diff --git a/gtk2_ardour/ardour_ui_startup.cc b/gtk2_ardour/ardour_ui_startup.cc
index 1c66c794ec..9bb1cdb993 100644
--- a/gtk2_ardour/ardour_ui_startup.cc
+++ b/gtk2_ardour/ardour_ui_startup.cc
@@ -866,7 +866,7 @@ ARDOUR_UI::load_from_application_api (const std::string& path)
 #else
 					"JACK",
 #endif
-					ARDOUR_COMMAND_LINE::backend_client_name, "")) {
+					ARDOUR_COMMAND_LINE::backend_session_id, "")) {
 			error << _("NSM: The JACK backend is mandatory and can not be loaded.") << endmsg;
 			return;
 		}
diff --git a/gtk2_ardour/engine_dialog.cc b/gtk2_ardour/engine_dialog.cc
index c570b4a2c3..318b314ad7 100644
--- a/gtk2_ardour/engine_dialog.cc
+++ b/gtk2_ardour/engine_dialog.cc
@@ -1030,7 +1030,7 @@ EngineControl::backend_changed ()
 	string                                  backend_name = backend_combo.get_active_text ();
 	std::shared_ptr<ARDOUR::AudioBackend> backend;
 
-	if (!(backend = ARDOUR::AudioEngine::instance ()->set_backend (backend_name, ARDOUR_COMMAND_LINE::backend_client_name, ""))) {
+	if (!(backend = ARDOUR::AudioEngine::instance ()->set_backend (backend_name, ARDOUR_COMMAND_LINE::backend_session_id, ""))) {
 		/* eh? setting the backend failed... how ? */
 		/* A: stale config contains a backend that does not exist in current build */
 		return;
@@ -1152,7 +1152,7 @@ EngineControl::get_default_device (const string&         current_device_name,
 	using namespace ARDOUR;
 
 	string default_device_name =
-	    AudioBackend::get_standard_device_name (AudioBackend::DeviceDefault);
+	    AudioBackend::get_default_device_name ();
 
 	vector<string>::const_iterator i;
 
@@ -1164,7 +1164,7 @@ EngineControl::get_default_device (const string&         current_device_name,
 	}
 
 	string none_device_name =
-	    AudioBackend::get_standard_device_name (AudioBackend::DeviceNone);
+	    AudioBackend::get_none_device_name ();
 
 	// Use the first device that isn't "None"
 	for (i = available_devices.begin (); i != available_devices.end (); ++i) {
@@ -1587,7 +1587,7 @@ EngineControl::input_device_changed ()
 
 	std::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance ()->current_backend ();
 	if (backend && backend->match_input_output_devices_or_none ()) {
-		const std::string& dev_none = ARDOUR::AudioBackend::get_standard_device_name (ARDOUR::AudioBackend::DeviceNone);
+		const std::string& dev_none = ARDOUR::AudioBackend::get_none_device_name ();
 
 		if (get_output_device_name () != dev_none && get_input_device_name () != dev_none && get_input_device_name () != get_output_device_name ()) {
 			block_changed_signals ();
@@ -1609,7 +1609,7 @@ EngineControl::output_device_changed ()
 	DEBUG_ECONTROL ("output_device_changed");
 	std::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance ()->current_backend ();
 	if (backend && backend->match_input_output_devices_or_none ()) {
-		const std::string& dev_none = ARDOUR::AudioBackend::get_standard_device_name (ARDOUR::AudioBackend::DeviceNone);
+		const std::string& dev_none = ARDOUR::AudioBackend::get_none_device_name ();
 
 		if (get_input_device_name () != dev_none && get_input_device_name () != dev_none && get_input_device_name () != get_output_device_name ()) {
 			block_changed_signals ();
@@ -2213,7 +2213,7 @@ EngineControl::set_current_state (const State& state)
 
 	std::shared_ptr<ARDOUR::AudioBackend> backend;
 
-	if (!(backend = ARDOUR::AudioEngine::instance ()->set_backend (state->backend, ARDOUR_COMMAND_LINE::backend_client_name, ""))) {
+	if (!(backend = ARDOUR::AudioEngine::instance ()->set_backend (state->backend, ARDOUR_COMMAND_LINE::backend_session_id, ""))) {
 		DEBUG_ECONTROL (string_compose ("Unable to set backend to %1", state->backend));
 		// this shouldn't happen as the invalid backend names should have been
 		// removed from the list of states.
@@ -2495,7 +2495,7 @@ EngineControl::push_state_to_backend (bool start)
 		error << string_compose (_("Cannot set buffer size to %1"), get_buffer_size ()) << endmsg;
 		return 1;
 	}
-	if (change_nperiods && backend->set_peridod_size (get_nperiods ())) {
+	if (change_nperiods && backend->set_period_size (get_nperiods ())) {
 		error << string_compose (_("Cannot set periods to %1"), get_nperiods ()) << endmsg;
 		return 1;
 	}
diff --git a/gtk2_ardour/nsm.cc b/gtk2_ardour/nsm.cc
index ee0938d4e2..1be285a7ce 100644
--- a/gtk2_ardour/nsm.cc
+++ b/gtk2_ardour/nsm.cc
@@ -48,7 +48,7 @@ NSM_Client::command_open(const char* name,
 {
 	int r = ERR_OK;
 
-	ARDOUR_COMMAND_LINE::backend_client_name = client_id;
+	ARDOUR_COMMAND_LINE::backend_session_id = client_id;
 	ARDOUR_COMMAND_LINE::session_name = "";
 
 	/* this appears asynchronous, but almost certainly is
diff --git a/gtk2_ardour/opts.cc b/gtk2_ardour/opts.cc
index 301957c5a2..e733fd1a34 100644
--- a/gtk2_ardour/opts.cc
+++ b/gtk2_ardour/opts.cc
@@ -41,7 +41,7 @@
 using namespace std;
 
 string ARDOUR_COMMAND_LINE::session_name = "";
-string ARDOUR_COMMAND_LINE::backend_client_name = PBD::downcase(PROGRAM_NAME);
+string ARDOUR_COMMAND_LINE::backend_session_id = PBD::downcase(PROGRAM_NAME);
 bool  ARDOUR_COMMAND_LINE::show_key_actions = false;
 bool  ARDOUR_COMMAND_LINE::show_actions = false;
 bool ARDOUR_COMMAND_LINE::no_splash = false;
@@ -72,7 +72,7 @@ print_help (const char *execname)
 		<< _("  -A, --actions               Print all possible menu action names\n")
 		<< _("  -b, --bindings              Display all current key bindings\n")
 		<< _("  -B, --bypass-plugins        Bypass all plugins in an existing session\n")
-		<< _("  -c, --name <name>           Use a specific backend client name, default is ardour\n")
+		<< _("  -c, --name <session-id>     Specify audio backend client session id, default is ardour\n")
 		<< _("  -d, --disable-plugins       Disable all plugins (safe mode)\n")
 #ifndef NDEBUG
 		<< _("  -D, --debug <options>       Set debug flags. Use \"-D list\" to see available options\n")
@@ -218,7 +218,7 @@ ARDOUR_COMMAND_LINE::parse_opts (int argc, char *argv[])
 			break;
 
 		case 'c':
-			backend_client_name = optarg;
+			backend_session_id = optarg;
 			break;
 
 		case 'k':
diff --git a/gtk2_ardour/opts.h b/gtk2_ardour/opts.h
index 56e0b2c031..d9f58351a8 100644
--- a/gtk2_ardour/opts.h
+++ b/gtk2_ardour/opts.h
@@ -29,7 +29,7 @@ extern bool        show_key_actions;
 extern bool        show_actions;
 extern bool        no_splash;
 extern bool        just_version;
-extern std::string backend_client_name;
+extern std::string backend_session_id;
 extern bool        new_session;
 extern bool        try_hw_optimization;
 extern bool        no_connect_ports;
diff --git a/headless/load_session.cc b/headless/load_session.cc
index f921b83676..247b34bf83 100644
--- a/headless/load_session.cc
+++ b/headless/load_session.cc
@@ -48,7 +48,7 @@ using namespace PBD;
 
 static const char* localedir = LOCALEDIR;
 
-static string             backend_client_name;
+static string             backend_session_id;
 static CrossThreadChannel xthread (true);
 static TestReceiver       test_receiver;
 
@@ -72,7 +72,7 @@ load_session (string dir, string state)
 
 	AudioEngine* engine = AudioEngine::create ();
 
-	if (!engine->set_backend (backend_name, backend_client_name, "")) {
+	if (!engine->set_backend (backend_name, backend_session_id, "")) {
 		std::cerr << "Cannot set Audio/MIDI engine backend\n";
 		exit (EXIT_FAILURE);
 	}
@@ -172,7 +172,7 @@ main (int argc, char* argv[])
 
 	bool try_hw_optimization = true;
 
-	backend_client_name = PBD::downcase (std::string (PROGRAM_NAME));
+	backend_session_id = PBD::downcase (std::string (PROGRAM_NAME));
 
 	int c;
 	while ((c = getopt_long (argc, argv, optstring, longopts, (int*)0)) != EOF) {
@@ -191,7 +191,7 @@ main (int argc, char* argv[])
 				break;
 
 			case 'c':
-				backend_client_name = optarg;
+				backend_session_id = optarg;
 				break;
 
 			case 'B':
diff --git a/libs/ardour/ardour/audio_backend.h b/libs/ardour/ardour/audio_backend.h
index e7cba2ed59..39f768c131 100644
--- a/libs/ardour/ardour/audio_backend.h
+++ b/libs/ardour/ardour/audio_backend.h
@@ -44,11 +44,11 @@ namespace ARDOUR
 struct LIBARDOUR_API AudioBackendInfo {
 	const char* name;
 
-	/** Using arg1 and arg2, initialize this audiobackend.
+	/** Using client_name and session_id, initialize this audiobackend.
 	 *
 	 * Returns zero on success, non-zero otherwise.
 	 */
-	int (*instantiate) (const std::string& arg1, const std::string& arg2);
+	int (*instantiate) (const std::string& client_name, const std::string& session_id);
 
 	/** Release all resources associated with this audiobackend */
 	int (*deinstantiate) (void);
@@ -131,12 +131,8 @@ public:
 
 	static std::string get_error_string (ErrorCode);
 
-	enum StandardDeviceName {
-		DeviceNone,
-		DeviceDefault
-	};
-
-	static std::string get_standard_device_name (StandardDeviceName);
+	static std::string get_none_device_name ();
+	static std::string get_default_device_name ();
 
 	/** Return the AudioBackendInfo object from which this backend
 	 * was constructed.
@@ -153,15 +149,10 @@ public:
 	 */
 	virtual std::string name () const = 0;
 
-	/** Return true if the callback from the underlying mechanism/API
-	 * (CoreAudio, JACK, ASIO etc.) occurs in a thread subject to realtime
-	 * constraints. Return false otherwise.
-	 */
-	virtual bool is_realtime () const = 0;
-
-	/** Return true if the backed is JACK */
+	/** Return true if the backend is JACK */
 	virtual bool is_jack () const { return false; }
 
+	/** Return the priority to be set with pbd_set_engine_rt_priority. */
 	virtual int client_real_time_priority () { return 0; }
 
 	/* Discovering devices and parameters */
@@ -232,7 +223,7 @@ public:
 	 * of allowing one to be "None".
 	 *
 	 * ie. Input Device must match Output Device, except if either of them
-	 * is get_standard_device_name (DeviceNone).
+	 * is get_none_device_name ().
 	 */
 	virtual bool match_input_output_devices_or_none () const
 	{
@@ -291,7 +282,7 @@ public:
 	/** Set the period size to be used.
 	 * must be called before starting the backend.
 	 */
-	virtual int set_peridod_size (uint32_t)
+	virtual int set_period_size (uint32_t)
 	{
 		return -1;
 	}
diff --git a/libs/ardour/ardour/audioengine.h b/libs/ardour/ardour/audioengine.h
index a63913747c..698bc96c2b 100644
--- a/libs/ardour/ardour/audioengine.h
+++ b/libs/ardour/ardour/audioengine.h
@@ -71,7 +71,7 @@ class LIBARDOUR_API AudioEngine : public PortManager, public SessionHandlePtr
 	int discover_backends();
 	std::vector<const AudioBackendInfo*> available_backends() const;
 	std::string current_backend_name () const;
-	std::shared_ptr<AudioBackend> set_backend (const std::string&, const std::string& arg1, const std::string& arg2);
+	std::shared_ptr<AudioBackend> set_backend (const std::string& name, const std::string& client_name, const std::string& session_id);
 	std::shared_ptr<AudioBackend> current_backend() const { return _backend; }
 	bool setup_required () const;
 	bool is_jack () const;
diff --git a/libs/ardour/audio_backend.cc b/libs/ardour/audio_backend.cc
index 30df66c6ff..1001c550ff 100644
--- a/libs/ardour/audio_backend.cc
+++ b/libs/ardour/audio_backend.cc
@@ -100,15 +100,15 @@ AudioBackend::get_error_string (ErrorCode error_code)
 }
 
 std::string
-AudioBackend::get_standard_device_name (StandardDeviceName device_name)
+AudioBackend::get_none_device_name ()
 {
-	switch (device_name) {
-	case DeviceNone:
-		return _("None");
-	case DeviceDefault:
-		return _("Default");
-	}
-	return std::string();
+	return _("None");
+}
+
+std::string
+AudioBackend::get_default_device_name ()
+{
+	return _("Default");
 }
 
 } // namespace ARDOUR
diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index a57e814e93..426cb734fa 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -1014,7 +1014,7 @@ AudioEngine::drop_backend ()
 }
 
 std::shared_ptr<AudioBackend>
-AudioEngine::set_backend (const std::string& name, const std::string& arg1, const std::string& arg2)
+AudioEngine::set_backend (const std::string& name, const std::string& client_name, const std::string& session_id)
 {
 	BackendMap::iterator b = _backends.find (name);
 
@@ -1025,7 +1025,7 @@ AudioEngine::set_backend (const std::string& name, const std::string& arg1, cons
 	drop_backend ();
 
 	try {
-		if (b->second->instantiate (arg1, arg2)) {
+		if (b->second->instantiate (client_name, session_id)) {
 			throw failed_constructor ();
 		}
 
@@ -1066,11 +1066,7 @@ AudioEngine::start (bool for_latency)
 		return -1;
 	}
 
-	if (_backend->is_realtime ()) {
-		pbd_set_engine_rt_priority (_backend->client_real_time_priority ());
-	} else {
-		pbd_set_engine_rt_priority (0);
-	}
+	pbd_set_engine_rt_priority (_backend->client_real_time_priority ());
 
 	_running = true;
 
diff --git a/libs/ardour/luabindings.cc b/libs/ardour/luabindings.cc
index 42503e4a17..1db514647d 100644
--- a/libs/ardour/luabindings.cc
+++ b/libs/ardour/luabindings.cc
@@ -2970,7 +2970,7 @@ LuaBindings::common (lua_State* L)
 
 		.addFunction ("set_sample_rate", &AudioBackend::set_sample_rate)
 		.addFunction ("set_buffer_size", &AudioBackend::set_buffer_size)
-		.addFunction ("set_peridod_size", &AudioBackend::set_peridod_size)
+		.addFunction ("set_period_size", &AudioBackend::set_period_size)
 
 		.addFunction ("enumerate_drivers", &AudioBackend::enumerate_drivers)
 		.addFunction ("driver_name", &AudioBackend::driver_name)
diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index ce61983b3f..3c7d128895 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -98,12 +98,6 @@ AlsaAudioBackend::name () const
 	return X_("ALSA");
 }
 
-bool
-AlsaAudioBackend::is_realtime () const
-{
-	return true;
-}
-
 std::vector<AudioBackend::DeviceStatus>
 AlsaAudioBackend::enumerate_devices () const
 {
@@ -128,7 +122,7 @@ AlsaAudioBackend::enumerate_input_devices () const
 	_input_audio_device_status.clear ();
 	std::map<std::string, std::string> devices;
 	get_alsa_audio_device_names (devices, HalfDuplexIn);
-	_input_audio_device_status.push_back (DeviceStatus (get_standard_device_name (DeviceNone), true));
+	_input_audio_device_status.push_back (DeviceStatus (get_none_device_name (), true));
 	for (std::map<std::string, std::string>::const_iterator i = devices.begin (); i != devices.end (); ++i) {
 		if (_input_audio_device == "") {
 			_input_audio_device = i->first;
@@ -144,7 +138,7 @@ AlsaAudioBackend::enumerate_output_devices () const
 	_output_audio_device_status.clear ();
 	std::map<std::string, std::string> devices;
 	get_alsa_audio_device_names (devices, HalfDuplexOut);
-	_output_audio_device_status.push_back (DeviceStatus (get_standard_device_name (DeviceNone), true));
+	_output_audio_device_status.push_back (DeviceStatus (get_none_device_name (), true));
 	for (std::map<std::string, std::string>::const_iterator i = devices.begin (); i != devices.end (); ++i) {
 		if (_output_audio_device == "") {
 			_output_audio_device = i->first;
@@ -158,11 +152,11 @@ std::vector<float>
 AlsaAudioBackend::available_sample_rates2 (const std::string& input_device, const std::string& output_device) const
 {
 	std::vector<float> sr;
-	if (input_device == get_standard_device_name (DeviceNone) && output_device == get_standard_device_name (DeviceNone)) {
+	if (input_device == get_none_device_name () && output_device == get_none_device_name ()) {
 		return sr;
-	} else if (input_device == get_standard_device_name (DeviceNone)) {
+	} else if (input_device == get_none_device_name ()) {
 		sr = available_sample_rates (output_device);
-	} else if (output_device == get_standard_device_name (DeviceNone)) {
+	} else if (output_device == get_none_device_name ()) {
 		sr = available_sample_rates (input_device);
 	} else {
 		std::vector<float> sr_in  = available_sample_rates (input_device);
@@ -177,7 +171,7 @@ AlsaAudioBackend::available_sample_rates (const std::string& device) const
 {
 	ALSADeviceInfo*    nfo = NULL;
 	std::vector<float> sr;
-	if (device == get_standard_device_name (DeviceNone)) {
+	if (device == get_none_device_name ()) {
 		return sr;
 	}
 	if (device == _input_audio_device && _input_audio_device_info.valid) {
@@ -201,11 +195,11 @@ std::vector<uint32_t>
 AlsaAudioBackend::available_buffer_sizes2 (const std::string& input_device, const std::string& output_device) const
 {
 	std::vector<uint32_t> bs;
-	if (input_device == get_standard_device_name (DeviceNone) && output_device == get_standard_device_name (DeviceNone)) {
+	if (input_device == get_none_device_name () && output_device == get_none_device_name ()) {
 		return bs;
-	} else if (input_device == get_standard_device_name (DeviceNone)) {
+	} else if (input_device == get_none_device_name ()) {
 		bs = available_buffer_sizes (output_device);
-	} else if (output_device == get_standard_device_name (DeviceNone)) {
+	} else if (output_device == get_none_device_name ()) {
 		bs = available_buffer_sizes (input_device);
 	} else {
 		std::vector<uint32_t> bs_in  = available_buffer_sizes (input_device);
@@ -220,7 +214,7 @@ AlsaAudioBackend::available_buffer_sizes (const std::string& device) const
 {
 	ALSADeviceInfo*       nfo = NULL;
 	std::vector<uint32_t> bs;
-	if (device == get_standard_device_name (DeviceNone)) {
+	if (device == get_none_device_name ()) {
 		return bs;
 	}
 	if (device == _input_audio_device && _input_audio_device_info.valid) {
@@ -261,7 +255,7 @@ AlsaAudioBackend::available_period_sizes (const std::string& driver, const std::
 	ps.push_back (2);
 
 	ALSADeviceInfo* nfo = NULL;
-	if (device == get_standard_device_name (DeviceNone)) {
+	if (device == get_none_device_name ()) {
 		return ps;
 	}
 
@@ -300,7 +294,7 @@ AlsaAudioBackend::set_input_device_name (const std::string& d)
 	}
 	_input_audio_device = d;
 
-	if (d == get_standard_device_name (DeviceNone)) {
+	if (d == get_none_device_name ()) {
 		_input_audio_device_info.valid = false;
 		return 0;
 	}
@@ -333,7 +327,7 @@ AlsaAudioBackend::set_output_device_name (const std::string& d)
 
 	_output_audio_device = d;
 
-	if (d == get_standard_device_name (DeviceNone)) {
+	if (d == get_none_device_name ()) {
 		_output_audio_device_info.valid = false;
 		return 0;
 	}
@@ -368,7 +362,7 @@ AlsaAudioBackend::set_device_name (const std::string& d)
 bool
 AlsaAudioBackend::can_measure_systemic_latency () const
 {
-	return _input_audio_device == _output_audio_device && _input_audio_device != get_standard_device_name (DeviceNone);
+	return _input_audio_device == _output_audio_device && _input_audio_device != get_none_device_name ();
 }
 
 int
@@ -383,7 +377,7 @@ AlsaAudioBackend::set_sample_rate (float sr)
 }
 
 int
-AlsaAudioBackend::set_peridod_size (uint32_t n)
+AlsaAudioBackend::set_period_size (uint32_t n)
 {
 	if (n == 0) {
 		return -1;
@@ -523,10 +517,10 @@ AlsaAudioBackend::update_systemic_midi_latencies ()
 std::string
 AlsaAudioBackend::device_name () const
 {
-	if (_input_audio_device != get_standard_device_name (DeviceNone)) {
+	if (_input_audio_device != get_none_device_name ()) {
 		return _input_audio_device;
 	}
-	if (_output_audio_device != get_standard_device_name (DeviceNone)) {
+	if (_output_audio_device != get_none_device_name ()) {
 		return _output_audio_device;
 	}
 	return "";
@@ -610,7 +604,7 @@ AlsaAudioBackend::midi_device_info (std::string const name) const
 		}
 	}
 
-	assert (_midi_driver_option != get_standard_device_name (DeviceNone));
+	assert (_midi_driver_option != get_none_device_name ());
 
 	std::map<std::string, std::string> devices;
 	if (_midi_driver_option == _("ALSA raw devices")) {
@@ -634,7 +628,7 @@ AlsaAudioBackend::enumerate_midi_options () const
 	if (_midi_options.empty ()) {
 		_midi_options.push_back (_("ALSA raw devices"));
 		_midi_options.push_back (_("ALSA sequencer"));
-		_midi_options.push_back (get_standard_device_name (DeviceNone));
+		_midi_options.push_back (get_none_device_name ());
 	}
 	return _midi_options;
 }
@@ -660,7 +654,7 @@ AlsaAudioBackend::enumerate_midi_devices () const
 int
 AlsaAudioBackend::set_midi_option (const std::string& opt)
 {
-	if (opt != get_standard_device_name (DeviceNone) && opt != _("ALSA raw devices") && opt != _("ALSA sequencer")) {
+	if (opt != get_none_device_name () && opt != _("ALSA raw devices") && opt != _("ALSA sequencer")) {
 		return -1;
 	}
 	if (_run && _midi_driver_option != opt) {
@@ -796,7 +790,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 
 	std::map<std::string, std::string> devices;
 
-	if (_input_audio_device == get_standard_device_name (DeviceNone) && _output_audio_device == get_standard_device_name (DeviceNone)) {
+	if (_input_audio_device == get_none_device_name () && _output_audio_device == get_none_device_name ()) {
 		PBD::error << _("AlsaAudioBackend: At least one of input or output device needs to be set.");
 		return AudioDeviceInvalidError;
 	}
@@ -807,7 +801,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 	if (_input_audio_device != _output_audio_device) {
 		std::string input_audio_device (_input_audio_device);
 		std::string output_audio_device (_output_audio_device);
-		if (_input_audio_device != get_standard_device_name (DeviceNone) && _output_audio_device != get_standard_device_name (DeviceNone)) {
+		if (_input_audio_device != get_none_device_name () && _output_audio_device != get_none_device_name ()) {
 			/* Different devices for In + Out.
 			 * Ideally use input as clock source, and resample output.
 			 * But when using separate devices, input is usually one (or more)
@@ -816,15 +810,15 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 			 */
 			if (getenv ("ARDOUR_ALSA_CLK")) {
 				slave_device        = _output_audio_device;
-				output_audio_device = get_standard_device_name (DeviceNone); //XXX
+				output_audio_device = get_none_device_name (); // XXX
 				slave_duplex        = AudioSlave::HalfDuplexOut;
 			} else {
 				slave_device       = _input_audio_device;
-				input_audio_device = get_standard_device_name (DeviceNone); //XXX
+				input_audio_device = get_none_device_name (); // XXX
 				slave_duplex       = AudioSlave::HalfDuplexIn;
 			}
 		}
-		if (input_audio_device != get_standard_device_name (DeviceNone)) {
+		if (input_audio_device != get_none_device_name ()) {
 			get_alsa_audio_device_names (devices, HalfDuplexIn);
 			audio_device = input_audio_device;
 			duplex       = 1;
@@ -1465,7 +1459,7 @@ AlsaAudioBackend::register_system_midi_ports (const std::string device)
 {
 	std::map<std::string, std::string> devices;
 
-	if (_midi_driver_option == get_standard_device_name (DeviceNone)) {
+	if (_midi_driver_option == get_none_device_name ()) {
 		return 0;
 	} else if (_midi_driver_option == _("ALSA raw devices")) {
 		get_alsa_rawmidi_device_names (devices);
@@ -2186,7 +2180,7 @@ AlsaAudioBackend::AudioSlave::update_latencies (uint32_t play, uint32_t capt)
 static std::shared_ptr<AlsaAudioBackend> _instance;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& e);
-static int  instantiate (const std::string& arg1, const std::string& /* arg2 */);
+static int  instantiate (const std::string& client_name, const std::string& /* session_id */);
 static int  deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -2210,9 +2204,9 @@ backend_factory (AudioEngine& e)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& /* arg2 */)
+instantiate (const std::string& client_name, const std::string& /* session_id */)
 {
-	s_instance_name = arg1;
+	s_instance_name = client_name;
 	return 0;
 }
 
diff --git a/libs/backends/alsa/alsa_audiobackend.h b/libs/backends/alsa/alsa_audiobackend.h
index 322bff1663..e7d8723a4f 100644
--- a/libs/backends/alsa/alsa_audiobackend.h
+++ b/libs/backends/alsa/alsa_audiobackend.h
@@ -125,7 +125,6 @@ class AlsaAudioBackend : public AudioBackend, public PortEngineSharedImpl
 		/* AUDIOBACKEND API */
 
 		std::string name () const;
-		bool is_realtime () const;
 
 		bool use_separate_input_and_output_devices () const { return true; }
 		bool match_input_output_devices_or_none () const { return false; }
@@ -154,7 +153,7 @@ class AlsaAudioBackend : public AudioBackend, public PortEngineSharedImpl
 		int set_output_device_name (const std::string&);
 		int set_sample_rate (float);
 		int set_buffer_size (uint32_t);
-		int set_peridod_size (uint32_t);
+		int set_period_size (uint32_t);
 		int set_interleaved (bool yn);
 		int set_systemic_input_latency (uint32_t);
 		int set_systemic_output_latency (uint32_t);
diff --git a/libs/backends/coreaudio/coreaudio_backend.cc b/libs/backends/coreaudio/coreaudio_backend.cc
index 7d4ee3e706..217dfdefd9 100644
--- a/libs/backends/coreaudio/coreaudio_backend.cc
+++ b/libs/backends/coreaudio/coreaudio_backend.cc
@@ -148,12 +148,6 @@ CoreAudioBackend::name () const
 	return X_("CoreAudio");
 }
 
-bool
-CoreAudioBackend::is_realtime () const
-{
-	return true;
-}
-
 std::vector<AudioBackend::DeviceStatus>
 CoreAudioBackend::enumerate_devices () const
 {
@@ -176,7 +170,7 @@ CoreAudioBackend::enumerate_input_devices () const
 	std::map<size_t, std::string> devices;
 	_pcmio->input_device_list(devices);
 
-	_input_audio_device_status.push_back (DeviceStatus (get_standard_device_name(DeviceNone), true));
+	_input_audio_device_status.push_back (DeviceStatus (get_none_device_name (), true));
 	for (std::map<size_t, std::string>::const_iterator i = devices.begin (); i != devices.end(); ++i) {
 		if (_input_audio_device == "") _input_audio_device = i->second;
 		_input_audio_device_status.push_back (DeviceStatus (i->second, true));
@@ -192,7 +186,7 @@ CoreAudioBackend::enumerate_output_devices () const
 	std::map<size_t, std::string> devices;
 	_pcmio->output_device_list(devices);
 
-	_output_audio_device_status.push_back (DeviceStatus (get_standard_device_name(DeviceNone), true));
+	_output_audio_device_status.push_back (DeviceStatus (get_none_device_name (), true));
 	for (std::map<size_t, std::string>::const_iterator i = devices.begin (); i != devices.end(); ++i) {
 		if (_output_audio_device == "") _output_audio_device = i->second;
 		_output_audio_device_status.push_back (DeviceStatus (i->second, true));
@@ -416,7 +410,7 @@ CoreAudioBackend::enumerate_midi_options () const
 {
 	if (_midi_options.empty()) {
 		_midi_options.push_back (_("CoreMidi"));
-		_midi_options.push_back (get_standard_device_name(DeviceNone));
+		_midi_options.push_back (get_none_device_name ());
 	}
 	return _midi_options;
 }
@@ -424,7 +418,7 @@ CoreAudioBackend::enumerate_midi_options () const
 int
 CoreAudioBackend::set_midi_option (const std::string& opt)
 {
-	if (opt != get_standard_device_name(DeviceNone) && opt != _("CoreMidi")) {
+	if (opt != get_none_device_name () && opt != _("CoreMidi")) {
 		return -1;
 	}
 	_midi_driver_option = opt;
@@ -1534,7 +1528,7 @@ CoreAudioBackend::hw_changed_callback ()
 static std::shared_ptr<CoreAudioBackend> _instance;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& e);
-static int instantiate (const std::string& arg1, const std::string& /* arg2 */);
+static int instantiate (const std::string& client_name, const std::string& /* session_id */);
 static int deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -1558,9 +1552,9 @@ backend_factory (AudioEngine& e)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& /* arg2 */)
+instantiate (const std::string& client_name, const std::string& /* session_id */)
 {
-	s_instance_name = arg1;
+	s_instance_name = client_name;
 	return 0;
 }
 
diff --git a/libs/backends/coreaudio/coreaudio_backend.h b/libs/backends/coreaudio/coreaudio_backend.h
index 8aa6bbccc5..e32ac82d55 100644
--- a/libs/backends/coreaudio/coreaudio_backend.h
+++ b/libs/backends/coreaudio/coreaudio_backend.h
@@ -160,7 +160,6 @@ class CoreAudioBackend : public AudioBackend, public PortEngineSharedImpl {
 	/* AUDIOBACKEND API */
 
 	std::string name () const;
-	bool is_realtime () const;
 
 	bool use_separate_input_and_output_devices () const { return true; }
 	std::vector<DeviceStatus> enumerate_devices () const;
diff --git a/libs/backends/dummy/dummy_audiobackend.cc b/libs/backends/dummy/dummy_audiobackend.cc
index d753681870..609fb5b15d 100644
--- a/libs/backends/dummy/dummy_audiobackend.cc
+++ b/libs/backends/dummy/dummy_audiobackend.cc
@@ -109,12 +109,6 @@ DummyAudioBackend::name () const
 	return X_("Dummy"); // internal name
 }
 
-bool
-DummyAudioBackend::is_realtime () const
-{
-	return false;
-}
-
 std::vector<AudioBackend::DeviceStatus>
 DummyAudioBackend::enumerate_devices () const
 {
@@ -1021,7 +1015,7 @@ DummyAudioBackend::main_process_thread ()
 static std::shared_ptr<DummyAudioBackend> _instance;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& e);
-static int instantiate (const std::string& arg1, const std::string& /* arg2 */);
+static int instantiate (const std::string& client_name, const std::string& /* session_id */);
 static int deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -1045,9 +1039,9 @@ backend_factory (AudioEngine& e)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& /* arg2 */)
+instantiate (const std::string& client_name, const std::string& /* session_id */)
 {
-	s_instance_name = arg1;
+	s_instance_name = client_name;
 	return 0;
 }
 
diff --git a/libs/backends/dummy/dummy_audiobackend.h b/libs/backends/dummy/dummy_audiobackend.h
index 610f05ef3d..1ef9a5633a 100644
--- a/libs/backends/dummy/dummy_audiobackend.h
+++ b/libs/backends/dummy/dummy_audiobackend.h
@@ -194,7 +194,6 @@ class DummyAudioBackend : public AudioBackend, public PortEngineSharedImpl
 		/* AUDIOBACKEND API */
 
 		std::string name () const;
-		bool is_realtime () const;
 
 		bool requires_driver_selection() const { return true; }
 		std::string driver_name () const;
diff --git a/libs/backends/jack/jack_api.cc b/libs/backends/jack/jack_api.cc
index 959e3e5838..f3123926c6 100644
--- a/libs/backends/jack/jack_api.cc
+++ b/libs/backends/jack/jack_api.cc
@@ -25,7 +25,7 @@ static std::shared_ptr<JACKAudioBackend> backend;
 static std::shared_ptr<JackConnection> jack_connection;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& ae);
-static int  instantiate (const std::string& arg1, const std::string& arg2);
+static int  instantiate (const std::string& client_name, const std::string& session_id);
 static int  deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -58,10 +58,10 @@ backend_factory (AudioEngine& ae)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& arg2)
+instantiate (const std::string& client_name, const std::string& session_id)
 {
 	try {
-		jack_connection.reset (new JackConnection (arg1, arg2));
+		jack_connection.reset (new JackConnection (client_name, session_id));
 		backend.reset ();
 	} catch (...) {
 		return -1;
diff --git a/libs/backends/jack/jack_audiobackend.cc b/libs/backends/jack/jack_audiobackend.cc
index 8f4f1f0a78..d62ceac193 100644
--- a/libs/backends/jack/jack_audiobackend.cc
+++ b/libs/backends/jack/jack_audiobackend.cc
@@ -105,13 +105,6 @@ JACKAudioBackend::available() const
 	return (private_handle() != 0);
 }
 
-bool
-JACKAudioBackend::is_realtime () const
-{
-	GET_PRIVATE_JACK_POINTER_RET (_priv_jack,false);
-	return jack_is_realtime (_priv_jack);
-}
-
 bool
 JACKAudioBackend::requires_driver_selection() const
 {
@@ -262,7 +255,7 @@ JACKAudioBackend::set_sample_rate (float sr)
 }
 
 int
-JACKAudioBackend::set_peridod_size (uint32_t nperiods)
+JACKAudioBackend::set_period_size (uint32_t nperiods)
 {
 	if (!available()) {
 		_target_num_periods = nperiods;
@@ -882,6 +875,8 @@ int
 JACKAudioBackend::client_real_time_priority ()
 {
 	GET_PRIVATE_JACK_POINTER_RET (_priv_jack, 0);
+	if (!jack_is_realtime (_priv_jack))
+		return 0;
 	return jack_client_real_time_priority (_priv_jack);
 }
 
diff --git a/libs/backends/jack/jack_audiobackend.h b/libs/backends/jack/jack_audiobackend.h
index 21c775e47f..54e8178435 100644
--- a/libs/backends/jack/jack_audiobackend.h
+++ b/libs/backends/jack/jack_audiobackend.h
@@ -58,7 +58,6 @@ class JACKAudioBackend : public AudioBackend {
 
 	std::string name() const;
 	void* private_handle() const;
-	bool is_realtime () const;
 
 	bool is_jack () const { return true; }
 
@@ -78,7 +77,7 @@ class JACKAudioBackend : public AudioBackend {
 	int set_device_name (const std::string&);
 	int set_sample_rate (float);
 	int set_buffer_size (uint32_t);
-	int set_peridod_size (uint32_t);
+	int set_period_size (uint32_t);
 	int set_interleaved (bool yn);
 	int set_systemic_input_latency (uint32_t);
 	int set_systemic_output_latency (uint32_t);
diff --git a/libs/backends/jack/jack_connection.cc b/libs/backends/jack/jack_connection.cc
index 207c4add79..540bbd6248 100644
--- a/libs/backends/jack/jack_connection.cc
+++ b/libs/backends/jack/jack_connection.cc
@@ -50,10 +50,10 @@ static void jack_halted_info_callback (jack_status_t code, const char* reason, v
 }
 
 
-JackConnection::JackConnection (const std::string& arg1, const std::string& arg2)
+JackConnection::JackConnection (const std::string& client_name, const std::string& session_id)
 	: _jack (0)
-	, _client_name (arg1)
-	, session_uuid (arg2)
+	, _client_name (client_name)
+	, _session_id (session_id)
 	, _probed_buffer_size (0)
 	, _probed_sample_rate (0)
 {
@@ -116,7 +116,7 @@ JackConnection::open ()
 	get_jack_server_dir_paths (dirs);
 	set_path_env_for_jack_autostart (dirs);
 
-	if ((_jack = jack_client_open (_client_name.c_str(), JackSessionID, &status, session_uuid.c_str())) == 0) {
+	if ((_jack = jack_client_open (_client_name.c_str(), JackSessionID, &status, _session_id.c_str())) == 0) {
 		return -1;
 	}
 
diff --git a/libs/backends/jack/jack_connection.h b/libs/backends/jack/jack_connection.h
index b9aaab7aa8..164525665a 100644
--- a/libs/backends/jack/jack_connection.h
+++ b/libs/backends/jack/jack_connection.h
@@ -10,7 +10,7 @@ namespace ARDOUR {
 
 class JackConnection {
   public:
-    JackConnection (const std::string& client_name, const std::string& session_uuid);
+    JackConnection (const std::string& client_name, const std::string& session_id);
     ~JackConnection ();
 
     const std::string& client_name() const { return _client_name; }
@@ -35,7 +35,7 @@ class JackConnection {
   private:
     jack_client_t* volatile _jack;
     std::string _client_name;
-    std::string session_uuid;
+    std::string _session_id;
     static bool _in_control;
     uint32_t _probed_buffer_size; // when not in control
     uint32_t _probed_sample_rate; // when not in control
diff --git a/libs/backends/portaudio/portaudio_backend.cc b/libs/backends/portaudio/portaudio_backend.cc
index c656e922c2..a2fa6d760a 100644
--- a/libs/backends/portaudio/portaudio_backend.cc
+++ b/libs/backends/portaudio/portaudio_backend.cc
@@ -116,12 +116,6 @@ PortAudioBackend::name () const
 	return X_("PortAudio");
 }
 
-bool
-PortAudioBackend::is_realtime () const
-{
-	return true;
-}
-
 bool
 PortAudioBackend::requires_driver_selection() const
 {
@@ -426,7 +420,7 @@ PortAudioBackend::enumerate_midi_options () const
 {
 	if (_midi_options.empty()) {
 		_midi_options.push_back (winmme_driver_name);
-		_midi_options.push_back (get_standard_device_name(DeviceNone));
+		_midi_options.push_back (get_none_device_name ());
 	}
 	return _midi_options;
 }
@@ -434,7 +428,7 @@ PortAudioBackend::enumerate_midi_options () const
 int
 PortAudioBackend::set_midi_option (const std::string& opt)
 {
-	if (opt != get_standard_device_name(DeviceNone) && opt != winmme_driver_name) {
+	if (opt != get_none_device_name () && opt != winmme_driver_name) {
 		return -1;
 	}
 	DEBUG_MIDI (string_compose ("Setting midi option to %1\n", opt));
@@ -1218,7 +1212,7 @@ PortAudioBackend::register_system_audio_ports()
 int
 PortAudioBackend::register_system_midi_ports (std::string const& device)
 {
-	if (_midi_driver_option == get_standard_device_name(DeviceNone)) {
+	if (_midi_driver_option == get_none_device_name ()) {
 		DEBUG_MIDI("No MIDI backend selected, not system midi ports available\n");
 		return 0;
 	}
@@ -1797,7 +1791,7 @@ PortAudioBackend::process_port_connection_changes ()
 static std::shared_ptr<PortAudioBackend> _instance;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& e);
-static int instantiate (const std::string& arg1, const std::string& /* arg2 */);
+static int instantiate (const std::string& client_name, const std::string& /* session_id */);
 static int deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -1821,9 +1815,9 @@ backend_factory (AudioEngine& e)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& /* arg2 */)
+instantiate (const std::string& client_name, const std::string& /* session_id */)
 {
-	s_instance_name = arg1;
+	s_instance_name = client_name;
 	return 0;
 }
 
diff --git a/libs/backends/portaudio/portaudio_backend.h b/libs/backends/portaudio/portaudio_backend.h
index f520d0b46a..384d68733b 100644
--- a/libs/backends/portaudio/portaudio_backend.h
+++ b/libs/backends/portaudio/portaudio_backend.h
@@ -99,7 +99,6 @@ class PortAudioBackend : public AudioBackend, public PortEngineSharedImpl {
 		/* AUDIOBACKEND API */
 
 		std::string name () const;
-		bool is_realtime () const;
 
 		bool requires_driver_selection() const;
 		std::string driver_name () const;
diff --git a/libs/backends/portaudio/portaudio_io.cc b/libs/backends/portaudio/portaudio_io.cc
index d2d6ac4c58..67a949f6e8 100644
--- a/libs/backends/portaudio/portaudio_io.cc
+++ b/libs/backends/portaudio/portaudio_io.cc
@@ -484,9 +484,9 @@ void
 PortAudioIO::add_none_devices ()
 {
 	_input_devices.insert(std::pair<int, paDevice*>(
-	    DeviceNone, new paDevice(AudioBackend::get_standard_device_name(AudioBackend::DeviceNone), 0, 0)));
+	    DeviceNone, new paDevice (AudioBackend::get_none_device_name (), 0, 0)));
 	_output_devices.insert(std::pair<int, paDevice*>(
-	    DeviceNone, new paDevice(AudioBackend::get_standard_device_name(AudioBackend::DeviceNone), 0, 0)));
+	    DeviceNone, new paDevice (AudioBackend::get_none_device_name (), 0, 0)));
 }
 
 void
@@ -499,12 +499,12 @@ PortAudioIO::add_default_devices ()
 	const PaDeviceInfo* nfo_o = Pa_GetDeviceInfo(get_default_output_device());
 	if (nfo_i && nfo_o) {
 		_input_devices.insert (std::pair<int, paDevice*> (DeviceDefault,
-					new paDevice(AudioBackend::get_standard_device_name(AudioBackend::DeviceDefault),
+					new paDevice(AudioBackend::get_default_device_name (),
 						nfo_i->maxInputChannels,
 						nfo_o->maxOutputChannels
 						)));
 		_output_devices.insert (std::pair<int, paDevice*> (DeviceDefault,
-					new paDevice(AudioBackend::get_standard_device_name(AudioBackend::DeviceDefault),
+					new paDevice(AudioBackend::get_default_device_name (),
 						nfo_i->maxInputChannels,
 						nfo_o->maxOutputChannels
 						)));
diff --git a/libs/backends/portaudio/portaudio_io.h b/libs/backends/portaudio/portaudio_io.h
index cfd6283d57..1874176d34 100644
--- a/libs/backends/portaudio/portaudio_io.h
+++ b/libs/backends/portaudio/portaudio_io.h
@@ -34,11 +34,6 @@ public:
 	PortAudioIO (void);
 	~PortAudioIO (void);
 
-	enum StandardDevices {
-		DeviceNone = -2,
-		DeviceDefault = -1
-	};
-
 	void host_api_list (std::vector<std::string>&);
 	bool set_host_api (const std::string& host_api_name);
 	std::string get_host_api () const { return _host_api_name; }
diff --git a/libs/backends/pulseaudio/pulseaudio_backend.cc b/libs/backends/pulseaudio/pulseaudio_backend.cc
index ae8873866b..b9e52b98c9 100644
--- a/libs/backends/pulseaudio/pulseaudio_backend.cc
+++ b/libs/backends/pulseaudio/pulseaudio_backend.cc
@@ -331,12 +331,6 @@ PulseAudioBackend::name () const
 	return X_("PulseAudio");
 }
 
-bool
-PulseAudioBackend::is_realtime () const
-{
-	return true;
-}
-
 std::vector<AudioBackend::DeviceStatus>
 PulseAudioBackend::enumerate_devices () const
 {
@@ -481,7 +475,7 @@ std::vector<std::string>
 PulseAudioBackend::enumerate_midi_options () const
 {
 	std::vector<std::string> midi_options;
-	midi_options.push_back (get_standard_device_name (DeviceNone));
+	midi_options.push_back (get_none_device_name ());
 	return midi_options;
 }
 
@@ -500,7 +494,7 @@ PulseAudioBackend::set_midi_option (const std::string& opt)
 std::string
 PulseAudioBackend::midi_option () const
 {
-	return get_standard_device_name (DeviceNone);
+	return get_none_device_name ();
 }
 
 /* External control app */
@@ -1089,7 +1083,7 @@ PulseAudioBackend::main_process_thread ()
 static std::shared_ptr<PulseAudioBackend> _instance;
 
 static std::shared_ptr<AudioBackend> backend_factory (AudioEngine& e);
-static int instantiate (const std::string& arg1, const std::string& /* arg2 */);
+static int instantiate (const std::string& client_name, const std::string& /* session_id */);
 static int  deinstantiate ();
 static bool already_configured ();
 static bool available ();
@@ -1113,9 +1107,9 @@ backend_factory (AudioEngine& e)
 }
 
 static int
-instantiate (const std::string& arg1, const std::string& /* arg2 */)
+instantiate (const std::string& client_name, const std::string& /* session_id */)
 {
-	s_instance_name = arg1;
+	s_instance_name = client_name;
 	return 0;
 }
 
diff --git a/libs/backends/pulseaudio/pulseaudio_backend.h b/libs/backends/pulseaudio/pulseaudio_backend.h
index 1e8c981990..4190706be3 100644
--- a/libs/backends/pulseaudio/pulseaudio_backend.h
+++ b/libs/backends/pulseaudio/pulseaudio_backend.h
@@ -102,7 +102,6 @@ public:
 	/* AUDIOBACKEND API */
 
 	std::string name () const;
-	bool is_realtime () const;
 
 	std::vector<DeviceStatus> enumerate_devices () const;
 	std::vector<float> available_sample_rates (const std::string& device) const;