controllers/controllerpreset.h
index 2eaa98b4f9a..931e655752a 100644
--- a/src/controllers/controllerpreset.h
+++ b/src/controllers/controllerpreset.h
@@ -55,14 +55,6 @@ class ControllerPreset {
         return m_scripts;
     }
 
-    void setModuleFileInfo(QFileInfo fileInfo) {
-        m_moduleFileInfo = std::move(fileInfo);
-    }
-
-    QFileInfo moduleFileInfo() const {
-        return m_moduleFileInfo;
-    }
-
     inline void setDirty(bool bDirty) {
         m_bDirty = bDirty;
     }
@@ -203,7 +195,6 @@ class ControllerPreset {
     QString m_mixxxVersion;
 
     QList<ScriptFileInfo> m_scripts;
-    QFileInfo m_moduleFileInfo;
 };
 
 typedef QSharedPointer<ControllerPreset> ControllerPresetPointer;
diff --git a/src/controllers/controllerpresetfilehandler.cpp b/src/controllers/controllerpresetfilehandler.cpp
index 7c351527054..55151d18582 100644
--- a/src/controllers/controllerpresetfilehandler.cpp
+++ b/src/controllers/controllerpresetfilehandler.cpp
@@ -142,20 +142,6 @@ void ControllerPresetFileHandler::addScriptFilesToPreset(
         preset->addScriptFile(filename, functionPrefix, file);
         scriptFile = scriptFile.nextSiblingElement("file");
     }
-
-    QString moduleFileName = controller.firstChildElement("module").text();
-
-    if (moduleFileName.isEmpty()) {
-        return;
-    }
-
-    QFileInfo moduleFileInfo(preset->dirPath().absoluteFilePath(moduleFileName));
-    if (!moduleFileInfo.isFile()) {
-        qWarning() << "Controller Module is not a file:" << moduleFileInfo.absoluteFilePath();
-        return;
-    }
-
-    preset->setModuleFileInfo(moduleFileInfo);
 }
 
 bool ControllerPresetFileHandler::writeDocument(
diff --git a/src/controllers/engine/controllerengine.cpp b/src/controllers/engine/controllerengine.cpp
deleted file mode 100644
index a802f1d31fa..00000000000
--- a/src/controllers/engine/controllerengine.cpp
+++ /dev/null
@@ -1,1377 +0,0 @@
-#include "controllers/engine/controllerengine.h"
-
-#include "control/controlobject.h"
-#include "control/controlobjectscript.h"
-#include "controllers/controller.h"
-#include "controllers/controllerdebug.h"
-#include "controllers/engine/colormapperjsproxy.h"
-#include "controllers/engine/controllerenginejsproxy.h"
-#include "controllers/engine/scriptconnectionjsproxy.h"
-#include "errordialoghandler.h"
-#include "mixer/playermanager.h"
-#include "moc_controllerengine.cpp"
-// to tell the msvs compiler about `isnan`
-#include "util/math.h"
-#include "util/time.h"
-
-namespace {
-constexpr int kDecks = 16;
-
-// Use 1ms for the Alpha-Beta dt. We're assuming the OS actually gives us a 1ms
-// timer.
-constexpr int kScratchTimerMs = 1;
-constexpr double kAlphaBetaDt = kScratchTimerMs / 1000.0;
-
-inline ControlFlags onlyAssertOnControllerDebug() {
-    if (ControllerDebug::enabled()) {
-        return ControlFlag::None;
-    }
-
-    return ControlFlag::AllowMissingOrInvalid;
-}
-} // namespace
-
-ControllerEngine::ControllerEngine(Controller* controller)
-        : m_bDisplayingExceptionDialog(false),
-          m_pScriptEngine(nullptr),
-          m_pController(controller),
-          m_bTesting(false) {
-    // Handle error dialog buttons
-    qRegisterMetaType<QMessageBox::StandardButton>("QMessageBox::StandardButton");
-
-    // Pre-allocate arrays for average number of virtual decks
-    m_intervalAccumulator.resize(kDecks);
-    m_lastMovement.resize(kDecks);
-    m_dx.resize(kDecks);
-    m_rampTo.resize(kDecks);
-    m_ramp.resize(kDecks);
-    m_scratchFilters.resize(kDecks);
-    m_rampFactor.resize(kDecks);
-    m_brakeActive.resize(kDecks);
-    m_softStartActive.resize(kDecks);
-    // Initialize arrays used for testing and pointers
-    for (int i = 0; i < kDecks; ++i) {
-        m_dx[i] = 0.0;
-        m_scratchFilters[i] = new AlphaBetaFilter();
-        m_ramp[i] = false;
-    }
-
-    initializeScriptEngine();
-}
-
-ControllerEngine::~ControllerEngine() {
-    // Clean up
-    for (int i = 0; i < kDecks; ++i) {
-        delete m_scratchFilters[i];
-        m_scratchFilters[i] = nullptr;
-    }
-
-    uninitializeScriptEngine();
-}
-
-bool ControllerEngine::callFunctionOnObjects(
-        const QList<QString>& scriptFunctionPrefixes,
-        const QString& function,
-        const QJSValueList& args,
-        bool bFatalError) {
-    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine) {
-        return false;
-    }
-
-    const QJSValue global = m_pScriptEngine->globalObject();
-
-    bool success = true;
-    for (const QString& prefixName : scriptFunctionPrefixes) {
-        QJSValue prefix = global.property(prefixName);
-        if (!prefix.isObject()) {
-            qWarning() << "ControllerEngine: No" << prefixName << "object in script";
-            continue;
-        }
-
-        QJSValue init = prefix.property(function);
-        if (!init.isCallable()) {
-            qWarning() << "ControllerEngine:" << prefixName << "has no" << function << " method";
-            continue;
-        }
-        controllerDebug("ControllerEngine: Executing" << prefixName << "." << function);
-        QJSValue result = init.callWithInstance(prefix, args);
-        if (result.isError()) {
-            showScriptExceptionDialog(result, bFatalError);
-            success = false;
-        }
-    }
-    return success;
-}
-
-QJSValue ControllerEngine::byteArrayToScriptValue(const QByteArray& byteArray) {
-    // The QJSEngine converts the QByteArray to an ArrayBuffer object.
-    QJSValue arrayBuffer = m_pScriptEngine->toScriptValue(byteArray);
-    // Convert the ArrayBuffer to a Uint8 typed array so scripts can access its bytes
-    // with the [] operator.
-    QJSValue result = m_byteArrayToScriptValueJSFunction.call(
-            QJSValueList{arrayBuffer});
-    if (result.isError()) {
-        showScriptExceptionDialog(result);
-    }
-    return result;
-}
-
-QJSValue ControllerEngine::wrapFunctionCode(const QString& codeSnippet,
-        int numberOfArgs) {
-    // This function is called from outside the controller engine, so we can't
-    // use VERIFY_OR_DEBUG_ASSERT here
-    if (m_pScriptEngine == nullptr) {
-        return QJSValue();
-    }
-
-    QJSValue wrappedFunction;
-
-    auto i = m_scriptWrappedFunctionCache.constFind(codeSnippet);
-    if (i != m_scriptWrappedFunctionCache.constEnd()) {
-        wrappedFunction = i.value();
-    } else {
-        QStringList wrapperArgList;
-        for (int i = 1; i <= numberOfArgs; i++) {
-            wrapperArgList << QString("arg%1").arg(i);
-        }
-        QString wrapperArgs = wrapperArgList.join(",");
-        QString wrappedCode = QStringLiteral("(function (") + wrapperArgs +
-                QStringLiteral(") { (") + codeSnippet + QStringLiteral(")(") +
-                wrapperArgs + QStringLiteral("); })");
-
-        wrappedFunction = evaluateCodeString(wrappedCode);
-        if (wrappedFunction.isError()) {
-            showScriptExceptionDialog(wrappedFunction);
-        }
-        m_scriptWrappedFunctionCache[codeSnippet] = wrappedFunction;
-    }
-    return wrappedFunction;
-}
-
-void ControllerEngine::gracefulShutdown() {
-    if (m_pScriptEngine == nullptr) {
-        return;
-    }
-
-    qDebug() << "ControllerEngine shutting down...";
-
-    // Stop all timers
-    stopAllTimers();
-
-    qDebug() << "Invoking shutdown() hook in scripts";
-    callFunctionOnObjects(m_scriptFunctionPrefixes, "shutdown");
-
-    if (m_shutdownFunction.isCallable()) {
-        executeFunction(m_shutdownFunction, QJSValueList{});
-    }
-
-    // Prevents leaving decks in an unstable state
-    //  if the controller is shut down while scratching
-    QHashIterator<int, int> i(m_scratchTimers);
-    while (i.hasNext()) {
-        i.next();
-        qDebug() << "Aborting scratching on deck" << i.value();
-        // Clear scratch2_enable. PlayerManager::groupForDeck is 0-indexed.
-        QString group = PlayerManager::groupForDeck(i.value() - 1);
-        ControlObjectScript* pScratch2Enable =
-                getControlObjectScript(group, "scratch2_enable");
-        if (pScratch2Enable != nullptr) {
-            pScratch2Enable->set(0);
-        }
-    }
-
-    qDebug() << "Clearing function wrapper cache";
-    m_scriptWrappedFunctionCache.clear();
-
-    // Free all the ControlObjectScripts
-    {
-        auto it = m_controlCache.begin();
-        while (it != m_controlCache.end()) {
-            qDebug()
-                    << "Deleting ControlObjectScript"
-                    << it.key().group
-                    << it.key().item;
-            delete it.value();
-            // Advance iterator
-            it = m_controlCache.erase(it);
-        }
-    }
-}
-
-void ControllerEngine::initializeScriptEngine() {
-    VERIFY_OR_DEBUG_ASSERT(!m_pScriptEngine) {
-        return;
-    }
-
-    // Create the Script Engine
-    m_pScriptEngine = new QJSEngine(this);
-
-    m_pScriptEngine->installExtensions(QJSEngine::ConsoleExtension);
-
-    // Make this ControllerEngine instance available to scripts as 'engine'.
-    QJSValue engineGlobalObject = m_pScriptEngine->globalObject();
-    ControllerEngineJSProxy* proxy = new ControllerEngineJSProxy(this);
-    engineGlobalObject.setProperty("engine", m_pScriptEngine->newQObject(proxy));
-
-    QJSValue mapper = m_pScriptEngine->newQMetaObject(&ColorMapperJSProxy::staticMetaObject);
-    engineGlobalObject.setProperty("ColorMapper", mapper);
-
-    if (m_pController) {
-        qDebug() << "Controller in script engine is:" << m_pController->getName();
-
-        ControllerJSProxy* controllerProxy = m_pController->jsProxy();
-
-        // Make the Controller instance available to scripts
-        engineGlobalObject.setProperty("controller", m_pScriptEngine->newQObject(controllerProxy));
-
-        // ...under the legacy name as well
-        engineGlobalObject.setProperty("midi", m_pScriptEngine->newQObject(controllerProxy));
-    }
-
-    m_byteArrayToScriptValueJSFunction = evaluateCodeString("(function(arg1) { return new Uint8Array(arg1) })");
-}
-
-void ControllerEngine::uninitializeScriptEngine() {
-    // Delete the script engine, first clearing the pointer so that
-    // other threads will not get the dead pointer after we delete it.
-    if (m_pScriptEngine != nullptr) {
-        QJSEngine* engine = m_pScriptEngine;
-        m_pScriptEngine = nullptr;
-        engine->deleteLater();
-    }
-}
-
-void ControllerEngine::loadModule(const QFileInfo& moduleFileInfo) {
-    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
-    // actually contains a reference, so we check if the filePath is empty as a
-    // workaround.
-    // See https://stackoverflow.com/a/45652741/1455128 for details.
-    VERIFY_OR_DEBUG_ASSERT(!moduleFileInfo.filePath().isEmpty()) {
-        return;
-    }
-
-    VERIFY_OR_DEBUG_ASSERT(moduleFileInfo.isFile()) {
-        return;
-    }
-#if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
-    m_moduleFileInfo = moduleFileInfo;
-
-    QJSValue mod = m_pScriptEngine->importModule(moduleFileInfo.absoluteFilePath());
-    if (mod.isError()) {
-        showScriptExceptionDialog(mod);
-        return;
-    }
-
-    connect(&m_scriptWatcher,
-            &QFileSystemWatcher::fileChanged,
-            this,
-            &ControllerEngine::scriptHasChanged);
-    m_scriptWatcher.addPath(moduleFileInfo.absoluteFilePath());
-
-    QJSValue initFunction = mod.property("init");
-    executeFunction(initFunction, QJSValueList{});
-
-    QJSValue handleInputFunction = mod.property("handleInput");
-    if (handleInputFunction.isCallable()) {
-        m_handleInputFunction = handleInputFunction;
-    } else {
-        scriptErrorDialog(
-                "Controller JavaScript module exports no handleInput function.",
-                QStringLiteral("handleInput"),
-                true);
-    }
-
-    QJSValue shutdownFunction = mod.property("shutdown");
-    if (shutdownFunction.isCallable()) {
-        m_shutdownFunction = shutdownFunction;
-    } else {
-        qDebug() << "Module exports no shutdown function.";
-    }
-#else
-    Q_UNUSED(moduleFileInfo);
-#endif
-}
-
-void ControllerEngine::handleInput(const QByteArray& data, mixxx::Duration timestamp) {
-    if (m_handleInputFunction.isCallable()) {
-        QJSValueList args;
-        args << byteArrayToScriptValue(data);
-        args << timestamp.toDoubleMillis();
-        executeFunction(m_handleInputFunction, args);
-    }
-}
-
-bool ControllerEngine::loadScriptFiles(const QList<ControllerPreset::ScriptFileInfo>& scripts) {
-    bool scriptsEvaluatedCorrectly = true;
-    for (const auto& script : scripts) {
-        if (!evaluateScriptFile(script.file)) {
-            scriptsEvaluatedCorrectly = false;
-        }
-    }
-
-    m_lastScriptFiles = scripts;
-
-    connect(&m_scriptWatcher,
-            &QFileSystemWatcher::fileChanged,
-            this,
-            &ControllerEngine::scriptHasChanged);
-
-    if (!scriptsEvaluatedCorrectly) {
-        gracefulShutdown();
-        uninitializeScriptEngine();
-    }
-
-    return scriptsEvaluatedCorrectly;
-}
-
-void ControllerEngine::scriptHasChanged(const QString& scriptFilename) {
-    Q_UNUSED(scriptFilename);
-    disconnect(&m_scriptWatcher, &QFileSystemWatcher::fileChanged, this, &ControllerEngine::scriptHasChanged);
-    reloadScripts();
-}
-
-void ControllerEngine::reloadScripts() {
-    qDebug() << "ControllerEngine: Reloading Scripts";
-    ControllerPresetPointer pPreset = m_pController->getPreset();
-
-    gracefulShutdown();
-    uninitializeScriptEngine();
-
-    initializeScriptEngine();
-    if (!loadScriptFiles(m_lastScriptFiles)) {
-        return;
-    }
-
-    qDebug() << "Re-initializing scripts";
-    initializeScripts(m_lastScriptFiles);
-
-    // QFileInfo does not have a isValid/isEmpty/isNull method to check if it
-    // actually contains a reference, so we check if the filePath is empty as a
-    // workaround.
-    // See https://stackoverflow.com/a/45652741/1455128 for details.
-    if (!m_moduleFileInfo.filePath().isEmpty()) {
-        loadModule(m_moduleFileInfo);
-    }
-}
-
-void ControllerEngine::initializeScripts(const QList<ControllerPreset::ScriptFileInfo>& scripts) {
-    m_scriptFunctionPrefixes.clear();
-    for (const ControllerPreset::ScriptFileInfo& script : scripts) {
-        // Skip empty prefixes.
-        if (!script.functionPrefix.isEmpty()) {
-            m_scriptFunctionPrefixes.append(script.functionPrefix);
-        }
-    }
-
-    QJSValueList args;
-    args << QJSValue(m_pController->getName());
-    args << QJSValue(ControllerDebug::enabled());
-
-    // Call the init method for all the prefixes.
-    bool success = callFunctionOnObjects(m_scriptFunctionPrefixes, "init", args, true);
-
-    // We failed to initialize the controller scripts, shutdown the script
-    // engine to avoid error popups on every button press or slider move
-    if (!success) {
-        gracefulShutdown();
-        uninitializeScriptEngine();
-    }
-}
-
-bool ControllerEngine::executeFunction(QJSValue functionObject, const QJSValueList& args) {
-    // This function is called from outside the controller engine, so we can't
-    // use VERIFY_OR_DEBUG_ASSERT here
-    if (!m_pScriptEngine) {
-        return false;
-    }
-
-    if (functionObject.isError()) {
-        qDebug() << "ControllerEngine::executeFunction:"
-                 << functionObject.toString();
-        return false;
-    }
-
-    // If it's not a function, we're done.
-    if (!functionObject.isCallable()) {
-        qDebug() << "ControllerEngine::executeFunction:"
-                 << functionObject.toVariant()
-                 << "Not a function";
-        return false;
-    }
-
-    // If it does happen to be a function, call it.
-    QJSValue returnValue = functionObject.call(args);
-    if (returnValue.isError()) {
-        showScriptExceptionDialog(returnValue);
-        return false;
-    }
-    return true;
-}
-
-bool ControllerEngine::executeFunction(const QJSValue& functionObject, const QByteArray& data) {
-    // This function is called from outside the controller engine, so we can't
-    // use VERIFY_OR_DEBUG_ASSERT here
-    if (!m_pScriptEngine) {
-        return false;
-    }
-    QJSValueList args;
-    args << byteArrayToScriptValue(data);
-    args << QJSValue(data.size());
-    return executeFunction(functionObject, args);
-}
-
-QJSValue ControllerEngine::evaluateCodeString(const QString& program, const QString& fileName, int lineNumber) {
-    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine) {
-        return QJSValue::UndefinedValue;
-    }
-    return m_pScriptEngine->evaluate(program, fileName, lineNumber);
-}
-
-void ControllerEngine::throwJSError(const QString& message) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 12, 0)
-    QString errorText = tr("Uncaught exception: %1").arg(message);
-    qWarning() << "ControllerEngine:" << errorText;
-    if (!m_bDisplayingExceptionDialog) {
-        scriptErrorDialog(errorText, errorText);
-    }
-#else
-    m_pScriptEngine->throwError(message);
-#endif
-}
-
-void ControllerEngine::showScriptExceptionDialog(
-        const QJSValue& evaluationResult, bool bFatalError) {
-    VERIFY_OR_DEBUG_ASSERT(evaluationResult.isError()) {
-        return;
-    }
-
-    QString errorMessage = evaluationResult.toString();
-    QString line = evaluationResult.property("lineNumber").toString();
-    QString backtrace = evaluationResult.property("stack").toString();
-    QString filename = evaluationResult.property("fileName").toString();
-
-    QString errorText;
-    if (filename.isEmpty()) {
-        errorText = QString("Uncaught exception at line %1 in passed code.").arg(line);
-    } else {
-        errorText = QString("Uncaught exception at line %1 in file %2.").arg(line, filename);
-    }
-
-    errorText += QStringLiteral("\n\nException:\n  ") + errorMessage;
-
-    // Do not include backtrace in dialog key because it might contain midi
-    // slider values that will differ most of the time. This would break
-    // the "Ignore" feature of the error dialog.
-    QString key = errorText;
-    qWarning() << "ControllerEngine:" << errorText;
-
-    // Add backtrace to the error details
-    errorText += QStringLiteral("\n\nBacktrace:\n") + backtrace;
-
-    if (!m_bDisplayingExceptionDialog) {
-        scriptErrorDialog(errorText, key, bFatalError);
-    }
-}
-
-void ControllerEngine::scriptErrorDialog(
-        const QString& detailedError, const QString& key, bool bFatalError) {
-    if (m_bTesting) {
-        return;
-    }
-
-    ErrorDialogProperties* props =
-            ErrorDialogHandler::instance()->newDialogProperties();
-
-    QString additionalErrorText;
-    if (bFatalError) {
-        additionalErrorText =
-                tr("The functionality provided by this controller mapping will "
-                   "be disabled until the issue has been resolved.");
-    } else {
-        additionalErrorText =
-                tr("You can ignore this error for this session but "
-                   "you may experience erratic behavior.") +
-                QString("<br>") +
-                tr("Try to recover by resetting your controller.");
-    }
-
-    props->setType(DLG_WARNING);
-    props->setTitle(tr("Controller Preset Error"));
-    props->setText(QString(tr("The preset for your controller \"%1\" is not "
-                              "working properly."))
-                           .arg(m_pController->getName()));
-    props->setInfoText(QStringLiteral("<html>") +
-            tr("The script code needs to be fixed.") + QStringLiteral("<p>") +
-            additionalErrorText + QStringLiteral("</p></html>"));
-
-    // Add "Details" text and set monospace font since they may contain
-    // backtraces and code.
-    props->setDetails(detailedError, true);
-
-    // To prevent multiple windows for the same error
-    props->setKey(key);
-
-    // Allow user to suppress further notifications about this particular error
-    if (!bFatalError) {
-        props->addButton(QMessageBox::Ignore);
-        props->addButton(QMessageBox::Retry);
-        props->setDefaultButton(QMessageBox::Ignore);
-        props->setEscapeButton(QMessageBox::Ignore);
-    } else {
-        props->addButton(QMessageBox::Close);
-        props->setDefaultButton(QMessageBox::Close);
-        props->setEscapeButton(QMessageBox::Close);
-    }
-    props->setModal(false);
-
-    if (ErrorDialogHandler::instance()->requestErrorDialog(props)) {
-        m_bDisplayingExceptionDialog = true;
-        // Enable custom handling of the dialog buttons
-        connect(ErrorDialogHandler::instance(),
-                &ErrorDialogHandler::stdButtonClicked,
-                this,
-                &ControllerEngine::errorDialogButton);
-    }
-}
-
-void ControllerEngine::errorDialogButton(
-        const QString& key, QMessageBox::StandardButton clickedButton) {
-    Q_UNUSED(key);
-
-    m_bDisplayingExceptionDialog = false;
-    // Something was clicked, so disable this signal now
-    disconnect(ErrorDialogHandler::instance(),
-            &ErrorDialogHandler::stdButtonClicked,
-            this,
-            &ControllerEngine::errorDialogButton);
-
-    if (clickedButton == QMessageBox::Retry) {
-        reloadScripts();
-    }
-}
-
-ControlObjectScript* ControllerEngine::getControlObjectScript(const QString& group, const QString& name) {
-    ConfigKey key = ConfigKey(group, name);
-
-    if (!key.isValid()) {
-        qWarning() << "ControllerEngine: Requested control with invalid key" << key;
-        // Throw a debug assertion if controllerDebug is enabled
-        DEBUG_ASSERT(!ControllerDebug::enabled());
-        return nullptr;
-    }
-
-    ControlObjectScript* coScript = m_controlCache.value(key, nullptr);
-    if (coScript == nullptr) {
-        // create COT
-        coScript = new ControlObjectScript(key, this);
-        if (coScript->valid()) {
-            m_controlCache.insert(key, coScript);
-        } else {
-            delete coScript;
-            coScript = nullptr;
-        }
-    }
-    return coScript;
-}
-
-double ControllerEngine::getValue(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    if (coScript == nullptr) {
-        qWarning() << "ControllerEngine: Unknown control" << group << name << ", returning 0.0";
-        return 0.0;
-    }
-    return coScript->get();
-}
-
-void ControllerEngine::setValue(const QString& group, const QString& name, double newValue) {
-    if (isnan(newValue)) {
-        qWarning() << "ControllerEngine: script setting [" << group << "," << name
-                   << "] to NotANumber, ignoring.";
-        return;
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-
-    if (coScript) {
-        ControlObject* pControl = ControlObject::getControl(
-                coScript->getKey(), onlyAssertOnControllerDebug());
-        if (pControl && !m_st.ignore(pControl, coScript->getParameterForValue(newValue))) {
-            coScript->slotSet(newValue);
-        }
-    }
-}
-
-double ControllerEngine::getParameter(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    if (coScript == nullptr) {
-        qWarning() << "ControllerEngine: Unknown control" << group << name << ", returning 0.0";
-        return 0.0;
-    }
-    return coScript->getParameter();
-}
-
-void ControllerEngine::setParameter(
-        const QString& group, const QString& name, double newParameter) {
-    if (isnan(newParameter)) {
-        qWarning() << "ControllerEngine: script setting [" << group << "," << name
-                   << "] to NotANumber, ignoring.";
-        return;
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-
-    if (coScript) {
-        ControlObject* pControl = ControlObject::getControl(
-                coScript->getKey(), onlyAssertOnControllerDebug());
-        if (pControl && !m_st.ignore(pControl, newParameter)) {
-            coScript->setParameter(newParameter);
-        }
-    }
-}
-
-double ControllerEngine::getParameterForValue(
-        const QString& group, const QString& name, double value) {
-    if (isnan(value)) {
-        qWarning() << "ControllerEngine: script setting [" << group << "," << name
-                   << "] to NotANumber, ignoring.";
-        return 0.0;
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-
-    if (coScript == nullptr) {
-        qWarning() << "ControllerEngine: Unknown control" << group << name << ", returning 0.0";
-        return 0.0;
-    }
-
-    return coScript->getParameterForValue(value);
-}
-
-void ControllerEngine::reset(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    if (coScript != nullptr) {
-        coScript->reset();
-    }
-}
-
-double ControllerEngine::getDefaultValue(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-
-    if (coScript == nullptr) {
-        qWarning() << "ControllerEngine: Unknown control" << group << name << ", returning 0.0";
-        return 0.0;
-    }
-
-    return coScript->getDefault();
-}
-
-double ControllerEngine::getDefaultParameter(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-
-    if (coScript == nullptr) {
-        qWarning() << "ControllerEngine: Unknown control" << group << name << ", returning 0.0";
-        return 0.0;
-    }
-
-    return coScript->getParameterForValue(coScript->getDefault());
-}
-
-void ControllerEngine::log(const QString& message) {
-    controllerDebug(message);
-}
-
-QJSValue ControllerEngine::makeConnection(
-        const QString& group, const QString& name, const QJSValue& callback) {
-    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine != nullptr) {
-        return QJSValue();
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    if (coScript == nullptr) {
-        // The test setups do not run all of Mixxx, so ControlObjects not
-        // existing during tests is okay.
-        if (!m_bTesting) {
-            throwJSError("ControllerEngine: script tried to connect to ControlObject (" +
-                    group + ", " + name +
-                    ") which is non-existent.");
-        }
-        return QJSValue();
-    }
-
-    if (!callback.isCallable()) {
-        throwJSError("Tried to connect (" + group + ", " + name + ")" + " to an invalid callback. Make sure that your code contains no syntax errors.");
-        return QJSValue();
-    }
-
-    ScriptConnection connection;
-    connection.key = ConfigKey(group, name);
-    connection.controllerEngine = this;
-    connection.callback = callback;
-    connection.id = QUuid::createUuid();
-
-    if (coScript->addScriptConnection(connection)) {
-        return m_pScriptEngine->newQObject(new ScriptConnectionJSProxy(connection));
-    }
-
-    return QJSValue();
-}
-
-bool ControllerEngine::removeScriptConnection(const ScriptConnection& connection) {
-    ControlObjectScript* coScript = getControlObjectScript(connection.key.group,
-            connection.key.item);
-
-    if (m_pScriptEngine == nullptr || coScript == nullptr) {
-        return false;
-    }
-
-    return coScript->removeScriptConnection(connection);
-}
-
-void ControllerEngine::triggerScriptConnection(const ScriptConnection& connection) {
-    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine) {
-        return;
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(connection.key.group,
-            connection.key.item);
-    if (coScript == nullptr) {
-        return;
-    }
-
-    connection.executeCallback(coScript->get());
-}
-
-// This function is a legacy version of makeConnection with several alternate
-// ways of invoking it. The callback function can be passed either as a string of
-// JavaScript code that evaluates to a function or an actual JavaScript function.
-// If "true" is passed as a 4th parameter, all connections to the ControlObject
-// are removed. If a ScriptConnectionInvokableWrapper is passed instead of a callback,
-// it is disconnected.
-// WARNING: These behaviors are quirky and confusing, so if you change this function,
-// be sure to run the ControllerEngineTest suite to make sure you do not break old scripts.
-QJSValue ControllerEngine::connectControl(const QString& group,
-        const QString& name,
-        const QJSValue& passedCallback,
-        bool disconnect) {
-    // The passedCallback may or may not actually be a function, so when
-    // the actual callback function is found, store it in this variable.
-    QJSValue actualCallbackFunction;
-
-    if (passedCallback.isCallable()) {
-        if (!disconnect) {
-            // skip all the checks below and just make the connection
-            return makeConnection(group, name, passedCallback);
-        }
-        actualCallbackFunction = passedCallback;
-    }
-
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    // This check is redundant with makeConnection, but the
-    // ControlObjectScript is also needed here to check for duplicate connections.
-    if (coScript == nullptr) {
-        // The test setups do not run all of Mixxx, so ControlObjects not
-        // existing during tests is okay.
-        if (!m_bTesting) {
-            if (disconnect) {
-                throwJSError("ControllerEngine: script tried to disconnect from ControlObject (" +
-                        group + ", " + name + ") which is non-existent.");
-            } else {
-                throwJSError("ControllerEngine: script tried to connect to ControlObject (" +
-                        group + ", " + name + ") which is non-existent.");
-            }
-        }
-        // This is inconsistent with other failures, which return false.
-        // QJSValue() with no arguments is undefined in JavaScript.
-        return QJSValue();
-    }
-
-    if (passedCallback.isString()) {
-        // This check is redundant with makeConnection, but it must be done here
-        // before evaluating the code string.
-        VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine != nullptr) {
-            return QJSValue(false);
-        }
-
-        actualCallbackFunction = evaluateCodeString(passedCallback.toString());
-
-        if (!actualCallbackFunction.isCallable()) {
-            QString sErrorMessage("Invalid connection callback provided to engine.connectControl.");
-            if (actualCallbackFunction.isError()) {
-                sErrorMessage.append("\n" + actualCallbackFunction.toString());
-            }
-            throwJSError(sErrorMessage);
-            return QJSValue(false);
-        }
-
-        if (coScript->countConnections() > 0 && !disconnect) {
-            // This is inconsistent with the behavior when passing the callback as
-            // a function, but keep the old behavior to make sure old scripts do
-            // not break.
-            ScriptConnection connection = coScript->firstConnection();
-
-            qWarning() << "Tried to make duplicate connection between (" +
-                            group + ", " + name + ") and " + passedCallback.toString() +
-                            " but this is not allowed when passing a callback as a string. " +
-                            "If you actually want to create duplicate connections, " +
-                            "use engine.makeConnection. Returning reference to connection " +
-                            connection.id.toString();
-
-            return m_pScriptEngine->newQObject(new ScriptConnectionJSProxy(connection));
-        }
-    } else if (passedCallback.isQObject()) {
-        // Assume a ScriptConnection and assume that the script author
-        // wants to disconnect it, regardless of the disconnect parameter
-        // and regardless of whether it is connected to the same ControlObject
-        // specified by the first two parameters to this function.
-        QObject* qobject = passedCallback.toQObject();
-        const QMetaObject* qmeta = qobject->metaObject();
-
-        qWarning() << "QObject passed to engine.connectControl. Assuming it is"
-                   << "a connection object to disconnect and returning false.";
-        if (!strcmp(qmeta->className(),
-                    "ScriptConnectionJSProxy")) {
-            ScriptConnectionJSProxy* proxy =
-                    (ScriptConnectionJSProxy*)qobject;
-            proxy->disconnect();
-        }
-        return QJSValue(false);
-    }
-
-    // Support removing connections by passing "true" as the last parameter
-    // to this function, regardless of whether the callback is provided
-    // as a function or a string.
-    if (disconnect) {
-        // There is no way to determine which
-        // ScriptConnection to disconnect unless the script calls
-        // ScriptConnectionInvokableWrapper::disconnect(), so
-        // disconnect all ScriptConnections connected to the
-        // callback function, even though there may be multiple connections.
-        coScript->disconnectAllConnectionsToFunction(actualCallbackFunction);
-        return QJSValue(true);
-    }
-
-    // If execution gets this far without returning, make
-    // a new connection to actualCallbackFunction.
-    return makeConnection(group, name, actualCallbackFunction);
-}
-
-void ControllerEngine::trigger(const QString& group, const QString& name) {
-    ControlObjectScript* coScript = getControlObjectScript(group, name);
-    if (coScript != nullptr) {
-        coScript->emitValueChanged();
-    }
-}
-
-bool ControllerEngine::evaluateScriptFile(const QFileInfo& scriptFile) {
-    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngine) {
-        return false;
-    }
-
-    if (!scriptFile.exists()) {
-        qWarning() << "ControllerEngine: File does not exist:" << scriptFile.absoluteFilePath();
-        return false;
-    }
-    m_scriptWatcher.addPath(scriptFile.absoluteFilePath());
-
-    qDebug() << "ControllerEngine: Loading" << scriptFile.absoluteFilePath();
-
-    // Read in the script file
-    QString filename = scriptFile.absoluteFilePath();
-    QFile input(filename);
-    if (!input.open(QIODevice::ReadOnly)) {
-        qWarning() << QString("ControllerEngine: Problem opening the script file: %1, error # %2, %3")
-                              .arg(filename, QString::number(input.error()), input.errorString());
-        // Set up error dialog
-        ErrorDialogProperties* props = ErrorDialogHandler::instance()->newDialogProperties();
-        props->setType(DLG_WARNING);
-        props->setTitle(tr("Controller Mapping File Problem"));
-        props->setText(tr("The mapping for controller \"%1\" cannot be opened.")
-                               .arg(m_pController->getName()));
-        props->setInfoText(
-                tr("The functionality provided by this controller mapping will "
-                   "be disabled until the issue has been resolved."));
-
-        // We usually don't translate the details field, but the cause of
-        // this problem lies in the user's system (e.g. a permission
-        // issue). Translating this will help users to fix the issue even
-        // when they don't speak english.
-        props->setDetails(tr("File:") + QStringLiteral(" ") + filename +
-                QStringLiteral("\n") + tr("Error:") + QStringLiteral(" ") +
-                input.errorString());
-
-        // Ask above layer to display the dialog & handle user response
-        ErrorDialogHandler::instance()->requestErrorDialog(props);
-        return false;
-    }
-
-    QString scriptCode = "";
-    scriptCode.append(input.readAll());
-    scriptCode.append('\n');
-    input.close();
-
-    // Evaluate the code
-    QJSValue scriptFunction = evaluateCodeString(scriptCode, filename);
-    if (scriptFunction.isError()) {
-        showScriptExceptionDialog(scriptFunction, true);
-        return false;
-    }
-
-    return true;
-}
-
-int ControllerEngine::beginTimer(int intervalMillis, QJSValue timerCallback, bool oneShot) {
-    if (timerCallback.isString()) {
-        timerCallback = evaluateCodeString(timerCallback.toString());
-    } else if (!timerCallback.isCallable()) {
-        QString sErrorMessage(
-                "Invalid timer callback provided to engine.beginTimer. Valid callbacks are strings and functions. "
-                "Make sure that your code contains no syntax errors.");
-        if (timerCallback.isError()) {
-            sErrorMessage.append("\n" + timerCallback.toString());
-        }
-        throwJSError(sErrorMessage);
-        return 0;
-    }
-
-    if (intervalMillis < 20) {
-        qWarning() << "Timer request for" << intervalMillis
-                   << "ms is too short. Setting to the minimum of 20ms.";
-        intervalMillis = 20;
-    }
-
-    // This makes use of every QObject's internal timer mechanism. Nice, clean,
-    // and simple. See http://doc.trolltech.com/4.6/qobject.html#startTimer for
-    // details
-    int timerId = startTimer(intervalMillis);
-    TimerInfo info;
-    info.callback = timerCallback;
-    info.oneShot = oneShot;
-    m_timers[timerId] = info;
-    if (timerId == 0) {
-        qWarning() << "Script timer could not be created";
-    } else if (oneShot) {
-        controllerDebug("Starting one-shot timer:" << timerId);
-    } else {
-        controllerDebug("Starting timer:" << timerId);
-    }
-    return timerId;
-}
-
-void ControllerEngine::stopTimer(int timerId) {
-    if (!m_timers.contains(timerId)) {
-        qWarning() << "Killing timer" << timerId << ": That timer does not exist!";
-        return;
-    }
-    controllerDebug("Killing timer:" << timerId);
-    killTimer(timerId);
-    m_timers.remove(timerId);
-}
-
-void ControllerEngine::stopAllTimers() {
-    QMutableHashIterator<int, TimerInfo> i(m_timers);
-    while (i.hasNext()) {
-        i.next();
-        stopTimer(i.key());
-    }
-}
-
-void ControllerEngine::timerEvent(QTimerEvent* event) {
-    int timerId = event->timerId();
-
-    // See if this is a scratching timer
-    if (m_scratchTimers.contains(timerId)) {
-        scratchProcess(timerId);
-        return;
-    }
-
-    auto it = m_timers.constFind(timerId);
-    if (it == m_timers.constEnd()) {
-        qWarning() << "Timer" << timerId << "fired but there's no function mapped to it!";
-        return;
-    }
-
-    // NOTE(rryan): Do not assign by reference -- make a copy. I have no idea
-    // why but this causes segfaults in ~QScriptValue while scratching if we
-    // don't copy here -- even though internalExecute passes the QScriptValues
-    // by value. *boggle*
-    const TimerInfo timerTarget = it.value();
-    if (timerTarget.oneShot) {
-        stopTimer(timerId);
-    }
-
-    executeFunction(timerTarget.callback, QJSValueList());
-}
-
-void ControllerEngine::softTakeover(const QString& group, const QString& name, bool set) {
-    ConfigKey key = ConfigKey(group, name);
-    ControlObject* pControl = ControlObject::getControl(key, onlyAssertOnControllerDebug());
-    if (!pControl) {
-        qWarning() << "Failed to" << (set ? "enable" : "disable")
-                   << "softTakeover for invalid control" << key;
-        return;
-    }
-    if (set) {
-        m_st.enable(pControl);
-    } else {
-        m_st.disable(pControl);
-    }
-}
-
-void ControllerEngine::softTakeoverIgnoreNextValue(const QString& group, const QString& name) {
-    ConfigKey key = ConfigKey(group, name);
-    ControlObject* pControl = ControlObject::getControl(key, onlyAssertOnControllerDebug());
-    if (!pControl) {
-        qWarning() << "Failed to call softTakeoverIgnoreNextValue for invalid control" << key;
-        return;
-    }
-
-    m_st.ignoreNext(pControl);
-}
-
-double ControllerEngine::getDeckRate(const QString& group) {
-    double rate = 0.0;
-    ControlObjectScript* pRateRatio = getControlObjectScript(group, "rate_ratio");
-    if (pRateRatio != nullptr) {
-        rate = pRateRatio->get();
-    }
-
-    // See if we're in reverse play
-    ControlObjectScript* pReverse = getControlObjectScript(group, "reverse");
-    if (pReverse != nullptr && pReverse->get() == 1) {
-        rate = -rate;
-    }
-    return rate;
-}
-
-bool ControllerEngine::isDeckPlaying(const QString& group) {
-    ControlObjectScript* pPlay = getControlObjectScript(group, "play");
-
-    if (pPlay == nullptr) {
-        QString error = QString("Could not getControlObjectScript()");
-        scriptErrorDialog(error, error);
-        return false;
-    }
-
-    return pPlay->get() > 0.0;
-}
-
-void ControllerEngine::scratchEnable(
-        int deck,
-        int intervalsPerRev,
-        double rpm,
-        double alpha,
-        double beta,
-        bool ramp) {
-    // If we're already scratching this deck, override that with this request
-    if (m_dx[deck] != 0) {
-        //qDebug() << "Already scratching deck" << deck << ". Overriding.";
-        int timerId = m_scratchTimers.key(deck);
-        killTimer(timerId);
-        m_scratchTimers.remove(timerId);
-    }
-
-    // Controller resolution in intervals per second at normal speed.
-    // (rev/min * ints/rev * mins/sec)
-    double intervalsPerSecond = (rpm * intervalsPerRev) / 60.0;
-
-    if (intervalsPerSecond == 0.0) {
-        qWarning() << "Invalid rpm or intervalsPerRev supplied to scratchEnable. Ignoring request.";
-        return;
-    }
-
-    m_dx[deck] = 1.0 / intervalsPerSecond;
-    m_intervalAccumulator[deck] = 0.0;
-    m_ramp[deck] = false;
-    m_rampFactor[deck] = 0.001;
-    m_brakeActive[deck] = false;
-
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-
-    // Ramp velocity, default to stopped.
-    double initVelocity = 0.0;
-
-    ControlObjectScript* pScratch2Enable =
-            getControlObjectScript(group, "scratch2_enable");
-
-    // If ramping is desired, figure out the deck's current speed
-    if (ramp) {
-        // See if the deck is already being scratched
-        if (pScratch2Enable != nullptr && pScratch2Enable->get() == 1) {
-            // If so, set the filter's initial velocity to the scratch speed
-            ControlObjectScript* pScratch2 =
-                    getControlObjectScript(group, "scratch2");
-            if (pScratch2 != nullptr) {
-                initVelocity = pScratch2->get();
-            }
-        } else if (isDeckPlaying(group)) {
-            // If the deck is playing, set the filter's initial velocity to the
-            // playback speed
-            initVelocity = getDeckRate(group);
-        }
-    }
-
-    // Initialize scratch filter
-    if (alpha != 0 && beta != 0) {
-        m_scratchFilters[deck]->init(kAlphaBetaDt, initVelocity, alpha, beta);
-    } else {
-        // Use filter's defaults if not specified
-        m_scratchFilters[deck]->init(kAlphaBetaDt, initVelocity);
-    }
-
-    // 1ms is shortest possible, OS dependent
-    int timerId = startTimer(kScratchTimerMs);
-
-    // Associate this virtual deck with this timer for later processing
-    m_scratchTimers[timerId] = deck;
-
-    // Set scratch2_enable
-    if (pScratch2Enable != nullptr) {
-        pScratch2Enable->slotSet(1);
-    }
-}
-
-void ControllerEngine::scratchTick(int deck, int interval) {
-    m_lastMovement[deck] = mixxx::Time::elapsed();
-    m_intervalAccumulator[deck] += interval;
-}
-
-void ControllerEngine::scratchProcess(int timerId) {
-    int deck = m_scratchTimers[timerId];
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-    AlphaBetaFilter* filter = m_scratchFilters[deck];
-    if (!filter) {
-        qWarning() << "Scratch filter pointer is null on deck" << deck;
-        return;
-    }
-
-    const double oldRate = filter->predictedVelocity();
-
-    // Give the filter a data point:
-
-    // If we're ramping to end scratching and the wheel hasn't been turned very
-    // recently (spinback after lift-off,) feed fixed data
-    if (m_ramp[deck] && !m_softStartActive[deck] &&
-            ((mixxx::Time::elapsed() - m_lastMovement[deck]) >= mixxx::Duration::fromMillis(1))) {
-        filter->observation(m_rampTo[deck] * m_rampFactor[deck]);
-        // Once this code path is run, latch so it always runs until reset
-        //m_lastMovement[deck] += mixxx::Duration::fromSeconds(1);
-    } else if (m_softStartActive[deck]) {
-        // pretend we have moved by (desired rate*default distance)
-        filter->observation(m_rampTo[deck] * kAlphaBetaDt);
-    } else {
-        // This will (and should) be 0 if no net ticks have been accumulated
-        // (i.e. the wheel is stopped)
-        filter->observation(m_dx[deck] * m_intervalAccumulator[deck]);
-    }
-
-    const double newRate = filter->predictedVelocity();
-
-    // Actually do the scratching
-    ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
-    if (pScratch2 == nullptr) {
-        return; // abort and maybe it'll work on the next pass
-    }
-    pScratch2->set(newRate);
-
-    // Reset accumulator
-    m_intervalAccumulator[deck] = 0;
-
-    // End scratching if we're ramping and the current rate is really close to the rampTo value
-    if ((m_ramp[deck] && fabs(m_rampTo[deck] - newRate) <= 0.00001) ||
-            // or if we brake or softStart and have crossed over the desired value,
-            ((m_brakeActive[deck] || m_softStartActive[deck]) && ((oldRate > m_rampTo[deck] && newRate < m_rampTo[deck]) || (oldRate < m_rampTo[deck] && newRate > m_rampTo[deck]))) ||
-            // or if the deck was stopped manually during brake or softStart
-            ((m_brakeActive[deck] || m_softStartActive[deck]) && (!isDeckPlaying(group)))) {
-        // Not ramping no mo'
-        m_ramp[deck] = false;
-
-        if (m_brakeActive[deck]) {
-            // If in brake mode, set scratch2 rate to 0 and turn off the play button.
-            pScratch2->slotSet(0.0);
-            ControlObjectScript* pPlay = getControlObjectScript(group, "play");
-            if (pPlay != nullptr) {
-                pPlay->slotSet(0.0);
-            }
-        }
-
-        // Clear scratch2_enable to end scratching.
-        ControlObjectScript* pScratch2Enable =
-                getControlObjectScript(group, "scratch2_enable");
-        if (pScratch2Enable == nullptr) {
-            return; // abort and maybe it'll work on the next pass
-        }
-        pScratch2Enable->slotSet(0);
-
-        // Remove timer
-        killTimer(timerId);
-        m_scratchTimers.remove(timerId);
-
-        m_dx[deck] = 0.0;
-        m_brakeActive[deck] = false;
-        m_softStartActive[deck] = false;
-    }
-}
-
-void ControllerEngine::scratchDisable(int deck, bool ramp) {
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-
-    m_rampTo[deck] = 0.0;
-
-    // If no ramping is desired, disable scratching immediately
-    if (!ramp) {
-        // Clear scratch2_enable
-        ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
-        if (pScratch2Enable != nullptr) {
-            pScratch2Enable->slotSet(0);
-        }
-        // Can't return here because we need scratchProcess to stop the timer.
-        // So it's still actually ramping, we just won't hear or see it.
-    } else if (isDeckPlaying(group)) {
-        // If so, set the target velocity to the playback speed
-        m_rampTo[deck] = getDeckRate(group);
-    }
-
-    m_lastMovement[deck] = mixxx::Time::elapsed();
-    m_ramp[deck] = true; // Activate the ramping in scratchProcess()
-}
-
-bool ControllerEngine::isScratching(int deck) {
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-    return getValue(group, "scratch2_enable") > 0;
-}
-
-void ControllerEngine::spinback(int deck, bool activate, double factor, double rate) {
-    // defaults for args set in header file
-    brake(deck, activate, factor, rate);
-}
-
-void ControllerEngine::brake(int deck, bool activate, double factor, double rate) {
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-
-    // kill timer when both enabling or disabling
-    int timerId = m_scratchTimers.key(deck);
-    killTimer(timerId);
-    m_scratchTimers.remove(timerId);
-
-    // enable/disable scratch2 mode
-    ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
-    if (pScratch2Enable != nullptr) {
-        pScratch2Enable->slotSet(activate ? 1 : 0);
-    }
-
-    // used in scratchProcess for the different timer behavior we need
-    m_brakeActive[deck] = activate;
-    double initRate = rate;
-
-    if (activate) {
-        // store the new values for this spinback/brake effect
-        if (initRate == 1.0) { // then rate is really 1.0 or was set to default
-            // in /res/common-controller-scripts.js so check for real value,
-            // taking pitch into account
-            initRate = getDeckRate(group);
-        }
-        // stop ramping at a rate which doesn't produce any audible output anymore
-        m_rampTo[deck] = 0.01;
-        // if we are currently softStart()ing, stop it
-        if (m_softStartActive[deck]) {
-            m_softStartActive[deck] = false;
-            AlphaBetaFilter* filter = m_scratchFilters[deck];
-            if (filter != nullptr) {
-                initRate = filter->predictedVelocity();
-            }
-        }
-
-        // setup timer and set scratch2
-        timerId = startTimer(kScratchTimerMs);
-        m_scratchTimers[timerId] = deck;
-
-        ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
-        if (pScratch2 != nullptr) {
-            pScratch2->slotSet(initRate);
-        }
-
-        // setup the filter with default alpha and beta*factor
-        double alphaBrake = 1.0 / 512;
-        // avoid decimals for fine adjusting
-        if (factor > 1) {
-            factor = ((factor - 1) / 10) + 1;
-        }
-        double betaBrake = ((1.0 / 512) / 1024) * factor; // default*factor
-        AlphaBetaFilter* filter = m_scratchFilters[deck];
-        if (filter != nullptr) {
-            filter->init(kAlphaBetaDt, initRate, alphaBrake, betaBrake);
-        }
-
-        // activate the ramping in scratchProcess()
-        m_ramp[deck] = true;
-    }
-}
-
-void ControllerEngine::softStart(int deck, bool activate, double factor) {
-    // PlayerManager::groupForDeck is 0-indexed.
-    QString group = PlayerManager::groupForDeck(deck - 1);
-
-    // kill timer when both enabling or disabling
-    int timerId = m_scratchTimers.key(deck);
-    killTimer(timerId);
-    m_scratchTimers.remove(timerId);
-
-    // enable/disable scratch2 mode
-    ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
-    if (pScratch2Enable != nullptr) {
-        pScratch2Enable->slotSet(activate ? 1 : 0);
-    }
-
-    // used in scratchProcess for the different timer behavior we need
-    m_softStartActive[deck] = activate;
-    double initRate = 0.0;
-
-    if (activate) {
-        // acquire deck rate
-        m_rampTo[deck] = getDeckRate(group);
-
-        // if brake()ing, get current rate from filter
-        if (m_brakeActive[deck]) {
-            m_brakeActive[deck] = false;
-
-            AlphaBetaFilter* filter = m_scratchFilters[deck];
-            if (filter != nullptr) {
-                initRate = filter->predictedVelocity();
-            }
-        }
-
-        // setup timer, start playing and set scratch2
-        timerId = startTimer(kScratchTimerMs);
-        m_scratchTimers[timerId] = deck;
-
-        ControlObjectScript* pPlay = getControlObjectScript(group, "play");
-        if (pPlay != nullptr) {
-            pPlay->slotSet(1.0);
-        }
-
-        ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
-        if (pScratch2 != nullptr) {
-            pScratch2->slotSet(initRate);
-        }
-
-        // setup the filter like in brake(), with default alpha and beta*factor
-        double alphaSoft = 1.0 / 512;
-        // avoid decimals for fine adjusting
-        if (factor > 1) {
-            factor = ((factor - 1) / 10) + 1;
-        }
-        double betaSoft = ((1.0 / 512) / 1024) * factor; // default: (1.0/512)/1024
-        AlphaBetaFilter* filter = m_scratchFilters[deck];
-        if (filter != nullptr) { // kAlphaBetaDt = 1/1000 seconds
-            filter->init(kAlphaBetaDt, initRate, alphaSoft, betaSoft);
-        }
-
-        // activate the ramping in scratchProcess()
-        m_ramp[deck] = true;
-    }
-}
diff --git a/src/controllers/engine/controllerengine.h b/src/controllers/engine/controllerengine.h
deleted file mode 100644
index 17a8b66e034..00000000000
--- a/src/controllers/engine/controllerengine.h
+++ /dev/null
@@ -1,184 +0,0 @@
-#pragma once
-
-#include <QFileSystemWatcher>
-#include <QJSEngine>
-#include <QJSValue>
-#include <QMessageBox>
-#include <QTimerEvent>
-
-#include "controllers/controllerpreset.h"
-#include "controllers/softtakeover.h"
-#include "preferences/usersettings.h"
-#include "util/alphabetafilter.h"
-#include "util/duration.h"
-
-class Controller;
-class ControlObjectScript;
-class ControllerEngine;
-class ControllerEngineJSProxy;
-class EvaluationException;
-class ScriptConnection;
-
-class ControllerEngine : public QObject {
-    Q_OBJECT
-  public:
-    ControllerEngine(Controller* controller);
-    virtual ~ControllerEngine();
-
-    void handleInput(const QByteArray& data, mixxx::Duration timestamp);
-
-    bool executeFunction(QJSValue functionObject, const QJSValueList& arguments);
-    bool executeFunction(const QJSValue& functionObject, const QByteArray& data);
-
-    /// Wrap a string of JS code in an anonymous function. This allows any JS
-    /// string that evaluates to a function to be used in MIDI mapping XML files
-    /// and ensures the function is executed with the correct 'this' object.
-    QJSValue wrapFunctionCode(const QString& codeSnippet, int numberOfArgs);
-
-    /// Look up registered script function prefixes
-    const QList<QString>& getScriptFunctionPrefixes() {
-        return m_scriptFunctionPrefixes;
-    };
-
-    /// Shows a UI dialog notifying of a script evaluation error.
-    /// Precondition: QJSValue.isError() == true
-    void showScriptExceptionDialog(const QJSValue& evaluationResult, bool bFatal = false);
-
-    bool removeScriptConnection(const ScriptConnection& conn);
-    /// Execute a ScriptConnection's JS callback
-    void triggerScriptConnection(const ScriptConnection& conn);
-
-    inline void setTesting(bool testing) {
-        m_bTesting = testing;
-    };
-
-  protected:
-    double getValue(const QString& group, const QString& name);
-    void setValue(const QString& group, const QString& name, double newValue);
-    double getParameter(const QString& group, const QString& name);
-    void setParameter(const QString& group, const QString& name, double newValue);
-    double getParameterForValue(const QString& group, const QString& name, double value);
-    void reset(const QString& group, const QString& name);
-    double getDefaultValue(const QString& group, const QString& name);
-    double getDefaultParameter(const QString& group, const QString& name);
-    /// Connect a ControlObject's valueChanged() signal to a script callback function
-    /// Returns to the script a ScriptConnectionJSProxy
-    QJSValue makeConnection(const QString& group, const QString& name, const QJSValue& callback);
-    /// DEPRECATED: Use makeConnection instead.
-    QJSValue connectControl(const QString& group,
-            const QString& name,
-            const QJSValue& passedCallback,
-            bool disconnect = false);
-    /// Execute callbacks for all ScriptConnections connected to a ControlObject
-    /// DEPRECATED: Use ScriptConnectionJSProxy::trigger instead.
-    void trigger(const QString& group, const QString& name);
-    void log(const QString& message);
-    /// Returns a timer ID to the script
-    int beginTimer(int intervalMillis, QJSValue scriptCode, bool oneShot = false);
-    void stopTimer(int timerId);
-
-    /// [En/dis]able soft-takeover status for a particular ControlObject
-    void softTakeover(const QString& group, const QString& name, bool set);
-    /// Ignores the next value for the given ControlObject. This should be called
-    /// before or after an absolute physical control (slider or knob with hard limits)
-    /// is changed to operate on a different ControlObject, allowing it to sync up to the
-    /// soft-takeover state without an abrupt jump.
-    void softTakeoverIgnoreNextValue(const QString& group, const QString& name);
-
-    void scratchEnable(
-            int deck,
-            int intervalsPerRev,
-            double rpm,
-            double alpha,
-            double beta,
-            bool ramp = true);
-    /// Accumulates ticks of the controller wheel
-    void scratchTick(int deck, int interval);
-    void scratchDisable(int deck, bool ramp = true);
-    bool isScratching(int deck);
-    void brake(int deck, bool activate, double factor = 1.0, double rate = 1.0);
-    void spinback(int deck, bool activate, double factor = 1.8, double rate = -10.0);
-    void softStart(int deck, bool activate, double factor = 1.0);
-
-    /// Handler for timers that scripts set.
-    virtual void timerEvent(QTimerEvent* event);
-
-  public slots:
-    void loadModule(const QFileInfo& moduleFileInfo);
-    bool loadScriptFiles(const QList<ControllerPreset::ScriptFileInfo>& scripts);
-    void initializeScripts(const QList<ControllerPreset::ScriptFileInfo>& scripts);
-    void gracefulShutdown();
-    void scriptHasChanged(const QString&);
-
-  private slots:
-    void errorDialogButton(const QString& key, QMessageBox::StandardButton button);
-
-  private:
-    bool evaluateScriptFile(const QFileInfo& scriptFile);
-    void initializeScriptEngine();
-    void uninitializeScriptEngine();
-    void reloadScripts();
-
-    void scriptErrorDialog(const QString& detailedError, const QString& key, bool bFatal = false);
-    void generateScriptFunctions(const QString& code);
-    /// Stops and removes all timers (for shutdown).
-    void stopAllTimers();
-
-    bool callFunctionOnObjects(
-            const QList<QString>&,
-            const QString&,
-            const QJSValueList& args = QJSValueList(),
-            bool bFatalError = false);
-    /// Convert a byteArray to a JS typed array over an ArrayBuffer
-    QJSValue byteArrayToScriptValue(const QByteArray& byteArray);
-    QJSValue evaluateCodeString(const QString& program, const QString& fileName = QString(), int lineNumber = 1);
-
-    void throwJSError(const QString& message);
-
-    bool m_bDisplayingExceptionDialog;
-    QJSEngine* m_pScriptEngine;
-
-    ControlObjectScript* getControlObjectScript(const QString& group, const QString& name);
-
-    // Scratching functions & variables
-
-    /// Applies the accumulated movement to the track speed
-    void scratchProcess(int timerId);
-
-    bool isDeckPlaying(const QString& group);
-    double getDeckRate(const QString& group);
-
-    Controller* m_pController;
-    QJSValue m_handleInputFunction;
-    QJSValue m_shutdownFunction;
-    QList<QString> m_scriptFunctionPrefixes;
-    QHash<ConfigKey, ControlObjectScript*> m_controlCache;
-    struct TimerInfo {
-        QJSValue callback;
-        bool oneShot;
-    };
-    QHash<int, TimerInfo> m_timers;
-    SoftTakeoverCtrl m_st;
-    // 256 (default) available virtual decks is enough I would think.
-    // If more are needed at run-time, these will move to the heap automatically
-    QVarLengthArray<int> m_intervalAccumulator;
-    QVarLengthArray<mixxx::Duration> m_lastMovement;
-    QVarLengthArray<double> m_dx, m_rampTo, m_rampFactor;
-    QVarLengthArray<bool> m_ramp, m_brakeActive, m_softStartActive;
-    QVarLengthArray<AlphaBetaFilter*> m_scratchFilters;
-    QHash<int, int> m_scratchTimers;
-    QHash<QString, QJSValue> m_scriptWrappedFunctionCache;
-    QJSValue m_byteArrayToScriptValueJSFunction;
-    // Filesystem watcher for script auto-reload
-    QFileSystemWatcher m_scriptWatcher;
-    QFileInfo m_moduleFileInfo;
-    QList<ControllerPreset::ScriptFileInfo> m_lastScriptFiles;
-
-    bool m_bTesting;
-
-    friend class ScriptConnection;
-    friend class ControllerEngineJSProxy;
-    friend class ColorJSProxy;
-    friend class ColorMapperJSProxy;
-    friend class ControllerEngineTest;
-};
diff --git a/src/controllers/engine/controllerenginejsproxy.cpp b/src/controllers/engine/controllerenginejsproxy.cpp
deleted file mode 100644
index 47bad8c9ca2..00000000000
--- a/src/controllers/engine/controllerenginejsproxy.cpp
+++ /dev/null
@@ -1,153 +0,0 @@
-#include "controllerenginejsproxy.h"
-
-#include "controllers/engine/controllerengine.h"
-#include "moc_controllerenginejsproxy.cpp"
-
-ControllerEngineJSProxy::ControllerEngineJSProxy(ControllerEngine* m_pEngine)
-        : m_pEngine(m_pEngine) {
-}
-
-ControllerEngineJSProxy::~ControllerEngineJSProxy() {
-}
-
-double ControllerEngineJSProxy::getValue(
-        const QString& group,
-        const QString& name) {
-    return m_pEngine->getValue(group, name);
-}
-
-void ControllerEngineJSProxy::setValue(
-        const QString& group,
-        const QString& name,
-        double newValue) {
-    m_pEngine->setValue(group, name, newValue);
-}
-
-double ControllerEngineJSProxy::getParameter(
-        const QString& group,
-        const QString& name) {
-    return m_pEngine->getParameter(group, name);
-}
-
-void ControllerEngineJSProxy::setParameter(
-        const QString& group,
-        const QString& name,
-        double newValue) {
-    m_pEngine->setParameter(group, name, newValue);
-}
-
-double ControllerEngineJSProxy::getParameterForValue(
-        const QString& group,
-        const QString& name,
-        double value) {
-    return m_pEngine->getParameterForValue(group, name, value);
-}
-
-void ControllerEngineJSProxy::reset(
-        const QString& group,
-        const QString& name) {
-    m_pEngine->reset(group, name);
-}
-
-double ControllerEngineJSProxy::getDefaultValue(
-        const QString& group,
-        const QString& name) {
-    return m_pEngine->getDefaultValue(group, name);
-}
-
-double ControllerEngineJSProxy::getDefaultParameter(
-        const QString& group,
-        const QString& name) {
-    return m_pEngine->getDefaultParameter(group, name);
-}
-
-QJSValue ControllerEngineJSProxy::makeConnection(
-        const QString& group,
-        const QString& name,
-        const QJSValue& callback) {
-    return m_pEngine->makeConnection(group, name, callback);
-}
-
-QJSValue ControllerEngineJSProxy::connectControl(
-        const QString& group,
-        const QString& name,
-        const QJSValue& passedCallback,
-        bool disconnect) {
-    return m_pEngine->connectControl(group, name, passedCallback, disconnect);
-}
-
-void ControllerEngineJSProxy::trigger(
-        const QString& group,
-        const QString& name) {
-    m_pEngine->trigger(group, name);
-}
-
-void ControllerEngineJSProxy::log(const QString& message) {
-    m_pEngine->log(message);
-}
-
-int ControllerEngineJSProxy::beginTimer(
-        int interval,
-        const QJSValue& scriptCode,
-        bool oneShot) {
-    return m_pEngine->beginTimer(interval, scriptCode, oneShot);
-}
-
-void ControllerEngineJSProxy::stopTimer(int timerId) {
-    m_pEngine->stopTimer(timerId);
-}
-
-void ControllerEngineJSProxy::scratchEnable(
-        int deck,
-        int intervalsPerRev,
-        double rpm,
-        double alpha,
-        double beta,
-        bool ramp) {
-    m_pEngine->scratchEnable(deck, intervalsPerRev, rpm, alpha, beta, ramp);
-}
-
-void ControllerEngineJSProxy::scratchTick(int deck, int interval) {
-    m_pEngine->scratchTick(deck, interval);
-}
-
-void ControllerEngineJSProxy::scratchDisable(int deck, bool ramp) {
-    m_pEngine->scratchDisable(deck, ramp);
-}
-
-bool ControllerEngineJSProxy::isScratching(int deck) {
-    return m_pEngine->isScratching(deck);
-}
-
-void ControllerEngineJSProxy::softTakeover(
-        const QString& group,
-        const QString& name,
-        bool set) {
-    m_pEngine->softTakeover(group, name, set);
-}
-
-void ControllerEngineJSProxy::softTakeoverIgnoreNextValue(
-        const QString& group,
-        const QString& name) {
-    m_pEngine->softTakeoverIgnoreNextValue(group, name);
-}
-
-void ControllerEngineJSProxy::brake(
-        int deck,
-        bool activate,
-        double factor,
-        double rate) {
-    m_pEngine->brake(deck, activate, factor, rate);
-}
-
-void ControllerEngineJSProxy::spinback(
-        int deck,
-        bool activate,
-        double factor,
-        double rate) {
-    m_pEngine->spinback(deck, activate, factor, rate);
-}
-
-void ControllerEngineJSProxy::softStart(int deck, bool activate, double factor) {
-    m_pEngine->softStart(deck, activate, factor);
-}
diff --git a/src/controllers/engine/controllerenginejsproxy.h b/src/controllers/engine/controllerenginejsproxy.h
deleted file mode 100644
index 6db1d10d5ec..00000000000
--- a/src/controllers/engine/controllerenginejsproxy.h
+++ /dev/null
@@ -1,60 +0,0 @@
-#ifndef CONTROLLERENGINEJSPROXY_H
-#define CONTROLLERENGINEJSPROXY_H
-
-#include <QJSValue>
-#include <QObject>
-
-class ControllerEngine;
-
-// An object of this class gets exposed to the JS engine, so the methods of this class
-// constitute the api that is provided to scripts under "engine" object.
-//
-// The implementation simply forwards its method calls to the ControllerEngine.
-// We cannot expose ControllerEngine directly to the JS engine because the JS engine would take
-// ownership of ControllerEngine. This is problematic when we reload a script file, because we
-// destroy the existing JS engine to create a new one. Then, since the JS engine owns ControllerEngine
-// it will try to delete it. See this Qt bug: https://bugreports.qt.io/browse/QTBUG-41171
-class ControllerEngineJSProxy : public QObject {
-    Q_OBJECT
-  public:
-    ControllerEngineJSProxy(ControllerEngine* m_pEngine);
-
-    virtual ~ControllerEngineJSProxy();
-
-    Q_INVOKABLE double getValue(const QString& group, const QString& name);
-    Q_INVOKABLE void setValue(const QString& group, const QString& name, double newValue);
-    Q_INVOKABLE double getParameter(const QString& group, const QString& name);
-    Q_INVOKABLE void setParameter(const QString& group, const QString& name, double newValue);
-    Q_INVOKABLE double getParameterForValue(
-            const QString& group, const QString& name, double value);
-    Q_INVOKABLE void reset(const QString& group, const QString& name);
-    Q_INVOKABLE double getDefaultValue(const QString& group, const QString& name);
-    Q_INVOKABLE double getDefaultParameter(const QString& group, const QString& name);
-    Q_INVOKABLE QJSValue makeConnection(const QString& group,
-            const QString& name,
-            const QJSValue& callback);
-    // DEPRECATED: Use makeConnection instead.
-    Q_INVOKABLE QJSValue connectControl(const QString& group,
-            const QString& name,
-            const QJSValue& passedCallback,
-            bool disconnect = false);
-    // Called indirectly by the objects returned by connectControl
-    Q_INVOKABLE void trigger(const QString& group, const QString& name);
-    Q_INVOKABLE void log(const QString& message);
-    Q_INVOKABLE int beginTimer(int interval, const QJSValue& scriptCode, bool oneShot = false);
-    Q_INVOKABLE void stopTimer(int timerId);
-    Q_INVOKABLE void scratchEnable(int deck, int intervalsPerRev, double rpm, double alpha, double beta, bool ramp = true);
-    Q_INVOKABLE void scratchTick(int deck, int interval);
-    Q_INVOKABLE void scratchDisable(int deck, bool ramp = true);
-    Q_INVOKABLE bool isScratching(int deck);
-    Q_INVOKABLE void softTakeover(const QString& group, const QString& name, bool set);
-    Q_INVOKABLE void softTakeoverIgnoreNextValue(const QString& group, const QString& name);
-    Q_INVOKABLE void brake(int deck, bool activate, double factor = 1.0, double rate = 1.0);
-    Q_INVOKABLE void spinback(int deck, bool activate, double factor = 1.8, double rate = -10.0);
-    Q_INVOKABLE void softStart(int deck, bool activate, double factor = 1.0);
-
-  private:
-    ControllerEngine* m_pEngine;
-};
-
-#endif // CONTROLLERENGINEJSPROXY_H
diff --git a/src/controllers/engine/scriptconnectionjsproxy.cpp b/src/controllers/engine/scriptconnectionjsproxy.cpp
deleted file mode 100644
index 7195e77ea94..00000000000
--- a/src/controllers/engine/scriptconnectionjsproxy.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-#include "controllers/engine/scriptconnectionjsproxy.h"
-
-#include "controllers/engine/controllerengine.h"
-#include "moc_scriptconnectionjsproxy.cpp"
-
-bool ScriptConnectionJSProxy::disconnect() {
-    // if the removeScriptConnection succeeded, the connection has been successfully disconnected
-    bool success = m_scriptConnection.controllerEngine->removeScriptConnection(m_scriptConnection);
-    m_isConnected = !success;
-    return success;
-}
-
-void ScriptConnectionJSProxy::trigger() {
-    m_scriptConnection.controllerEngine->triggerScriptConnection(m_scriptConnection);
-}
diff --git a/src/controllers/hid/hidcontroller.cpp b/src/controllers/hid/hidcontroller.cpp
index fbddbab6580..db784d61542 100644
--- a/src/controllers/hid/hidcontroller.cpp
+++ b/src/controllers/hid/hidcontroller.cpp
@@ -204,7 +204,7 @@ void HidController::sendBytesReport(QByteArray data, unsigned int reportID) {
 
     int result = hid_write(m_pHidDevice, (unsigned char*)data.constData(), data.size());
     if (result == -1) {
-        if (ControllerDebug::enabled()) {
+        if (ControllerDebug::isEnabled()) {
             qWarning() << "Unable to send data to" << getName()
                        << "serial #" << m_deviceInfo.serialNumber() << ":"
                        << mixxx::convertWCStringToQString(
diff --git a/src/controllers/midi/hss1394controller.cpp b/src/controllers/midi/hss1394controller.cpp
index d35554bd29b..d73e2062124 100644
--- a/src/controllers/midi/hss1394controller.cpp
+++ b/src/controllers/midi/hss1394controller.cpp
@@ -35,7 +35,7 @@ void DeviceChannelListener::Process(const hss1394::uint8 *pBuffer, hss1394::uint
                 if (i + 2 < uBufferSize) {
                     note = pBuffer[i+1];
                     velocity = pBuffer[i+2];
-                    emit incomingData(status, note, velocity, timestamp);
+                    emit receivedShortMessage(status, note, velocity, timestamp);
                 } else {
                     qWarning() << "Buffer underflow in DeviceChannelListener::Process()";
                 }
@@ -43,8 +43,8 @@ void DeviceChannelListener::Process(const hss1394::uint8 *pBuffer, hss1394::uint
                 break;
             default:
                 // Handle platter messages and any others that are not 3 bytes
-                QByteArray outArray((char*)pBuffer,uBufferSize);
-                emit incomingData(outArray, timestamp);
+                QByteArray byteArray(reinterpret_cast<const char*>(pBuffer), uBufferSize);
+                emit receivedSysex(byteArray, timestamp);
                 i = uBufferSize;
                 break;
         }
@@ -106,19 +106,13 @@ int Hss1394Controller::open() {
 
     m_pChannelListener = new DeviceChannelListener(this, getName());
     connect(m_pChannelListener,
-            QOverload<unsigned char,
-                    unsigned char,
-                    unsigned char,
-                    mixxx::Duration>::of(&DeviceChannelListener::incomingData),
+            &DeviceChannelListener::receivedShortMessage,
             this,
-            QOverload<unsigned char,
-                    unsigned char,
-                    unsigned char,
-                    mixxx::Duration>::of(&Hss1394Controller::receive));
+            &Hss1394Controller::receivedShortMessage);
     connect(m_pChannelListener,
-            QOverload<const QByteArray&, mixxx::Duration>::of(&DeviceChannelListener::incomingData),
+            &DeviceChannelListener::receivedSysex,
             this,
-            QOverload<const QByteArray&, mixxx::Duration>::of(&Hss1394Controller::receive));
+            &Hss1394Controller::receive);
 
     if (!m_pChannel->InstallChannelListener(m_pChannelListener)) {
         qDebug() << "HSS1394 channel listener could not be installed for device" << getName();
@@ -154,19 +148,13 @@ int Hss1394Controller::close() {
     }
 
     disconnect(m_pChannelListener,
-            QOverload<unsigned char,
-                    unsigned char,
-                    unsigned char,
-                    mixxx::Duration>::of(&DeviceChannelListener::incomingData),
+            &DeviceChannelListener::receivedShortMessage,
             this,
-            QOverload<unsigned char,
-                    unsigned char,
-                    unsigned char,
-                    mixxx::Duration>::of(&Hss1394Controller::receive));
+            &Hss1394Controller::receivedShortMessage);
     disconnect(m_pChannelListener,
-            QOverload<const QByteArray&, mixxx::Duration>::of(&DeviceChannelListener::incomingData),
+            &DeviceChannelListener::receivedSysex,
             this,
-            QOverload<const QByteArray&, mixxx::Duration>::of(&Hss1394Controller::receive));
+            &Hss1394Controller::receive);
 
     stopEngine();
     MidiController::close();
diff --git a/src/controllers/midi/hss1394controller.h b/src/controllers/midi/hss1394controller.h
index 622316eadfc..1f1cbf57e55 100644
--- a/src/controllers/midi/hss1394controller.h
+++ b/src/controllers/midi/hss1394controller.h
@@ -24,9 +24,11 @@ class DeviceChannelListener : public QObject, public hss1394::ChannelListener {
     void Disconnected();
     void Reconnected();
   signals:
-    void incomingData(unsigned char status, unsigned char control, unsigned char value,
-                      mixxx::Duration timestamp);
-    void incomingData(const QByteArray& data, mixxx::Duration timestamp);
+    void receivedShortMessage(unsigned char status,
+            unsigned char control,
+            unsigned char value,
+            mixxx::Duration timestamp);
+    void receivedSysex(const QByteArray& data, mixxx::Duration timestamp);
 
   private:
     QString m_sName;
diff --git a/src/controllers/midi/midicontroller.cpp b/src/controllers/midi/midicontroller.cpp
index d484574f392..22c64458fce 100644
--- a/src/controllers/midi/midicontroller.cpp
+++ b/src/controllers/midi/midicontroller.cpp
@@ -51,9 +51,9 @@ bool MidiController::matchPreset(const PresetInfo& preset) {
     return false;
 }
 
-bool MidiController::applyPreset(bool initializeScripts) {
+bool MidiController::applyPreset() {
     // Handles the engine
-    bool result = Controller::applyPreset(initializeScripts);
+    bool result = Controller::applyPreset();
 
     // Only execute this code if this is an output device
     if (isOutputDevice()) {
@@ -109,7 +109,7 @@ void MidiController::createOutputHandlers() {
             qWarning() << errorLog;
 
             int deckNum = 0;
-            if (ControllerDebug::enabled()) {
+            if (ControllerDebug::isEnabled()) {
                 failures.append(errorLog);
             } else if (PlayerManager::isDeckGroup(group, &deckNum)) {
                 int numDecks = PlayerManager::numDecks();
@@ -195,20 +195,10 @@ void MidiController::commitTemporaryInputMappings() {
     m_temporaryInputMappings.clear();
 }
 
-void MidiController::receive(unsigned char status, unsigned char control,
-                             unsigned char value, mixxx::Duration timestamp) {
-    QByteArray byteArray;
-    byteArray.append(status);
-    byteArray.append(control);
-    byteArray.append(value);
-
-    ControllerEngine* pEngine = getEngine();
-    // pEngine is nullptr in tests.
-    if (pEngine) {
-        pEngine->handleInput(byteArray, timestamp);
-    }
-    // legacy stuff below
-
+void MidiController::receivedShortMessage(unsigned char status,
+        unsigned char control,
+        unsigned char value,
+        mixxx::Duration timestamp) {
     // The rest of this function is for legacy mappings
     unsigned char channel = MidiUtils::channelFromStatus(status);
     unsigned char opCode = MidiUtils::opCodeFromStatus(status);
@@ -256,7 +246,7 @@ void MidiController::processInputMapping(const MidiInputMapping& mapping,
     unsigned char opCode = MidiUtils::opCodeFromStatus(status);
 
     if (mapping.options.script) {
-        ControllerEngine* pEngine = getEngine();
+        ControllerScriptEngineLegacy* pEngine = getScriptEngine();
         if (pEngine == nullptr) {
             return;
         }
@@ -481,8 +471,6 @@ double MidiController::computeValue(
 
 void MidiController::receive(const QByteArray& data, mixxx::Duration timestamp) {
     controllerDebug(MidiUtils::formatSysexMessage(getName(), data, timestamp));
-    getEngine()->handleInput(data, timestamp);
-    // legacy stuff below
 
     MidiKey mappingKey(data.at(0), 0xFF);
 
@@ -513,15 +501,11 @@ void MidiController::processInputMapping(const MidiInputMapping& mapping,
                                          mixxx::Duration timestamp) {
     // Custom script handler
     if (mapping.options.script) {
-        ControllerEngine* pEngine = getEngine();
+        ControllerScriptEngineLegacy* pEngine = getScriptEngine();
         if (pEngine == nullptr) {
             return;
         }
-        QJSValue function = pEngine->wrapFunctionCode(mapping.control.item, 2);
-        if (!pEngine->executeFunction(function, data)) {
-            qDebug() << "MidiController: Invalid script function"
-                     << mapping.control.item;
-        }
+        pEngine->handleIncomingData(data);
         return;
     }
     qWarning() << "MidiController: No script function specified for"
diff --git a/src/controllers/midi/midicontroller.h b/src/controllers/midi/midicontroller.h
index f3e5a1f971a..aa46335c2a3 100644
--- a/src/controllers/midi/midicontroller.h
+++ b/src/controllers/midi/midicontroller.h
@@ -63,7 +63,8 @@ class MidiController : public Controller {
     }
 
   protected slots:
-    virtual void receive(unsigned char status,
+    virtual void receivedShortMessage(
+            unsigned char status,
             unsigned char control,
             unsigned char value,
             mixxx::Duration timestamp);
@@ -72,27 +73,23 @@ class MidiController : public Controller {
     int close() override;
 
   private slots:
-    /// Apply the preset to the controller.
-    /// Initializes both controller engine and static output mappings.
-    ///
-    /// @param initializeScripts Can be set to false to skip script
-    /// initialization for unit tests.
-    /// @return Returns whether it was successful.
-    bool applyPreset(bool initializeScripts = false) override;
+    bool applyPreset() override;
 
     void learnTemporaryInputMappings(const MidiInputMappings& mappings);
     void clearTemporaryInputMappings();
     void commitTemporaryInputMappings();
 
   private:
-    void processInputMapping(const MidiInputMapping& mapping,
-                             unsigned char status,
-                             unsigned char control,
-                             unsigned char value,
-                             mixxx::Duration timestamp);
-    void processInputMapping(const MidiInputMapping& mapping,
-                             const QByteArray& data,
-                             mixxx::Duration timestamp);
+    void processInputMapping(
+            const MidiInputMapping& mapping,
+            unsigned char status,
+            unsigned char control,
+            unsigned char value,
+            mixxx::Duration timestamp);
+    void processInputMapping(
+            const MidiInputMapping& mapping,
+            const QByteArray& data,
+            mixxx::Duration timestamp);
 
     double computeValue(MidiOptions options, double _prevmidivalue, double _newmidivalue);
     void createOutputHandlers();
diff --git a/src/controllers/midi/portmidicontroller.cpp b/src/controllers/midi/portmidicontroller.cpp
index 30a44cd0fda..d7eea579aa0 100644
--- a/src/controllers/midi/portmidicontroller.cpp
+++ b/src/controllers/midi/portmidicontroller.cpp
@@ -143,7 +143,7 @@ bool PortMidiController::poll() {
 
         if ((status & 0xF8) == 0xF8) {
             // Handle real-time MIDI messages at any time
-            receive(status, 0, 0, timestamp);
+            receivedShortMessage(status, 0, 0, timestamp);
             continue;
         }
 
@@ -157,7 +157,7 @@ bool PortMidiController::poll() {
                 //unsigned char channel = status & 0x0F;
                 unsigned char note = Pm_MessageData1(m_midiBuffer[i].message);
                 unsigned char velocity = Pm_MessageData2(m_midiBuffer[i].message);
-                receive(status, note, velocity, timestamp);
+                receivedShortMessage(status, note, velocity, timestamp);
             }
         }
 
diff --git a/src/controllers/engine/colormapper.cpp b/src/controllers/scripting/colormapper.cpp
similarity index 98%
rename from src/controllers/engine/colormapper.cpp
rename to src/controllers/scripting/colormapper.cpp
index 5e6514ae411..2600b94dcf1 100644
--- a/src/controllers/engine/colormapper.cpp
+++ b/src/controllers/scripting/colormapper.cpp
@@ -1,4 +1,4 @@
-#include "controllers/engine/colormapper.h"
+#include "controllers/scripting/colormapper.h"
 
 #include <cmath>
 #include <cstdint>
diff --git a/src/controllers/engine/colormapper.h b/src/controllers/scripting/colormapper.h
similarity index 100%
rename from src/controllers/engine/colormapper.h
rename to src/controllers/scripting/colormapper.h
diff --git a/src/controllers/engine/colormapperjsproxy.cpp b/src/controllers/scripting/colormapperjsproxy.cpp
similarity index 97%
rename from src/controllers/engine/colormapperjsproxy.cpp
rename to src/controllers/scripting/colormapperjsproxy.cpp
index 940f6ad4b4c..582bb2aa372 100644
--- a/src/controllers/engine/colormapperjsproxy.cpp
+++ b/src/controllers/scripting/colormapperjsproxy.cpp
@@ -1,4 +1,4 @@
-#include "controllers/engine/colormapperjsproxy.h"
+#include "controllers/scripting/colormapperjsproxy.h"
 
 #include "moc_colormapperjsproxy.cpp"
 
diff --git a/src/controllers/engine/colormapperjsproxy.h b/src/controllers/scripting/colormapperjsproxy.h
similarity index 96%
rename from src/controllers/engine/colormapperjsproxy.h
rename to src/controllers/scripting/colormapperjsproxy.h
index 13bf3b2f5dd..8b6cd79c423 100644
--- a/src/controllers/engine/colormapperjsproxy.h
+++ b/src/controllers/scripting/colormapperjsproxy.h
@@ -2,7 +2,7 @@
 #include <QJSValue>
 #include <memory>
 
-#include "controllers/engine/colormapper.h"
+#include "controllers/scripting/colormapper.h"
 
 /// ColorMapperJSProxy is a wrapper class that exposes ColorMapper via the
 /// QJSEngine and makes it possible to create and use ColorMapper object from
diff --git a/src/controllers/scripting/controllerscriptenginebase.cpp b/src/controllers/scripting/controllerscriptenginebase.cpp
new file mode 100644
index 00000000000..7c8a7c407d6
--- /dev/null
+++ b/src/controllers/scripting/controllerscriptenginebase.cpp
@@ -0,0 +1,218 @@
+#include "controllers/scripting/controllerscriptenginebase.h"
+
+#include "control/controlobject.h"
+#include "controllers/controller.h"
+#include "controllers/controllerdebug.h"
+#include "controllers/scripting/colormapperjsproxy.h"
+#include "errordialoghandler.h"
+#include "mixer/playermanager.h"
+
+ControllerScriptEngineBase::ControllerScriptEngineBase(Controller* controller)
+        : m_bDisplayingExceptionDialog(false),
+          m_pJSEngine(nullptr),
+          m_pController(controller),
+          m_bTesting(false) {
+    // Handle error dialog buttons
+    qRegisterMetaType<QMessageBox::StandardButton>("QMessageBox::StandardButton");
+}
+
+bool ControllerScriptEngineBase::initialize() {
+    VERIFY_OR_DEBUG_ASSERT(!m_pJSEngine) {
+        return false;
+    }
+
+    // Create the Script Engine
+    m_pJSEngine = std::make_shared<QJSEngine>(this);
+
+    QJSValue engineGlobalObject = m_pJSEngine->globalObject();
+
+    QJSValue mapper = m_pJSEngine->newQMetaObject(
+            &ColorMapperJSProxy::staticMetaObject);
+    engineGlobalObject.setProperty("ColorMapper", mapper);
+
+    if (m_pController) {
+        qDebug() << "Controller in script engine is:"
+                 << m_pController->getName();
+
+        ControllerJSProxy* controllerProxy = m_pController->jsProxy();
+
+        // Make the Controller instance available to scripts
+        engineGlobalObject.setProperty(
+                "controller", m_pJSEngine->newQObject(controllerProxy));
+
+        // ...under the legacy name as well
+        engineGlobalObject.setProperty(
+                "midi", m_pJSEngine->newQObject(controllerProxy));
+    }
+
+    return true;
+}
+
+void ControllerScriptEngineBase::shutdown() {
+    DEBUG_ASSERT(m_pJSEngine.use_count() == 1);
+    m_pJSEngine.reset();
+}
+
+void ControllerScriptEngineBase::reload() {
+    shutdown();
+    initialize();
+}
+
+bool ControllerScriptEngineBase::executeFunction(
+        QJSValue functionObject, const QJSValueList& args) {
+    // This function is called from outside the controller engine, so we can't
+    // use VERIFY_OR_DEBUG_ASSERT here
+    if (!m_pJSEngine) {
+        return false;
+    }
+
+    if (functionObject.isError()) {
+        qDebug() << "ControllerScriptHandlerBase::executeFunction:"
+                 << functionObject.toString();
+        return false;
+    }
+
+    // If it's not a function, we're done.
+    if (!functionObject.isCallable()) {
+        qDebug() << "ControllerScriptHandlerBase::executeFunction:"
+                 << functionObject.toVariant() << "Not a function";
+        return false;
+    }
+
+    // If it does happen to be a function, call it.
+    QJSValue returnValue = functionObject.call(args);
+    if (returnValue.isError()) {
+        showScriptExceptionDialog(returnValue);
+        return false;
+    }
+    return true;
+}
+
+void ControllerScriptEngineBase::showScriptExceptionDialog(
+        const QJSValue& evaluationResult, bool bFatalError) {
+    VERIFY_OR_DEBUG_ASSERT(evaluationResult.isError()) {
+        return;
+    }
+
+    QString errorMessage = evaluationResult.toString();
+    QString line = evaluationResult.property("lineNumber").toString();
+    QString backtrace = evaluationResult.property("stack").toString();
+    QString filename = evaluationResult.property("fileName").toString();
+
+    QString errorText;
+    if (filename.isEmpty()) {
+        errorText = QString("Uncaught exception at line %1 in passed code.")
+                            .arg(line);
+    } else {
+        errorText = QString("Uncaught exception at line %1 in file %2.")
+                            .arg(line, filename);
+    }
+
+    errorText += QStringLiteral("\n\nException:\n  ") + errorMessage;
+
+    // Do not include backtrace in dialog key because it might contain midi
+    // slider values that will differ most of the time. This would break
+    // the "Ignore" feature of the error dialog.
+    QString key = errorText;
+    qWarning() << "ControllerScriptHandlerBase:" << errorText;
+
+    // Add backtrace to the error details
+    errorText += QStringLiteral("\n\nBacktrace:\n") + backtrace;
+
+    if (!m_bDisplayingExceptionDialog) {
+        scriptErrorDialog(errorText, key, bFatalError);
+    }
+}
+
+void ControllerScriptEngineBase::scriptErrorDialog(
+        const QString& detailedError, const QString& key, bool bFatalError) {
+    if (m_bTesting) {
+        return;
+    }
+
+    ErrorDialogProperties* props =
+            ErrorDialogHandler::instance()->newDialogProperties();
+
+    QString additionalErrorText;
+    if (bFatalError) {
+        additionalErrorText =
+                tr("The functionality provided by this controller mapping will "
+                   "be disabled until the issue has been resolved.");
+    } else {
+        // This happens when an exception is throws in an input handler (e. g.
+        // when pressing a button on the midi controller).  In case you ignore
+        // the issue, the button might not work if there's a bug in the
+        // mapping, but the other buttons probably will.
+        additionalErrorText =
+                tr("You can ignore this error for this session but "
+                   "you may experience erratic behavior.") +
+                QString("<br>") +
+                tr("Try to recover by resetting your controller.");
+    }
+
+    props->setType(DLG_WARNING);
+    props->setTitle(tr("Controller Preset Error"));
+    props->setText(tr("The preset for your controller \"%1\" is not working properly.")
+                           .arg(m_pController->getName()));
+    props->setInfoText(QStringLiteral("<html>") +
+            tr("The script code needs to be fixed.") + QStringLiteral("<p>") +
+            additionalErrorText + QStringLiteral("</p></html>"));
+
+    // Add "Details" text and set monospace font since they may contain
+    // backtraces and code.
+    props->setDetails(detailedError, true);
+
+    // To prevent multiple windows for the same error
+    props->setKey(key);
+
+    if (bFatalError) {
+        props->addButton(QMessageBox::Close);
+        props->setDefaultButton(QMessageBox::Close);
+        props->setEscapeButton(QMessageBox::Close);
+    } else {
+        // Allow user to suppress further notifications about this particular
+        // error
+        props->addButton(QMessageBox::Ignore);
+        props->addButton(QMessageBox::Retry);
+        props->setDefaultButton(QMessageBox::Ignore);
+        props->setEscapeButton(QMessageBox::Ignore);
+    }
+    props->setModal(false);
+
+    if (ErrorDialogHandler::instance()->requestErrorDialog(props)) {
+        m_bDisplayingExceptionDialog = true;
+        // Enable custom handling of the dialog buttons
+        connect(ErrorDialogHandler::instance(),
+                &ErrorDialogHandler::stdButtonClicked,
+                this,
+                &ControllerScriptEngineBase::errorDialogButton);
+    }
+}
+
+void ControllerScriptEngineBase::errorDialogButton(
+        const QString& key, QMessageBox::StandardButton clickedButton) {
+    Q_UNUSED(key);
+
+    m_bDisplayingExceptionDialog = false;
+    // Something was clicked, so disable this signal now
+    disconnect(ErrorDialogHandler::instance(),
+            &ErrorDialogHandler::stdButtonClicked,
+            this,
+            &ControllerScriptEngineBase::errorDialogButton);
+
+    if (clickedButton == QMessageBox::Retry) {
+        reload();
+    }
+}
+
+void ControllerScriptEngineBase::throwJSError(const QString& message) {
+#if QT_VERSION < QT_VERSION_CHECK(5, 12, 0)
+    QString errorText = tr("Uncaught exception: %1").arg(message);
+    qWarning() << "ControllerEngine:" << errorText;
+    if (!m_bDisplayingExceptionDialog) {
+        scriptErrorDialog(errorText, errorText);
+    }
+#else
+    m_pJSEngine->throwError(message);
+#endif
+}
diff --git a/src/controllers/scripting/controllerscriptenginebase.h b/src/controllers/scripting/controllerscriptenginebase.h
new file mode 100644
index 00000000000..8760673ce93
--- /dev/null
+++ b/src/controllers/scripting/controllerscriptenginebase.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QFileSystemWatcher>
+#include <QJSEngine>
+#include <QJSValue>
+#include <QMessageBox>
+#include <memory>
+
+#include "controllers/controllerpreset.h"
+#include "util/duration.h"
+
+class Controller;
+class EvaluationException;
+
+/// ControllerScriptEngineBase manages the JavaScript engine for controller scripts.
+/// ControllerScriptModuleEngine implements the current system using JS modules.
+/// ControllerScriptEngineLegacy implements the legacy hybrid JS/XML system.
+class ControllerScriptEngineBase : public QObject {
+    Q_OBJECT
+  public:
+    explicit ControllerScriptEngineBase(Controller* controller);
+    virtual ~ControllerScriptEngineBase() override = default;
+
+    virtual bool initialize();
+
+    bool executeFunction(QJSValue functionObject, const QJSValueList& arguments);
+
+    /// Shows a UI dialog notifying of a script evaluation error.
+    /// Precondition: QJSValue.isError() == true
+    void showScriptExceptionDialog(const QJSValue& evaluationResult, bool bFatal = false);
+    void throwJSError(const QString& message);
+
+    inline void setTesting(bool testing) {
+        m_bTesting = testing;
+    };
+
+    bool isTesting() const {
+        return m_bTesting;
+    }
+
+  protected:
+    virtual void shutdown();
+
+    void scriptErrorDialog(const QString& detailedError, const QString& key, bool bFatal = false);
+
+    bool m_bDisplayingExceptionDialog;
+    std::shared_ptr<QJSEngine> m_pJSEngine;
+
+    Controller* m_pController;
+
+    bool m_bTesting;
+
+  protected slots:
+    void reload();
+
+  private slots:
+    void errorDialogButton(const QString& key, QMessageBox::StandardButton button);
+
+    friend class ColorMapperJSProxy;
+};
diff --git a/src/controllers/scripting/controllerscriptmoduleengine.cpp b/src/controllers/scripting/controllerscriptmoduleengine.cpp
new file mode 100644
index 00000000000..540c19c980e
--- /dev/null
+++ b/src/controllers/scripting/controllerscriptmoduleengine.cpp
@@ -0,0 +1,52 @@
+#include "controllers/scripting/controllerscriptmoduleengine.h"
+
+ControllerScriptModuleEngine::ControllerScriptModuleEngine(Controller* controller)
+        : ControllerScriptEngineBase(controller) {
+    connect(&m_fileWatcher,
+            &QFileSystemWatcher::fileChanged,
+            this,
+            &ControllerScriptModuleEngine::reload);
+}
+
+ControllerScriptModuleEngine::~ControllerScriptModuleEngine() {
+    shutdown();
+}
+
+bool ControllerScriptModuleEngine::initialize() {
+    ControllerScriptEngineBase::initialize();
+#if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
+    m_pJSEngine->installExtensions(QJSEngine::ConsoleExtension);
+    // TODO: Add new ControlObject JS API to scripting environment.
+
+    QJSValue mod =
+            m_pJSEngine->importModule(m_moduleFileInfo.absoluteFilePath());
+    if (mod.isError()) {
+        showScriptExceptionDialog(mod);
+        shutdown();
+        return false;
+    }
+
+    if (!m_fileWatcher.addPath(m_moduleFileInfo.absoluteFilePath())) {
+        qWarning() << "Failed to watch script file" << m_moduleFileInfo.absoluteFilePath();
+    }
+
+    QJSValue initFunction = mod.property("init");
+    if (!executeFunction(initFunction, QJSValueList{})) {
+        shutdown();
+        return false;
+    }
+
+    QJSValue shutdownFunction = mod.property("shutdown");
+    if (shutdownFunction.isCallable()) {
+        m_shutdownFunction = shutdownFunction;
+    } else {
+        qDebug() << "Module exports no shutdown function.";
+    }
+#endif
+    return true;
+}
+
+void ControllerScriptModuleEngine::shutdown() {
+    executeFunction(m_shutdownFunction, QJSValueList());
+    ControllerScriptEngineBase::shutdown();
+}
diff --git a/src/controllers/scripting/controllerscriptmoduleengine.h b/src/controllers/scripting/controllerscriptmoduleengine.h
new file mode 100644
index 00000000000..76b14ee774c
--- /dev/null
+++ b/src/controllers/scripting/controllerscriptmoduleengine.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include "controllers/scripting/controllerscriptenginebase.h"
+
+/// ControllerScriptModuleEngine loads and executes script module files for controller mappings.
+class ControllerScriptModuleEngine : public ControllerScriptEngineBase {
+    Q_OBJECT
+  public:
+    explicit ControllerScriptModuleEngine(Controller* controller);
+    ~ControllerScriptModuleEngine() override;
+
+    bool initialize() override;
+
+    void setModuleFileInfo(const QFileInfo& moduleFileInfo) {
+        m_moduleFileInfo = moduleFileInfo;
+    }
+
+  private:
+    void shutdown() override;
+
+    QJSValue m_shutdownFunction;
+
+    QFileInfo m_moduleFileInfo;
+    QFileSystemWatcher m_fileWatcher;
+};
diff --git a/src/controllers/scripting/legacy/controllerscriptenginelegacy.cpp b/src/controllers/scripting/legacy/controllerscriptenginelegacy.cpp
new file mode 100644
index 00000000000..cdac16e0ce9
--- /dev/null
+++ b/src/controllers/scripting/legacy/controllerscriptenginelegacy.cpp
@@ -0,0 +1,254 @@
+#include "controllers/scripting/legacy/controllerscriptenginelegacy.h"
+
+#include "control/controlobject.h"
+#include "controllers/controller.h"
+#include "controllers/controllerdebug.h"
+#include "controllers/scripting/colormapperjsproxy.h"
+#include "controllers/scripting/legacy/controllerscriptinterfacelegacy.h"
+#include "errordialoghandler.h"
+#include "mixer/playermanager.h"
+
+ControllerScriptEngineLegacy::ControllerScriptEngineLegacy(Controller* controller)
+        : ControllerScriptEngineBase(controller) {
+    connect(&m_fileWatcher,
+            &QFileSystemWatcher::fileChanged,
+            this,
+            &ControllerScriptEngineLegacy::reload);
+}
+
+ControllerScriptEngineLegacy::~ControllerScriptEngineLegacy() {
+    shutdown();
+}
+
+bool ControllerScriptEngineLegacy::callFunctionOnObjects(
+        const QList<QString>& scriptFunctionPrefixes,
+        const QString& function,
+        const QJSValueList& args,
+        bool bFatalError) {
+    VERIFY_OR_DEBUG_ASSERT(m_pJSEngine) {
+        return false;
+    }
+
+    const QJSValue global = m_pJSEngine->globalObject();
+
+    bool success = true;
+    for (const QString& prefixName : scriptFunctionPrefixes) {
+        QJSValue prefix = global.property(prefixName);
+        if (!prefix.isObject()) {
+            qWarning() << "No" << prefixName << "object in script";
+            continue;
+        }
+
+        QJSValue init = prefix.property(function);
+        if (!init.isCallable()) {
+            qWarning() << prefixName << "has no"
+                       << function << " method";
+            continue;
+        }
+        controllerDebug("Executing"
+                << prefixName << "." << function);
+        QJSValue result = init.callWithInstance(prefix, args);
+        if (result.isError()) {
+            showScriptExceptionDialog(result, bFatalError);
+            success = false;
+        }
+    }
+    return success;
+}
+
+QJSValue ControllerScriptEngineLegacy::wrapFunctionCode(
+        const QString& codeSnippet, int numberOfArgs) {
+    // This function is called from outside the controller engine, so we can't
+    // use VERIFY_OR_DEBUG_ASSERT here
+    if (!m_pJSEngine) {
+        return QJSValue();
+    }
+
+    QJSValue wrappedFunction;
+
+    const auto it = m_scriptWrappedFunctionCache.constFind(codeSnippet);
+    if (it != m_scriptWrappedFunctionCache.constEnd()) {
+        wrappedFunction = it.value();
+    } else {
+        QStringList wrapperArgList;
+        wrapperArgList.reserve(numberOfArgs);
+        for (int i = 1; i <= numberOfArgs; i++) {
+            wrapperArgList << QString("arg%1").arg(i);
+        }
+        QString wrapperArgs = wrapperArgList.join(",");
+        QString wrappedCode = QStringLiteral("(function (") + wrapperArgs +
+                QStringLiteral(") { (") + codeSnippet + QStringLiteral(")(") +
+                wrapperArgs + QStringLiteral("); })");
+
+        wrappedFunction = m_pJSEngine->evaluate(wrappedCode);
+        if (wrappedFunction.isError()) {
+            showScriptExceptionDialog(wrappedFunction);
+        }
+        m_scriptWrappedFunctionCache[codeSnippet] = wrappedFunction;
+    }
+    return wrappedFunction;
+}
+
+bool ControllerScriptEngineLegacy::initialize() {
+    if (!ControllerScriptEngineBase::initialize()) {
+        return false;
+    }
+
+    // Binary data is passed from the Controller as a QByteArray, which
+    // QJSEngine::toScriptValue converts to an ArrayBuffer in JavaScript.
+    // ArrayBuffer cannot be accessed with the [] operator in JS; it needs
+    // to be converted to a typed array (Uint8Array in this case) first.
+    // This function generates a wrapper function from a JS callback to do
+    // that conversion automatically.
+    m_makeArrayBufferWrapperFunction = m_pJSEngine->evaluate(QStringLiteral(
+            // arg2 is the timestamp for ControllerScriptModuleEngine.
+            // In ControllerScriptEngineLegacy it is the length of the array.
+            "(function(callback) {"
+            "    return function(arrayBuffer, arg2) {"
+            "        callback(new Uint8Array(arrayBuffer), arg2);"
+            "    };"
+            "})"));
+
+    // Make this ControllerScriptHandler instance available to scripts as 'engine'.
+    QJSValue engineGlobalObject = m_pJSEngine->globalObject();
+    ControllerScriptInterfaceLegacy* legacyScriptInterface =
+            new ControllerScriptInterfaceLegacy(this);
+    engineGlobalObject.setProperty(
+            "engine", m_pJSEngine->newQObject(legacyScriptInterface));
+
+    for (const ControllerPreset::ScriptFileInfo& script : std::as_const(m_scriptFiles)) {
+        if (!evaluateScriptFile(script.file)) {
+            shutdown();
+            return false;
+        }
+        if (!script.functionPrefix.isEmpty()) {
+            m_scriptFunctionPrefixes.append(script.functionPrefix);
+        }
+    }
+
+    // For testing, do not actually initialize the scripts, just check for
+    // syntax errors above.
+    if (m_bTesting) {
+        return true;
+    }
+
+    for (QString functionName : std::as_const(m_scriptFunctionPrefixes)) {
+        if (functionName.isEmpty()) {
+            continue;
+        }
+        functionName.append(QStringLiteral(".incomingData"));
+        m_incomingDataFunctions.append(
+                wrapArrayBufferCallback(
+                        wrapFunctionCode(functionName, 2)));
+    }
+
+    QJSValueList args;
+    if (m_pController) {
+        args << QJSValue(m_pController->getName());
+    } else { // m_pController is nullptr in tests.
+        args << QJSValue();
+    }
+    args << QJSValue(ControllerDebug::isEnabled());
+    if (!callFunctionOnObjects(m_scriptFunctionPrefixes, "init", args, true)) {
+        shutdown();
+        return false;
+    }
+
+    return true;
+}
+
+void ControllerScriptEngineLegacy::shutdown() {
+    callFunctionOnObjects(m_scriptFunctionPrefixes, "shutdown");
+    m_scriptWrappedFunctionCache.clear();
+    m_incomingDataFunctions.clear();
+    m_scriptFunctionPrefixes.clear();
+    ControllerScriptEngineBase::shutdown();
+}
+
+bool ControllerScriptEngineLegacy::handleIncomingData(const QByteArray& data) {
+    // This function is called from outside the controller engine, so we can't
+    // use VERIFY_OR_DEBUG_ASSERT here
+    if (!m_pJSEngine) {
+        return false;
+    }
+
+    QJSValueList args;
+    args << m_pJSEngine->toScriptValue(data);
+    args << QJSValue(data.size());
+
+    for (const QJSValue& function : std::as_const(m_incomingDataFunctions)) {
+        ControllerScriptEngineBase::executeFunction(function, args);
+    }
+
+    return true;
+}
+
+bool ControllerScriptEngineLegacy::evaluateScriptFile(const QFileInfo& scriptFile) {
+    VERIFY_OR_DEBUG_ASSERT(m_pJSEngine) {
+        return false;
+    }
+
+    if (!scriptFile.exists()) {
+        qWarning() << "File does not exist:"
+                   << scriptFile.absoluteFilePath();
+        return false;
+    }
+
+    // If the script is invalid, it should be watched so the user can fix it
+    // without having to restart Mixxx. So, add it to the watcher before
+    // evaluating it.
+    if (!m_fileWatcher.addPath(scriptFile.absoluteFilePath())) {
+        qWarning() << "Failed to watch script file" << scriptFile.absoluteFilePath();
+    };
+
+    qDebug() << "Loading"
+             << scriptFile.absoluteFilePath();
+
+    // Read in the script file
+    QString filename = scriptFile.absoluteFilePath();
+    QFile input(filename);
+    if (!input.open(QIODevice::ReadOnly)) {
+        qWarning() << QString(
+                "Problem opening the script file: %1, "
+                "error # %2, %3")
+                              .arg(filename,
+                                      QString::number(input.error()),
+                                      input.errorString());
+        // Set up error dialog
+        ErrorDialogProperties* props = ErrorDialogHandler::instance()->newDialogProperties();
+        props->setType(DLG_WARNING);
+        props->setTitle(tr("Controller Mapping File Problem"));
+        props->setText(tr("The mapping for controller \"%1\" cannot be opened.")
+                               .arg(m_pController->getName()));
+        props->setInfoText(
+                tr("The functionality provided by this controller mapping will "
+                   "be disabled until the issue has been resolved."));
+
+        // We usually don't translate the details field, but the cause of
+        // this problem lies in the user's system (e.g. a permission
+        // issue). Translating this will help users to fix the issue even
+        // when they don't speak english.
+        props->setDetails(tr("File:") + QStringLiteral(" ") + filename +
+                QStringLiteral("\n") + tr("Error:") + QStringLiteral(" ") +
+                input.errorString());
+
+        // Ask above layer to display the dialog & handle user response
+        ErrorDialogHandler::instance()->requestErrorDialog(props);
+        return false;
+    }
+
+    QString scriptCode = QString(input.readAll()) + QStringLiteral("\n");
+    input.close();
+
+    QJSValue scriptFunction = m_pJSEngine->evaluate(scriptCode, filename);
+    if (scriptFunction.isError()) {
+        showScriptExceptionDialog(scriptFunction, true);
+        return false;
+    }
+
+    return true;
+}
+
+QJSValue ControllerScriptEngineLegacy::wrapArrayBufferCallback(const QJSValue& callback) {
+    return m_makeArrayBufferWrapperFunction.call(QJSValueList{callback});
+}
diff --git a/src/controllers/scripting/legacy/controllerscriptenginelegacy.h b/src/controllers/scripting/legacy/controllerscriptenginelegacy.h
new file mode 100644
index 00000000000..b488e3e547b
--- /dev/null
+++ b/src/controllers/scripting/legacy/controllerscriptenginelegacy.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QFileSystemWatcher>
+#include <QJSEngine>
+#include <QJSValue>
+#include <QMessageBox>
+
+#include "controllers/controllerpreset.h"
+#include "controllers/scripting/controllerscriptenginebase.h"
+
+/// ControllerScriptEngineLegacy loads and executes controller scripts for the legacy
+/// JS/XML hybrid controller mapping system.
+class ControllerScriptEngineLegacy : public ControllerScriptEngineBase {
+    Q_OBJECT
+  public:
+    explicit ControllerScriptEngineLegacy(Controller* controller);
+    ~ControllerScriptEngineLegacy() override;
+
+    bool initialize() override;
+
+    bool handleIncomingData(const QByteArray& data);
+
+    /// Wrap a string of JS code in an anonymous function. This allows any JS
+    /// string that evaluates to a function to be used in MIDI mapping XML files
+    /// and ensures the function is executed with the correct 'this' object.
+    QJSValue wrapFunctionCode(const QString& codeSnippet, int numberOfArgs);
+
+  public slots:
+    void setScriptFiles(const QList<ControllerPreset::ScriptFileInfo>& scripts) {
+        m_fileWatcher.removePaths(m_fileWatcher.files());
+        m_scriptFiles = scripts;
+    }
+
+  private:
+    bool evaluateScriptFile(const QFileInfo& scriptFile);
+    void shutdown() override;
+
+    QJSValue wrapArrayBufferCallback(const QJSValue& callback);
+    bool callFunctionOnObjects(const QList<QString>& scriptFunctionPrefixes,
+            const QString&,
+            const QJSValueList& args = QJSValueList(),
+            bool bFatalError = false);
+
+    QJSValue m_makeArrayBufferWrapperFunction;
+    QList<QString> m_scriptFunctionPrefixes;
+    QList<QJSValue> m_incomingDataFunctions;
+    QHash<QString, QJSValue> m_scriptWrappedFunctionCache;
+    QList<ControllerPreset::ScriptFileInfo> m_scriptFiles;
+
+    QFileSystemWatcher m_fileWatcher;
+
+    // There is lots of tight coupling between ControllerScriptEngineLegacy
+    // and ControllerScriptInterface. This is probably not worth improving in legacy code.
+    friend class ControllerScriptInterfaceLegacy;
+    std::shared_ptr<QJSEngine> jsEngine() const {
+        return m_pJSEngine;
+    }
+
+    friend class ControllerScriptEngineLegacyTest;
+};
diff --git a/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.cpp b/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.cpp
new file mode 100644
index 00000000000..8215b7d2804
--- /dev/null
+++ b/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.cpp
@@ -0,0 +1,876 @@
+#include "controllerscriptinterfacelegacy.h"
+
+#include "control/controlobject.h"
+#include "control/controlobjectscript.h"
+#include "controllers/controllerdebug.h"
+#include "controllers/scripting/legacy/controllerscriptenginelegacy.h"
+#include "controllers/scripting/legacy/scriptconnectionjsproxy.h"
+#include "mixer/playermanager.h"
+#include "util/math.h"
+#include "util/time.h"
+
+namespace {
+const int kDecks = 16;
+
+// Use 1ms for the Alpha-Beta dt. We're assuming the OS actually gives us a 1ms
+// timer.
+const int kScratchTimerMs = 1;
+const double kAlphaBetaDt = kScratchTimerMs / 1000.0;
+} // anonymous namespace
+
+ControllerScriptInterfaceLegacy::ControllerScriptInterfaceLegacy(
+        ControllerScriptEngineLegacy* m_pEngine)
+        : m_pScriptEngineLegacy(m_pEngine) {
+    // Pre-allocate arrays for average number of virtual decks
+    m_intervalAccumulator.resize(kDecks);
+    m_lastMovement.resize(kDecks);
+    m_dx.resize(kDecks);
+    m_rampTo.resize(kDecks);
+    m_ramp.resize(kDecks);
+    m_scratchFilters.resize(kDecks);
+    m_rampFactor.resize(kDecks);
+    m_brakeActive.resize(kDecks);
+    m_softStartActive.resize(kDecks);
+    // Initialize arrays used for testing and pointers
+    for (int i = 0; i < kDecks; ++i) {
+        m_dx[i] = 0.0;
+        m_scratchFilters[i] = new AlphaBetaFilter();
+        m_ramp[i] = false;
+    }
+}
+
+ControllerScriptInterfaceLegacy::~ControllerScriptInterfaceLegacy() {
+    // Stop all timers
+    QMutableHashIterator<int, TimerInfo> i(m_timers);
+    while (i.hasNext()) {
+        i.next();
+        stopTimer(i.key());
+    }
+
+    // Prevents leaving decks in an unstable state
+    //  if the controller is shut down while scratching
+    QHashIterator<int, int> it(m_scratchTimers);
+    while (it.hasNext()) {
+        it.next();
+        qDebug() << "Aborting scratching on deck" << it.value();
+        // Clear scratch2_enable. PlayerManager::groupForDeck is 0-indexed.
+        QString group = PlayerManager::groupForDeck(it.value() - 1);
+        ControlObjectScript* pScratch2Enable =
+                getControlObjectScript(group, "scratch2_enable");
+        if (pScratch2Enable != nullptr) {
+            pScratch2Enable->set(0);
+        }
+    }
+
+    for (int i = 0; i < kDecks; ++i) {
+        delete m_scratchFilters[i];
+        m_scratchFilters[i] = nullptr;
+    }
+
+    // Free all the ControlObjectScripts
+    {
+        auto it = m_controlCache.begin();
+        while (it != m_controlCache.end()) {
+            qDebug()
+                    << "Deleting ControlObjectScript"
+                    << it.key().group
+                    << it.key().item;
+            delete it.value();
+            // Advance iterator
+            it = m_controlCache.erase(it);
+        }
+    }
+}
+
+ControlObjectScript* ControllerScriptInterfaceLegacy::getControlObjectScript(
+        const QString& group, const QString& name) {
+    ConfigKey key = ConfigKey(group, name);
+    ControlObjectScript* coScript = m_controlCache.value(key, nullptr);
+    if (coScript == nullptr) {
+        // create COT
+        coScript = new ControlObjectScript(key, this);
+        if (coScript->valid()) {
+            m_controlCache.insert(key, coScript);
+        } else {
+            delete coScript;
+            coScript = nullptr;
+        }
+    }
+    return coScript;
+}
+
+double ControllerScriptInterfaceLegacy::getValue(const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    if (coScript == nullptr) {
+        qWarning() << "Unknown control" << group << name
+                   << ", returning 0.0";
+        return 0.0;
+    }
+    return coScript->get();
+}
+
+void ControllerScriptInterfaceLegacy::setValue(
+        const QString& group, const QString& name, double newValue) {
+    if (isnan(newValue)) {
+        qWarning() << "script setting [" << group << ","
+                   << name << "] to NotANumber, ignoring.";
+        return;
+    }
+
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+
+    if (coScript != nullptr) {
+        ControlObject* pControl = ControlObject::getControl(
+                coScript->getKey(), ControllerDebug::controlFlags());
+        if (pControl &&
+                !m_st.ignore(
+                        pControl, coScript->getParameterForValue(newValue))) {
+            coScript->slotSet(newValue);
+        }
+    }
+}
+
+double ControllerScriptInterfaceLegacy::getParameter(const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    if (coScript == nullptr) {
+        qWarning() << "Unknown control" << group << name
+                   << ", returning 0.0";
+        return 0.0;
+    }
+    return coScript->getParameter();
+}
+
+void ControllerScriptInterfaceLegacy::setParameter(
+        const QString& group, const QString& name, double newParameter) {
+    if (isnan(newParameter)) {
+        qWarning() << "script setting [" << group << ","
+                   << name << "] to NotANumber, ignoring.";
+        return;
+    }
+
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+
+    if (coScript != nullptr) {
+        ControlObject* pControl = ControlObject::getControl(
+                coScript->getKey(), ControllerDebug::controlFlags());
+        if (pControl && !m_st.ignore(pControl, newParameter)) {
+            coScript->setParameter(newParameter);
+        }
+    }
+}
+
+double ControllerScriptInterfaceLegacy::getParameterForValue(
+        const QString& group, const QString& name, double value) {
+    if (isnan(value)) {
+        qWarning() << "script setting [" << group << ","
+                   << name << "] to NotANumber, ignoring.";
+        return 0.0;
+    }
+
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+
+    if (coScript == nullptr) {
+        qWarning() << "Unknown control" << group << name
+                   << ", returning 0.0";
+        return 0.0;
+    }
+
+    return coScript->getParameterForValue(value);
+}
+
+void ControllerScriptInterfaceLegacy::reset(const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    if (coScript != nullptr) {
+        coScript->reset();
+    }
+}
+
+double ControllerScriptInterfaceLegacy::getDefaultValue(const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+
+    if (coScript == nullptr) {
+        qWarning() << "Unknown control" << group << name
+                   << ", returning 0.0";
+        return 0.0;
+    }
+
+    return coScript->getDefault();
+}
+
+double ControllerScriptInterfaceLegacy::getDefaultParameter(
+        const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+
+    if (coScript == nullptr) {
+        qWarning() << "Unknown control" << group << name
+                   << ", returning 0.0";
+        return 0.0;
+    }
+
+    return coScript->getParameterForValue(coScript->getDefault());
+}
+
+QJSValue ControllerScriptInterfaceLegacy::makeConnection(
+        const QString& group, const QString& name, const QJSValue& callback) {
+    auto pJsEngine = m_pScriptEngineLegacy->jsEngine();
+    VERIFY_OR_DEBUG_ASSERT(pJsEngine) {
+        return QJSValue();
+    }
+
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    if (coScript == nullptr) {
+        // The test setups do not run all of Mixxx, so ControlObjects not
+        // existing during tests is okay.
+        if (!m_pScriptEngineLegacy->isTesting()) {
+            m_pScriptEngineLegacy->throwJSError(
+                    "script tried to connect to "
+                    "ControlObject (" +
+                    group + ", " + name + ") which is non-existent.");
+        }
+        return QJSValue();
+    }
+
+    if (!callback.isCallable()) {
+        m_pScriptEngineLegacy->throwJSError("Tried to connect (" + group + ", " + name +
+                ")" +
+                " to an invalid callback. Make sure that your code contains no "
+                "syntax errors.");
+        return QJSValue();
+    }
+
+    ScriptConnection connection;
+    connection.key = ConfigKey(group, name);
+    connection.engineJSProxy = this;
+    connection.controllerEngine = m_pScriptEngineLegacy;
+    connection.callback = callback;
+    connection.id = QUuid::createUuid();
+
+    if (coScript->addScriptConnection(connection)) {
+        return pJsEngine->newQObject(
+                new ScriptConnectionJSProxy(connection));
+    }
+
+    return QJSValue();
+}
+
+bool ControllerScriptInterfaceLegacy::removeScriptConnection(
+        const ScriptConnection& connection) {
+    ControlObjectScript* coScript =
+            getControlObjectScript(connection.key.group, connection.key.item);
+
+    if (m_pScriptEngineLegacy->jsEngine() == nullptr || coScript == nullptr) {
+        return false;
+    }
+
+    return coScript->removeScriptConnection(connection);
+}
+
+void ControllerScriptInterfaceLegacy::triggerScriptConnection(
+        const ScriptConnection& connection) {
+    VERIFY_OR_DEBUG_ASSERT(m_pScriptEngineLegacy->jsEngine()) {
+        return;
+    }
+
+    ControlObjectScript* coScript =
+            getControlObjectScript(connection.key.group, connection.key.item);
+    if (coScript == nullptr) {
+        return;
+    }
+
+    connection.executeCallback(coScript->get());
+}
+
+// This function is a legacy version of makeConnection with several alternate
+// ways of invoking it. The callback function can be passed either as a string of
+// JavaScript code that evaluates to a function or an actual JavaScript function.
+// If "true" is passed as a 4th parameter, all connections to the ControlObject
+// are removed. If a ScriptConnectionInvokableWrapper is passed instead of a callback,
+// it is disconnected.
+// WARNING: These behaviors are quirky and confusing, so if you change this function,
+// be sure to run the ControllerScriptInterfaceTest suite to make sure you do not break old scripts.
+QJSValue ControllerScriptInterfaceLegacy::connectControl(const QString& group,
+        const QString& name,
+        const QJSValue& passedCallback,
+        bool disconnect) {
+    // The passedCallback may or may not actually be a function, so when
+    // the actual callback function is found, store it in this variable.
+    QJSValue actualCallbackFunction;
+
+    if (passedCallback.isCallable()) {
+        if (!disconnect) {
+            // skip all the checks below and just make the connection
+            return makeConnection(group, name, passedCallback);
+        }
+        actualCallbackFunction = passedCallback;
+    }
+
+    auto pJsEngine = m_pScriptEngineLegacy->jsEngine();
+
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    // This check is redundant with makeConnection, but the
+    // ControlObjectScript is also needed here to check for duplicate connections.
+    if (coScript == nullptr) {
+        // The test setups do not run all of Mixxx, so ControlObjects not
+        // existing during tests is okay.
+        if (!m_pScriptEngineLegacy->isTesting()) {
+            if (disconnect) {
+                m_pScriptEngineLegacy->throwJSError(
+                        "script tried to disconnect from "
+                        "ControlObject (" +
+                        group + ", " + name + ") which is non-existent.");
+            } else {
+                m_pScriptEngineLegacy->throwJSError(
+                        "script tried to connect to "
+                        "ControlObject (" +
+                        group + ", " + name + ") which is non-existent.");
+            }
+        }
+        // This is inconsistent with other failures, which return false.
+        // QJSValue() with no arguments is undefined in JavaScript.
+        return QJSValue();
+    }
+
+    if (passedCallback.isString()) {
+        // This check is redundant with makeConnection, but it must be done here
+        // before evaluating the code string.
+        VERIFY_OR_DEBUG_ASSERT(pJsEngine != nullptr) {
+            return QJSValue(false);
+        }
+
+        actualCallbackFunction =
+                pJsEngine->evaluate(passedCallback.toString());
+
+        if (!actualCallbackFunction.isCallable()) {
+            QString sErrorMessage(
+                    "Invalid connection callback provided to "
+                    "engine.connectControl.");
+            if (actualCallbackFunction.isError()) {
+                sErrorMessage.append("\n" + actualCallbackFunction.toString());
+            }
+            m_pScriptEngineLegacy->throwJSError(sErrorMessage);
+            return QJSValue(false);
+        }
+
+        if (coScript->countConnections() > 0 && !disconnect) {
+            // This is inconsistent with the behavior when passing the callback as
+            // a function, but keep the old behavior to make sure old scripts do
+            // not break.
+            ScriptConnection connection = coScript->firstConnection();
+
+            qWarning() << "Tried to make duplicate connection between (" +
+                            group + ", " + name + ") and " +
+                            passedCallback.toString() +
+                            " but this is not allowed when passing a callback "
+                            "as a string. " +
+                            "If you actually want to create duplicate "
+                            "connections, " +
+                            "use engine.makeConnection. Returning reference to "
+                            "connection " +
+                            connection.id.toString();
+
+            return pJsEngine->newQObject(
+                    new ScriptConnectionJSProxy(connection));
+        }
+    } else if (passedCallback.isQObject()) {
+        // Assume a ScriptConnection and assume that the script author
+        // wants to disconnect it, regardless of the disconnect parameter
+        // and regardless of whether it is connected to the same ControlObject
+        // specified by the first two parameters to this function.
+        QObject* qobject = passedCallback.toQObject();
+        const QMetaObject* qmeta = qobject->metaObject();
+
+        qWarning() << "QObject passed to engine.connectControl. Assuming it is"
+                   << "a connection object to disconnect and returning false.";
+        if (!strcmp(qmeta->className(), "ScriptConnectionJSProxy")) {
+            ScriptConnectionJSProxy* proxy = (ScriptConnectionJSProxy*)qobject;
+            proxy->disconnect();
+        }
+        return QJSValue(false);
+    }
+
+    // Support removing connections by passing "true" as the last parameter
+    // to this function, regardless of whether the callback is provided
+    // as a function or a string.
+    if (disconnect) {
+        // There is no way to determine which
+        // ScriptConnection to disconnect unless the script calls
+        // ScriptConnectionInvokableWrapper::disconnect(), so
+        // disconnect all ScriptConnections connected to the
+        // callback function, even though there may be multiple connections.
+        coScript->disconnectAllConnectionsToFunction(actualCallbackFunction);
+        return QJSValue(true);
+    }
+
+    // If execution gets this far without returning, make
+    // a new connection to actualCallbackFunction.
+    return makeConnection(group, name, actualCallbackFunction);
+}
+
+void ControllerScriptInterfaceLegacy::trigger(const QString& group, const QString& name) {
+    ControlObjectScript* coScript = getControlObjectScript(group, name);
+    if (coScript != nullptr) {
+        coScript->emitValueChanged();
+    }
+}
+
+void ControllerScriptInterfaceLegacy::log(const QString& message) {
+    controllerDebug(message);
+}
+int ControllerScriptInterfaceLegacy::beginTimer(
+        int intervalMillis, QJSValue timerCallback, bool oneShot) {
+    if (timerCallback.isString()) {
+        timerCallback = m_pScriptEngineLegacy->jsEngine()->evaluate(timerCallback.toString());
+    } else if (!timerCallback.isCallable()) {
+        QString sErrorMessage(
+                "Invalid timer callback provided to engine.beginTimer. Valid "
+                "callbacks are strings and functions. "
+                "Make sure that your code contains no syntax errors.");
+        if (timerCallback.isError()) {
+            sErrorMessage.append("\n" + timerCallback.toString());
+        }
+        m_pScriptEngineLegacy->throwJSError(sErrorMessage);
+        return 0;
+    }
+
+    if (intervalMillis < 20) {
+        qWarning() << "Timer request for" << intervalMillis
+                   << "ms is too short. Setting to the minimum of 20ms.";
+        intervalMillis = 20;
+    }
+
+    // This makes use of every QObject's internal timer mechanism. Nice, clean,
+    // and simple. See http://doc.trolltech.com/4.6/qobject.html#startTimer for
+    // details
+    int timerId = startTimer(intervalMillis);
+    TimerInfo info;
+    info.callback = timerCallback;
+    info.oneShot = oneShot;
+    m_timers[timerId] = info;
+    if (timerId == 0) {
+        qWarning() << "Script timer could not be created";
+    } else if (oneShot) {
+        controllerDebug("Starting one-shot timer:" << timerId);
+    } else {
+        controllerDebug("Starting timer:" << timerId);
+    }
+    return timerId;
+}
+
+void ControllerScriptInterfaceLegacy::stopTimer(int timerId) {
+    if (!m_timers.contains(timerId)) {
+        qWarning() << "Killing timer" << timerId
+                   << ": That timer does not exist!";
+        return;
+    }
+    controllerDebug("Killing timer:" << timerId);
+    killTimer(timerId);
+    m_timers.remove(timerId);
+}
+
+void ControllerScriptInterfaceLegacy::timerEvent(QTimerEvent* event) {
+    int timerId = event->timerId();
+
+    // See if this is a scratching timer
+    if (m_scratchTimers.contains(timerId)) {
+        scratchProcess(timerId);
+        return;
+    }
+
+    auto it = m_timers.constFind(timerId);
+    if (it == m_timers.constEnd()) {
+        qWarning() << "Timer" << timerId
+                   << "fired but there's no function mapped to it!";
+        return;
+    }
+
+    // NOTE(rryan): Do not assign by reference -- make a copy. I have no idea
+    // why but this causes segfaults in ~QScriptValue while scratching if we
+    // don't copy here -- even though internalExecute passes the QScriptValues
+    // by value. *boggle*
+    const TimerInfo timerTarget = it.value();
+    if (timerTarget.oneShot) {
+        stopTimer(timerId);
+    }
+
+    m_pScriptEngineLegacy->executeFunction(timerTarget.callback, QJSValueList());
+}
+
+void ControllerScriptInterfaceLegacy::softTakeover(
+        const QString& group, const QString& name, bool set) {
+    ControlObject* pControl = ControlObject::getControl(
+            ConfigKey(group, name), ControllerDebug::controlFlags());
+    if (!pControl) {
+        return;
+    }
+    if (set) {
+        m_st.enable(pControl);
+    } else {
+        m_st.disable(pControl);
+    }
+}
+
+void ControllerScriptInterfaceLegacy::softTakeoverIgnoreNextValue(
+        const QString& group, const QString& name) {
+    ControlObject* pControl = ControlObject::getControl(
+            ConfigKey(group, name), ControllerDebug::controlFlags());
+    if (!pControl) {
+        return;
+    }
+
+    m_st.ignoreNext(pControl);
+}
+
+double ControllerScriptInterfaceLegacy::getDeckRate(const QString& group) {
+    double rate = 0.0;
+    ControlObjectScript* pRateRatio =
+            getControlObjectScript(group, "rate_ratio");
+    if (pRateRatio != nullptr) {
+        rate = pRateRatio->get();
+    }
+
+    // See if we're in reverse play
+    ControlObjectScript* pReverse = getControlObjectScript(group, "reverse");
+    if (pReverse != nullptr && pReverse->get() == 1) {
+        rate = -rate;
+    }
+    return rate;
+}
+
+bool ControllerScriptInterfaceLegacy::isDeckPlaying(const QString& group) {
+    ControlObjectScript* pPlay = getControlObjectScript(group, "play");
+
+    if (pPlay == nullptr) {
+        QString error = QString("Could not getControlObjectScript()");
+        m_pScriptEngineLegacy->scriptErrorDialog(error, error);
+        return false;
+    }
+
+    return pPlay->get() > 0.0;
+}
+
+void ControllerScriptInterfaceLegacy::scratchEnable(int deck,
+        int intervalsPerRev,
+        double rpm,
+        double alpha,
+        double beta,
+        bool ramp) {
+    // If we're already scratching this deck, override that with this request
+    if (static_cast<bool>(m_dx[deck])) {
+        //qDebug() << "Already scratching deck" << deck << ". Overriding.";
+        int timerId = m_scratchTimers.key(deck);
+        killTimer(timerId);
+        m_scratchTimers.remove(timerId);
+    }
+
+    // Controller resolution in intervals per second at normal speed.
+    // (rev/min * ints/rev * mins/sec)
+    double intervalsPerSecond = (rpm * intervalsPerRev) / 60.0;
+
+    if (intervalsPerSecond == 0.0) {
+        qWarning() << "Invalid rpm or intervalsPerRev supplied to "
+                      "scratchEnable. Ignoring request.";
+        return;
+    }
+
+    m_dx[deck] = 1.0 / intervalsPerSecond;
+    m_intervalAccumulator[deck] = 0.0;
+    m_ramp[deck] = false;
+    m_rampFactor[deck] = 0.001;
+    m_brakeActive[deck] = false;
+
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+
+    // Ramp velocity, default to stopped.
+    double initVelocity = 0.0;
+
+    ControlObjectScript* pScratch2Enable =
+            getControlObjectScript(group, "scratch2_enable");
+
+    // If ramping is desired, figure out the deck's current speed
+    if (ramp) {
+        // See if the deck is already being scratched
+        if (pScratch2Enable != nullptr && pScratch2Enable->get() == 1) {
+            // If so, set the filter's initial velocity to the scratch speed
+            ControlObjectScript* pScratch2 =
+                    getControlObjectScript(group, "scratch2");
+            if (pScratch2 != nullptr) {
+                initVelocity = pScratch2->get();
+            }
+        } else if (isDeckPlaying(group)) {
+            // If the deck is playing, set the filter's initial velocity to the
+            // playback speed
+            initVelocity = getDeckRate(group);
+        }
+    }
+
+    // Initialize scratch filter
+    if (static_cast<bool>(alpha) && static_cast<bool>(beta)) {
+        m_scratchFilters[deck]->init(kAlphaBetaDt, initVelocity, alpha, beta);
+    } else {
+        // Use filter's defaults if not specified
+        m_scratchFilters[deck]->init(kAlphaBetaDt, initVelocity);
+    }
+
+    // 1ms is shortest possible, OS dependent
+    int timerId = startTimer(kScratchTimerMs);
+
+    // Associate this virtual deck with this timer for later processing
+    m_scratchTimers[timerId] = deck;
+
+    // Set scratch2_enable
+    if (pScratch2Enable != nullptr) {
+        pScratch2Enable->slotSet(1);
+    }
+}
+
+void ControllerScriptInterfaceLegacy::scratchTick(int deck, int interval) {
+    m_lastMovement[deck] = mixxx::Time::elapsed();
+    m_intervalAccumulator[deck] += interval;
+}
+
+void ControllerScriptInterfaceLegacy::scratchProcess(int timerId) {
+    int deck = m_scratchTimers[timerId];
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+    AlphaBetaFilter* filter = m_scratchFilters[deck];
+    if (!filter) {
+        qWarning() << "Scratch filter pointer is null on deck" << deck;
+        return;
+    }
+
+    const double oldRate = filter->predictedVelocity();
+
+    // Give the filter a data point:
+
+    // If we're ramping to end scratching and the wheel hasn't been turned very
+    // recently (spinback after lift-off,) feed fixed data
+    if (m_ramp[deck] && !m_softStartActive[deck] &&
+            ((mixxx::Time::elapsed() - m_lastMovement[deck]) >=
+                    mixxx::Duration::fromMillis(1))) {
+        filter->observation(m_rampTo[deck] * m_rampFactor[deck]);
+        // Once this code path is run, latch so it always runs until reset
+        //m_lastMovement[deck] += mixxx::Duration::fromSeconds(1);
+    } else if (m_softStartActive[deck]) {
+        // pretend we have moved by (desired rate*default distance)
+        filter->observation(m_rampTo[deck] * kAlphaBetaDt);
+    } else {
+        // This will (and should) be 0 if no net ticks have been accumulated
+        // (i.e. the wheel is stopped)
+        filter->observation(m_dx[deck] * m_intervalAccumulator[deck]);
+    }
+
+    const double newRate = filter->predictedVelocity();
+
+    // Actually do the scratching
+    ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
+    if (pScratch2 == nullptr) {
+        return; // abort and maybe it'll work on the next pass
+    }
+    pScratch2->set(newRate);
+
+    // Reset accumulator
+    m_intervalAccumulator[deck] = 0;
+
+    // End scratching if we're ramping and the current rate is really close to the rampTo value
+    if ((m_ramp[deck] && fabs(m_rampTo[deck] - newRate) <= 0.00001) ||
+            // or if we brake or softStart and have crossed over the desired value,
+            ((m_brakeActive[deck] || m_softStartActive[deck]) &&
+                    ((oldRate > m_rampTo[deck] && newRate < m_rampTo[deck]) ||
+                            (oldRate < m_rampTo[deck] &&
+                                    newRate > m_rampTo[deck]))) ||
+            // or if the deck was stopped manually during brake or softStart
+            ((m_brakeActive[deck] || m_softStartActive[deck]) &&
+                    (!isDeckPlaying(group)))) {
+        // Not ramping no mo'
+        m_ramp[deck] = false;
+
+        if (m_brakeActive[deck]) {
+            // If in brake mode, set scratch2 rate to 0 and turn off the play button.
+            pScratch2->slotSet(0.0);
+            ControlObjectScript* pPlay = getControlObjectScript(group, "play");
+            if (pPlay != nullptr) {
+                pPlay->slotSet(0.0);
+            }
+        }
+
+        // Clear scratch2_enable to end scratching.
+        ControlObjectScript* pScratch2Enable =
+                getControlObjectScript(group, "scratch2_enable");
+        if (pScratch2Enable == nullptr) {
+            return; // abort and maybe it'll work on the next pass
+        }
+        pScratch2Enable->slotSet(0);
+
+        // Remove timer
+        killTimer(timerId);
+        m_scratchTimers.remove(timerId);
+
+        m_dx[deck] = 0.0;
+        m_brakeActive[deck] = false;
+        m_softStartActive[deck] = false;
+    }
+}
+
+void ControllerScriptInterfaceLegacy::scratchDisable(int deck, bool ramp) {
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+
+    m_rampTo[deck] = 0.0;
+
+    // If no ramping is desired, disable scratching immediately
+    if (!ramp) {
+        // Clear scratch2_enable
+        ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
+        if (pScratch2Enable != nullptr) {
+            pScratch2Enable->slotSet(0);
+        }
+        // Can't return here because we need scratchProcess to stop the timer.
+        // So it's still actually ramping, we just won't hear or see it.
+    } else if (isDeckPlaying(group)) {
+        // If so, set the target velocity to the playback speed
+        m_rampTo[deck] = getDeckRate(group);
+    }
+
+    m_lastMovement[deck] = mixxx::Time::elapsed();
+    m_ramp[deck] = true; // Activate the ramping in scratchProcess()
+}
+
+bool ControllerScriptInterfaceLegacy::isScratching(int deck) {
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+    return getValue(group, "scratch2_enable") > 0;
+}
+
+void ControllerScriptInterfaceLegacy::spinback(
+        int deck, bool activate, double factor, double rate) {
+    // defaults for args set in header file
+    brake(deck, activate, factor, rate);
+}
+
+void ControllerScriptInterfaceLegacy::brake(int deck, bool activate, double factor, double rate) {
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+
+    // kill timer when both enabling or disabling
+    int timerId = m_scratchTimers.key(deck);
+    killTimer(timerId);
+    m_scratchTimers.remove(timerId);
+
+    // enable/disable scratch2 mode
+    ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
+    if (pScratch2Enable != nullptr) {
+        pScratch2Enable->slotSet(activate ? 1 : 0);
+    }
+
+    // used in scratchProcess for the different timer behavior we need
+    m_brakeActive[deck] = activate;
+    double initRate = rate;
+
+    if (activate) {
+        // store the new values for this spinback/brake effect
+        if (initRate == 1.0) { // then rate is really 1.0 or was set to default
+            // in /res/common-controller-scripts.js so check for real value,
+            // taking pitch into account
+            initRate = getDeckRate(group);
+        }
+        // stop ramping at a rate which doesn't produce any audible output anymore
+        m_rampTo[deck] = 0.01;
+        // if we are currently softStart()ing, stop it
+        if (m_softStartActive[deck]) {
+            m_softStartActive[deck] = false;
+            AlphaBetaFilter* filter = m_scratchFilters[deck];
+            if (filter != nullptr) {
+                initRate = filter->predictedVelocity();
+            }
+        }
+
+        // setup timer and set scratch2
+        timerId = startTimer(kScratchTimerMs);
+        m_scratchTimers[timerId] = deck;
+
+        ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
+        if (pScratch2 != nullptr) {
+            pScratch2->slotSet(initRate);
+        }
+
+        // setup the filter with default alpha and beta*factor
+        double alphaBrake = 1.0 / 512;
+        // avoid decimals for fine adjusting
+        if (factor > 1) {
+            factor = ((factor - 1) / 10) + 1;
+        }
+        double betaBrake = ((1.0 / 512) / 1024) * factor; // default*factor
+        AlphaBetaFilter* filter = m_scratchFilters[deck];
+        if (filter != nullptr) {
+            filter->init(kAlphaBetaDt, initRate, alphaBrake, betaBrake);
+        }
+
+        // activate the ramping in scratchProcess()
+        m_ramp[deck] = true;
+    }
+}
+
+void ControllerScriptInterfaceLegacy::softStart(int deck, bool activate, double factor) {
+    // PlayerManager::groupForDeck is 0-indexed.
+    QString group = PlayerManager::groupForDeck(deck - 1);
+
+    // kill timer when both enabling or disabling
+    int timerId = m_scratchTimers.key(deck);
+    killTimer(timerId);
+    m_scratchTimers.remove(timerId);
+
+    // enable/disable scratch2 mode
+    ControlObjectScript* pScratch2Enable = getControlObjectScript(group, "scratch2_enable");
+    if (pScratch2Enable != nullptr) {
+        pScratch2Enable->slotSet(activate ? 1 : 0);
+    }
+
+    // used in scratchProcess for the different timer behavior we need
+    m_softStartActive[deck] = activate;
+    double initRate = 0.0;
+
+    if (activate) {
+        // acquire deck rate
+        m_rampTo[deck] = getDeckRate(group);
+
+        // if brake()ing, get current rate from filter
+        if (m_brakeActive[deck]) {
+            m_brakeActive[deck] = false;
+
+            AlphaBetaFilter* filter = m_scratchFilters[deck];
+            if (filter != nullptr) {
+                initRate = filter->predictedVelocity();
+            }
+        }
+
+        // setup timer, start playing and set scratch2
+        timerId = startTimer(kScratchTimerMs);
+        m_scratchTimers[timerId] = deck;
+
+        ControlObjectScript* pPlay = getControlObjectScript(group, "play");
+        if (pPlay != nullptr) {
+            pPlay->slotSet(1.0);
+        }
+
+        ControlObjectScript* pScratch2 = getControlObjectScript(group, "scratch2");
+        if (pScratch2 != nullptr) {
+            pScratch2->slotSet(initRate);
+        }
+
+        // setup the filter like in brake(), with default alpha and beta*factor
+        double alphaSoft = 1.0 / 512;
+        // avoid decimals for fine adjusting
+        if (factor > 1) {
+            factor = ((factor - 1) / 10) + 1;
+        }
+        double betaSoft = ((1.0 / 512) / 1024) * factor; // default: (1.0/512)/1024
+        AlphaBetaFilter* filter = m_scratchFilters[deck];
+        if (filter != nullptr) { // kAlphaBetaDt = 1/1000 seconds
+            filter->init(kAlphaBetaDt, initRate, alphaSoft, betaSoft);
+        }
+
+        // activate the ramping in scratchProcess()
+        m_ramp[deck] = true;
+    }
+}
diff --git a/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.h b/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.h
new file mode 100644
index 00000000000..11087394eb5
--- /dev/null
+++ b/src/controllers/scripting/legacy/controllerscriptinterfacelegacy.h
@@ -0,0 +1,90 @@
+#pragma once
+
+#include <QJSValue>
+#include <QObject>
+
+#include "controllers/softtakeover.h"
+#include "util/alphabetafilter.h"
+
+class ControllerScriptEngineLegacy;
+class ControlObjectScript;
+class ScriptConnection;
+class ConfigKey;
+
+/// ControllerScriptInterfaceLegacy is the legacy API for controller scripts to interact
+/// with Mixxx. It is inserted into the JS environment as the "engine" object.
+class ControllerScriptInterfaceLegacy : public QObject {
+    Q_OBJECT
+  public:
+    ControllerScriptInterfaceLegacy(ControllerScriptEngineLegacy* m_pEngine);
+
+    virtual ~ControllerScriptInterfaceLegacy();
+
+    Q_INVOKABLE double getValue(const QString& group, const QString& name);
+    Q_INVOKABLE void setValue(const QString& group, const QString& name, double newValue);
+    Q_INVOKABLE double getParameter(const QString& group, const QString& name);
+    Q_INVOKABLE void setParameter(const QString& group, const QString& name, double newValue);
+    Q_INVOKABLE double getParameterForValue(
+            const QString& group, const QString& name, double value);
+    Q_INVOKABLE void reset(const QString& group, const QString& name);
+    Q_INVOKABLE double getDefaultValue(const QString& group, const QString& name);
+    Q_INVOKABLE double getDefaultParameter(const QString& group, const QString& name);
+    Q_INVOKABLE QJSValue makeConnection(
+            const QString& group, const QString& name, const QJSValue& callback);
+    // DEPRECATED: Use makeConnection instead.
+    Q_INVOKABLE QJSValue connectControl(const QString& group,
+            const QString& name,
+            const QJSValue& passedCallback,
+            bool disconnect = false);
+    // Called indirectly by the objects returned by connectControl
+    Q_INVOKABLE void trigger(const QString& group, const QString& name);
+    Q_INVOKABLE void log(const QString& message);
+    Q_INVOKABLE int beginTimer(int interval, QJSValue scriptCode, bool oneShot = false);
+    Q_INVOKABLE void stopTimer(int timerId);
+    Q_INVOKABLE void scratchEnable(int deck,
+            int intervalsPerRev,
+            double rpm,
+            double alpha,
+            double beta,
+            bool ramp = true);
+    Q_INVOKABLE void scratchTick(int deck, int interval);
+    Q_INVOKABLE void scratchDisable(int deck, bool ramp = true);
+    Q_INVOKABLE bool isScratching(int deck);
+    Q_INVOKABLE void softTakeover(const QString& group, const QString& name, bool set);
+    Q_INVOKABLE void softTakeoverIgnoreNextValue(const QString& group, const QString& name);
+    Q_INVOKABLE void brake(int deck, bool activate, double factor = 1.0, double rate = 1.0);
+    Q_INVOKABLE void spinback(int deck, bool activate, double factor = 1.8, double rate = -10.0);
+    Q_INVOKABLE void softStart(int deck, bool activate, double factor = 1.0);
+
+    bool removeScriptConnection(const ScriptConnection& conn);
+    /// Execute a ScriptConnection's JS callback
+    void triggerScriptConnection(const ScriptConnection& conn);
+
+    /// Handler for timers that scripts set.
+    virtual void timerEvent(QTimerEvent* event);
+
+  private:
+    QHash<ConfigKey, ControlObjectScript*> m_controlCache;
+    ControlObjectScript* getControlObjectScript(const QString& group, const QString& name);
+
+    SoftTakeoverCtrl m_st;
+
+    struct TimerInfo {
+        QJSValue callback;
+        bool oneShot;
+    };
+    QHash<int, TimerInfo> m_timers;
+
+    QVarLengthArray<int> m_intervalAccumulator;
+    QVarLengthArray<mixxx::Duration> m_lastMovement;
+    QVarLengthArray<double> m_dx, m_rampTo, m_rampFactor;
+    QVarLengthArray<bool> m_ramp, m_brakeActive, m_softStartActive;
+    QVarLengthArray<AlphaBetaFilter*> m_scratchFilters;
+    QHash<int, int> m_scratchTimers;
+    /// Applies the accumulated movement to the track speed
+    void scratchProcess(int timerId);
+    bool isDeckPlaying(const QString& group);
+    double getDeckRate(const QString& group);
+
+    ControllerScriptEngineLegacy* m_pScriptEngineLegacy;
+};
diff --git a/src/controllers/engine/scriptconnection.cpp b/src/controllers/scripting/legacy/scriptconnection.cpp
similarity index 83%
rename from src/controllers/engine/scriptconnection.cpp
rename to src/controllers/scripting/legacy/scriptconnection.cpp
index f059d127e9a..2f66346db3f 100644
--- a/src/controllers/engine/scriptconnection.cpp
+++ b/src/controllers/scripting/legacy/scriptconnection.cpp
@@ -1,6 +1,6 @@
-#include "controllers/engine/scriptconnection.h"
+#include "controllers/scripting/legacy/scriptconnection.h"
 
-#include "controllers/engine/controllerengine.h"
+#include "controllers/scripting/legacy/controllerscriptenginelegacy.h"
 
 void ScriptConnection::executeCallback(double value) const {
     QJSValueList args;
diff --git a/src/controllers/engine/scriptconnection.h b/src/controllers/scripting/legacy/scriptconnection.h
similarity index 78%
rename from src/controllers/engine/scriptconnection.h
rename to src/controllers/scripting/legacy/scriptconnection.h
index 153a4b83f86..f2e6558e64b 100644
--- a/src/controllers/engine/scriptconnection.h
+++ b/src/controllers/scripting/legacy/scriptconnection.h
@@ -5,7 +5,8 @@
 
 #include "preferences/configobject.h"
 
-class ControllerEngine;
+class ControllerScriptEngineLegacy;
+class ControllerScriptInterfaceLegacy;
 
 /// ScriptConnection is a connection between a ControlObject and a
 /// script callback function that gets executed when the value
@@ -15,7 +16,8 @@ class ScriptConnection {
     ConfigKey key;
     QUuid id;
     QJSValue callback;
-    ControllerEngine* controllerEngine;
+    ControllerScriptInterfaceLegacy* engineJSProxy;
+    ControllerScriptEngineLegacy* controllerEngine;
 
     void executeCallback(double value) const;
 
diff --git a/src/controllers/scripting/legacy/scriptconnectionjsproxy.cpp b/src/controllers/scripting/legacy/scriptconnectionjsproxy.cpp
new file mode 100644
index 00000000000..7ba44b18c4d
--- /dev/null
+++ b/src/controllers/scripting/legacy/scriptconnectionjsproxy.cpp
@@ -0,0 +1,14 @@
+#include "controllers/scripting/legacy/scriptconnectionjsproxy.h"
+
+#include "controllers/scripting/legacy/controllerscriptinterfacelegacy.h"
+
+bool ScriptConnectionJSProxy::disconnect() {
+    // if the removeScriptConnection succeeded, the connection has been successfully disconnected
+    bool success = m_scriptConnection.engineJSProxy->removeScriptConnection(m_scriptConnection);
+    m_isConnected = !success;
+    return success;
+}
+
+void ScriptConnectionJSProxy::trigger() {
+    m_scriptConnection.engineJSProxy->triggerScriptConnection(m_scriptConnection);
+}
diff --git a/src/controllers/engine/scriptconnectionjsproxy.h b/src/controllers/scripting/legacy/scriptconnectionjsproxy.h
similarity index 92%
rename from src/controllers/engine/scriptconnectionjsproxy.h
rename to src/controllers/scripting/legacy/scriptconnectionjsproxy.h
index 344fb38c010..2b80b5e4c08 100644
--- a/src/controllers/engine/scriptconnectionjsproxy.h
+++ b/src/controllers/scripting/legacy/scriptconnectionjsproxy.h
@@ -2,7 +2,7 @@
 
 #include <QObject>
 
-#include "controllers/engine/scriptconnection.h"
+#include "controllers/scripting/legacy/scriptconnection.h"
 
 /// ScriptConnectionJSProxy provides scripts with an interface to ScriptConnection.
 class ScriptConnectionJSProxy : public QObject {
diff --git a/src/test/colormapperjsproxy_test.cpp b/src/test/colormapperjsproxy_test.cpp
index f6a9e29bf5f..753f6fe79c5 100644
--- a/src/test/colormapperjsproxy_test.cpp
+++ b/src/test/colormapperjsproxy_test.cpp
@@ -1,4 +1,4 @@
-#include "controllers/engine/colormapperjsproxy.h"
+#include "controllers/scripting/colormapperjsproxy.h"
 
 #include <gtest/gtest.h>
 
diff --git a/src/test/controller_preset_validation_test.cpp b/src/test/controller_preset_validation_test.cpp
index f941c08ed20..bf458dcb0f7 100644
--- a/src/test/controller_preset_validation_test.cpp
+++ b/src/test/controller_preset_validation_test.cpp
@@ -30,7 +30,7 @@ FakeController::FakeController()
         : m_bMidiPreset(false),
           m_bHidPreset(false) {
     startEngine();
-    getEngine()->setTesting(true);
+    getScriptEngine()->setTesting(true);
 }
 
 FakeController::~FakeController() {
@@ -82,8 +82,7 @@ bool ControllerPresetValidationTest::testLoadPreset(const PresetInfo& preset) {
     FakeController controller;
     controller.setDeviceName("Test Controller");
     controller.setPreset(*pPreset);
-    // Do not initialize the scripts.
-    bool result = controller.applyPreset(false);
+    bool result = controller.applyPreset();
     controller.stopEngine();
     return result;
 }
diff --git a/src/test/controllerengine_test.cpp b/src/test/controllerscriptenginelegacy_test.cpp
similarity index 89%
rename from src/test/controllerengine_test.cpp
rename to src/test/controllerscriptenginelegacy_test.cpp
index fc29ef15d9b..ff6b97ed7d4 100644
--- a/src/test/controllerengine_test.cpp
+++ b/src/test/controllerscriptenginelegacy_test.cpp
@@ -1,4 +1,4 @@
-#include "controllers/engine/controllerengine.h"
+#include "controllers/scripting/legacy/controllerscriptenginelegacy.h"
 
 #include <QScopedPointer>
 #include <QTemporaryFile>
@@ -17,7 +17,7 @@
 
 typedef std::unique_ptr<QTemporaryFile> ScopedTemporaryFile;
 
-class ControllerEngineTest : public MixxxTest {
+class ControllerScriptEngineLegacyTest : public MixxxTest {
   protected:
     static ScopedTemporaryFile makeTemporaryFile(const QString& contents) {
         QByteArray contentsBa = contents.toLocal8Bit();
@@ -32,12 +32,12 @@ class ControllerEngineTest : public MixxxTest {
         mixxx::Time::setTestMode(true);
         mixxx::Time::setTestElapsedTime(mixxx::Duration::fromMillis(10));
         QThread::currentThread()->setObjectName("Main");
-        cEngine = new ControllerEngine(nullptr);
-        ControllerDebug::enable();
+        cEngine = new ControllerScriptEngineLegacy(nullptr);
+        cEngine->initialize();
+        ControllerDebug::setTesting(true);
     }
 
     void TearDown() override {
-        cEngine->gracefulShutdown();
         delete cEngine;
         mixxx::Time::setTestMode(false);
     }
@@ -47,11 +47,11 @@ class ControllerEngineTest : public MixxxTest {
     }
 
     QJSValue evaluate(const QString& code) {
-        return cEngine->evaluateCodeString(code);
+        return cEngine->jsEngine()->evaluate(code);
     }
 
     bool evaluateAndAssert(const QString& code) {
-        return !cEngine->evaluateCodeString(code).isError();
+        return !evaluate(code).isError();
     }
 
     void processEvents() {
@@ -65,50 +65,62 @@ class ControllerEngineTest : public MixxxTest {
         application()->processEvents();
     }
 
-    ControllerEngine* cEngine;
+    ControllerScriptEngineLegacy* cEngine;
 };
 
-TEST_F(ControllerEngineTest, commonScriptHasNoErrors) {
+TEST_F(ControllerScriptEngineLegacyTest, commonScriptHasNoErrors) {
     QFileInfo commonScript("./res/controllers/common-controller-scripts.js");
     EXPECT_TRUE(evaluateScriptFile(commonScript));
 }
 
-TEST_F(ControllerEngineTest, setValue) {
+TEST_F(ControllerScriptEngineLegacyTest, setValue) {
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     EXPECT_TRUE(evaluateAndAssert("engine.setValue('[Test]', 'co', 1.0);"));
     EXPECT_DOUBLE_EQ(1.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, getValue_InvalidKey) {
-    ControllerDebug::disable();
+TEST_F(ControllerScriptEngineLegacyTest, getValue_InvalidKey) {
+    ControllerDebug::setEnabled(false);
+    ControllerDebug::setTesting(false);
     EXPECT_TRUE(evaluateAndAssert("engine.getValue('', '');"));
     EXPECT_TRUE(evaluateAndAssert("engine.getValue('', 'invalid');"));
     EXPECT_TRUE(evaluateAndAssert("engine.getValue('[Invalid]', '');"));
-    ControllerDebug::enable();
+    ControllerDebug::setTesting(true);
+    ControllerDebug::setEnabled(true);
 }
 
-TEST_F(ControllerEngineTest, setValue_InvalidControl) {
+TEST_F(ControllerScriptEngineLegacyTest, setValue_InvalidControl) {
+    ControllerDebug::setEnabled(false);
+    ControllerDebug::setTesting(false);
     EXPECT_TRUE(evaluateAndAssert("engine.setValue('[Nothing]', 'nothing', 1.0);"));
+    ControllerDebug::setTesting(true);
+    ControllerDebug::setEnabled(true);
 }
 
-TEST_F(ControllerEngineTest, getValue_InvalidControl) {
+TEST_F(ControllerScriptEngineLegacyTest, getValue_InvalidControl) {
+    ControllerDebug::setEnabled(false);
+    ControllerDebug::setTesting(false);
     EXPECT_TRUE(evaluateAndAssert("engine.getValue('[Nothing]', 'nothing');"));
+    ControllerDebug::setTesting(true);
+    ControllerDebug::setEnabled(true);
 }
 
-TEST_F(ControllerEngineTest, setValue_IgnoresNaN) {
+TEST_F(ControllerScriptEngineLegacyTest, setValue_IgnoresNaN) {
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     co->set(10.0);
     EXPECT_TRUE(evaluateAndAssert("engine.setValue('[Test]', 'co', NaN);"));
     EXPECT_DOUBLE_EQ(10.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, getSetValue) {
+TEST_F(ControllerScriptEngineLegacyTest, getSetValue) {
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
-    EXPECT_TRUE(evaluateAndAssert("engine.setValue('[Test]', 'co', engine.getValue('[Test]', 'co') + 1);"));
+    EXPECT_TRUE(
+            evaluateAndAssert("engine.setValue('[Test]', 'co', "
+                              "engine.getValue('[Test]', 'co') + 1);"));
     EXPECT_DOUBLE_EQ(1.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, setParameter) {
+TEST_F(ControllerScriptEngineLegacyTest, setParameter) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -120,7 +132,7 @@ TEST_F(ControllerEngineTest, setParameter) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, setParameter_OutOfRange) {
+TEST_F(ControllerScriptEngineLegacyTest, setParameter_OutOfRange) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -130,7 +142,7 @@ TEST_F(ControllerEngineTest, setParameter_OutOfRange) {
     EXPECT_DOUBLE_EQ(-10.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, setParameter_NaN) {
+TEST_F(ControllerScriptEngineLegacyTest, setParameter_NaN) {
     // Test that NaNs are ignored.
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
@@ -139,7 +151,7 @@ TEST_F(ControllerEngineTest, setParameter_NaN) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, getSetParameter) {
+TEST_F(ControllerScriptEngineLegacyTest, getSetParameter) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -149,7 +161,7 @@ TEST_F(ControllerEngineTest, getSetParameter) {
     EXPECT_DOUBLE_EQ(2.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, softTakeover_setValue) {
+TEST_F(ControllerScriptEngineLegacyTest, softTakeover_setValue) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -181,7 +193,7 @@ TEST_F(ControllerEngineTest, softTakeover_setValue) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, softTakeover_setParameter) {
+TEST_F(ControllerScriptEngineLegacyTest, softTakeover_setParameter) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -213,7 +225,7 @@ TEST_F(ControllerEngineTest, softTakeover_setParameter) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, softTakeover_ignoreNextValue) {
+TEST_F(ControllerScriptEngineLegacyTest, softTakeover_ignoreNextValue) {
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
             10.0);
@@ -236,7 +248,7 @@ TEST_F(ControllerEngineTest, softTakeover_ignoreNextValue) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, reset) {
+TEST_F(ControllerScriptEngineLegacyTest, reset) {
     // Test that NaNs are ignored.
     auto co = std::make_unique<ControlPotmeter>(ConfigKey("[Test]", "co"),
             -10.0,
@@ -246,11 +258,11 @@ TEST_F(ControllerEngineTest, reset) {
     EXPECT_DOUBLE_EQ(0.0, co->get());
 }
 
-TEST_F(ControllerEngineTest, log) {
+TEST_F(ControllerScriptEngineLegacyTest, log) {
     EXPECT_TRUE(evaluateAndAssert("engine.log('Test that logging works.');"));
 }
 
-TEST_F(ControllerEngineTest, trigger) {
+TEST_F(ControllerScriptEngineLegacyTest, trigger) {
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
 
@@ -271,7 +283,7 @@ TEST_F(ControllerEngineTest, trigger) {
 // depending on how it is invoked, so we need a lot of tests to make sure old scripts
 // do not break.
 
-TEST_F(ControllerEngineTest, connectControl_ByString) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_ByString) {
     // Test that connecting and disconnecting by function name works.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
@@ -294,7 +306,7 @@ TEST_F(ControllerEngineTest, connectControl_ByString) {
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectControl_ByStringForbidDuplicateConnections) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_ByStringForbidDuplicateConnections) {
     // Test that connecting a control to a callback specified by a string
     // does not make duplicate connections. This behavior is inconsistent
     // with the behavior when specifying a callback as a function, but
@@ -317,7 +329,7 @@ TEST_F(ControllerEngineTest, connectControl_ByStringForbidDuplicateConnections)
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest,
+TEST_F(ControllerScriptEngineLegacyTest,
         connectControl_ByStringRedundantConnectionObjectsAreNotIndependent) {
     // Test that multiple connections are not allowed when passing
     // the callback to engine.connectControl as a function name string.
@@ -359,7 +371,7 @@ TEST_F(ControllerEngineTest,
     EXPECT_EQ(1.0, counter->get());
 }
 
-TEST_F(ControllerEngineTest, connectControl_ByFunction) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_ByFunction) {
     // Test that connecting and disconnecting with a function value works.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
@@ -377,7 +389,7 @@ TEST_F(ControllerEngineTest, connectControl_ByFunction) {
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectControl_ByFunctionAllowDuplicateConnections) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_ByFunctionAllowDuplicateConnections) {
     // Test that duplicate connections are allowed when passing callbacks as functions.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
@@ -398,7 +410,7 @@ TEST_F(ControllerEngineTest, connectControl_ByFunctionAllowDuplicateConnections)
     EXPECT_DOUBLE_EQ(2.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectControl_toDisconnectRemovesAllConnections) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_toDisconnectRemovesAllConnections) {
     // Test that every connection to a ControlObject is disconnected
     // by calling engine.connectControl(..., true). Individual connections
     // can only be disconnected by storing the connection object returned by
@@ -425,7 +437,7 @@ TEST_F(ControllerEngineTest, connectControl_toDisconnectRemovesAllConnections) {
     EXPECT_DOUBLE_EQ(2.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectControl_ByLambda) {
+TEST_F(ControllerScriptEngineLegacyTest, connectControl_ByLambda) {
     // Test that connecting with an anonymous function works.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
@@ -447,7 +459,7 @@ TEST_F(ControllerEngineTest, connectControl_ByLambda) {
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectionObject_Disconnect) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionObject_Disconnect) {
     // Test that disconnecting using the 'disconnect' method on the connection
     // object returned from connectControl works.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
@@ -471,7 +483,7 @@ TEST_F(ControllerEngineTest, connectionObject_Disconnect) {
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectionObject_reflectDisconnect) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionObject_reflectDisconnect) {
     // Test that checks if disconnecting yields the appropriate feedback
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
     auto pass = std::make_unique<ControlObject>(ConfigKey("[Test]", "passed"));
@@ -494,7 +506,7 @@ TEST_F(ControllerEngineTest, connectionObject_reflectDisconnect) {
     EXPECT_DOUBLE_EQ(4.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectionObject_DisconnectByPassingToConnectControl) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionObject_DisconnectByPassingToConnectControl) {
     // Test that passing a connection object back to engine.connectControl
     // removes the connection
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
@@ -535,7 +547,7 @@ TEST_F(ControllerEngineTest, connectionObject_DisconnectByPassingToConnectContro
     EXPECT_DOUBLE_EQ(1.0, pass->get());
 }
 
-TEST_F(ControllerEngineTest, connectionObject_MakesIndependentConnection) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionObject_MakesIndependentConnection) {
     // Test that multiple connections can be made to the same CO with
     // the same callback function and that calling their 'disconnect' method
     // only disconnects the callback for that object.
@@ -574,7 +586,7 @@ TEST_F(ControllerEngineTest, connectionObject_MakesIndependentConnection) {
     EXPECT_EQ(3.0, counter->get());
 }
 
-TEST_F(ControllerEngineTest, connectionObject_trigger) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionObject_trigger) {
     // Test that triggering using the 'trigger' method on the connection
     // object returned from connectControl works.
     auto co = std::make_unique<ControlObject>(ConfigKey("[Test]", "co"));
@@ -595,7 +607,7 @@ TEST_F(ControllerEngineTest, connectionObject_trigger) {
     EXPECT_DOUBLE_EQ(1.0, counter->get());
 }
 
-TEST_F(ControllerEngineTest, connectionExecutesWithCorrectThisObject) {
+TEST_F(ControllerScriptEngineLegacyTest, connectionExecutesWithCorrectThisObject) {
     // Test that callback functions are executed with JavaScript's
     // 'this' keyword referring to the object in which the connection
     // was created.
diff --git a/src/test/midicontrollertest.cpp b/src/test/midicontrollertest.cpp
index fa66aa5f680..e0b875fa620 100644
--- a/src/test/midicontrollertest.cpp
+++ b/src/test/midicontrollertest.cpp
@@ -38,10 +38,9 @@ class MidiControllerTest : public MixxxTest {
         m_pController->visit(&preset);
     }
 
-    void receive(unsigned char status, unsigned char control,
-                 unsigned char value) {
+    void receivedShortMessage(unsigned char status, unsigned char control, unsigned char value) {
         // TODO(rryan): This test doesn't care about timestamps.
-        m_pController->receive(status, control, value, mixxx::Time::elapsed());
+        m_pController->receivedShortMessage(status, control, value, mixxx::Time::elapsed());
     }
 
     MidiControllerPreset m_preset;
@@ -64,15 +63,15 @@ TEST_F(MidiControllerTest, ReceiveMessage_PushButtonCO_PushOnOff) {
     loadPreset(m_preset);
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
 
@@ -90,15 +89,15 @@ TEST_F(MidiControllerTest, ReceiveMessage_PushButtonCO_PushOnOn) {
     loadPreset(m_preset);
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_NOTE_ON | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_NOTE_ON | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
 
@@ -123,13 +122,13 @@ TEST_F(MidiControllerTest, ReceiveMessage_PushButtonCO_ToggleOnOff_ButtonMidiOpt
     // NOTE(rryan): This behavior is broken!
 
     // Toggle the switch on, sets the push button on.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
 
     // The push button is stuck down here!
 
     // Toggle the switch off, sets the push button off.
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
 
@@ -154,13 +153,13 @@ TEST_F(MidiControllerTest, ReceiveMessage_PushButtonCO_ToggleOnOff_SwitchMidiOpt
     // NOTE(rryan): This behavior is broken!
 
     // Toggle the switch on, sets the push button on.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
 
     // The push button is stuck down here!
 
     // Toggle the switch off, sets the push button on again.
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_LT(0.0, cpb.get());
 
     // NOTE(rryan): What is supposed to happen in this case? It's an open
@@ -196,15 +195,15 @@ TEST_F(MidiControllerTest, ReceiveMessage_PushButtonCO_PushCC) {
     loadPreset(m_preset);
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_CC | channel, control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_CC | channel, control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 
     // Receive an on/off, sets the control on/off with each press.
-    receive(MIDI_CC | channel, control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
-    receive(MIDI_CC | channel, control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
 
@@ -225,14 +224,14 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_PushOnOff) {
     loadPreset(m_preset);
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
 
     EXPECT_LT(0.0, cpb.get());
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
 
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
@@ -252,14 +251,14 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_PushOnOn) {
     loadPreset(m_preset);
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
-    receive(MIDI_NOTE_ON | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x00);
 
     EXPECT_LT(0.0, cpb.get());
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
-    receive(MIDI_NOTE_ON | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x00);
 
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
@@ -289,12 +288,12 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_ToggleOnOff_ButtonMidiOption)
 
     // Toggle the switch on, since it is interpreted as a button press it
     // toggles the button on.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
 
     // Toggle the switch off, since it is interpreted as a button release it
     // does nothing to the toggle button.
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_LT(0.0, cpb.get());
 }
 
@@ -324,12 +323,12 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_ToggleOnOff_SwitchMidiOption)
 
     // Toggle the switch on, since it is interpreted as a button press it
     // toggles the control on.
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_LT(0.0, cpb.get());
 
     // Toggle the switch off, since it is interpreted as a button press it
     // toggles the control off.
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 
     // Meanwhile, the GUI toggles the control on again.
@@ -339,12 +338,12 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_ToggleOnOff_SwitchMidiOption)
 
     // Toggle the switch on, since it is interpreted as a button press it
     // toggles the control off (since it was on).
-    receive(MIDI_NOTE_ON | channel, control, 0x7F);
+    receivedShortMessage(MIDI_NOTE_ON | channel, control, 0x7F);
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 
     // Toggle the switch off, since it is interpreted as a button press it
     // toggles the control on (since it was off).
-    receive(MIDI_NOTE_OFF | channel, control, 0x00);
+    receivedShortMessage(MIDI_NOTE_OFF | channel, control, 0x00);
     EXPECT_LT(0.0, cpb.get());
 }
 
@@ -363,14 +362,14 @@ TEST_F(MidiControllerTest, ReceiveMessage_ToggleCO_PushCC) {
     loadPreset(m_preset);
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_CC | channel, control, 0x7F);
-    receive(MIDI_CC | channel, control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, control, 0x00);
 
     EXPECT_LT(0.0, cpb.get());
 
     // Receive an on/off, toggles the control.
-    receive(MIDI_CC | channel, control, 0x7F);
-    receive(MIDI_CC | channel, control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, control, 0x00);
 
     EXPECT_DOUBLE_EQ(0.0, cpb.get());
 }
@@ -391,15 +390,15 @@ TEST_F(MidiControllerTest, ReceiveMessage_PotMeterCO_7BitCC) {
     loadPreset(m_preset);
 
     // Receive a 0, MIDI parameter should map to the min value.
-    receive(MIDI_CC | channel, control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, control, 0x00);
     EXPECT_DOUBLE_EQ(kMinValue, potmeter.get());
 
     // Receive a 0x7F, MIDI parameter should map to the potmeter max value.
-    receive(MIDI_CC | channel, control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, control, 0x7F);
     EXPECT_DOUBLE_EQ(kMaxValue, potmeter.get());
 
     // Receive a 0x40, MIDI parameter should map to the potmeter middle value.
-    receive(MIDI_CC | channel, control, 0x40);
+    receivedShortMessage(MIDI_CC | channel, control, 0x40);
     EXPECT_DOUBLE_EQ(kMiddleValue, potmeter.get());
 }
 
@@ -434,40 +433,40 @@ TEST_F(MidiControllerTest, ReceiveMessage_PotMeterCO_14BitCC) {
 
     // Receive a 0x0000 (lsb-first), MIDI parameter should map to the min value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, lsb_control, 0x00);
-    receive(MIDI_CC | channel, msb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x00);
     EXPECT_DOUBLE_EQ(kMinValue, potmeter.get());
 
     // Receive a 0x0000 (msb-first), MIDI parameter should map to the min value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, msb_control, 0x00);
-    receive(MIDI_CC | channel, lsb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x00);
     EXPECT_DOUBLE_EQ(kMinValue, potmeter.get());
 
     // Receive a 0x3FFF (lsb-first), MIDI parameter should map to the max value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, lsb_control, 0x7F);
-    receive(MIDI_CC | channel, msb_control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x7F);
     EXPECT_DOUBLE_EQ(kMaxValue, potmeter.get());
 
     // Receive a 0x3FFF (msb-first), MIDI parameter should map to the max value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, msb_control, 0x7F);
-    receive(MIDI_CC | channel, lsb_control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x7F);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x7F);
     EXPECT_DOUBLE_EQ(kMaxValue, potmeter.get());
 
     // Receive a 0x2000 (lsb-first), MIDI parameter should map to the middle
     // value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, lsb_control, 0x00);
-    receive(MIDI_CC | channel, msb_control, 0x40);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x40);
     EXPECT_DOUBLE_EQ(kMiddleValue, potmeter.get());
 
     // Receive a 0x2000 (msb-first), MIDI parameter should map to the middle
     // value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, msb_control, 0x40);
-    receive(MIDI_CC | channel, lsb_control, 0x00);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x40);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x00);
     EXPECT_DOUBLE_EQ(kMiddleValue, potmeter.get());
 
     // Check the 14-bit resolution is actually present. Receive a 0x2001
@@ -475,8 +474,8 @@ TEST_F(MidiControllerTest, ReceiveMessage_PotMeterCO_14BitCC) {
     // amount. Scaling is not quite linear for MIDI parameters so just check
     // that incrementing the LSB by 1 is greater than the middle value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, msb_control, 0x40);
-    receive(MIDI_CC | channel, lsb_control, 0x01);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x40);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x01);
     EXPECT_LT(kMiddleValue, potmeter.get());
 
     // Check the 14-bit resolution is actually present. Receive a 0x2001
@@ -484,8 +483,8 @@ TEST_F(MidiControllerTest, ReceiveMessage_PotMeterCO_14BitCC) {
     // amount. Scaling is not quite linear for MIDI parameters so just check
     // that incrementing the LSB by 1 is greater than the middle value.
     potmeter.set(0);
-    receive(MIDI_CC | channel, lsb_control, 0x01);
-    receive(MIDI_CC | channel, msb_control, 0x40);
+    receivedShortMessage(MIDI_CC | channel, lsb_control, 0x01);
+    receivedShortMessage(MIDI_CC | channel, msb_control, 0x40);
     EXPECT_LT(kMiddleValue, potmeter.get());
 }
 
@@ -505,21 +504,21 @@ TEST_F(MidiControllerTest, ReceiveMessage_PotMeterCO_14BitPitchBend) {
     loadPreset(m_preset);
 
     // Receive a 0x0000, MIDI parameter should map to the min value.
-    receive(MIDI_PITCH_BEND | channel, 0x00, 0x00);
+    receivedShortMessage(MIDI_PITCH_BEND | channel, 0x00, 0x00);
     EXPECT_DOUBLE_EQ(kMinValue, potmeter.get());
 
     // Receive a 0x3FFF, MIDI parameter should map to the potmeter max value.
-    receive(MIDI_PITCH_BEND | channel, 0x7F, 0x7F);
+    receivedShortMessage(MIDI_PITCH_BEND | channel, 0x7F, 0x7F);
     EXPECT_DOUBLE_EQ(kMaxValue, potmeter.get());
 
     // Receive a 0x2000, MIDI parameter should map to the potmeter middle value.
-    receive(MIDI_PITCH_BEND | channel, 0x00, 0x40);
+    receivedShortMessage(MIDI_PITCH_BEND | channel, 0x00, 0x40);
     EXPECT_DOUBLE_EQ(kMiddleValue, potmeter.get());
 
     // Check the 14-bit resolution is actually present. Receive a 0x2001, MIDI
     // parameter should map to the middle value plus a tiny amount. Scaling is
     // not quite linear for MIDI parameters so just check that incrementing the
     // LSB by 1 is greater than the middle value.
-    receive(MIDI_PITCH_BEND | channel, 0x01, 0x40);
+    receivedShortMessage(MIDI_PITCH_BEND | channel, 0x01, 0x40);
     EXPECT_LT(kMiddleValue, potmeter.get());
 }
diff --git a/src/test/portmidicontroller_test.cpp b/src/test/portmidicontroller_test.cpp
index 3e53a3c3e34..b443d52fac2 100644
--- a/src/test/portmidicontroller_test.cpp
+++ b/src/test/portmidicontroller_test.cpp
@@ -35,9 +35,13 @@ class MockPortMidiController : public PortMidiController {
         PortMidiController::sendSysexMsg(data, length);
     }
 
-    MOCK_METHOD4(receive, void(unsigned char, unsigned char, unsigned char,
-                               mixxx::Duration));
+    MOCK_METHOD4(receivedShortMessage,
+            void(unsigned char, unsigned char, unsigned char, mixxx::Duration));
     MOCK_METHOD2(receive, void(const QByteArray&, mixxx::Duration));
+
+    // These tests are unrelated to scripting.
+    MOCK_METHOD0(startEngine, void());
+    MOCK_METHOD0(stopEngine, void());
 };
 
 class MockPortMidiDevice : public PortMidiDevice {
@@ -228,9 +232,9 @@ TEST_F(PortMidiControllerTest, Poll_Read_Basic) {
             .WillOnce(DoAll(SetArrayArgument<0>(messages.begin(), messages.end()),
                             Return(messages.size())));
 
-    EXPECT_CALL(*m_pController, receive(0x90, 0x3C, 0x40, _))
+    EXPECT_CALL(*m_pController, receivedShortMessage(0x90, 0x3C, 0x40, _))
             .InSequence(read);
-    EXPECT_CALL(*m_pController, receive(0x80, 0x3C, 0x40, _))
+    EXPECT_CALL(*m_pController, receivedShortMessage(0x80, 0x3C, 0x40, _))
             .InSequence(read);
 
     pollDevice();
@@ -265,9 +269,9 @@ TEST_F(PortMidiControllerTest, Poll_Read_SysExWithRealtime) {
             .InSequence(read)
             .WillOnce(DoAll(SetArrayArgument<0>(messages.begin(), messages.end()),
                             Return(messages.size())));
-    EXPECT_CALL(*m_pController, receive(0xF8, 0x00, 0x00, _))
+    EXPECT_CALL(*m_pController, receivedShortMessage(0xF8, 0x00, 0x00, _))
             .InSequence(read);
-    EXPECT_CALL(*m_pController, receive(0xFA, 0x00, 0x00, _))
+    EXPECT_CALL(*m_pController, receivedShortMessage(0xFA, 0x00, 0x00, _))
             .InSequence(read);
     EXPECT_CALL(*m_pController, receive(sysex, _))
             .InSequence(read);
@@ -363,7 +367,7 @@ TEST_F(PortMidiControllerTest, Poll_Read_SysExInterrupted_FollowedByNormalMessag
             .InSequence(read)
             .WillOnce(DoAll(SetArrayArgument<0>(messages.begin(), messages.end()),
                             Return(messages.size())));
-    EXPECT_CALL(*m_pController, receive(0x90, 0x3C, 0x40, _))
+    EXPECT_CALL(*m_pController, receivedShortMessage(0x90, 0x3C, 0x40, _))
             .InSequence(read);
 
     pollDevice();