diff --git a/src/carla-backend/Makefile b/src/carla-backend/Makefile
index 428d616..d4fc33b 100644
--- a/src/carla-backend/Makefile
+++ b/src/carla-backend/Makefile
@@ -4,6 +4,10 @@
 # Created by falkTX
 #
 
+# backend ouput driver, default JACK
+driver = JACK
+# driver = RtAudio
+
 CC  ?= gcc
 CXX ?= g++
 
@@ -16,8 +20,13 @@ HAVE_SUIL         = $(shell pkg-config --exists suil-0 && echo true)
 CARLA_C_FLAGS     = $(BASE_FLAGS) $(CFLAGS)
 
 CARLA_CXX_FLAGS   = $(BASE_FLAGS) -std=c++0x $(CXXFLAGS)
-CARLA_CXX_FLAGS  += $(shell pkg-config --cflags jack liblo QtCore QtGui) -DCARLA_BACKEND_NO_NAMESPACE -DCARLA_ENGINE_JACK
-# CARLA_CXX_FLAGS  += $(shell pkg-config --cflags jack liblo QtCore QtGui) -DCARLA_BACKEND_NO_NAMESPACE -DCARLA_ENGINE_RTAUDIO -D_FORTIFY_SOURCE=2 -DHAVE_GETTIMEOFDAY -D__UNIX_JACK__ -D__LINUX_ALSA__ -D__LINUX_PULSE__
+CARLA_CXX_FLAGS  += $(shell pkg-config --cflags jack liblo QtCore QtGui) -DCARLA_BACKEND_NO_NAMESPACE
+ifeq ($(driver),JACK)
+CARLA_CXX_FLAGS  += -DCARLA_ENGINE_JACK
+endif
+ifeq ($(driver),RtAudio)
+CARLA_CXX_FLAGS  += -DCARLA_ENGINE_RTAUDIO -D_FORTIFY_SOURCE=2 -DHAVE_GETTIMEOFDAY -D__LINUX_ALSA__ -D__LINUX_PULSE__
+endif
 CARLA_CXX_FLAGS  += -DNDEBUG -DQT_NO_DEBUG -DQT_NO_DEBUG_STREAM -DQT_NO_DEBUG_OUTPUT
 CARLA_CXX_FLAGS  += -DVESTIGE_HEADER -I../carla-includes/vestige # Comment this line to not use vestige header
 
@@ -51,9 +60,11 @@ OBJS = \
 	lv2-rtmempool/rtmempool.o \
 	../carla-lilv/carla_lilv.a
 
-# OBJS += rtaudio/rtaudio-4.0.11/RtAudio.o
-# CARLA_CXX_FLAGS += -Irtaudio/rtaudio-4.0.11
-# CARLA_LD_FLAGS  += -lasound -lpulse -lpulse-simple
+ifeq ($(driver),RtAudio)
+OBJS += rtaudio/rtaudio-4.0.11/RtAudio.o
+CARLA_CXX_FLAGS += $(shell pkg-config --cflags alsa libpulse-simple) -Irtaudio/rtaudio-4.0.11
+CARLA_LD_FLAGS  += $(shell pkg-config --libs alsa libpulse-simple)
+endif
 
 # --------------------------------------------------------------
 
diff --git a/src/carla-backend/carla_backend.cpp b/src/carla-backend/carla_backend.cpp
index 07c1fb9..5dcea10 100644
--- a/src/carla-backend/carla_backend.cpp
+++ b/src/carla-backend/carla_backend.cpp
@@ -1277,6 +1277,8 @@ int main(int argc, char* argv[])
     if (engine_init("carla_demo"))
     {
         set_callback_function(main_callback);
+        set_option(OPTION_PROCESS_MODE, PROCESS_MODE_CONTINUOUS_RACK, nullptr);
+
         short id = add_plugin_lv2("xxx", "name!!!", "http://linuxdsp.co.uk/lv2/peq-2a.lv2");
 
         if (id >= 0)
diff --git a/src/carla-backend/carla_engine.h b/src/carla-backend/carla_engine.h
index 50a5db3..0cc44b8 100644
--- a/src/carla-backend/carla_engine.h
+++ b/src/carla-backend/carla_engine.h
@@ -36,6 +36,8 @@ struct CarlaEnginePortNativeHandle {
 
 typedef void* CarlaEngineClientNativeHandle;
 typedef void* CarlaEnginePortNativeHandle;
+#else
+#error Engine type undefined!
 #endif
 
 CARLA_BACKEND_START_NAMESPACE
diff --git a/src/carla-backend/carla_engine_rtaudio.cpp b/src/carla-backend/carla_engine_rtaudio.cpp
index 7504799..1444bc6 100644
--- a/src/carla-backend/carla_engine_rtaudio.cpp
+++ b/src/carla-backend/carla_engine_rtaudio.cpp
@@ -28,8 +28,47 @@ CARLA_BACKEND_START_NAMESPACE
 } /* adjust editor indent */
 #endif
 
+// get initial options from environment
+RtAudio::Api getRtApiFromEnvironment()
+{
+#if defined(Q_OS_LINUX)
+    RtAudio::Api defaultRtApi = RtAudio::LINUX_PULSE;
+#elif defined(Q_OS_MACOS)
+    RtAudio::Api defaultRtApi = RtAudio::MACOSX_CORE;
+#elif defined(Q_OS_WIN)
+    RtAudio::Api defaultRtApi = RtAudio::WINDOWS_DS;
+#endif
+
+    const char* const driver  = getenv("CARLA_BACKEND_DRIVER");
+
+    if (! driver)
+        return defaultRtApi;
+#ifdef Q_OS_LINUX
+    if (strcmp(driver, "LINUX_ALSA") == 0)
+        return RtAudio::LINUX_ALSA;
+    if (strcmp(driver, "LINUX_PULSE") == 0)
+        return RtAudio::LINUX_PULSE;
+    if (strcmp(driver, "LINUX_OSS") == 0)
+        return RtAudio::LINUX_OSS;
+#endif
+    if (strcmp(driver, "UNIX_JACK") == 0)
+        return RtAudio::UNIX_JACK;
+#ifdef Q_OS_MACOS
+    if (strcmp(driver, "MACOSX_CORE") == 0)
+        return RtAudio::MACOSX_CORE;
+#endif
+#ifdef Q_OS_WIN
+    if (strcmp(driver, "WINDOWS_ASIO") == 0)
+        return RtAudio::WINDOWS_ASIO;
+    if (strcmp(driver, "WINDOWS_DS") == 0)
+        return RtAudio::WINDOWS_DS;
+#endif
+
+    return defaultRtApi;
+}
+
 // Global RtAudio stuff
-static RtAudio adac(RtAudio::LINUX_PULSE);
+static RtAudio adac(getRtApiFromEnvironment());
 
 static uint32_t carla_buffer_size = 512;
 static const char* carla_client_name = nullptr;
@@ -244,6 +283,7 @@ CarlaEngineBasePort::CarlaEngineBasePort(CarlaEngineClientNativeHandle* const cl
     isInput(isInput_),
     client(clientHandle)
 {
+    handle = nullptr;
 }
 
 CarlaEngineBasePort::~CarlaEngineBasePort()
@@ -255,6 +295,7 @@ CarlaEngineBasePort::~CarlaEngineBasePort()
 
 CarlaEngineClient::CarlaEngineClient(CarlaPlugin* const plugin)
 {
+    handle = nullptr;
     m_active = false;
     Q_UNUSED(plugin);
 }
@@ -280,7 +321,8 @@ bool CarlaEngineClient::isActive()
 
 bool CarlaEngineClient::isOk()
 {
-    return bool(handle);
+    //return bool(handle);
+    return true;
 }
 
 CarlaEngineBasePort* CarlaEngineClient::addPort(const char* name, CarlaEnginePortType type, bool isInput)
@@ -307,9 +349,8 @@ CarlaEngineAudioPort::CarlaEngineAudioPort(CarlaEngineClientNativeHandle* const
     Q_UNUSED(name);
 }
 
-void* CarlaEngineAudioPort::getBuffer()
+void CarlaEngineAudioPort::initBuffer()
 {
-    return nullptr;
 }
 
 // -------------------------------------------------------------------------------------------------------------------
@@ -321,42 +362,23 @@ CarlaEngineControlPort::CarlaEngineControlPort(CarlaEngineClientNativeHandle* co
     Q_UNUSED(name);
 }
 
-void* CarlaEngineControlPort::getBuffer()
-{
-    return nullptr;
-}
-
-void CarlaEngineControlPort::initBuffer(void* buffer)
+void CarlaEngineControlPort::initBuffer()
 {
-    //if (isInput)
-    return;
-
-    Q_UNUSED(buffer);
 }
 
-uint32_t CarlaEngineControlPort::getEventCount(void* buffer)
+uint32_t CarlaEngineControlPort::getEventCount()
 {
-    //if (! isInput)
     return 0;
-
-    Q_UNUSED(buffer);
 }
 
-const CarlaEngineControlEvent* CarlaEngineControlPort::getEvent(void* buffer, uint32_t index)
+const CarlaEngineControlEvent* CarlaEngineControlPort::getEvent(uint32_t index)
 {
-    //if (! isInput)
     return nullptr;
-
-    Q_UNUSED(buffer);
     Q_UNUSED(index);
 }
 
-void CarlaEngineControlPort::writeEvent(void* buffer, CarlaEngineControlEventType type, uint32_t time, uint8_t channel, uint8_t controller, double value)
+void CarlaEngineControlPort::writeEvent(CarlaEngineControlEventType type, uint32_t time, uint8_t channel, uint8_t controller, double value)
 {
-    //if (isInput)
-    return;
-
-    Q_UNUSED(buffer);
     Q_UNUSED(type);
     Q_UNUSED(time);
     Q_UNUSED(channel);
@@ -373,44 +395,23 @@ CarlaEngineMidiPort::CarlaEngineMidiPort(CarlaEngineClientNativeHandle* const cl
     Q_UNUSED(name);
 }
 
-void* CarlaEngineMidiPort::getBuffer()
-{
-    return nullptr;
-}
-
-void CarlaEngineMidiPort::initBuffer(void* buffer)
+void CarlaEngineMidiPort::initBuffer()
 {
-    //if (isInput)
-    return;
-
-    Q_UNUSED(buffer);
 }
 
-uint32_t CarlaEngineMidiPort::getEventCount(void* buffer)
+uint32_t CarlaEngineMidiPort::getEventCount()
 {
-    //if (! isInput)
     return 0;
-
-    Q_UNUSED(buffer);
 }
 
-const CarlaEngineMidiEvent* CarlaEngineMidiPort::getEvent(void* buffer, uint32_t index)
+const CarlaEngineMidiEvent* CarlaEngineMidiPort::getEvent(uint32_t index)
 {
-    //if (! isInput)
     return nullptr;
-
-    return nullptr;
-
-    Q_UNUSED(buffer);
     Q_UNUSED(index);
 }
 
-void CarlaEngineMidiPort::writeEvent(void* buffer, uint32_t time, uint8_t* data, uint8_t size)
+void CarlaEngineMidiPort::writeEvent(uint32_t time, uint8_t* data, uint8_t size)
 {
-    //if (! isInput)
-    return;
-
-    Q_UNUSED(buffer);
     Q_UNUSED(time);
     Q_UNUSED(data);
     Q_UNUSED(size);
diff --git a/src/carla-backend/carla_plugin.h b/src/carla-backend/carla_plugin.h
index 44ad788..cedfbe0 100644
--- a/src/carla-backend/carla_plugin.h
+++ b/src/carla-backend/carla_plugin.h
@@ -1264,10 +1264,10 @@ public:
         float* aouts_buffer[aout.count];
 
         for (uint32_t i=0; i < ain.count; i++)
-            ains_buffer[i] = (float*)ain.ports[i]->getJackAudioBuffer();
+            ains_buffer[i] = ain.ports[i]->getJackAudioBuffer();
 
         for (uint32_t i=0; i < aout.count; i++)
-            aouts_buffer[i] = (float*)aout.ports[i]->getJackAudioBuffer();
+            aouts_buffer[i] = aout.ports[i]->getJackAudioBuffer();
 
 #ifndef BUILD_BRIDGE
         if (carla_options.proccess_hq)
diff --git a/src/carla-backend/qtcreator/carla-backend.pro b/src/carla-backend/qtcreator/carla-backend.pro
index a04b74e..7ace283 100644
--- a/src/carla-backend/qtcreator/carla-backend.pro
+++ b/src/carla-backend/qtcreator/carla-backend.pro
@@ -45,13 +45,13 @@ INCLUDEPATH = .. \
     ../../carla-includes/vst
 
 DEFINES = QTCREATOR_TEST HAVE_SUIL WANT_FLUIDSYNTH WANT_LINUXSAMPLER CARLA_BACKEND_NO_NAMESPACE
-DEFINES += CARLA_ENGINE_JACK
-#DEFINES += CARLA_ENGINE_RTAUDIO
+#DEFINES += CARLA_ENGINE_JACK
+DEFINES += CARLA_ENGINE_RTAUDIO
 LIBS    = ../../carla-lilv/carla_lilv.a -ldl -lasound -lpulse -lpulse-simple
 
 QMAKE_CXXFLAGS *= -std=c++0x
 
 
-#INCLUDEPATH += ../rtaudio/rtaudio-4.0.11
-#SOURCES += ../rtaudio/rtaudio-4.0.11/RtAudio.cpp
-#DEFINES += _FORTIFY_SOURCE=2 HAVE_GETTIMEOFDAY __UNIX_JACK__ __LINUX_ALSA__ __LINUX_PULSE__
+INCLUDEPATH += ../rtaudio/rtaudio-4.0.11
+SOURCES += ../rtaudio/rtaudio-4.0.11/RtAudio.cpp
+DEFINES += _FORTIFY_SOURCE=2 HAVE_GETTIMEOFDAY __UNIX_JACK__ __LINUX_ALSA__ __LINUX_PULSE__