Merge branch 'master' into refactor-samplebuffer

2023-09-25 21:13:26 -04:00
parent e890aac3dc 23ef89b4a1
commit 8d18010932
24 changed files with 808 additions and 73 deletions
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -71,6 +71,7 @@ set(LMMS_SRCS
 	core/SamplePlayHandle.cpp
 	core/SampleRecordHandle.cpp
 	core/Scale.cpp
+	core/LmmsSemaphore.cpp
 	core/SerializingObject.cpp
 	core/Song.cpp
 	core/TempoSyncKnobModel.cpp
@@ -113,6 +114,7 @@ set(LMMS_SRCS
 	core/lv2/Lv2SubPluginFeatures.cpp
 	core/lv2/Lv2UridCache.cpp
 	core/lv2/Lv2UridMap.cpp
+	core/lv2/Lv2Worker.cpp

 	core/midi/MidiAlsaRaw.cpp
 	core/midi/MidiAlsaSeq.cpp
--- a/src/core/LmmsSemaphore.cpp
+++ b/src/core/LmmsSemaphore.cpp
@@ -0,0 +1,143 @@
+/*
+ * Semaphore.cpp - Semaphore implementation
+ *
+ * Copyright (c) 2022-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*
+ * This code has been copied and adapted from https://github.com/drobilla/jalv
+ * File src/zix/sem.h
+ */
+
+#include "LmmsSemaphore.h"
+
+#if defined(LMMS_BUILD_WIN32)
+#    include <limits.h>
+#else
+#    include <errno.h>
+#endif
+
+#include <system_error>
+
+namespace lmms {
+
+#ifdef LMMS_BUILD_APPLE
+Semaphore::Semaphore(unsigned val)
+{
+	kern_return_t rval = semaphore_create(mach_task_self(), &m_sem, SYNC_POLICY_FIFO, val);
+	if(rval != 0) {
+		throw std::system_error(rval, std::system_category(), "Could not create semaphore");
+	}
+}
+
+Semaphore::~Semaphore()
+{
+	semaphore_destroy(mach_task_self(), m_sem);
+}
+
+void Semaphore::post()
+{
+	semaphore_signal(m_sem);
+}
+
+void Semaphore::wait()
+{
+	kern_return_t rval = semaphore_wait(m_sem);
+	if (rval != KERN_SUCCESS) {
+		throw std::system_error(rval, std::system_category(), "Waiting for semaphore failed");
+	}
+}
+
+bool Semaphore::tryWait()
+{
+	const mach_timespec_t zero = { 0, 0 };
+	return semaphore_timedwait(m_sem, zero) == KERN_SUCCESS;
+}
+
+#elif defined(LMMS_BUILD_WIN32)
+
+Semaphore::Semaphore(unsigned initial)
+{
+	if(CreateSemaphore(nullptr, initial, LONG_MAX, nullptr) == nullptr) {
+		throw std::system_error(GetLastError(), std::system_category(), "Could not create semaphore");
+	}
+}
+
+Semaphore::~Semaphore()
+{
+	CloseHandle(m_sem);
+}
+
+void Semaphore::post()
+{
+	ReleaseSemaphore(m_sem, 1, nullptr);
+}
+
+void Semaphore::wait()
+{
+	if (WaitForSingleObject(m_sem, INFINITE) != WAIT_OBJECT_0) {
+		throw std::system_error(GetLastError(), std::system_category(), "Waiting for semaphore failed");
+	}
+}
+
+bool Semaphore::tryWait()
+{
+	return WaitForSingleObject(m_sem, 0) == WAIT_OBJECT_0;
+}
+
+#else  /* !defined(LMMS_BUILD_APPLE) && !defined(LMMS_BUILD_WIN32) */
+
+Semaphore::Semaphore(unsigned initial)
+{
+	if(sem_init(&m_sem, 0, initial) != 0) {
+		throw std::system_error(errno, std::generic_category(), "Could not create semaphore");
+	}
+}
+
+Semaphore::~Semaphore()
+{
+	sem_destroy(&m_sem);
+}
+
+void Semaphore::post()
+{
+	sem_post(&m_sem);
+}
+
+void Semaphore::wait()
+{
+	while (sem_wait(&m_sem) != 0) {
+		if (errno != EINTR) {
+			throw std::system_error(errno, std::generic_category(), "Waiting for semaphore failed");
+		}
+		/* Otherwise, interrupted, so try again. */
+	}
+}
+
+bool Semaphore::tryWait()
+{
+	return (sem_trywait(&m_sem) == 0);
+}
+
+#endif
+
+} // namespace lmms
+
--- a/src/core/lv2/Lv2Features.cpp
+++ b/src/core/lv2/Lv2Features.cpp
@@ -48,7 +48,7 @@ Lv2Features::Lv2Features()
 {
 	const Lv2Manager* man = Engine::getLv2Manager();
 	// create (yet empty) map feature URI -> feature
-	for(const char* uri : man->supportedFeatureURIs())
+	for(auto uri : man->supportedFeatureURIs())
 	{
 		m_featureByUri.emplace(uri, nullptr);
 	}
@@ -71,7 +71,7 @@ void Lv2Features::initCommon()
 void Lv2Features::createFeatureVectors()
 {
 	// create vector of features
-	for(std::pair<const char* const, void*>& pr : m_featureByUri)
+	for(const auto& [uri, feature] : m_featureByUri)
 	{
 		/*
 			If pr.second is nullptr here, this means that the LV2_feature
@@ -82,7 +82,7 @@ void Lv2Features::createFeatureVectors()
 			  vector creation (This can be done in
 			  Lv2Proc::initPluginSpecificFeatures or in Lv2Features::initCommon)
 		*/
-		m_features.push_back(LV2_Feature { pr.first, pr.second });
+		m_features.push_back(LV2_Feature{(const char*)uri.data(), (void*)feature});
 	}

 	// create pointer vector (for lilv_plugin_instantiate)
--- a/src/core/lv2/Lv2Manager.cpp
+++ b/src/core/lv2/Lv2Manager.cpp
@@ -28,13 +28,14 @@

 #include <algorithm>
 #include <cstdlib>
-#include <cstring>
 #include <lilv/lilv.h>
 #include <lv2/lv2plug.in/ns/ext/buf-size/buf-size.h>
 #include <lv2/lv2plug.in/ns/ext/options/options.h>
+#include <lv2/lv2plug.in/ns/ext/worker/worker.h>
 #include <QDebug>
 #include <QElapsedTimer>

+#include "AudioEngine.h"
 #include "Engine.h"
 #include "Plugin.h"
 #include "Lv2ControlBase.h"
@@ -46,7 +47,7 @@ namespace lmms
 {


-const std::set<const char*, Lv2Manager::CmpStr> Lv2Manager::pluginBlacklist =
+const std::set<std::string_view> Lv2Manager::pluginBlacklist =
 {
 	// github.com/calf-studio-gear/calf, #278
 	"http://calf.sourceforge.net/plugins/Analyzer",
@@ -137,6 +138,26 @@ const std::set<const char*, Lv2Manager::CmpStr> Lv2Manager::pluginBlacklist =
 	"urn:juced:DrumSynth"
 };

+const std::set<std::string_view> Lv2Manager::pluginBlacklistBuffersizeLessThan32 =
+{
+	"http://moddevices.com/plugins/mod-devel/2Voices",
+	"http://moddevices.com/plugins/mod-devel/Capo",
+	"http://moddevices.com/plugins/mod-devel/Drop",
+	"http://moddevices.com/plugins/mod-devel/Harmonizer",
+	"http://moddevices.com/plugins/mod-devel/Harmonizer2",
+	"http://moddevices.com/plugins/mod-devel/HarmonizerCS",
+	"http://moddevices.com/plugins/mod-devel/SuperCapo",
+	"http://moddevices.com/plugins/mod-devel/SuperWhammy",
+	"http://moddevices.com/plugins/mod-devel/Gx2Voices",
+	"http://moddevices.com/plugins/mod-devel/GxCapo",
+	"http://moddevices.com/plugins/mod-devel/GxDrop",
+	"http://moddevices.com/plugins/mod-devel/GxHarmonizer",
+	"http://moddevices.com/plugins/mod-devel/GxHarmonizer2",
+	"http://moddevices.com/plugins/mod-devel/GxHarmonizerCS",
+	"http://moddevices.com/plugins/mod-devel/GxSuperCapo",
+	"http://moddevices.com/plugins/mod-devel/GxSuperWhammy"
+};
+



@@ -152,10 +173,15 @@ Lv2Manager::Lv2Manager() :
 	m_supportedFeatureURIs.insert(LV2_URID__map);
 	m_supportedFeatureURIs.insert(LV2_URID__unmap);
 	m_supportedFeatureURIs.insert(LV2_OPTIONS__options);
+	m_supportedFeatureURIs.insert(LV2_WORKER__schedule);
 	// min/max is always passed in the options
 	m_supportedFeatureURIs.insert(LV2_BUF_SIZE__boundedBlockLength);
 	// block length is only changed initially in AudioEngine CTOR
 	m_supportedFeatureURIs.insert(LV2_BUF_SIZE__fixedBlockLength);
+	if (const auto fpp = Engine::audioEngine()->framesPerPeriod(); (fpp & (fpp - 1)) == 0)  // <=> ffp is power of 2 (for ffp > 0)
+	{
+		m_supportedFeatureURIs.insert(LV2_BUF_SIZE__powerOf2BlockLength);
+	}

 	auto supportOpt = [this](Lv2UridCache::Id id)
 	{
@@ -288,14 +314,6 @@ void Lv2Manager::initPlugins()



-bool Lv2Manager::CmpStr::operator()(const char *a, const char *b) const
-{
-	return std::strcmp(a, b) < 0;
-}
-
-
-
-
 bool Lv2Manager::isFeatureSupported(const char *featName) const
 {
 	return m_supportedFeatureURIs.find(featName) != m_supportedFeatureURIs.end();
--- a/src/core/lv2/Lv2Proc.cpp
+++ b/src/core/lv2/Lv2Proc.cpp
@@ -1,7 +1,7 @@
 /*
 * Lv2Proc.cpp - Lv2 processor class
 *
- * Copyright (c) 2019-2020 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ * Copyright (c) 2019-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
 *
 * This file is part of LMMS - https://lmms.io
 *
@@ -30,6 +30,7 @@
 #include <lv2/lv2plug.in/ns/ext/midi/midi.h>
 #include <lv2/lv2plug.in/ns/ext/atom/atom.h>
 #include <lv2/lv2plug.in/ns/ext/resize-port/resize-port.h>
+#include <lv2/lv2plug.in/ns/ext/worker/worker.h>
 #include <QDebug>
 #include <QDomDocument>
 #include <QtGlobal>
@@ -75,11 +76,19 @@ Plugin::Type Lv2Proc::check(const LilvPlugin *plugin,
 	// TODO: manage a global blacklist outside of the code
 	//       for now, this will help
 	//       this is only a fix for the meantime
-	const auto& pluginBlacklist = Lv2Manager::getPluginBlacklist();
-	if (!Engine::ignorePluginBlacklist() &&
-		pluginBlacklist.find(pluginUri) != pluginBlacklist.end())
+	if (!Engine::ignorePluginBlacklist())
 	{
-		issues.emplace_back(PluginIssueType::Blacklisted);
+		const auto& pluginBlacklist = Lv2Manager::getPluginBlacklist();
+		const auto& pluginBlacklist32 = Lv2Manager::getPluginBlacklistBuffersizeLessThan32();
+		if(pluginBlacklist.find(pluginUri) != pluginBlacklist.end())
+		{
+			issues.emplace_back(PluginIssueType::Blacklisted);
+		}
+		else if(Engine::audioEngine()->framesPerPeriod() <= 32 &&
+			pluginBlacklist32.find(pluginUri) != pluginBlacklist32.end())
+		{
+			issues.emplace_back(PluginIssueType::Blacklisted);  // currently no special blacklist category
+		}
 	}

 	for (unsigned portNum = 0; portNum < maxPorts; ++portNum)
@@ -162,6 +171,7 @@ Plugin::Type Lv2Proc::check(const LilvPlugin *plugin,
 Lv2Proc::Lv2Proc(const LilvPlugin *plugin, Model* parent) :
 	LinkedModelGroup(parent),
 	m_plugin(plugin),
+	m_workLock(1),
 	m_midiInputBuf(m_maxMidiInputEvents),
 	m_midiInputReader(m_midiInputBuf)
 {
@@ -352,7 +362,19 @@ void Lv2Proc::copyBuffersToCore(sampleFrame* buf,

 void Lv2Proc::run(fpp_t frames)
 {
+	if (m_worker)
+	{
+		// Process any worker replies
+		m_worker->emitResponses();
+	}
+
 	lilv_instance_run(m_instance, static_cast<uint32_t>(frames));
+
+	if (m_worker)
+	{
+		// Notify the plugin the run() cycle is finished
+		m_worker->notifyPluginThatRunFinished();
+	}
 }


@@ -420,6 +442,9 @@ void Lv2Proc::initPlugin()

 	if (m_instance)
 	{
+		if(m_worker) {
+			m_worker->setHandle(lilv_instance_get_handle(m_instance));
+		}
 		for (std::size_t portNum = 0; portNum < m_ports.size(); ++portNum)
 			connectPort(portNum);
 		lilv_instance_activate(m_instance);
@@ -496,8 +521,20 @@ void Lv2Proc::initMOptions()

 void Lv2Proc::initPluginSpecificFeatures()
 {
+	// options
 	initMOptions();
 	m_features[LV2_OPTIONS__options] = const_cast<LV2_Options_Option*>(m_options.feature());
+
+	// worker (if plugin has worker extension)
+	Lv2Manager* mgr = Engine::getLv2Manager();
+	if (lilv_plugin_has_extension_data(m_plugin, mgr->uri(LV2_WORKER__interface).get())) {
+		const auto iface = static_cast<const LV2_Worker_Interface*>(
+			lilv_instance_get_extension_data(m_instance, LV2_WORKER__interface));
+		bool threaded = !Engine::audioEngine()->renderOnly();
+		m_worker.emplace(iface, &m_workLock, threaded);
+		m_features[LV2_WORKER__schedule] = m_worker->feature();
+		// Note: m_worker::setHandle will still need to be called later
+	}
 }


@@ -566,21 +603,35 @@ void Lv2Proc::createPort(std::size_t portNum)
 						break;
 					case Lv2Ports::Vis::Enumeration:
 					{
-						auto comboModel = new ComboBoxModel(nullptr, dispName);
-						LilvScalePoints* sps =
-							lilv_port_get_scale_points(m_plugin, lilvPort);
-						LILV_FOREACH(scale_points, i, sps)
+						ComboBoxModel* comboModel = new ComboBoxModel(nullptr, dispName);
+
 						{
-							const LilvScalePoint* sp = lilv_scale_points_get(sps, i);
-							ctrl->m_scalePointMap.push_back(lilv_node_as_float(
-											lilv_scale_point_get_value(sp)));
-							comboModel->addItem(
-								lilv_node_as_string(
-									lilv_scale_point_get_label(sp)));
+							AutoLilvScalePoints sps (static_cast<LilvScalePoints*>(lilv_port_get_scale_points(m_plugin, lilvPort)));
+							// temporary map, since lilv may return scale points in random order
+							std::map<float, const char*> scalePointMap;
+							LILV_FOREACH(scale_points, i, sps.get())
+							{
+								const LilvScalePoint* sp = lilv_scale_points_get(sps.get(), i);
+								const float f = lilv_node_as_float(lilv_scale_point_get_value(sp));
+								const char* s = lilv_node_as_string(lilv_scale_point_get_label(sp));
+								scalePointMap[f] = s;
+							}
+							for (const auto& [f,s] : scalePointMap)
+							{
+								ctrl->m_scalePointMap.push_back(f);
+								comboModel->addItem(s);
+							}
+						}
+						for(std::size_t i = 0; i < ctrl->m_scalePointMap.size(); ++i)
+						{
+							if(meta.def() == ctrl->m_scalePointMap[i])
+							{
+								comboModel->setValue(i);
+								comboModel->setInitValue(i);
+								break;
+							}
 						}
-						lilv_scale_points_free(sps);
 						ctrl->m_connectedModel.reset(comboModel);
-						// TODO: use default value on comboModel, too?
 						break;
 					}
 					case Lv2Ports::Vis::Toggled:
--- a/src/core/lv2/Lv2Worker.cpp
+++ b/src/core/lv2/Lv2Worker.cpp
@@ -0,0 +1,203 @@
+/*
+ * Lv2Worker.cpp - Lv2Worker implementation
+ *
+ * Copyright (c) 2022-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "Lv2Worker.h"
+
+#include <cassert>
+#include <QDebug>
+
+#ifdef LMMS_HAVE_LV2
+
+#include "Engine.h"
+
+
+namespace lmms
+{
+
+
+// static wrappers
+
+static LV2_Worker_Status
+staticWorkerRespond(LV2_Worker_Respond_Handle handle,
+	uint32_t size, const void* data)
+{
+	Lv2Worker* worker = static_cast<Lv2Worker*>(handle);
+	return worker->respond(size, data);
+}
+
+
+
+
+std::size_t Lv2Worker::bufferSize() const
+{
+	// ardour uses this fixed size for ALSA:
+	return 8192 * 4;
+	// for jack, they use 4 * jack_port_type_get_buffer_size (..., JACK_DEFAULT_MIDI_TYPE)
+	// (possible extension for AudioDevice)
+}
+
+
+
+
+Lv2Worker::Lv2Worker(const LV2_Worker_Interface* iface,
+	Semaphore* common_work_lock,
+	bool threaded) :
+	m_iface(iface),
+	m_threaded(threaded),
+	m_response(bufferSize()),
+	m_requests(bufferSize()),
+	m_responses(bufferSize()),
+	m_requestsReader(m_requests),
+	m_responsesReader(m_responses),
+	m_sem(0),
+	m_workLock(common_work_lock)
+{
+	assert(iface);
+	m_scheduleFeature.handle = static_cast<LV2_Worker_Schedule_Handle>(this);
+	m_scheduleFeature.schedule_work = [](LV2_Worker_Schedule_Handle handle,
+		uint32_t size, const void* data) -> LV2_Worker_Status
+		{
+			Lv2Worker* worker = static_cast<Lv2Worker*>(handle);
+			return worker->scheduleWork(size, data);
+		};
+
+	if (threaded) { m_thread = std::thread(&Lv2Worker::workerFunc, this); }
+
+	m_requests.mlock();
+	m_responses.mlock();
+}
+
+
+
+
+Lv2Worker::~Lv2Worker()
+{
+	m_exit = true;
+	if(m_threaded) {
+		m_sem.post();
+		m_thread.join();
+	}
+}
+
+
+
+
+// Let the worker send responses to the audio thread
+LV2_Worker_Status Lv2Worker::respond(uint32_t size, const void* data)
+{
+	if(m_threaded)
+	{
+		if(m_responses.free() < sizeof(size) + size)
+		{
+			return LV2_WORKER_ERR_NO_SPACE;
+		}
+		else
+		{
+			m_responses.write((const char*)&size, sizeof(size));
+			if(size && data) { m_responses.write((const char*)data, size); }
+		}
+	}
+	else
+	{
+		m_iface->work_response(m_handle, size, data);
+	}
+	return LV2_WORKER_SUCCESS;
+}
+
+
+
+
+// Let the worker receive work from the audio thread and "work" on it
+void Lv2Worker::workerFunc()
+{
+	std::vector<char> buf;
+	uint32_t size;
+	while (true) {
+		m_sem.wait();
+		if (m_exit) { break; }
+		const std::size_t readSpace = m_requestsReader.read_space();
+		if (readSpace <= sizeof(size)) { continue; } // (should not happen)
+
+		m_requestsReader.read(sizeof(size)).copy((char*)&size, sizeof(size));
+		assert(size <= readSpace - sizeof(size));
+		if(size > buf.size()) { buf.resize(size); }
+		if(size) { m_requestsReader.read(size).copy(buf.data(), size); }
+
+		m_workLock->wait();
+		m_iface->work(m_handle, staticWorkerRespond, this, size, buf.data());
+		m_workLock->post();
+	}
+}
+
+
+
+
+// Let the audio thread schedule work for the worker
+LV2_Worker_Status Lv2Worker::scheduleWork(uint32_t size, const void *data)
+{
+	if (m_threaded)
+	{
+		if(m_requests.free() < sizeof(size) + size)
+		{
+			return LV2_WORKER_ERR_NO_SPACE;
+		}
+		else
+		{
+			// Schedule a request to be executed by the worker thread
+			m_requests.write((const char*)&size, sizeof(size));
+			if(size && data) { m_requests.write((const char*)data, size); }
+			m_sem.post();
+		}
+	}
+	else
+	{
+		// Execute work immediately in this thread
+		m_workLock->wait();
+		m_iface->work(m_handle, staticWorkerRespond, this, size, data);
+		m_workLock->post();
+	}
+
+	return LV2_WORKER_SUCCESS;
+}
+
+
+
+
+// Let the audio thread read incoming worker responses, and process it
+void Lv2Worker::emitResponses()
+{
+	std::size_t read_space = m_responsesReader.read_space();
+	uint32_t size;
+	while (read_space > sizeof(size)) {
+		m_responsesReader.read(sizeof(size)).copy((char*)&size, sizeof(size));
+		if(size) { m_responsesReader.read(size).copy(m_response.data(), size); }
+		m_iface->work_response(m_handle, size, m_response.data());
+		read_space -= sizeof(size) + size;
+	}
+}
+
+
+} // namespace lmms
+
+#endif // LMMS_HAVE_LV2
--- a/src/gui/Lv2ViewBase.cpp
+++ b/src/gui/Lv2ViewBase.cpp
@@ -39,6 +39,7 @@
 #include "GuiApplication.h"
 #include "embed.h"
 #include "gui_templates.h"
+#include "lmms_math.h"
 #include "Lv2ControlBase.h"
 #include "Lv2Manager.h"
 #include "Lv2Proc.h"
@@ -51,13 +52,13 @@ namespace lmms::gui
 {


-Lv2ViewProc::Lv2ViewProc(QWidget* parent, Lv2Proc* ctrlBase, int colNum) :
-	LinkedModelGroupView (parent, ctrlBase, colNum)
+Lv2ViewProc::Lv2ViewProc(QWidget* parent, Lv2Proc* proc, int colNum) :
+	LinkedModelGroupView (parent, proc, colNum)
 {
-	class SetupWidget : public Lv2Ports::ConstVisitor
+	class SetupTheWidget : public Lv2Ports::ConstVisitor
 	{
 	public:
-		QWidget* m_par; // input
+		QWidget* m_parent; // input
 		const LilvNode* m_commentUri; // input
 		Control* m_control = nullptr; // output
 		void visit(const Lv2Ports::Control& port) override
@@ -69,20 +70,22 @@ Lv2ViewProc::Lv2ViewProc(QWidget* parent, Lv2Proc* ctrlBase, int colNum) :
 				switch (port.m_vis)
 				{
 					case PortVis::Generic:
-						m_control = new KnobControl(m_par);
+						m_control = new KnobControl(m_parent);
 						break;
 					case PortVis::Integer:
 					{
 						sample_rate_t sr = Engine::audioEngine()->processingSampleRate();
-						m_control = new LcdControl((port.max(sr) <= 9.0f) ? 1 : 2,
-													m_par);
+						auto pMin = port.min(sr);
+						auto pMax = port.max(sr);
+						int numDigits = std::max(numDigitsAsInt(pMin), numDigitsAsInt(pMax));
+						m_control = new LcdControl(numDigits, m_parent);
 						break;
 					}
 					case PortVis::Enumeration:
-						m_control = new ComboControl(m_par);
+						m_control = new ComboControl(m_parent);
 						break;
 					case PortVis::Toggled:
-						m_control = new CheckControl(m_par);
+						m_control = new CheckControl(m_parent);
 						break;
 				}
 				m_control->setText(port.name());
@@ -100,14 +103,14 @@ Lv2ViewProc::Lv2ViewProc(QWidget* parent, Lv2Proc* ctrlBase, int colNum) :
 	};

 	AutoLilvNode commentUri = uri(LILV_NS_RDFS "comment");
-	ctrlBase->foreach_port(
+	proc->foreach_port(
 		[this, &commentUri](const Lv2Ports::PortBase* port)
 		{
 			if(!lilv_port_has_property(port->m_plugin, port->m_port,
 										uri(LV2_PORT_PROPS__notOnGUI).get()))
 			{
-				SetupWidget setup;
-				setup.m_par = this;
+				SetupTheWidget setup;
+				setup.m_parent = this;
 				setup.m_commentUri = commentUri.get();
 				port->accept(setup);

--- a/src/gui/modals/SetupDialog.cpp
+++ b/src/gui/modals/SetupDialog.cpp
@@ -579,32 +579,39 @@ SetupDialog::SetupDialog(ConfigTab tab_to_open) :

 	// Buffer size tab.
 	auto bufferSize_tw = new TabWidget(tr("Buffer size"), audio_w);
-	bufferSize_tw->setFixedHeight(76);
+	auto bufferSize_layout = new QVBoxLayout(bufferSize_tw);
+	bufferSize_layout->setSpacing(10);
+	bufferSize_layout->setContentsMargins(10, 18, 10, 10);

 	m_bufferSizeSlider = new QSlider(Qt::Horizontal, bufferSize_tw);
 	m_bufferSizeSlider->setRange(1, 128);
 	m_bufferSizeSlider->setTickInterval(8);
 	m_bufferSizeSlider->setPageStep(8);
 	m_bufferSizeSlider->setValue(m_bufferSize / BUFFERSIZE_RESOLUTION);
-	m_bufferSizeSlider->setGeometry(10, 18, 340, 18);
 	m_bufferSizeSlider->setTickPosition(QSlider::TicksBelow);

+	m_bufferSizeLbl = new QLabel(bufferSize_tw);
+
+	m_bufferSizeWarnLbl = new QLabel(bufferSize_tw);
+	m_bufferSizeWarnLbl->setWordWrap(true);
+
 	connect(m_bufferSizeSlider, SIGNAL(valueChanged(int)),
 			this, SLOT(setBufferSize(int)));
 	connect(m_bufferSizeSlider, SIGNAL(valueChanged(int)),
 			this, SLOT(showRestartWarning()));
-
-	m_bufferSizeLbl = new QLabel(bufferSize_tw);
-	m_bufferSizeLbl->setGeometry(10, 40, 200, 24);
 	setBufferSize(m_bufferSizeSlider->value());

 	auto bufferSize_reset_btn = new QPushButton(embed::getIconPixmap("reload"), "", bufferSize_tw);
-	bufferSize_reset_btn->setGeometry(320, 40, 28, 28);
 	connect(bufferSize_reset_btn, SIGNAL(clicked()),
 			this, SLOT(resetBufferSize()));
 	bufferSize_reset_btn->setToolTip(
 			tr("Reset to default value"));

+	bufferSize_layout->addWidget(m_bufferSizeSlider);
+	bufferSize_layout->addWidget(m_bufferSizeLbl);
+	bufferSize_layout->addWidget(m_bufferSizeWarnLbl);
+	bufferSize_layout->addWidget(bufferSize_reset_btn);
+

 	// Audio layout ordering.
 	audio_layout->addWidget(audioiface_tw);
@@ -1172,6 +1179,24 @@ void SetupDialog::audioInterfaceChanged(const QString & iface)
 }


+void SetupDialog::updateBufferSizeWarning(int value)
+{
+	QString text = "<ul>";
+	if((value & (value - 1)) != 0)  // <=> value is not a power of 2 (for value > 0)
+	{
+		text += "<li>" + tr("The currently selected value is not a power of 2 "
+					"(32, 64, 128, 256, 512, 1024, ...). Some plugins may not be available.") + "</li>";
+	}
+	if(value <= 32)
+	{
+		text += "<li>" + tr("The currently selected value is less than or equal to 32. "
+					"Some plugins may not be available.") + "</li>";
+	}
+	text += "</ul>";
+	m_bufferSizeWarnLbl->setText(text);
+}
+
+
 void SetupDialog::setBufferSize(int value)
 {
 	const int step = DEFAULT_BUFFER_SIZE / BUFFERSIZE_RESOLUTION;
@@ -1197,6 +1222,7 @@ void SetupDialog::setBufferSize(int value)
 	m_bufferSize = value * BUFFERSIZE_RESOLUTION;
 	m_bufferSizeLbl->setText(tr("Frames: %1\nLatency: %2 ms").arg(m_bufferSize).arg(
 		1000.0f * m_bufferSize / Engine::audioEngine()->processingSampleRate(), 0, 'f', 1));
+	updateBufferSizeWarning(m_bufferSize);
 }