Moved widgets in subfolder

widgets/djwidget.cpp

@@ -0,0 +1,102 @@
+#include "djwidget.h"
+#include "ui_djwidget.h"
+
+#include <QDebug>
+#include <QStandardPaths>
+
+DjWidget::DjWidget(QWidget *parent) :
+    QWidget{parent},
+    m_ui{std::make_unique<Ui::DjWidget>()}
+{
+    m_ui->setupUi(this);
+
+    const auto createSlot = [this](TrackDeck &trackDeck){
+        return [this,&trackDeck](){
+            const auto index = m_ui->treeViewFiles->currentIndex();
+            if (!index.isValid())
+                return;
+            trackDeck.loadTrack(m_filesModel.filePath(m_filesTableModel.mapToSource(m_sortFilterProxyModel.mapToSource(index))));
+        };
+    };
+
+    connect(m_ui->pushButtonLoadDeckA, &QAbstractButton::pressed, m_ui->trackDeckA, createSlot(*m_ui->trackDeckA));
+    connect(m_ui->pushButtonLoadDeckB, &QAbstractButton::pressed, m_ui->trackDeckB, createSlot(*m_ui->trackDeckB));
+
+    m_directoryModel.setFilter(QDir::Dirs|QDir::Drives|QDir::NoDotAndDotDot);
+    const auto rootIndex = m_directoryModel.setRootPath(QDir::homePath());
+    m_ui->treeViewDirectories->setModel(&m_directoryModel);
+    m_ui->treeViewDirectories->setRootIndex(rootIndex);
+    for (auto i = 0, count = m_directoryModel.columnCount(); i < count; i++)
+        m_ui->treeViewDirectories->setColumnHidden(i, i!=0);
+
+    connect(m_ui->treeViewDirectories->selectionModel(), &QItemSelectionModel::currentRowChanged, this, &DjWidget::directorySelected);
+
+    m_filesModel.setFilter(QDir::Files);
+    m_filesTableModel.setSourceModel(&m_filesModel);
+    m_sortFilterProxyModel.setFilterCaseSensitivity(Qt::CaseInsensitive);
+    m_sortFilterProxyModel.setSourceModel(&m_filesTableModel);
+    m_ui->treeViewFiles->setModel(&m_sortFilterProxyModel);
+
+    if (const auto locations = QStandardPaths::standardLocations(QStandardPaths::MusicLocation); !locations.isEmpty())
+    {
+        const auto index = m_directoryModel.index(locations.first());
+        m_ui->treeViewDirectories->selectionModel()->select(index, QItemSelectionModel::Clear|QItemSelectionModel::Select|QItemSelectionModel::Current|QItemSelectionModel::Rows);
+
+        const auto rootIndex = m_filesModel.setRootPath(m_directoryModel.filePath(index));
+        m_filesTableModel.setRootIndex(rootIndex);
+    }
+
+    connect(m_ui->lineEditSearch, &QLineEdit::textChanged, &m_sortFilterProxyModel, &QSortFilterProxyModel::setFilterFixedString);
+}
+
+DjWidget::~DjWidget() = default;
+
+void DjWidget::injectDecodingThread(QThread &thread)
+{
+    m_ui->trackDeckA->injectDecodingThread(thread);
+    m_ui->trackDeckB->injectDecodingThread(thread);
+}
+
+void DjWidget::writeSamples(frame_t *begin, frame_t *end)
+{
+    const auto count = std::distance(begin, end);
+
+    for (TrackDeck *trackDeck : {m_ui->trackDeckA, m_ui->trackDeckB})
+    {
+        frame_t buffer[count];
+        std::fill(buffer, buffer+count, frame_t{0.f,0.f});
+        trackDeck->writeSamples(buffer, buffer+count);
+        std::transform(static_cast<const frame_t *>(begin), static_cast<const frame_t *>(end), buffer, begin, [volume=1.f](const frame_t &frame, const frame_t &frame2){
+            frame_t newFrame;
+            std::transform(std::cbegin(frame), std::cend(frame), std::begin(frame2), std::begin(newFrame),
+                           [&volume](const sample_t &left, const sample_t &right) { return left + (right*volume); });
+            return newFrame;
+        });
+    }
+}
+
+void DjWidget::loadSettings(DrumMachineSettings &settings)
+{
+}
+
+void DjWidget::unsendColors()
+{
+}
+
+void DjWidget::sendColors()
+{
+}
+
+void DjWidget::messageReceived(const midi::MidiMessage &message)
+{
+}
+
+void DjWidget::directorySelected()
+{
+    const auto selected = m_ui->treeViewDirectories->currentIndex();
+    if (selected.isValid())
+    {
+        const auto rootIndex = m_filesModel.setRootPath(m_directoryModel.filePath(selected));
+        m_filesTableModel.setRootIndex(rootIndex);
+    }
+}

widgets/djwidget.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <QWidget>
+#include <QFileSystemModel>
+#include <QSortFilterProxyModel>
+
+#include <memory>
+
+#include "audioformat.h"
+#include "midicontainers.h"
+#include "treetotableproxymodel.h"
+
+namespace Ui { class DjWidget; }
+class DrumMachineSettings;
+
+class DjWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit DjWidget(QWidget *parent = nullptr);
+    ~DjWidget() override;
+
+    void injectDecodingThread(QThread &thread);
+    void writeSamples(frame_t *begin, frame_t *end);
+    void loadSettings(DrumMachineSettings &settings);
+    void unsendColors();
+    void sendColors();
+
+signals:
+    void sendMidi(const midi::MidiMessage &midiMsg);
+
+public slots:
+    void messageReceived(const midi::MidiMessage &message);
+
+private slots:
+    void directorySelected();
+
+private:
+    const std::unique_ptr<Ui::DjWidget> m_ui;
+
+    QFileSystemModel m_directoryModel;
+    QFileSystemModel m_filesModel;
+    TreeToTableProxyModel m_filesTableModel;
+    QSortFilterProxyModel m_sortFilterProxyModel;
+};

widgets/djwidget.ui

@@ -0,0 +1,149 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>DjWidget</class>
+ <widget class="QWidget" name="DjWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>765</width>
+    <height>519</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout" stretch="0,0,1">
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout" stretch="1,0,1">
+     <item>
+      <widget class="TrackDeck" name="trackDeckA" native="true"/>
+     </item>
+     <item>
+      <widget class="QFrame" name="frame">
+       <property name="frameShape">
+        <enum>QFrame::VLine</enum>
+       </property>
+       <property name="frameShadow">
+        <enum>QFrame::Sunken</enum>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="TrackDeck" name="trackDeckB" native="true"/>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_2">
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QSlider" name="horizontalSlider">
+       <property name="minimum">
+        <number>-100</number>
+       </property>
+       <property name="maximum">
+        <number>100</number>
+       </property>
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="invertedAppearance">
+        <bool>true</bool>
+       </property>
+       <property name="tickPosition">
+        <enum>QSlider::TicksBothSides</enum>
+       </property>
+       <property name="tickInterval">
+        <number>50</number>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QSplitter" name="splitter">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <widget class="QTreeView" name="treeViewDirectories">
+      <property name="headerHidden">
+       <bool>true</bool>
+      </property>
+     </widget>
+     <widget class="QWidget" name="layoutWidget">
+      <layout class="QVBoxLayout">
+       <item>
+        <layout class="QHBoxLayout">
+         <item>
+          <widget class="QLineEdit" name="lineEditSearch">
+           <property name="clearButtonEnabled">
+            <bool>true</bool>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QPushButton" name="pushButtonLoadDeckA">
+           <property name="text">
+            <string>Load in Deck A</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QPushButton" name="pushButtonLoadDeckB">
+           <property name="text">
+            <string>Load in Deck B</string>
+           </property>
+          </widget>
+         </item>
+        </layout>
+       </item>
+       <item>
+        <widget class="QTreeView" name="treeViewFiles">
+         <property name="dragEnabled">
+          <bool>true</bool>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>TrackDeck</class>
+   <extends>QWidget</extends>
+   <header>widgets/trackdeck.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

widgets/drumpadwidget.cpp

@@ -0,0 +1,150 @@
+#include "drumpadwidget.h"
+#include "ui_drumpadwidget.h"
+
+#include <QNetworkRequest>
+#include <QNetworkReply>
+#include <QNetworkAccessManager>
+#include <QMessageBox>
+
+#include "jsonconverters.h"
+
+DrumPadWidget::DrumPadWidget(QWidget *parent) :
+    QSplitter{parent},
+    m_ui{std::make_unique<Ui::DrumPadWidget>()}
+{
+    m_ui->setupUi(this);
+
+    connect(m_ui->samplesWidget, &SamplesWidget::sendMidi, this, &DrumPadWidget::sendMidi);
+
+    connect(m_ui->sequencerWidget, &SequencerWidget::triggerSample, m_ui->samplesWidget, &SamplesWidget::sequencerTriggerSample);
+
+    m_presetsProxyModel.setFilterCaseSensitivity(Qt::CaseInsensitive);
+    m_presetsProxyModel.setSortRole(Qt::EditRole);
+    m_presetsProxyModel.setSourceModel(&m_presetsModel);
+    m_ui->presetsView->setModel(&m_presetsProxyModel);
+
+    m_presetsProxyModel.setFilterKeyColumn(1);
+
+    connect(m_ui->lineEdit, &QLineEdit::textChanged, &m_presetsProxyModel, &QSortFilterProxyModel::setFilterFixedString);
+
+    m_ui->filesView->setModel(&m_filesModel);
+
+    connect(m_ui->presetsView->selectionModel(), &QItemSelectionModel::currentRowChanged, this, &DrumPadWidget::currentRowChanged);
+
+    connect(m_ui->pushButtonRefresh, &QAbstractButton::pressed, this, &DrumPadWidget::loadPresets);
+}
+
+DrumPadWidget::~DrumPadWidget() = default;
+
+void DrumPadWidget::selectFirstPreset()
+{
+    if (!m_presetsProxyModel.rowCount())
+        return;
+
+    const auto index = m_presetsProxyModel.index(0, 0);
+    if (index.isValid())
+    {
+        m_ui->presetsView->selectionModel()->select(index, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
+        currentRowChanged(index);
+    }
+}
+
+void DrumPadWidget::writeSamples(frame_t *begin, frame_t *end)
+{
+    m_ui->samplesWidget->writeSamples(begin, end);
+}
+
+void DrumPadWidget::injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager)
+{
+    m_networkAccessManager = &networkAccessManager;
+    loadPresets();
+    m_ui->samplesWidget->injectNetworkAccessManager(networkAccessManager);
+}
+
+void DrumPadWidget::injectDecodingThread(QThread &thread)
+{
+    m_ui->samplesWidget->injectDecodingThread(thread);
+}
+
+void DrumPadWidget::loadSettings(DrumMachineSettings &settings)
+{
+    m_ui->samplesWidget->loadSettings(settings);
+}
+
+void DrumPadWidget::unsendColors()
+{
+    m_ui->samplesWidget->unsendColors();
+}
+
+void DrumPadWidget::sendColors()
+{
+    m_ui->samplesWidget->sendColors();
+}
+
+void DrumPadWidget::messageReceived(const midi::MidiMessage &message)
+{
+    m_ui->samplesWidget->messageReceived(message);
+}
+
+void DrumPadWidget::currentRowChanged(const QModelIndex &current)
+{
+    if (!current.isValid())
+        return;
+
+    const auto &preset = m_presetsModel.getPreset(m_presetsProxyModel.mapToSource(current));
+
+    m_ui->presetDetailWidget->setPreset(preset);
+    m_filesModel.setPreset(preset);
+    m_ui->sequencerWidget->setPreset(preset);
+    m_ui->samplesWidget->setPreset(preset);
+}
+
+void DrumPadWidget::loadPresets()
+{
+    if (!m_networkAccessManager)
+    {
+        qWarning() << "no network access manager available";
+        return;
+    }
+
+    m_ui->pushButtonRefresh->setEnabled(false);
+
+    QNetworkRequest request{QUrl{"https://brunner.ninja/komposthaufen/dpm/presets_config_v12.json"}};
+    request.setAttribute(QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferCache);
+    request.setAttribute(QNetworkRequest::CacheSaveControlAttribute, true);
+
+    m_reply = std::unique_ptr<QNetworkReply>(m_networkAccessManager->get(request));
+    connect(m_reply.get(), &QNetworkReply::finished, this, &DrumPadWidget::requestFinished);
+}
+
+void DrumPadWidget::requestFinished()
+{
+    if (!m_reply)
+    {
+        qWarning() << "no valid reply";
+        return;
+    }
+
+    auto reply = std::move(m_reply);
+    if (reply->error() != QNetworkReply::NoError)
+    {
+        QMessageBox::warning(this, tr("Could not load presets!"), tr("Could not load presets!") + "\n\n" + reply->errorString());
+        return;
+    }
+
+    try
+    {
+        auto result = json_converters::parsePresetsConfig(json_converters::loadJson(reply->readAll()));
+
+        if (!result.presets)
+            throw std::runtime_error("presets missing in response");
+
+        m_presetsModel.setPresets(std::move(*std::move(result).presets));
+
+        selectFirstPreset();
+    }
+    catch (const std::exception &e)
+    {
+        QMessageBox::warning(this, tr("error"), tr("error") + "\n\n" + QString::fromStdString(e.what()));
+    }
+}

widgets/drumpadwidget.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QSplitter>
+#include <QSortFilterProxyModel>
+
+#include <memory>
+
+#include "audioformat.h"
+#include "midicontainers.h"
+#include "presetsmodel.h"
+#include "filesmodel.h"
+
+namespace Ui { class DrumPadWidget; }
+class SamplesWidget;
+class SequencerWidget;
+class QModelIndex;
+class QNetworkAccessManager;
+class QThread;
+class DrumMachineSettings;
+class QNetworkReply;
+
+class DrumPadWidget : public QSplitter
+{
+    Q_OBJECT
+
+public:
+    explicit DrumPadWidget(QWidget *parent = nullptr);
+    ~DrumPadWidget() override;
+
+    void selectFirstPreset();
+    void writeSamples(frame_t *begin, frame_t *end);
+    void injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager);
+    void injectDecodingThread(QThread &thread);
+    void loadSettings(DrumMachineSettings &settings);
+    void unsendColors();
+    void sendColors();
+
+signals:
+    void sendMidi(const midi::MidiMessage &midiMsg);
+
+public slots:
+    void messageReceived(const midi::MidiMessage &message);
+
+private slots:
+    void currentRowChanged(const QModelIndex &current);
+    void loadPresets();
+    void requestFinished();
+
+private:
+    const std::unique_ptr<Ui::DrumPadWidget> m_ui;
+
+    PresetsModel m_presetsModel;
+    QSortFilterProxyModel m_presetsProxyModel;
+
+    FilesModel m_filesModel;
+
+    QNetworkAccessManager *m_networkAccessManager{};
+
+    std::unique_ptr<QNetworkReply> m_reply;
+};

widgets/drumpadwidget.ui

@@ -0,0 +1,108 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>DrumPadWidget</class>
+ <widget class="QSplitter">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>805</width>
+    <height>525</height>
+   </rect>
+  </property>
+  <property name="orientation">
+   <enum>Qt::Horizontal</enum>
+  </property>
+  <widget class="QWidget" name="layoutWidget">
+   <layout class="QVBoxLayout">
+    <item>
+     <layout class="QVBoxLayout">
+      <item>
+       <layout class="QHBoxLayout">
+        <item>
+         <widget class="QLineEdit" name="lineEdit">
+          <property name="clearButtonEnabled">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QPushButton" name="pushButtonRefresh">
+          <property name="maximumSize">
+           <size>
+            <width>32</width>
+            <height>16777215</height>
+           </size>
+          </property>
+          <property name="text">
+           <string>↻</string>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </item>
+      <item>
+       <widget class="QTreeView" name="presetsView">
+        <property name="rootIsDecorated">
+         <bool>false</bool>
+        </property>
+        <property name="sortingEnabled">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <widget class="QTabWidget" name="tabWidget">
+      <property name="currentIndex">
+       <number>2</number>
+      </property>
+      <widget class="PresetDetailWidget" name="presetDetailWidget">
+       <attribute name="title">
+        <string>Properties</string>
+       </attribute>
+      </widget>
+      <widget class="QTreeView" name="filesView">
+       <property name="rootIsDecorated">
+        <bool>false</bool>
+       </property>
+       <attribute name="title">
+        <string>Samples</string>
+       </attribute>
+      </widget>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QSplitter">
+  <property name="orientation">
+   <enum>Qt::Vertical</enum>
+  </property>
+   <widget class="SequencerWidget" name="sequencerWidget" />
+   <widget class="SamplesWidget" name="samplesWidget" />
+  </widget>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>SamplesWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/sampleswidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>PresetDetailWidget</class>
+   <extends>QScrollArea</extends>
+   <header>widgets/presetdetailwidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>SequencerWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/sequencerwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

widgets/mainwindow.cpp

@@ -0,0 +1,372 @@
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+#include <QEventLoop>
+#include <QMetaEnum>
+#include <QMessageBox>
+#include <QTimer>
+#include <QAbstractEventDispatcher>
+#include <QAudioDeviceInfo>
+#include <QDebug>
+
+#include "presets.h"
+#include "midiinwrapper.h"
+#include "midicontainers.h"
+#include "sampleswidget.h"
+#include "sequencerwidget.h"
+
+namespace {
+void DummyDeleter(PaStream *stream);
+void PaStreamCloser(PaStream *stream);
+void PaStreamStopperAndCloser(PaStream *stream);
+void paStreamFinished(void* userData);
+int paCallback(const void *inputBuffer, void *outputBuffer,
+               unsigned long framesPerBuffer,
+               const PaStreamCallbackTimeInfo* timeInfo,
+               PaStreamCallbackFlags statusFlags,
+               void *userData);
+} // namespace
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow{parent},
+    m_ui{std::make_unique<Ui::MainWindow>()},
+    m_paStream{nullptr, DummyDeleter},
+    m_midiIn{RtMidi::UNSPECIFIED, "DrumMachine"},
+    m_midiOut{RtMidi::UNSPECIFIED, "DrumMachine"}
+{
+    m_ui->setupUi(this);
+
+    m_cache.setCacheDirectory("cache");
+    m_cache.setMaximumCacheSize(2ull * 1024 * 1024 * 1024);
+    m_networkAccessManager.setCache(&m_cache);
+
+    m_ui->drumPadWidget->injectNetworkAccessManager(m_networkAccessManager);
+
+    connect(&m_midiIn, &MidiInWrapper::messageReceived, this, &MainWindow::messageReceived);
+
+    {
+        QEventLoop eventLoop;
+        connect(&m_decoderThread, &QThread::started, &eventLoop, &QEventLoop::quit);
+        m_decoderThread.start(QThread::HighestPriority);
+        eventLoop.exec();
+    }
+
+    m_ui->drumPadWidget->injectDecodingThread(m_decoderThread);
+    m_ui->djWidget->injectDecodingThread(m_decoderThread);
+
+    updateAudioDevices();
+    connect(m_ui->pushButtonRefreshAudioDevices, &QAbstractButton::pressed, this, &MainWindow::updateAudioDevices);
+    if (const auto &lastAudioDevice = m_settings.lastAudioDevice(); !lastAudioDevice.isEmpty())
+    {
+        if (const auto index = m_ui->comboBoxAudioDevice->findText(lastAudioDevice); index >= 0)
+            m_ui->comboBoxAudioDevice->setCurrentIndex(index);
+        else
+            goto paDefault;
+    }
+    else
+    {
+paDefault:
+        m_ui->comboBoxAudioDevice->setCurrentIndex(Pa_GetDefaultOutputDevice());
+    }
+    m_ui->spinBoxBufferSize->setValue(m_settings.framesPerBuffer());
+    connect(m_ui->pushButtonAudioDevice, &QAbstractButton::pressed, this, &MainWindow::openAudioDevice);
+
+    updateMidiInDevices();    
+    connect(m_ui->pushButtonRefreshMidiIn, &QAbstractButton::pressed, this, &MainWindow::updateMidiInDevices);
+    if (const auto &lastMidiInDevice = m_settings.lastMidiInDevice(); !lastMidiInDevice.isEmpty())
+    {
+        if (const auto index = m_ui->comboBoxMidiIn->findText(lastMidiInDevice); index >= 0)
+            m_ui->comboBoxMidiIn->setCurrentIndex(index);
+    }
+    connect(m_ui->pushButtonMidiIn, &QAbstractButton::pressed, this, &MainWindow::openMidiInDevice);
+
+    updateMidiOutDevices();
+    connect(m_ui->pushButtonRefreshMidiOut, &QAbstractButton::pressed, this, &MainWindow::updateMidiOutDevices);
+    if (const auto &lastMidiOutDevice = m_settings.lastMidiOutDevice(); !lastMidiOutDevice.isEmpty())
+    {
+        if (const auto index = m_ui->comboBoxMidiOut->findText(lastMidiOutDevice); index >= 0)
+            m_ui->comboBoxMidiOut->setCurrentIndex(index);
+    }
+    connect(m_ui->pushButtonMidiOut, &QAbstractButton::pressed, this, &MainWindow::openMidiOutDevice);
+
+    loadSettings();
+
+    connect(m_ui->drumPadWidget, &DrumPadWidget::sendMidi, this, &MainWindow::sendMidi);
+    connect(m_ui->djWidget, &DjWidget::sendMidi, this, &MainWindow::sendMidi);
+    connect(m_ui->synthisizerWidget, &SynthisizerWidget::sendMidi, this, &MainWindow::sendMidi);
+
+    m_lastIndex = m_ui->tabWidget->currentIndex();
+    connect(m_ui->tabWidget, &QTabWidget::currentChanged, this, &MainWindow::currentChanged);
+}
+
+MainWindow::~MainWindow()
+{
+    m_paStream = nullptr;
+
+    m_decoderThread.exit();
+    m_decoderThread.wait();
+}
+
+int MainWindow::writeSamples(frame_t *begin, frame_t *end)
+{
+    std::fill(begin, end, frame_t{0.,0.});
+
+    m_ui->drumPadWidget->writeSamples(begin, end);
+    m_ui->djWidget->writeSamples(begin, end);
+    m_ui->synthisizerWidget->writeSamples(begin, end);
+
+    std::transform(begin, end, begin, [factor=float(m_ui->horizontalSliderMaster->value())/100.f](frame_t frame){
+        std::transform(std::cbegin(frame), std::cend(frame), std::begin(frame), [&factor](const sample_t &sample){
+            return sample*factor;
+        });
+        return frame;
+    });
+
+    return paContinue;
+}
+
+void MainWindow::openAudioDevice()
+{
+    if (m_paStream)
+    {
+        m_paStream = nullptr;
+        m_ui->comboBoxAudioDevice->setEnabled(true);
+        m_ui->spinBoxBufferSize->setEnabled(true);
+        m_ui->pushButtonAudioDevice->setText(tr("Open"));
+    }
+    else
+    {
+        PaDeviceIndex index = m_ui->comboBoxAudioDevice->currentIndex();
+
+        const PaDeviceInfo* pInfo = Pa_GetDeviceInfo(index);
+
+        const PaStreamParameters outputParameters {
+            .device = index,
+            .channelCount = channelCount,
+            .sampleFormat = paFloat32, /* 32 bit floating point output */
+            .suggestedLatency = pInfo->defaultLowOutputLatency,
+            .hostApiSpecificStreamInfo = NULL
+        };
+
+        PaStream *stream{};
+
+        if (PaError err = Pa_OpenStream(&stream, NULL, &outputParameters, frameRate, m_ui->spinBoxBufferSize->value(), paNoFlag, &paCallback, this); err != paNoError)
+        {
+            QMessageBox::warning(this, tr("Error opening stream!"), tr("Error opening stream!") + "\n\n" + Pa_GetErrorText(err));
+            return;
+        }
+
+        auto smartPtr = std::unique_ptr<PaStream, void(*)(PaStream*)>(stream, PaStreamCloser);
+        stream = nullptr;
+
+        if (PaError err = Pa_SetStreamFinishedCallback(smartPtr.get(), &paStreamFinished); err != paNoError)
+        {
+            QMessageBox::warning(this, tr("Error setting finished callback!"), tr("Error setting finished callback!") + "\n\n" + Pa_GetErrorText(err));
+            return;
+        }
+
+        if (PaError err = Pa_StartStream(smartPtr.get()); err != paNoError)
+        {
+            QMessageBox::warning(this, tr("Error starting stream!"), tr("Error starting stream!") + "\n\n" + Pa_GetErrorText(err));
+            return;
+        }
+
+        // stream has been started and from now on we not only need to delete it, but also stop it first
+        smartPtr.get_deleter() = PaStreamStopperAndCloser;
+
+        m_paStream = std::move(smartPtr);
+        m_ui->comboBoxAudioDevice->setEnabled(false);
+        m_ui->spinBoxBufferSize->setEnabled(false);
+        m_ui->pushButtonAudioDevice->setText(tr("Close"));
+
+        m_settings.setLastAudioDevice(m_ui->comboBoxAudioDevice->currentText());
+        m_settings.setFramesPerBuffer(m_ui->spinBoxBufferSize->value());
+    }
+}
+
+void MainWindow::openMidiInDevice()
+{
+    if (m_midiIn.isPortOpen())
+        m_midiIn.closePort();
+    else
+    {
+        const auto index = m_ui->comboBoxMidiIn->currentIndex();
+        if (index != -1)
+            m_midiIn.openPort(index, "Input");
+        m_settings.setLastMidiInDevice(m_ui->comboBoxMidiIn->currentText());
+    }
+
+    m_ui->comboBoxMidiIn->setDisabled(m_midiIn.isPortOpen());
+    m_ui->pushButtonMidiIn->setText(m_midiIn.isPortOpen() ? tr("Close") : tr("Open"));
+}
+
+void MainWindow::openMidiOutDevice()
+{
+    if (m_midiOut.isPortOpen())
+    {
+        qDebug() << "closing port";
+        unsendColors(m_ui->tabWidget->currentIndex());
+        m_midiOut.closePort();
+    }
+    else
+    {
+        const auto index = m_ui->comboBoxMidiOut->currentIndex();
+        if (index != -1)
+        {
+            m_midiOut.openPort(index, "Output");
+            m_settings.setLastMidiOutDevice(m_ui->comboBoxMidiOut->currentText());
+            sendColors(m_ui->tabWidget->currentIndex());
+        }
+    }
+
+    m_ui->comboBoxMidiOut->setDisabled(m_midiOut.isPortOpen());
+    m_ui->pushButtonMidiOut->setText(m_midiOut.isPortOpen() ? tr("Close") : tr("Open"));
+}
+
+void MainWindow::messageReceived(const midi::MidiMessage &message)
+{
+    m_ui->statusbar->showMessage(tr("Received midi message: flag: %0 cmd: %1 channel: %2 note: %3 velocity: %4")
+                                 .arg(message.flag?"true":"false", QMetaEnum::fromType<midi::Command>().valueToKey(int(message.cmd)))
+                                 .arg(message.channel).arg(message.note).arg(message.velocity), 1000);
+
+    if (m_ui->tabWidget->currentIndex() == 0)
+        m_ui->drumPadWidget->messageReceived(message);
+    else if (m_ui->tabWidget->currentIndex() == 1)
+        m_ui->djWidget->messageReceived(message);
+    else if (m_ui->tabWidget->currentIndex() == 2)
+        m_ui->synthisizerWidget->messageReceived(message);
+}
+
+void MainWindow::sendMidi(const midi::MidiMessage &midiMsg)
+{
+    if (m_midiOut.isPortOpen())
+        m_midiOut.sendMessage(midiMsg);
+}
+
+void MainWindow::currentChanged(int index)
+{
+    unsendColors(m_lastIndex);
+    m_lastIndex = index;
+    sendColors(index);
+}
+
+void MainWindow::updateAudioDevices()
+{
+    m_ui->comboBoxAudioDevice->clear();
+
+    const auto count = Pa_GetDeviceCount();
+
+    for (PaDeviceIndex i = 0; i < count; i++)
+    {
+        const auto info = Pa_GetDeviceInfo(i);
+        m_ui->comboBoxAudioDevice->addItem(info->name);
+    }
+}
+
+void MainWindow::updateMidiInDevices()
+{
+    m_ui->comboBoxMidiIn->clear();
+
+    for (const auto &name : m_midiIn.portNames())
+        m_ui->comboBoxMidiIn->addItem(name);
+
+    m_ui->pushButtonMidiIn->setEnabled(m_ui->comboBoxMidiIn->count() > 0);
+}
+
+void MainWindow::updateMidiOutDevices()
+{
+    m_ui->comboBoxMidiOut->clear();
+
+    for (const auto &name : m_midiOut.portNames())
+        m_ui->comboBoxMidiOut->addItem(name);
+
+    m_ui->pushButtonMidiOut->setEnabled(m_ui->comboBoxMidiOut->count() > 0);
+}
+
+void MainWindow::loadSettings()
+{
+    m_ui->drumPadWidget->loadSettings(m_settings);
+    m_ui->djWidget->loadSettings(m_settings);
+    m_ui->synthisizerWidget->loadSettings(m_settings);
+}
+
+void MainWindow::unsendColors(int index)
+{
+    if (index == 0)
+        m_ui->drumPadWidget->unsendColors();
+    else if (index == 1)
+        m_ui->djWidget->unsendColors();
+    else if (index == 2)
+        m_ui->synthisizerWidget->unsendColors();
+}
+
+void MainWindow::sendColors(int index)
+{
+    if (index == 0)
+        m_ui->drumPadWidget->sendColors();
+    else if (index == 1)
+        m_ui->djWidget->sendColors();
+    else if (index == 2)
+        m_ui->synthisizerWidget->sendColors();
+
+    return;
+
+    // this was just for debugging all the available colors on novation launchpad mk1
+
+    int k{0};
+    for (int j = 0; j < 128; j+= 16)
+    {
+        qDebug() << k;
+        for (auto i = 0; i < 8; i++)
+        {
+            midi::MidiMessage midiMsg;
+            midiMsg.channel = 0;
+            midiMsg.cmd = midi::Command::NoteOn;
+            midiMsg.flag = true;
+            midiMsg.note = i + j;
+            midiMsg.velocity = k++;
+            sendMidi(midiMsg);
+        }
+    }
+}
+
+namespace {
+void DummyDeleter(PaStream *stream)
+{
+    Q_UNUSED(stream);
+}
+void PaStreamCloser(PaStream *stream)
+{
+    if (PaError err = Pa_CloseStream(stream); err != paNoError)
+        fprintf(stderr, "Could not close stream!\n");
+}
+void PaStreamStopperAndCloser(PaStream *stream)
+{
+    if (PaError err = Pa_StopStream(stream); err != paNoError)
+        fprintf(stderr, "Could not stop stream!\n");
+    PaStreamCloser(stream);
+}
+
+void paStreamFinished(void* userData)
+{
+    printf("Stream Completed\n");
+}
+
+int paCallback(const void *inputBuffer, void *outputBuffer,
+               unsigned long framesPerBuffer,
+               const PaStreamCallbackTimeInfo* timeInfo,
+               PaStreamCallbackFlags statusFlags,
+               void *userData)
+{
+    Q_UNUSED(inputBuffer)
+    Q_ASSERT(outputBuffer);
+    Q_ASSERT(framesPerBuffer);
+    Q_UNUSED(timeInfo)
+    Q_UNUSED(statusFlags)
+    Q_ASSERT(userData);
+
+    auto begin = static_cast<frame_t*>(outputBuffer);
+
+    return static_cast<MainWindow*>(userData)->writeSamples(begin, begin+framesPerBuffer);
+}
+} // namespace

widgets/mainwindow.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include <memory>
+
+#include <QMainWindow>
+#include <QThread>
+#include <QNetworkAccessManager>
+#include <QNetworkDiskCache>
+
+#include "portaudio.h"
+
+#include "audioformat.h"
+#include "midiinwrapper.h"
+#include "midioutwrapper.h"
+#include "drummachinesettings.h"
+
+namespace Ui { class MainWindow; }
+namespace presets { struct PresetsConfig; }
+namespace midi { struct MidiMessage; }
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+    ~MainWindow() override;
+
+    int writeSamples(frame_t *begin, frame_t *end);
+
+private slots:
+    void openAudioDevice();
+    void openMidiInDevice();
+    void openMidiOutDevice();
+    void messageReceived(const midi::MidiMessage &message);
+    void sendMidi(const midi::MidiMessage &midiMsg);
+    void currentChanged(int index);
+
+private:
+    void updateAudioDevices();
+    void updateMidiInDevices();
+    void updateMidiOutDevices();
+    void loadSettings();
+    void unsendColors(int index);
+    void sendColors(int index);
+
+    const std::unique_ptr<Ui::MainWindow> m_ui;
+
+    DrumMachineSettings m_settings;
+
+    std::unique_ptr<PaStream, void(*)(PaStream*)> m_paStream;
+
+    MidiInWrapper m_midiIn;
+    MidiOutWrapper m_midiOut;
+
+    QNetworkAccessManager m_networkAccessManager;
+    QNetworkDiskCache m_cache;
+
+    QThread m_decoderThread;
+
+    int m_lastIndex;
+};

widgets/mainwindow.ui

@@ -0,0 +1,261 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>1520</width>
+    <height>890</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>MainWindow</string>
+  </property>
+  <widget class="QWidget" name="widget">
+   <layout class="QVBoxLayout" stretch="0,0,0">
+    <property name="leftMargin">
+     <number>0</number>
+    </property>
+    <property name="topMargin">
+     <number>0</number>
+    </property>
+    <property name="rightMargin">
+     <number>0</number>
+    </property>
+    <property name="bottomMargin">
+     <number>0</number>
+    </property>
+    <item>
+     <layout class="QHBoxLayout">
+      <item>
+       <widget class="QLabel" name="labelDrumMachine">
+        <property name="text">
+         <string>&lt;b&gt;DrumMachine&lt;/b&gt;</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer>
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+        <property name="sizeHint" stdset="0">
+         <size>
+          <width>40</width>
+          <height>20</height>
+         </size>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="QLabel" name="labelMaster">
+        <property name="text">
+         <string>Master:</string>
+        </property>
+        <property name="buddy">
+         <cstring>horizontalSliderMaster</cstring>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QSlider" name="horizontalSliderMaster">
+        <property name="maximumSize">
+         <size>
+          <width>100</width>
+          <height>16777215</height>
+         </size>
+        </property>
+        <property name="maximum">
+         <number>100</number>
+        </property>
+        <property name="value">
+         <number>100</number>
+        </property>
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer>
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+        <property name="sizeHint" stdset="0">
+         <size>
+          <width>40</width>
+          <height>20</height>
+         </size>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="QComboBox" name="comboBoxAudioDevice"/>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonRefreshAudioDevices">
+        <property name="maximumSize">
+         <size>
+          <width>32</width>
+          <height>16777215</height>
+         </size>
+        </property>
+        <property name="text">
+         <string>↻</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QSpinBox" name="spinBoxBufferSize">
+        <property name="maximum">
+         <number>65535</number>
+        </property>
+        <property name="value">
+         <number>32</number>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonAudioDevice">
+        <property name="text">
+         <string>Open</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <layout class="QHBoxLayout" name="horizontalLayout">
+      <item>
+       <widget class="QLabel" name="labelMidiIn">
+        <property name="text">
+         <string>Midi in:</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QComboBox" name="comboBoxMidiIn"/>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonRefreshMidiIn">
+        <property name="maximumSize">
+         <size>
+          <width>32</width>
+          <height>16777215</height>
+         </size>
+        </property>
+        <property name="text">
+         <string>↻</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonMidiIn">
+        <property name="text">
+         <string>Open</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <spacer name="horizontalSpacer_2">
+        <property name="orientation">
+         <enum>Qt::Horizontal</enum>
+        </property>
+        <property name="sizeHint" stdset="0">
+         <size>
+          <width>40</width>
+          <height>20</height>
+         </size>
+        </property>
+       </spacer>
+      </item>
+      <item>
+       <widget class="QLabel" name="labelMidiOut">
+        <property name="text">
+         <string>Midi out:</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QComboBox" name="comboBoxMidiOut"/>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonRefreshMidiOut">
+        <property name="maximumSize">
+         <size>
+          <width>32</width>
+          <height>16777215</height>
+         </size>
+        </property>
+        <property name="text">
+         <string>↻</string>
+        </property>
+       </widget>
+      </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonMidiOut">
+        <property name="text">
+         <string>Open</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </item>
+    <item>
+     <widget class="QTabWidget" name="tabWidget">
+      <widget class="DrumPadWidget" name="drumPadWidget">
+       <attribute name="title">
+        <string>DrumPad</string>
+       </attribute>
+      </widget>
+      <widget class="DjWidget" name="djWidget">
+       <attribute name="title">
+        <string>DJ</string>
+       </attribute>
+      </widget>
+      <widget class="SynthisizerWidget" name="synthisizerWidget">
+       <attribute name="title">
+        <string>Synthisizer</string>
+       </attribute>
+      </widget>
+     </widget>
+    </item>
+   </layout>
+  </widget>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>1520</width>
+     <height>23</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>DjWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/djwidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>DrumPadWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/drumpadwidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>SynthisizerWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/synthisizerwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

widgets/presetdetailwidget.cpp

@@ -0,0 +1,16 @@
+#include "presetdetailwidget.h"
+#include "ui_presetdetailwidget.h"
+
+PresetDetailWidget::PresetDetailWidget(QWidget *parent) :
+    QScrollArea{parent},
+    m_ui{std::make_unique<Ui::PresetDetailWidget>()}
+{
+    m_ui->setupUi(this);
+}
+
+PresetDetailWidget::~PresetDetailWidget() = default;
+
+void PresetDetailWidget::setPreset(const presets::Preset &preset)
+{
+    // TODO
+}

widgets/presetdetailwidget.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <memory>
+
+#include <QScrollArea>
+
+namespace Ui { class PresetDetailWidget; }
+namespace presets { class Preset; }
+
+class PresetDetailWidget : public QScrollArea
+{
+    Q_OBJECT
+
+public:
+    explicit PresetDetailWidget(QWidget *parent = nullptr);
+    ~PresetDetailWidget() override;
+
+    void setPreset(const presets::Preset &preset);
+
+private:
+    const std::unique_ptr<Ui::PresetDetailWidget> m_ui;
+};

widgets/presetdetailwidget.ui

@@ -0,0 +1,306 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>PresetDetailWidget</class>
+ <widget class="QScrollArea" name="PresetDetailWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>320</width>
+    <height>633</height>
+   </rect>
+  </property>
+  <property name="widgetResizable">
+   <bool>true</bool>
+  </property>
+  <widget class="QWidget" name="scrollAreaWidgetContents">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>318</width>
+     <height>631</height>
+    </rect>
+   </property>
+   <layout class="QFormLayout" name="formLayout">
+    <item row="0" column="0">
+     <widget class="QLabel" name="labelId">
+      <property name="text">
+       <string>id:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditId</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="1" column="0">
+     <widget class="QLabel" name="labelName">
+      <property name="text">
+       <string>name:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditName</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="2" column="0">
+     <widget class="QLabel" name="labelAuthor">
+      <property name="text">
+       <string>author:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditAuthor</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="3" column="0">
+     <widget class="QLabel" name="labelOrderBy">
+      <property name="text">
+       <string>orderBy:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditOrderBy</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="4" column="0">
+     <widget class="QLabel" name="labelVersion">
+      <property name="text">
+       <string>version:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditVersion</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="5" column="0">
+     <widget class="QLabel" name="labelTempo">
+      <property name="text">
+       <string>tempo:</string>
+      </property>
+      <property name="buddy">
+       <cstring>spinBoxTempo</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="6" column="0">
+     <widget class="QLabel" name="labelIcon">
+      <property name="text">
+       <string>icon:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditIcon</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="7" column="0">
+     <widget class="QLabel" name="labelPrice">
+      <property name="text">
+       <string>price:</string>
+      </property>
+      <property name="buddy">
+       <cstring>spinBoxPrice</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="8" column="0">
+     <widget class="QLabel" name="labelPriceForSession">
+      <property name="text">
+       <string>priceForSession:</string>
+      </property>
+      <property name="buddy">
+       <cstring>spinBoxPriceForSession</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="9" column="0">
+     <widget class="QLabel" name="labelHasInfo">
+      <property name="text">
+       <string>hasInfo:</string>
+      </property>
+      <property name="buddy">
+       <cstring>checkBoxHasInfo</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="10" column="0">
+     <widget class="QLabel" name="labelTags">
+      <property name="text">
+       <string>tags:</string>
+      </property>
+     </widget>
+    </item>
+    <item row="11" column="0">
+     <widget class="QLabel" name="labelDeleted">
+      <property name="text">
+       <string>DELETED:</string>
+      </property>
+      <property name="buddy">
+       <cstring>checkBoxDeleted</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="12" column="0">
+     <widget class="QLabel" name="labelDifficulty">
+      <property name="text">
+       <string>difficulty:</string>
+      </property>
+      <property name="buddy">
+       <cstring>spinBoxDifficulty</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="13" column="0">
+     <widget class="QLabel" name="labelSample">
+      <property name="text">
+       <string>sample:</string>
+      </property>
+      <property name="buddy">
+       <cstring>spinBoxSample</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="14" column="0">
+     <widget class="QLabel" name="labelAudioPreview1Name">
+      <property name="text">
+       <string>audioPreview1Name:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditAudioPreview1Name</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="15" column="0">
+     <widget class="QLabel" name="labelAudioPreview1URL">
+      <property name="text">
+       <string>audioPreview1URL:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditAudioPreview1URL</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="16" column="0">
+     <widget class="QLabel" name="labelAudioPreview2Name">
+      <property name="text">
+       <string>audioPreview2Name:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditAudioPreview2Name</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="17" column="0">
+     <widget class="QLabel" name="labelAudioPreview2URL">
+      <property name="text">
+       <string>audioPreview2URL:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditAudioPreview2URL</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="18" column="0">
+     <widget class="QLabel" name="labelImagePreview1">
+      <property name="text">
+       <string>imagePreview1:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditImagePreview1</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="19" column="0">
+     <widget class="QLabel" name="labelVideoPreview">
+      <property name="text">
+       <string>videoPreview:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditVideoPreview</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="20" column="0">
+     <widget class="QLabel" name="labelVideoTutorial">
+      <property name="text">
+       <string>videoTutorial:</string>
+      </property>
+      <property name="buddy">
+       <cstring>lineEditVideoTutorial</cstring>
+      </property>
+     </widget>
+    </item>
+    <item row="0" column="1">
+     <widget class="QLineEdit" name="lineEditId"/>
+    </item>
+    <item row="1" column="1">
+     <widget class="QLineEdit" name="lineEditName"/>
+    </item>
+    <item row="2" column="1">
+     <widget class="QLineEdit" name="lineEditAuthor"/>
+    </item>
+    <item row="3" column="1">
+     <widget class="QLineEdit" name="lineEditOrderBy"/>
+    </item>
+    <item row="4" column="1">
+     <widget class="QLineEdit" name="lineEditVersion"/>
+    </item>
+    <item row="5" column="1">
+     <widget class="QSpinBox" name="spinBoxTempo"/>
+    </item>
+    <item row="6" column="1">
+     <widget class="QLineEdit" name="lineEditIcon"/>
+    </item>
+    <item row="7" column="1">
+     <widget class="QSpinBox" name="spinBoxPrice"/>
+    </item>
+    <item row="8" column="1">
+     <widget class="QSpinBox" name="spinBoxPriceForSession"/>
+    </item>
+    <item row="9" column="1">
+     <widget class="QCheckBox" name="checkBoxHasInfo">
+      <property name="text">
+       <string>CheckBox</string>
+      </property>
+     </widget>
+    </item>
+    <item row="11" column="1">
+     <widget class="QCheckBox" name="checkBoxDeleted">
+      <property name="text">
+       <string>CheckBox</string>
+      </property>
+     </widget>
+    </item>
+    <item row="12" column="1">
+     <widget class="QSpinBox" name="spinBoxDifficulty"/>
+    </item>
+    <item row="13" column="1">
+     <widget class="QSpinBox" name="spinBoxSample"/>
+    </item>
+    <item row="14" column="1">
+     <widget class="QLineEdit" name="lineEditAudioPreview1Name"/>
+    </item>
+    <item row="15" column="1">
+     <widget class="QLineEdit" name="lineEditAudioPreview1URL"/>
+    </item>
+    <item row="16" column="1">
+     <widget class="QLineEdit" name="lineEditAudioPreview2Name"/>
+    </item>
+    <item row="17" column="1">
+     <widget class="QLineEdit" name="lineEditAudioPreview2URL"/>
+    </item>
+    <item row="18" column="1">
+     <widget class="QLineEdit" name="lineEditImagePreview1"/>
+    </item>
+    <item row="19" column="1">
+     <widget class="QLineEdit" name="lineEditVideoPreview"/>
+    </item>
+    <item row="20" column="1">
+     <widget class="QLineEdit" name="lineEditVideoTutorial"/>
+    </item>
+   </layout>
+  </widget>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

widgets/previewwidget.cpp

@@ -0,0 +1,90 @@
+#include "previewwidget.h"
+
+#include <QPainter>
+#include <QPen>
+#include <QMouseEvent>
+
+#include "graphrenderer.h"
+
+PreviewWidget::PreviewWidget(QWidget *parent) :
+    QWidget(parent)
+{
+}
+
+void PreviewWidget::paintEvent(QPaintEvent *event)
+{
+    Q_UNUSED(event)
+
+    if (m_graphCache.isNull() || m_graphCache.size() != size())
+    {
+        m_graphCache = QPixmap{size()};
+
+        QPainter painter;
+        painter.begin(&m_graphCache);
+
+        painter.setBrush(palette().base());
+        painter.drawRect(m_graphCache.rect());
+
+        painter.setPen(QPen{palette().color(QPalette::Text)});
+        painter.setBrush(palette().text());
+
+        if (m_buffer.isValid())
+            GraphRenderer::render(m_graphCache.rect(), m_buffer.constData<frame_t>(), m_buffer.constData<frame_t>() + m_buffer.frameCount(), painter);
+
+        painter.end();
+    }
+
+    QPainter painter;
+    painter.begin(this);
+
+    painter.drawPixmap(0, 0, m_graphCache);
+
+    if (m_buffer.frameCount())
+    {
+        std::size_t currentSample = double(m_position) / m_buffer.frameCount() * width();
+
+        QPen pen(Qt::red);
+        pen.setWidth(3);
+        painter.setPen(pen);
+        painter.drawLine(currentSample, 0, currentSample, height());
+    }
+
+    painter.end();
+}
+
+void PreviewWidget::mousePressEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton)
+    {
+        setMouseTracking(true);
+        clicked(event->x(), event->y());
+    }
+
+    QWidget::mousePressEvent(event);
+}
+
+void PreviewWidget::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton)
+        setMouseTracking(false);
+
+    QWidget::mouseReleaseEvent(event);
+}
+
+void PreviewWidget::mouseMoveEvent(QMouseEvent *event)
+{
+    if (event->buttons().testFlag(Qt::LeftButton))
+        clicked(event->x(), event->y());
+
+    QWidget::mouseMoveEvent(event);
+}
+
+void PreviewWidget::clicked(int x, int y)
+{
+    if (!m_buffer.isValid())
+        return;
+
+    const auto samplesPerPixel = m_buffer.frameCount() / width();
+
+    emit positionSelected(x * samplesPerPixel);
+}

widgets/previewwidget.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <QWidget>
+#include <QPixmap>
+#include <QAudioBuffer>
+
+class PreviewWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit PreviewWidget(QWidget *parent = nullptr);
+
+    const QAudioBuffer &buffer() const { return m_buffer; }
+    void setBuffer(const QAudioBuffer &buffer) { m_buffer = buffer; m_graphCache = {}; repaint(); }
+
+    double position() const { return m_position; }
+    void setPosition(double position) { m_position = position; repaint(); }
+
+signals:
+    void positionSelected(double sample);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+
+private:
+    void clicked(int x, int y);
+
+    QAudioBuffer m_buffer;
+    double m_position{};
+    QPixmap m_graphCache;
+};

widgets/sampleswidget.cpp

@@ -0,0 +1,175 @@
+#include "sampleswidget.h"
+#include "ui_sampleswidget.h"
+
+#include <iterator>
+
+#include <QDebug>
+
+#include "midicontainers.h"
+
+SamplesWidget::SamplesWidget(QWidget *parent) :
+    QWidget{parent},
+    m_ui{std::make_unique<Ui::SamplesWidget>()}
+{
+    m_ui->setupUi(this);
+
+    connect(m_ui->checkBox, &QCheckBox::toggled, this, &SamplesWidget::updateWidgets);
+
+    connect(m_ui->pushButtonStopAll, &QAbstractButton::pressed, this, &SamplesWidget::stopAll);
+
+    quint8 padNr{};
+    for (SampleWidget &widget : getWidgets())
+    {
+        widget.setPadNr(padNr++);
+        connect(&widget, &SampleWidget::chokeTriggered, this, &SamplesWidget::chokeTriggered);
+        connect(&widget, &SampleWidget::sendMidi, this, &SamplesWidget::sendMidi);
+    }
+}
+
+SamplesWidget::~SamplesWidget() = default;
+
+void SamplesWidget::loadSettings(DrumMachineSettings &settings)
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.loadSettings(settings);
+}
+
+void SamplesWidget::setPreset(const presets::Preset &preset)
+{
+    m_preset = preset;
+
+    updateWidgets();
+}
+
+void SamplesWidget::messageReceived(const midi::MidiMessage &message)
+{
+    if (message == midi::MidiMessage{.channel=0,.cmd=midi::Command::ControlChange,.flag=true,.note=64,.velocity=127})
+    {
+        m_ui->checkBox->toggle();
+        return;
+    }
+
+    if (message.cmd != midi::Command::NoteOn && message.cmd != midi::Command::NoteOff)
+        return;
+
+    for (SampleWidget &widget : getWidgets())
+    {
+        if (widget.isLearning())
+        {
+            widget.learn(message.channel, message.note);
+        }
+        else if (widget.channel() == message.channel && widget.note() == message.note)
+        {
+            if (message.cmd == midi::Command::NoteOff || (message.cmd == midi::Command::NoteOn && message.velocity == 0))
+                widget.released();
+            else if (message.cmd == midi::Command::NoteOn)
+                widget.pressed(message.velocity);
+        }
+    }
+}
+
+void SamplesWidget::writeSamples(frame_t *begin, frame_t *end)
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.writeSamples(begin, end);
+}
+
+void SamplesWidget::injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager)
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.injectNetworkAccessManager(networkAccessManager);
+}
+
+void SamplesWidget::injectDecodingThread(QThread &thread)
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.injectDecodingThread(thread);
+}
+
+void SamplesWidget::unsendColors()
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.unsendColor();
+}
+
+void SamplesWidget::sendColors()
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.sendColor();
+}
+
+void SamplesWidget::sequencerTriggerSample(int index)
+{
+    const auto widgets = getWidgets();
+    if (index < 0 || index >= std::size(widgets))
+    {
+        qDebug() << "index out of range" << index;
+        return;
+    }
+    widgets[index].get().pressed(127);
+}
+
+void SamplesWidget::chokeTriggered(int choke)
+{
+    for (SampleWidget &widget : getWidgets())
+    {
+        if (&widget == sender())
+            continue;
+
+        if (widget.choke() && *widget.choke() && *widget.choke() == choke)
+            widget.forceStop();
+    }
+}
+
+void SamplesWidget::updateWidgets()
+{
+    const auto widgets = getWidgets();
+
+    auto files = *m_preset.files;
+
+    if (m_ui->checkBox->isChecked())
+        for (int i = 0; i < 12; i++)
+            std::swap(files[i], files[i+12]);
+
+    auto filesIter = std::cbegin(files);
+    auto widgetsIter = std::cbegin(widgets);
+
+    for (; filesIter != std::cend(files) && widgetsIter != std::cend(widgets); std::advance(filesIter, 1), std::advance(widgetsIter, 1))
+        widgetsIter->get().setFile(*m_preset.id, *filesIter);
+}
+
+void SamplesWidget::stopAll()
+{
+    for (SampleWidget &widget : getWidgets())
+        widget.forceStop();
+}
+
+std::array<std::reference_wrapper<SampleWidget>, 24> SamplesWidget::getWidgets()
+{
+    return {
+        std::ref(*m_ui->sampleWidget_1),
+        std::ref(*m_ui->sampleWidget_2),
+        std::ref(*m_ui->sampleWidget_3),
+        std::ref(*m_ui->sampleWidget_4),
+        std::ref(*m_ui->sampleWidget_5),
+        std::ref(*m_ui->sampleWidget_6),
+        std::ref(*m_ui->sampleWidget_7),
+        std::ref(*m_ui->sampleWidget_8),
+        std::ref(*m_ui->sampleWidget_9),
+        std::ref(*m_ui->sampleWidget_10),
+        std::ref(*m_ui->sampleWidget_11),
+        std::ref(*m_ui->sampleWidget_12),
+        std::ref(*m_ui->sampleWidget_13),
+        std::ref(*m_ui->sampleWidget_14),
+        std::ref(*m_ui->sampleWidget_15),
+        std::ref(*m_ui->sampleWidget_16),
+        std::ref(*m_ui->sampleWidget_17),
+        std::ref(*m_ui->sampleWidget_18),
+        std::ref(*m_ui->sampleWidget_19),
+        std::ref(*m_ui->sampleWidget_20),
+        std::ref(*m_ui->sampleWidget_21),
+        std::ref(*m_ui->sampleWidget_22),
+        std::ref(*m_ui->sampleWidget_23),
+        std::ref(*m_ui->sampleWidget_24)
+    };
+}

widgets/sampleswidget.h

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <memory>
+#include <array>
+#include <functional>
+
+#include <QWidget>
+
+#include "audioformat.h"
+#include "presets.h"
+
+namespace Ui { class SamplesWidget; }
+namespace midi { class MidiMessage; }
+class QNetworkAccessManager;
+class SampleWidget;
+class DrumMachineSettings;
+
+class SamplesWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit SamplesWidget(QWidget *parent = nullptr);
+    ~SamplesWidget() override;
+
+    void loadSettings(DrumMachineSettings &settings);
+
+    void setPreset(const presets::Preset &preset);
+
+    void messageReceived(const midi::MidiMessage &message);
+
+    void writeSamples(frame_t *begin, frame_t *end);
+
+    void injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager);
+    void injectDecodingThread(QThread &thread);
+
+    void unsendColors();
+    void sendColors();
+
+signals:
+    void sendMidi(const midi::MidiMessage &midiMsg);
+
+public slots:
+    void sequencerTriggerSample(int index);
+
+private slots:
+    void chokeTriggered(int choke);
+    void updateWidgets();
+    void stopAll();
+
+private:
+    std::array<std::reference_wrapper<SampleWidget>, 24> getWidgets();
+
+    const std::unique_ptr<Ui::SamplesWidget> m_ui;
+
+    presets::Preset m_preset;
+};

widgets/sampleswidget.ui

@@ -0,0 +1,184 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SamplesWidget</class>
+ <widget class="QWidget" name="SamplesWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>660</width>
+    <height>421</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <layout class="QGridLayout" name="gridLayout" rowstretch="0,0,0,0,0" columnstretch="0,0,0,0,0,0,0,0,0">
+   <item row="3" column="3">
+    <widget class="SampleWidget" name="sampleWidget_9" native="true"/>
+   </item>
+   <item row="4" column="3">
+    <widget class="SampleWidget" name="sampleWidget_12" native="true"/>
+   </item>
+   <item row="1" column="5">
+    <widget class="SampleWidget" name="sampleWidget_13" native="true"/>
+   </item>
+   <item row="1" column="7">
+    <widget class="SampleWidget" name="sampleWidget_15" native="true"/>
+   </item>
+   <item row="2" column="7">
+    <widget class="SampleWidget" name="sampleWidget_18" native="true"/>
+   </item>
+   <item row="4" column="6">
+    <widget class="SampleWidget" name="sampleWidget_23" native="true"/>
+   </item>
+   <item row="0" column="0" colspan="9">
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <spacer name="horizontalSpacer_4">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QCheckBox" name="checkBox">
+       <property name="text">
+        <string>Swap left/right</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="pushButtonStopAll">
+       <property name="text">
+        <string>Stop all</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer_5">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+    </layout>
+   </item>
+   <item row="3" column="2">
+    <widget class="SampleWidget" name="sampleWidget_8" native="true"/>
+   </item>
+   <item row="4" column="7">
+    <widget class="SampleWidget" name="sampleWidget_24" native="true"/>
+   </item>
+   <item row="1" column="0">
+    <spacer name="horizontalSpacer_2">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>40</width>
+       <height>20</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item row="1" column="1">
+    <widget class="SampleWidget" name="sampleWidget_1" native="true"/>
+   </item>
+   <item row="3" column="5">
+    <widget class="SampleWidget" name="sampleWidget_19" native="true"/>
+   </item>
+   <item row="3" column="7">
+    <widget class="SampleWidget" name="sampleWidget_21" native="true"/>
+   </item>
+   <item row="1" column="8">
+    <spacer name="horizontalSpacer_3">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>40</width>
+       <height>20</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item row="2" column="2">
+    <widget class="SampleWidget" name="sampleWidget_5" native="true"/>
+   </item>
+   <item row="1" column="2">
+    <widget class="SampleWidget" name="sampleWidget_2" native="true"/>
+   </item>
+   <item row="2" column="6">
+    <widget class="SampleWidget" name="sampleWidget_17" native="true"/>
+   </item>
+   <item row="3" column="6">
+    <widget class="SampleWidget" name="sampleWidget_20" native="true"/>
+   </item>
+   <item row="1" column="4">
+    <spacer name="horizontalSpacer">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="sizeHint" stdset="0">
+      <size>
+       <width>40</width>
+       <height>20</height>
+      </size>
+     </property>
+    </spacer>
+   </item>
+   <item row="2" column="5">
+    <widget class="SampleWidget" name="sampleWidget_16" native="true"/>
+   </item>
+   <item row="2" column="1">
+    <widget class="SampleWidget" name="sampleWidget_4" native="true"/>
+   </item>
+   <item row="4" column="5">
+    <widget class="SampleWidget" name="sampleWidget_22" native="true"/>
+   </item>
+   <item row="4" column="2">
+    <widget class="SampleWidget" name="sampleWidget_11" native="true"/>
+   </item>
+   <item row="1" column="3">
+    <widget class="SampleWidget" name="sampleWidget_3" native="true"/>
+   </item>
+   <item row="1" column="6">
+    <widget class="SampleWidget" name="sampleWidget_14" native="true"/>
+   </item>
+   <item row="4" column="1">
+    <widget class="SampleWidget" name="sampleWidget_10" native="true"/>
+   </item>
+   <item row="2" column="3">
+    <widget class="SampleWidget" name="sampleWidget_6" native="true"/>
+   </item>
+   <item row="3" column="1">
+    <widget class="SampleWidget" name="sampleWidget_7" native="true"/>
+   </item>
+  </layout>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>SampleWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/samplewidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

widgets/samplewidget.cpp

@@ -0,0 +1,340 @@
+#include "samplewidget.h"
+#include "ui_samplewidget.h"
+
+#include <QAbstractEventDispatcher>
+#include <QSoundEffect>
+#include <QNetworkRequest>
+#include <QNetworkReply>
+#include <QNetworkAccessManager>
+#include <QMetaEnum>
+#include <QDebug>
+
+#include "audiodecoder.h"
+#include "drummachinesettings.h"
+#include "midicontainers.h"
+
+namespace {
+QString toString(QString value) { return value; }
+QString toString(int value) { return QString::number(value); }
+QString toString(bool value) { return value?"true":"false"; }
+}
+
+SampleWidget::SampleWidget(QWidget *parent) :
+    QFrame{parent},
+    m_ui{std::make_unique<Ui::SampleWidget>()}
+{
+    m_ui->setupUi(this);
+
+    connect(m_ui->dialSpeed, &QAbstractSlider::valueChanged, &m_player, [&player=m_player](int value){ player.setSpeed(float(value)/100.f); });
+    connect(m_ui->dialVolume, &QAbstractSlider::valueChanged, &m_player, [&player=m_player](int value){ player.setVolume(float(value)/100.f); });
+
+    connect(&m_player, &AudioPlayer::playingChanged, this, &SampleWidget::updateStatus);
+
+    connect(m_ui->pushButton, &QAbstractButton::pressed, this, [this](){ pressed(127); });
+    connect(m_ui->pushButton, &QAbstractButton::released, this, &SampleWidget::released);
+    connect(m_ui->toolButtonLearn, &QAbstractButton::pressed, this, &SampleWidget::learnPressed);
+
+    updateStatus();
+}
+
+SampleWidget::~SampleWidget() = default;
+
+void SampleWidget::loadSettings(DrumMachineSettings &settings)
+{
+    m_ui->channelSpinBox->setValue(settings.padChannel(m_padNr));
+    m_ui->noteSpinBox->setValue(settings.padNote(m_padNr));
+
+    m_settings = &settings;
+}
+
+void SampleWidget::setFile(const QString &presetId, const presets::File &file)
+{
+    m_presetId = presetId;
+    m_file = file;
+
+    m_player.setBuffer({});
+
+    startRequest();
+
+    const auto setupLabel = [&](const auto &value, QLabel *label){
+        QString text;
+        QFont font;
+        QPalette pal;
+
+        if (value)
+            text = toString(*value);
+        else
+        {
+            text = tr("(null)");
+            font.setItalic(true);
+            pal.setColor(label->foregroundRole(), Qt::gray);
+        }
+
+        label->setText(text);
+        label->setFont(font);
+        label->setPalette(pal);
+    };
+
+    setupLabel(file.stopOnRelease, m_ui->stopOnReleaseLabel);
+    setupLabel(file.looped, m_ui->loopedLabel);
+    setupLabel(file.choke, m_ui->chokeLabel);
+}
+
+quint8 SampleWidget::channel() const
+{
+    return m_ui->channelSpinBox->value();
+}
+
+void SampleWidget::setChannel(quint8 channel)
+{
+    m_ui->channelSpinBox->setValue(channel);
+
+    if (m_settings)
+        m_settings->setPadChannel(m_padNr, channel);
+}
+
+quint8 SampleWidget::note() const
+{
+    return m_ui->noteSpinBox->value();
+}
+
+void SampleWidget::setNote(quint8 note)
+{
+    m_ui->noteSpinBox->setValue(note);
+
+    if (m_settings)
+        m_settings->setPadNote(m_padNr, note);
+}
+
+int SampleWidget::speed() const
+{
+    return m_ui->dialSpeed->value();
+}
+
+void SampleWidget::setSpeed(int speed)
+{
+    m_ui->dialSpeed->setValue(speed);
+}
+
+int SampleWidget::volume() const
+{
+    return m_ui->dialVolume->value();
+}
+
+void SampleWidget::setVolume(int volume)
+{
+    m_ui->dialVolume->setValue(volume);
+}
+
+std::optional<int> SampleWidget::choke() const
+{
+    if (!m_file)
+        return {};
+    return m_file->choke;
+}
+
+void SampleWidget::pressed(quint8 velocity)
+{
+    Q_UNUSED(velocity)
+
+    m_player.restart();
+
+    if (m_file && m_file->choke && *m_file->choke)
+        emit chokeTriggered(*m_file->choke);
+}
+
+void SampleWidget::released()
+{
+}
+
+void SampleWidget::forceStop()
+{
+    m_player.setPlaying(false);
+}
+
+void SampleWidget::injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager)
+{
+    m_networkAccessManager = &networkAccessManager;
+    if (m_file)
+        startRequest();
+}
+
+void SampleWidget::injectDecodingThread(QThread &thread)
+{
+    QMetaObject::invokeMethod(QAbstractEventDispatcher::instance(&thread), [this](){
+        m_decoder = std::make_unique<AudioDecoder>();
+        connect(this, &SampleWidget::startDecoding, m_decoder.get(), &AudioDecoder::startDecodingDevice);
+        connect(m_decoder.get(), &AudioDecoder::decodingFinished, this, &SampleWidget::decodingFinished);
+        if (m_reply && m_reply->isFinished() && m_reply->error() == QNetworkReply::NoError)
+            m_decoder->startDecodingDevice(m_reply);
+    });
+}
+
+void SampleWidget::writeSamples(frame_t *begin, frame_t *end)
+{
+    m_player.writeSamples(begin, end);
+}
+
+void SampleWidget::learn(quint8 channel, quint8 note)
+{
+    setChannel(channel);
+    setNote(note);
+    if (m_learning)
+        learnPressed();
+}
+
+void SampleWidget::unsendColor()
+{
+    m_sendColors = false;
+    midi::MidiMessage midiMsg;
+
+    midiMsg.channel = m_ui->channelSpinBox->value();
+    midiMsg.cmd = midi::Command::NoteOn;
+    midiMsg.flag = true;
+    midiMsg.note = m_ui->noteSpinBox->value();
+    midiMsg.velocity = 0;
+
+    emit sendMidi(midiMsg);
+}
+
+void SampleWidget::sendColor()
+{
+    m_sendColors = true;
+    midi::MidiMessage midiMsg;
+
+    midiMsg.channel = m_ui->channelSpinBox->value();
+    midiMsg.cmd = midi::Command::NoteOn;
+    midiMsg.flag = true;
+    midiMsg.note = m_ui->noteSpinBox->value();
+
+    if (m_file && m_file->color && m_player.buffer().isValid())
+    {
+        const auto &color = *m_file->color;
+        if (color == "purple")
+            midiMsg.velocity = m_player.playing() ? 43 : 18;
+        else if (color == "red")
+            midiMsg.velocity = m_player.playing() ? 3 : 1;
+        else if (color == "yellow")
+            midiMsg.velocity = m_player.playing() ? 58 : 33;
+        else if (color == "green")
+            midiMsg.velocity = m_player.playing() ? 56 : 16;
+        else if (color == "blue")
+            midiMsg.velocity = m_player.playing() ? 49 : 51;
+        else
+            goto noColor;
+    }
+    else
+    {
+        noColor:
+        midiMsg.velocity = 0;
+    }
+
+    emit sendMidi(midiMsg);
+}
+
+void SampleWidget::updateStatus()
+{
+    QPalette pal;
+
+
+    if (m_file && m_file->color && m_player.buffer().isValid())
+    {
+        const auto bright = m_player.playing() ? 255 : 155;
+        const auto dark = m_player.playing() ?
+#if !defined(Q_OS_WIN)
+        80 : 0
+#else
+        180 : 80
+#endif
+;
+
+        const auto &color = *m_file->color;
+        if (color == "purple")
+            pal.setColor(QPalette::Window, QColor{bright, dark, bright});
+        else if (color == "red")
+            pal.setColor(QPalette::Window, QColor{bright, dark, dark});
+        else if (color == "yellow")
+            pal.setColor(QPalette::Window, QColor{bright, bright, dark});
+        else if (color == "green")
+            pal.setColor(QPalette::Window, QColor{dark, bright, dark});
+        else if (color == "blue")
+            pal.setColor(QPalette::Window, QColor{dark, dark, bright});
+        else
+            qWarning() << "unknown color:" << color;
+    }
+    setPalette(pal);
+
+    if (m_sendColors)
+        sendColor();
+
+    if (m_reply)
+    {
+        if (!m_reply->isFinished())
+            m_ui->statusLabel->setText(tr("Downloading..."));
+        else if (m_reply->error() != QNetworkReply::NoError)
+            m_ui->statusLabel->setText(QMetaEnum::fromType<QNetworkReply::NetworkError>().valueToKey(m_reply->error()));
+        else
+        {
+            if (!m_decoder)
+                m_ui->statusLabel->setText(tr("Waiting for decoder thread..."));
+            else
+                m_ui->statusLabel->setText(tr("Decoding"));
+        }
+    }
+    else
+        m_ui->statusLabel->setText(m_player.playing() ? tr("Playing") : tr("Ready"));
+}
+
+void SampleWidget::requestFinished()
+{
+    if (m_reply->error() == QNetworkReply::NoError)
+    {
+        emit startDecoding(m_reply);
+    }
+    updateStatus();
+}
+
+void SampleWidget::decodingFinished(const QAudioBuffer &buffer)
+{
+    m_reply = nullptr;
+    m_player.setBuffer(buffer);
+    setSpeed(100);
+    setVolume(100);
+    updateStatus();
+}
+
+void SampleWidget::learnPressed()
+{
+    auto palette = m_ui->toolButtonLearn->palette();
+
+    if (m_learning)
+    {
+        palette.setColor(m_ui->toolButtonLearn->backgroundRole(), m_oldColor);
+        palette.setBrush(m_ui->toolButtonLearn->backgroundRole(), m_oldBrush);
+    }
+    else
+    {
+        m_oldColor = palette.color(m_ui->toolButtonLearn->backgroundRole());
+        m_oldBrush = palette.brush(m_ui->toolButtonLearn->backgroundRole());
+        palette.setColor(m_ui->toolButtonLearn->backgroundRole(), Qt::red);
+        palette.setBrush(m_ui->toolButtonLearn->backgroundRole(), Qt::red);
+    }
+    m_ui->toolButtonLearn->setPalette(palette);
+
+    m_learning = !m_learning;
+    qDebug() << m_learning;
+}
+
+void SampleWidget::startRequest()
+{
+    if (m_networkAccessManager && m_file->filename)
+    {
+        QNetworkRequest request{QUrl{QString{"https://brunner.ninja/komposthaufen/dpm/presets/extracted/%0/%1"}.arg(m_presetId, *m_file->filename)}};
+        request.setAttribute(QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferCache);
+        request.setAttribute(QNetworkRequest::CacheSaveControlAttribute, true);
+        m_reply = std::shared_ptr<QNetworkReply>{m_networkAccessManager->get(request)};
+        connect(m_reply.get(), &QNetworkReply::finished, this, &SampleWidget::requestFinished);
+    }
+
+    updateStatus();
+}

widgets/samplewidget.h

@@ -0,0 +1,100 @@
+#pragma once
+
+#include <memory>
+
+#include <QFrame>
+
+#include "audioformat.h"
+#include "presets.h"
+#include "audioplayer.h"
+#include "midicontainers.h"
+
+namespace Ui { class SampleWidget; }
+class QNetworkAccessManager;
+class QNetworkReply;
+class QAudioBuffer;
+class AudioDecoder;
+class DrumMachineSettings;
+
+class SampleWidget : public QFrame
+{
+    Q_OBJECT
+
+public:
+    explicit SampleWidget(QWidget *parent = nullptr);
+    ~SampleWidget() override;
+
+    quint8 padNr() const { return m_padNr; }
+    void setPadNr(quint8 padNr) { m_padNr = padNr; }
+
+    void loadSettings(DrumMachineSettings &settings);
+
+    void setFile(const QString &presetId, const presets::File &file);
+
+    quint8 channel() const;
+    void setChannel(quint8 channel);
+
+    quint8 note() const;
+    void setNote(quint8 note);
+
+    int speed() const;
+    void setSpeed(int speed);
+
+    int volume() const;
+    void setVolume(int volume);
+
+    std::optional<int> choke() const;
+
+    void pressed(quint8 velocity);
+    void released();
+
+    void forceStop();
+
+    void injectNetworkAccessManager(QNetworkAccessManager &networkAccessManager);
+    void injectDecodingThread(QThread &thread);
+
+    void writeSamples(frame_t *begin, frame_t *end);
+
+    bool isLearning() const { return m_learning; }
+    void learn(quint8 channel, quint8 note);
+
+    void unsendColor();
+    void sendColor();
+
+signals:
+    void chokeTriggered(int choke);
+    void startDecoding(std::shared_ptr<QIODevice> device);
+    void sendMidi(const midi::MidiMessage &midiMsg);
+
+private slots:
+    void updateStatus();
+    void requestFinished();
+    void decodingFinished(const QAudioBuffer &buffer);
+    void learnPressed();
+
+private:
+    void startRequest();
+
+    const std::unique_ptr<Ui::SampleWidget> m_ui;
+
+    DrumMachineSettings *m_settings{};
+
+    std::shared_ptr<QNetworkReply> m_reply;
+
+    std::unique_ptr<AudioDecoder> m_decoder;
+
+    AudioPlayer m_player;
+
+    QString m_presetId;
+    std::optional<presets::File> m_file;
+
+    QNetworkAccessManager *m_networkAccessManager{};
+
+    quint8 m_padNr{};
+
+    bool m_learning{};
+    QColor m_oldColor;
+    QBrush m_oldBrush;
+
+    bool m_sendColors{};
+};

widgets/samplewidget.ui

@@ -0,0 +1,156 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SampleWidget</class>
+ <widget class="QFrame" name="SampleWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>140</width>
+    <height>157</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <property name="autoFillBackground">
+   <bool>true</bool>
+  </property>
+  <property name="frameShape">
+   <enum>QFrame::Panel</enum>
+  </property>
+  <property name="frameShadow">
+   <enum>QFrame::Sunken</enum>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_5">
+     <item>
+      <widget class="QLabel" name="statusLabel">
+       <property name="text">
+        <string>TextLabel</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QDial" name="dialSpeed">
+       <property name="maximumSize">
+        <size>
+         <width>32</width>
+         <height>32</height>
+        </size>
+       </property>
+       <property name="minimum">
+        <number>80</number>
+       </property>
+       <property name="maximum">
+        <number>120</number>
+       </property>
+       <property name="value">
+        <number>100</number>
+       </property>
+       <property name="notchTarget">
+        <double>10.000000000000000</double>
+       </property>
+       <property name="notchesVisible">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_4">
+     <item>
+      <widget class="QPushButton" name="pushButton">
+       <property name="maximumSize">
+        <size>
+         <width>32</width>
+         <height>16777215</height>
+        </size>
+       </property>
+       <property name="text">
+        <string>▶</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QDial" name="dialVolume">
+       <property name="maximumSize">
+        <size>
+         <width>32</width>
+         <height>32</height>
+        </size>
+       </property>
+       <property name="maximum">
+        <number>100</number>
+       </property>
+       <property name="value">
+        <number>100</number>
+       </property>
+       <property name="notchTarget">
+        <double>10.000000000000000</double>
+       </property>
+       <property name="notchesVisible">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <widget class="QSpinBox" name="channelSpinBox"/>
+     </item>
+     <item>
+      <widget class="QSpinBox" name="noteSpinBox"/>
+     </item>
+     <item>
+      <widget class="QToolButton" name="toolButtonLearn">
+       <property name="text">
+        <string>...</string>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_2">
+     <item>
+      <widget class="QLabel" name="stopOnReleaseLabel">
+       <property name="frameShape">
+        <enum>QFrame::Panel</enum>
+       </property>
+       <property name="frameShadow">
+        <enum>QFrame::Sunken</enum>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="loopedLabel">
+       <property name="frameShape">
+        <enum>QFrame::Panel</enum>
+       </property>
+       <property name="frameShadow">
+        <enum>QFrame::Sunken</enum>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="chokeLabel">
+       <property name="frameShape">
+        <enum>QFrame::Panel</enum>
+       </property>
+       <property name="frameShadow">
+        <enum>QFrame::Sunken</enum>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

widgets/scratchwidget.cpp

@@ -0,0 +1,142 @@
+#include "scratchwidget.h"
+
+#include <QPainter>
+#include <QRect>
+#include <QMouseEvent>
+#include <QDebug>
+
+#include "graphrenderer.h"
+
+ScratchWidget::ScratchWidget(QWidget *parent) :
+    QWidget{parent}
+{
+    connect(&m_timer, &QTimer::timeout, this, &ScratchWidget::timeout);
+    m_timer.setSingleShot(true);
+    m_timer.setInterval(100);
+}
+
+void ScratchWidget::paintEvent(QPaintEvent *event)
+{
+    QPainter painter;
+    painter.begin(this);
+
+    painter.setPen({});
+    painter.setBrush(palette().window());
+    painter.drawRect(rect());
+
+    if (m_buffer.isValid() && m_position < m_buffer.frameCount() - m_framesPerBeat)
+    {
+        {
+            QPen pen{Qt::blue};
+            pen.setWidth(3);
+            painter.setPen(pen);
+        }
+
+        const auto doit = [&](int offset)
+        {
+            int x = ((width()/2)-(float(m_position % m_framesPerBeat) / m_framesPerBeat * m_beatWidth)) + (m_beatWidth*offset);
+            const auto pixmap = getPixmap((m_position/m_framesPerBeat)+offset);
+            if (!pixmap.isNull())
+                painter.drawPixmap(x, 0, pixmap);
+        };
+
+        doit(-2);
+        doit(-1);
+        doit(0);
+        doit(1);
+        doit(2);
+    }
+
+    {
+        QPen pen{Qt::red};
+        pen.setWidth(3);
+        painter.setPen(pen);
+    }
+
+    painter.drawLine(width()/2, 0, width()/2, height());
+
+    painter.end();
+}
+
+void ScratchWidget::mousePressEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton)
+    {
+        m_scratching = true;
+        m_mouseX = event->x();
+        m_timestamp = QDateTime::currentDateTime();
+        setMouseTracking(true);
+        emit scratchBegin();
+        emit scratchSpeed(0.f);
+    }
+}
+
+void ScratchWidget::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (event->button() == Qt::LeftButton)
+    {
+        m_timer.stop();
+        emit scratchSpeed(1.f);
+        m_scratching = false;
+        setMouseTracking(false);
+        emit scratchEnd();
+    }
+}
+
+void ScratchWidget::mouseMoveEvent(QMouseEvent *event)
+{
+    if (m_scratching)
+    {
+        const auto now = QDateTime::currentDateTime();
+
+        int dx = m_mouseX - event->x();
+        int dt = m_timestamp.msecsTo(now);
+
+        emit scratchSpeed(float(dx) / dt * m_framesPerBeat / m_beatWidth / 50);
+
+        m_mouseX = event->x();
+        m_timestamp = now;
+        m_timer.start();
+    }
+}
+
+void ScratchWidget::timeout()
+{
+    emit scratchSpeed(0.f);
+}
+
+QPixmap ScratchWidget::getPixmap(int index)
+{
+    {
+        const auto pixmap = m_graphCache[index];
+        if (pixmap)
+            return *pixmap;
+    }
+
+    if (!m_buffer.isValid() || index < 0 || index >= m_buffer.frameCount()/m_framesPerBeat)
+    {
+        qWarning() << index;
+        return {};
+    }
+
+    const auto *begin = m_buffer.constData<frame_t>() + (index*m_framesPerBeat);
+
+    const auto pixmap = new QPixmap{QSize{m_beatWidth, height()}};
+
+    {
+        QPainter painter;
+        painter.begin(pixmap);
+
+        painter.setPen(Qt::blue);
+        painter.setBrush(palette().base());
+        painter.drawRect(pixmap->rect());
+
+        painter.setPen(QPen{palette().color(QPalette::Text)});
+        painter.setBrush(palette().text());
+        GraphRenderer::render(pixmap->rect(), begin, begin+m_framesPerBeat, painter);
+    }
+
+    m_graphCache.insert(index, pixmap);
+
+    return *pixmap;
+}

widgets/scratchwidget.h

@@ -0,0 +1,59 @@
+#pragma once
+
+#include <QWidget>
+#include <QAudioBuffer>
+#include <QCache>
+#include <QDateTime>
+#include <QTimer>
+
+#include "audioformat.h"
+
+class ScratchWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit ScratchWidget(QWidget *parent = nullptr);
+
+    const QAudioBuffer &buffer() const { return m_buffer; }
+    void setBuffer(const QAudioBuffer &buffer) { m_buffer = buffer; m_graphCache.clear(); repaint(); }
+
+    std::ptrdiff_t position() const { return m_position; }
+    void setPosition(std::ptrdiff_t position) { m_position = position; repaint(); }
+
+    int beatWidth() const { return m_beatWidth; };
+    void setBeatWidth(int beatWidth) { m_beatWidth = beatWidth; m_graphCache.clear(); repaint(); };
+
+    int framesPerBeat() const { return m_framesPerBeat; }
+    void setFramesPerBeat(int framesPerBeat) { m_framesPerBeat = framesPerBeat; m_graphCache.clear(); repaint(); }
+
+signals:
+    void scratchBegin();
+    void scratchSpeed(float speed);
+    void scratchEnd();
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+
+private slots:
+    void timeout();
+
+private:
+    QPixmap getPixmap(int index);
+
+    QAudioBuffer m_buffer;
+    std::ptrdiff_t m_position{};
+    QCache<int, QPixmap> m_graphCache;
+
+    int m_beatWidth{100};
+    int m_framesPerBeat{frameRate/4};
+
+    bool m_scratching{};
+    bool m_dragging{};
+    int m_mouseX;
+    QDateTime m_timestamp;
+    QTimer m_timer;
+};

widgets/sequencerwidget.cpp

@@ -0,0 +1,153 @@
+#include "sequencerwidget.h"
+#include "ui_sequencerwidget.h"
+
+#include <algorithm>
+
+#include <QDebug>
+
+#include "presets.h"
+
+SequencerWidget::SequencerWidget(QWidget *parent) :
+    QWidget{parent},
+    m_ui{std::make_unique<Ui::SequencerWidget>()}
+{
+    m_ui->setupUi(this);
+
+    connect(m_ui->spinBoxTempo, qOverload<int>(&QSpinBox::valueChanged), this, &SequencerWidget::tempoChanged);
+    connect(m_ui->comboBoxSequence, qOverload<int>(&QComboBox::currentIndexChanged), this, &SequencerWidget::sequenceSelected);
+    connect(m_ui->horizontalSlider, &QSlider::valueChanged, this, [=](int value){ m_pos = value; updateStatusLabel(); });
+
+    connect(m_ui->pushButtonPlayPause, &QAbstractButton::pressed, this, &SequencerWidget::playPause);
+    connect(m_ui->pushButtonStop, &QAbstractButton::pressed, this, &SequencerWidget::stop);
+
+    connect(&m_timer, &QTimer::timeout, this, &SequencerWidget::timeout);
+
+    updateStatusLabel();
+}
+
+SequencerWidget::~SequencerWidget() = default;
+
+void SequencerWidget::setPreset(const presets::Preset &preset)
+{
+    if (preset.tempo)
+        m_ui->spinBoxTempo->setValue(*preset.tempo);
+
+    for (int i = 0; i < 24; i++)
+        qobject_cast<QLabel*>(m_ui->gridLayout->itemAtPosition(2+(i*2), 0)->widget())->setText(*preset.files->at(i).filename);
+
+    m_selectedSequence = nullptr;
+    m_ui->horizontalSlider->setMaximum(0);
+
+    m_ui->comboBoxSequence->clear();
+    m_sequences.clear();
+    m_selectedSequence = nullptr;
+
+    const auto doit = [&](const QString &prefix, const std::optional<std::map<QString, std::vector<presets::Sequence>>> &value)
+    {
+        if (!value)
+            return;
+
+        for (const auto &pair : *value)
+        {
+            for (const auto &sequence : pair.second)
+            {
+                m_ui->comboBoxSequence->addItem(QString{"%0/%1/%2"}.arg(prefix, pair.first, sequence.name?*sequence.name:"(null)"));
+                m_sequences.emplace_back(sequence);
+            }
+        }
+    };
+
+    {
+        QSignalBlocker blocker{m_ui->comboBoxSequence};
+        doit("beatSchool", preset.beatSchool);
+        doit("easyPlay", preset.easyPlay);
+    }
+
+    sequenceSelected();
+}
+
+void SequencerWidget::playPause()
+{
+    if (m_timer.isActive())
+    {
+        m_timer.stop();
+        m_ui->pushButtonPlayPause->setText(tr("▶"));
+    }
+    else
+    {
+        m_timer.start();
+        m_ui->pushButtonPlayPause->setText(tr("▮▮"));
+    }
+}
+
+void SequencerWidget::stop()
+{
+    m_timer.stop();
+    m_ui->pushButtonPlayPause->setText(tr("▶"));
+    m_pos = 0;
+    m_ui->horizontalSlider->setValue(0);
+    updateStatusLabel();
+}
+
+void SequencerWidget::tempoChanged(int tempo)
+{
+    m_timer.setInterval(1000. * 60. / tempo / 4.);
+}
+
+void SequencerWidget::sequenceSelected()
+{
+    const auto index = m_ui->comboBoxSequence->currentIndex();
+
+    if (index == -1)
+        m_selectedSequence = nullptr;
+    else
+        m_selectedSequence = &m_sequences[index];
+
+    m_ui->horizontalSlider->setMaximum(m_selectedSequence && m_selectedSequence->sequencerSize ? *m_selectedSequence->sequencerSize-2 : 0);
+
+    m_ui->pushButtonPlayPause->setEnabled(m_selectedSequence != nullptr);
+    m_ui->pushButtonStop->setEnabled(m_selectedSequence != nullptr);
+
+    m_pos = 0;
+    m_ui->horizontalSlider->setValue(0);
+    updateStatusLabel();
+}
+
+void SequencerWidget::timeout()
+{
+    if (m_selectedSequence && m_selectedSequence->pads)
+    {
+        for (const auto &pair : *m_selectedSequence->pads)
+        {
+            const auto iter = std::find_if(std::cbegin(pair.second), std::cend(pair.second), [&](const presets::SequencePad &sequencePad){
+                return sequencePad.start && *sequencePad.start == m_pos;
+            });
+
+            if (iter == std::cend(pair.second))
+                continue;
+
+            //TODO: iter->duration;
+
+            bool ok;
+            const auto index = pair.first.toInt(&ok);
+            if (!ok)
+                continue;
+
+            emit triggerSample(index);
+        }
+    }
+
+    m_pos++;
+
+    if (m_pos >= (m_selectedSequence && m_selectedSequence->sequencerSize ? *m_selectedSequence->sequencerSize-1 : -1))
+        m_pos = 0;
+
+    m_ui->horizontalSlider->setValue(m_pos);
+
+    updateStatusLabel();
+}
+
+void SequencerWidget::updateStatusLabel()
+{
+    m_ui->labelStatus->setText(QString{"%0 / %1"}.arg(m_pos+1).arg(m_selectedSequence && m_selectedSequence->sequencerSize ? *m_selectedSequence->sequencerSize-1 : -1));
+}

widgets/sequencerwidget.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include <array>
+
+#include <QWidget>
+#include <QTimer>
+
+namespace Ui { class SequencerWidget; }
+namespace presets { class Preset; class Sequence; }
+class QLabel;
+
+class SequencerWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit SequencerWidget(QWidget *parent = nullptr);
+    ~SequencerWidget() override;
+
+    void setPreset(const presets::Preset &preset);
+
+signals:
+    void triggerSample(int index);
+
+private slots:
+    void playPause();
+    void stop();
+
+    void tempoChanged(int tempo);
+    void sequenceSelected();
+    void timeout();
+
+    void updateStatusLabel();
+
+private:
+    const std::unique_ptr<Ui::SequencerWidget> m_ui;
+
+    std::vector<presets::Sequence> m_sequences;
+    const presets::Sequence *m_selectedSequence{};
+
+    QTimer m_timer;
+
+    int m_pos{};
+    std::array<QLabel*, 24> m_sampleLabels;
+};

widgets/sequencerwidget.ui

@@ -0,0 +1,522 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SequencerWidget</class>
+ <widget class="QWidget" name="SequencerWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>912</width>
+    <height>611</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout" stretch="0,1">
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout" stretch="0,0,0,0,0,1">
+     <item>
+      <widget class="QSpinBox" name="spinBoxTempo">
+       <property name="suffix">
+        <string>BPM</string>
+       </property>
+       <property name="maximum">
+        <number>999</number>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QComboBox" name="comboBoxSequence"/>
+     </item>
+     <item>
+      <widget class="QPushButton" name="pushButtonPlayPause">
+       <property name="maximumSize">
+        <size>
+         <width>32</width>
+         <height>16777215</height>
+        </size>
+       </property>
+       <property name="text">
+        <string>▶</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="pushButtonStop">
+       <property name="maximumSize">
+        <size>
+         <width>32</width>
+         <height>16777215</height>
+        </size>
+       </property>
+       <property name="text">
+        <string>◼</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="labelStatus">
+       <property name="text">
+        <string>TextLabel</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QSlider" name="horizontalSlider">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QScrollArea" name="scrollArea">
+     <property name="widgetResizable">
+      <bool>true</bool>
+     </property>
+     <widget class="QWidget" name="scrollAreaWidgetContents">
+      <property name="geometry">
+       <rect>
+        <x>0</x>
+        <y>0</y>
+        <width>878</width>
+        <height>921</height>
+       </rect>
+      </property>
+      <layout class="QGridLayout" name="gridLayout" columnstretch="0,0,1">
+       <item row="38" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="34" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="19" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="10" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="7" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="14" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="5" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="15" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="41" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="44" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="47" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="29" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="32" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="12" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="27" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="48" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="11" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="28" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="18" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="16" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="13" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="25" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="40" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="6" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="30" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="26" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="43" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="42" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="3" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="39" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="21" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="31" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="23" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="37" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="4" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="35" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="9" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="20" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="17" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="36" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="0" column="1" rowspan="49" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::VLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="8" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="2" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="33" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="22" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="46" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="45" column="0" colspan="3">
+        <widget class="QFrame">
+         <property name="frameShape">
+          <enum>QFrame::HLine</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Sunken</enum>
+         </property>
+        </widget>
+       </item>
+       <item row="24" column="0">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+       <item row="0" column="2">
+        <widget class="QLabel">
+         <property name="text">
+          <string>TextLabel</string>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

widgets/synthisizerwidget.cpp

@@ -0,0 +1,46 @@
+#include "synthisizerwidget.h"
+#include "ui_synthisizerwidget.h"
+
+#include <cmath>
+
+#include "midicontainers.h"
+
+SynthisizerWidget::SynthisizerWidget(QWidget *parent) :
+    QWidget{parent},
+    m_ui{std::make_unique<Ui::SynthisizerWidget>()}
+{
+    m_ui->setupUi(this);
+
+    connect(m_ui->horizontalSliderVolume, &QSlider::valueChanged,
+            &m_synthisizer, [&synthisizer=m_synthisizer](int value){ synthisizer.setVolume(float(value) / 100.f); });
+}
+
+SynthisizerWidget::~SynthisizerWidget() = default;
+
+void SynthisizerWidget::writeSamples(frame_t *begin, frame_t *end)
+{
+    m_synthisizer.writeSamples(begin, end);
+}
+
+void SynthisizerWidget::loadSettings(DrumMachineSettings &settings)
+{
+}
+
+void SynthisizerWidget::unsendColors()
+{
+}
+
+void SynthisizerWidget::sendColors()
+{
+}
+
+void SynthisizerWidget::messageReceived(const midi::MidiMessage &message)
+{
+    if (message.cmd == midi::Command::NoteOff || (message.cmd == midi::Command::NoteOn && message.velocity == 0))
+    {
+        if (m_synthisizer.frequency() == int16_t(440.*std::pow(std::pow(2., 1./12.), message.note-48)))
+            m_synthisizer.setFrequency(0);
+    }
+    else if (message.cmd == midi::Command::NoteOn)
+        m_synthisizer.setFrequency(440.*std::pow(std::pow(2., 1./12.), message.note-48));
+}

widgets/synthisizerwidget.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <QWidget>
+#include <memory>
+
+#include "synthisizer.h"
+#include "audioformat.h"
+
+namespace Ui { class SynthisizerWidget; }
+class DrumMachineSettings;
+
+class SynthisizerWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit SynthisizerWidget(QWidget *parent = nullptr);
+    ~SynthisizerWidget() override;
+
+    void writeSamples(frame_t *begin, frame_t *end);
+    void loadSettings(DrumMachineSettings &settings);
+    void unsendColors();
+    void sendColors();
+
+signals:
+    void sendMidi(const midi::MidiMessage &midiMsg);
+
+public slots:
+    void messageReceived(const midi::MidiMessage &message);
+
+private:
+    const std::unique_ptr<Ui::SynthisizerWidget> m_ui;
+
+    Synthisizer m_synthisizer;
+};

widgets/synthisizerwidget.ui

@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SynthisizerWidget</class>
+ <widget class="QWidget" name="SynthisizerWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>300</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <widget class="QLabel" name="label">
+   <property name="geometry">
+    <rect>
+     <x>30</x>
+     <y>60</y>
+     <width>221</width>
+     <height>31</height>
+    </rect>
+   </property>
+   <property name="text">
+    <string>Hier könnte ihr Synthisizer stehen.</string>
+   </property>
+  </widget>
+  <widget class="QSlider" name="horizontalSliderVolume">
+   <property name="geometry">
+    <rect>
+     <x>110</x>
+     <y>110</y>
+     <width>160</width>
+     <height>16</height>
+    </rect>
+   </property>
+   <property name="maximum">
+    <number>100</number>
+   </property>
+   <property name="value">
+    <number>100</number>
+   </property>
+   <property name="orientation">
+    <enum>Qt::Horizontal</enum>
+   </property>
+  </widget>
+  <widget class="QLabel" name="labelVolume">
+   <property name="geometry">
+    <rect>
+     <x>20</x>
+     <y>110</y>
+     <width>55</width>
+     <height>18</height>
+    </rect>
+   </property>
+   <property name="text">
+    <string>Volume:</string>
+   </property>
+   <property name="buddy">
+    <cstring>horizontalSliderVolume</cstring>
+   </property>
+  </widget>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

widgets/trackdeck.cpp

@@ -0,0 +1,264 @@
+#include "trackdeck.h"
+#include "ui_trackdeck.h"
+
+#include <QAbstractEventDispatcher>
+#include <QDragEnterEvent>
+#include <QDragLeaveEvent>
+#include <QDropEvent>
+#include <QMimeData>
+#include <QTextStream>
+#include <QUrl>
+#include <QFileInfo>
+#include <QButtonGroup>
+#include <QDebug>
+
+#include "audiodecoder.h"
+
+TrackDeck::TrackDeck(QWidget *parent) :
+    QWidget{parent},
+    m_ui{std::make_unique<Ui::TrackDeck>()}
+{
+    m_ui->setupUi(this);
+    m_ui->progressBar->hide();
+
+    m_loopGroup.addButton(m_ui->pushButtonLoopOff, -1);
+    m_loopGroup.addButton(m_ui->pushButtonLoop1, 1);
+    m_loopGroup.addButton(m_ui->pushButtonLoop2, 2);
+    m_loopGroup.addButton(m_ui->pushButtonLoop4, 4);
+    m_loopGroup.addButton(m_ui->pushButtonLoop8, 8);
+    connect(&m_loopGroup, &QButtonGroup::idClicked, [&player=m_player,&bpmInput=*m_ui->doubleSpinBoxBpm](int id){
+        const auto position = player.position();
+
+        const auto bpm = bpmInput.value();
+        const auto beatsPerSecond = bpm / 60.;
+        const auto framesPerBeat = frameRate / beatsPerSecond;
+
+        switch (id)
+        {
+        case 1: player.setLoop(std::make_pair(position, position + (framesPerBeat/4))); break;
+        case 2: player.setLoop(std::make_pair(position, position + (framesPerBeat/2))); break;
+        case 4: player.setLoop(std::make_pair(position, position + framesPerBeat)); break;
+        case 8: player.setLoop(std::make_pair(position, position + (framesPerBeat*2))); break;
+        default: player.setLoop({});
+        }
+    });
+
+    connect(m_ui->pushButtonBpm, &QAbstractButton::pressed, this, &TrackDeck::bpmTap);
+
+    connect(m_ui->pushButtonPlay, &QAbstractButton::pressed, &m_player, &AudioPlayer::togglePlaying);
+    connect(m_ui->pushButtonStop, &QAbstractButton::pressed, &m_player, &AudioPlayer::stop);
+
+    connect(m_ui->sliderZoom, &QAbstractSlider::valueChanged, m_ui->scratchWidget, &ScratchWidget::setBeatWidth);
+    connect(m_ui->sliderSpeed, &QAbstractSlider::valueChanged, this, &TrackDeck::speedChanged);
+    connect(m_ui->sliderVolume, &QAbstractSlider::valueChanged, &m_player, [&player=m_player](int value){ player.setVolume(float(value)/100.f); });
+
+    connect(m_ui->previewWidget, &PreviewWidget::positionSelected, &m_player, &AudioPlayer::setPosition);
+    connect(&m_player, &AudioPlayer::positionChanged, m_ui->previewWidget, &PreviewWidget::setPosition);
+    connect(m_ui->scratchWidget, &ScratchWidget::scratchBegin, this, &TrackDeck::scratchBegin);
+    connect(m_ui->scratchWidget, &ScratchWidget::scratchEnd, this, &TrackDeck::scratchEnd);
+    connect(&m_player, &AudioPlayer::positionChanged, m_ui->scratchWidget, &ScratchWidget::setPosition);
+    connect(&m_player, &AudioPlayer::playingChanged, this, &TrackDeck::updatePlayButtonText);
+
+    connect(m_ui->sliderSpeed, &QAbstractSlider::valueChanged, this, &TrackDeck::updatePlaybackBpm);
+    connect(m_ui->doubleSpinBoxBpm, &QDoubleSpinBox::valueChanged, this, &TrackDeck::updatePlaybackBpm);
+
+    connect(&m_timer, &QTimer::timeout, this, &TrackDeck::timeout);
+    m_timer.setSingleShot(true);
+    m_timer.setInterval(1000);
+
+    updatePlaybackBpm();
+}
+
+TrackDeck::~TrackDeck() = default;
+
+void TrackDeck::loadTrack(const QString &filename)
+{
+    m_filename = filename;
+    emit startDecoding(filename);
+    m_ui->progressBar->show();
+    m_ui->progressBar->setValue(0);
+}
+
+void TrackDeck::injectDecodingThread(QThread &thread)
+{
+    QMetaObject::invokeMethod(QAbstractEventDispatcher::instance(&thread), [this](){
+        m_decoder = std::make_unique<AudioDecoder>();
+        connect(this, &TrackDeck::startDecoding, m_decoder.get(), &AudioDecoder::startDecodingFilename);
+        connect(m_decoder.get(), &AudioDecoder::progress, this, &TrackDeck::decodingProgress);
+        connect(m_decoder.get(), &AudioDecoder::decodingFinished, this, &TrackDeck::decodingFinished);
+        if (!m_filename.isEmpty())
+            m_decoder->startDecodingFilename(m_filename);
+    });
+}
+
+void TrackDeck::writeSamples(frame_t *begin, frame_t *end)
+{
+    m_player.writeSamples(begin, end);
+}
+
+void TrackDeck::dragEnterEvent(QDragEnterEvent *event)
+{
+    if (!event->mimeData()->hasFormat("text/uri-list"))
+        return;
+
+    auto data = event->mimeData()->data("text/uri-list");
+
+    QTextStream textStream(data, QIODevice::ReadOnly | QIODevice::Text);
+    if (textStream.atEnd())
+        return;
+
+    const QUrl url(textStream.readLine());
+    if (!url.isLocalFile())
+        return;
+
+    const QFileInfo fileInfo(url.toLocalFile());
+    if (!fileInfo.exists())
+        return;
+
+    if (!fileInfo.isFile())
+        return;
+
+    event->acceptProposedAction();
+}
+
+void TrackDeck::dragLeaveEvent(QDragLeaveEvent *event)
+{
+    Q_UNUSED(event)
+}
+
+void TrackDeck::dropEvent(QDropEvent *event)
+{
+    if (!event->mimeData()->hasFormat("text/uri-list"))
+    {
+        qWarning() << "wrong type";
+        return;
+    }
+
+    auto data = event->mimeData()->data("text/uri-list");
+
+    QTextStream textStream(data, QIODevice::ReadOnly | QIODevice::Text);
+    if (textStream.atEnd())
+    {
+        qWarning() << "no lines";
+        return;
+    }
+
+    const QUrl url(textStream.readLine());
+    if (!url.isLocalFile())
+    {
+        qWarning() << "isnt local file";
+        return;
+    }
+
+    const QFileInfo fileInfo(url.toLocalFile());
+    if (!fileInfo.exists())
+    {
+        qWarning() << "doesnt exist";
+        return;
+    }
+
+    if (!fileInfo.isFile())
+    {
+        qWarning() << "isnt file";
+        return;
+    }
+
+    loadTrack(url.toLocalFile());
+}
+
+void TrackDeck::decodingProgress(int progress, int total)
+{
+    m_ui->progressBar->setMaximum(total);
+    m_ui->progressBar->setValue(progress);
+}
+
+void TrackDeck::decodingFinished(const QAudioBuffer &buffer)
+{
+    m_player.setBuffer(buffer);
+
+    m_ui->labelTitle->setText(QFileInfo{m_filename}.fileName());
+
+    for (auto *btn : m_loopGroup.buttons())
+        btn->setEnabled(true);
+
+    m_ui->previewWidget->setBuffer(buffer);
+    m_ui->scratchWidget->setBuffer(buffer);
+    m_ui->progressBar->hide();
+}
+
+void TrackDeck::scratchBegin()
+{
+    disconnect(m_ui->sliderSpeed, &QAbstractSlider::valueChanged, this, &TrackDeck::speedChanged);
+    m_ui->sliderSpeed->setEnabled(false);
+    connect(m_ui->scratchWidget, &ScratchWidget::scratchSpeed, &m_player, &AudioPlayer::setSpeed);
+    disconnect(&m_player, &AudioPlayer::playingChanged, this, &TrackDeck::updatePlayButtonText);
+
+    m_playingBeforeScratch = m_player.playing();
+    m_player.setPlaying(true);
+
+    m_speedBeforeScratch = m_player.speed();
+
+    m_stopOnEndBeforeScratch = m_player.stopOnEnd();
+    m_player.setStopOnEnd(false);
+}
+
+void TrackDeck::scratchEnd()
+{
+    m_player.setPlaying(m_playingBeforeScratch);
+    m_player.setSpeed(m_speedBeforeScratch);
+    m_player.setStopOnEnd(m_stopOnEndBeforeScratch);
+
+    disconnect(m_ui->scratchWidget, &ScratchWidget::scratchSpeed, &m_player, &AudioPlayer::setSpeed);
+    m_ui->sliderSpeed->setEnabled(true);
+    connect(m_ui->sliderSpeed, &QAbstractSlider::valueChanged, this, &TrackDeck::speedChanged);
+    connect(&m_player, &AudioPlayer::playingChanged, this, &TrackDeck::updatePlayButtonText);
+}
+
+void TrackDeck::speedChanged(int value)
+{
+    m_player.setSpeed(float(value)/100.f);
+}
+
+void TrackDeck::updatePlayButtonText(bool playing)
+{
+    m_ui->pushButtonBpm->setEnabled(playing);
+    m_ui->pushButtonPlay->setText(playing ? tr("▮▮") : tr("▶"));
+}
+
+void TrackDeck::bpmTap()
+{
+    const auto position = m_player.position();
+    if (m_bpmTap)
+    {
+        std::get<1>(*m_bpmTap) = position;
+        std::get<2>(*m_bpmTap)++;
+        const auto framesPerBeat = (std::get<1>(*m_bpmTap)-std::get<0>(*m_bpmTap))/std::get<2>(*m_bpmTap);
+        m_ui->scratchWidget->setFramesPerBeat(framesPerBeat);
+        const auto beatsPerSecond = frameRate/framesPerBeat;
+        const auto bpm = 60.*beatsPerSecond;
+        m_ui->doubleSpinBoxBpm->setValue(bpm);
+    }
+    else
+    {
+        m_bpmTap = std::make_tuple(position, position, 0);
+    }
+
+    m_ui->pushButtonBpm->setText(QString::number(std::get<2>(*m_bpmTap)));
+    m_timer.start();
+}
+
+void TrackDeck::timeout()
+{
+    const auto framesPerBeat = (std::get<1>(*m_bpmTap)-std::get<0>(*m_bpmTap))/std::get<2>(*m_bpmTap);
+    m_ui->scratchWidget->setFramesPerBeat(framesPerBeat);
+    const auto beatsPerSecond = frameRate/framesPerBeat;
+    const auto bpm = 60.*beatsPerSecond;
+    m_ui->pushButtonBpm->setText(tr("BPM tap"));
+    m_ui->doubleSpinBoxBpm->setValue(bpm);
+    m_bpmTap = {};
+}
+
+void TrackDeck::updatePlaybackBpm()
+{
+    m_ui->labelPlaybackBpm->setText(QString::number(m_ui->doubleSpinBoxBpm->value() * m_ui->sliderSpeed->value() / 100., 'f', 2));
+}

widgets/trackdeck.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <tuple>
+
+#include <QWidget>
+#include <QButtonGroup>
+#include <QTimer>
+
+#include "audioformat.h"
+#include "audioplayer.h"
+
+namespace Ui { class TrackDeck; }
+class AudioDecoder;
+class QAudioBuffer;
+
+class TrackDeck : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit TrackDeck(QWidget *parent = nullptr);
+    ~TrackDeck() override;
+
+    void loadTrack(const QString &filename);
+
+    void injectDecodingThread(QThread &thread);
+
+    void writeSamples(frame_t *begin, frame_t *end);
+
+signals:
+    void startDecoding(const QString &filename);
+
+protected:
+    void dragEnterEvent(QDragEnterEvent *event) override;
+    void dragLeaveEvent(QDragLeaveEvent *event) override;
+    void dropEvent(QDropEvent *event) override;
+
+private slots:
+    void decodingProgress(int progress, int total);
+    void decodingFinished(const QAudioBuffer &buffer);
+    void scratchBegin();
+    void scratchEnd();
+    void speedChanged(int value);
+    void updatePlayButtonText(bool playing);
+    void bpmTap();
+    void timeout();
+    void updatePlaybackBpm();
+
+private:
+    const std::unique_ptr<Ui::TrackDeck> m_ui;
+
+    QButtonGroup m_loopGroup;
+
+    std::unique_ptr<AudioDecoder> m_decoder;
+
+    AudioPlayer m_player;
+
+    QString m_filename;
+
+    bool m_playingBeforeScratch;
+    float m_speedBeforeScratch;
+    bool m_stopOnEndBeforeScratch;
+
+    QTimer m_timer;
+
+    std::optional<std::tuple<double, double, int>> m_bpmTap;
+};

widgets/trackdeck.ui

@@ -0,0 +1,414 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>TrackDeck</class>
+ <widget class="QWidget" name="TrackDeck">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>567</width>
+    <height>283</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Preferred" vsizetype="Minimum">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="acceptDrops">
+   <bool>true</bool>
+  </property>
+  <property name="windowTitle">
+   <string>Form</string>
+  </property>
+  <layout class="QHBoxLayout" name="horizontalLayout_2" stretch="0,0">
+   <item>
+    <layout class="QVBoxLayout" name="verticalLayout_2" stretch="0,0,0">
+     <item>
+      <layout class="QHBoxLayout" name="horizontalLayout_5" stretch="1,0">
+       <item>
+        <widget class="QLabel" name="labelTitle"/>
+       </item>
+       <item>
+        <widget class="QProgressBar" name="progressBar">
+         <property name="value">
+          <number>24</number>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </item>
+     <item>
+      <layout class="QHBoxLayout" name="horizontalLayout">
+       <item>
+        <widget class="QPushButton" name="pushButtonBpm">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>60</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="text">
+          <string>BPM tap</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QDoubleSpinBox" name="doubleSpinBoxBpm">
+         <property name="suffix">
+          <string>BPM</string>
+         </property>
+         <property name="minimum">
+          <double>80.000000000000000</double>
+         </property>
+         <property name="maximum">
+          <double>250.000000000000000</double>
+         </property>
+         <property name="value">
+          <double>130.000000000000000</double>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <spacer name="horizontalSpacer">
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>40</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item>
+        <widget class="QSlider" name="sliderZoom">
+         <property name="maximumSize">
+          <size>
+           <width>100</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="minimum">
+          <number>25</number>
+         </property>
+         <property name="maximum">
+          <number>200</number>
+         </property>
+         <property name="value">
+          <number>100</number>
+         </property>
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="tickPosition">
+          <enum>QSlider::TicksBothSides</enum>
+         </property>
+         <property name="tickInterval">
+          <number>50</number>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QPushButton" name="pushButtonPlay">
+         <property name="maximumSize">
+          <size>
+           <width>32</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="text">
+          <string>▶</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QPushButton" name="pushButtonStop">
+         <property name="maximumSize">
+          <size>
+           <width>32</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="text">
+          <string>◼</string>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </item>
+     <item>
+      <layout class="QHBoxLayout" name="horizontalLayout_3" stretch="1,0">
+       <item>
+        <layout class="QVBoxLayout" name="verticalLayout" stretch="1,1,0">
+         <item>
+          <widget class="PreviewWidget" name="previewWidget" native="true">
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
+           <property name="minimumSize">
+            <size>
+             <width>0</width>
+             <height>50</height>
+            </size>
+           </property>
+           <property name="maximumSize">
+            <size>
+             <width>16777215</width>
+             <height>50</height>
+            </size>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="ScratchWidget" name="scratchWidget" native="true">
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Preferred" vsizetype="Fixed">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
+           <property name="minimumSize">
+            <size>
+             <width>0</width>
+             <height>100</height>
+            </size>
+           </property>
+           <property name="maximumSize">
+            <size>
+             <width>16777215</width>
+             <height>100</height>
+            </size>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <layout class="QHBoxLayout" name="horizontalLayout_6">
+           <item>
+            <widget class="QLabel" name="labelLoop">
+             <property name="text">
+              <string>Loop:</string>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QPushButton" name="pushButtonLoopOff">
+             <property name="maximumSize">
+              <size>
+               <width>16</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>-</string>
+             </property>
+             <property name="checkable">
+              <bool>true</bool>
+             </property>
+             <property name="checked">
+              <bool>true</bool>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QPushButton" name="pushButtonLoop1">
+             <property name="maximumSize">
+              <size>
+               <width>16</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>1</string>
+             </property>
+             <property name="checkable">
+              <bool>true</bool>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QPushButton" name="pushButtonLoop2">
+             <property name="maximumSize">
+              <size>
+               <width>16</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>2</string>
+             </property>
+             <property name="checkable">
+              <bool>true</bool>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QPushButton" name="pushButtonLoop4">
+             <property name="maximumSize">
+              <size>
+               <width>16</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>4</string>
+             </property>
+             <property name="checkable">
+              <bool>true</bool>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QPushButton" name="pushButtonLoop8">
+             <property name="maximumSize">
+              <size>
+               <width>16</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>8</string>
+             </property>
+             <property name="checkable">
+              <bool>true</bool>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <spacer name="horizontalSpacer_4">
+             <property name="orientation">
+              <enum>Qt::Horizontal</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>40</width>
+               <height>20</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+          </layout>
+         </item>
+        </layout>
+       </item>
+       <item>
+        <layout class="QVBoxLayout" name="verticalLayout_3" stretch="0,1">
+         <item>
+          <widget class="QLabel" name="labelPlaybackBpm">
+           <property name="font">
+            <font>
+             <pointsize>8</pointsize>
+            </font>
+           </property>
+           <property name="text">
+            <string>100.00</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <layout class="QHBoxLayout" name="horizontalLayout_4" stretch="0,1,0">
+           <property name="spacing">
+            <number>0</number>
+           </property>
+           <item>
+            <spacer name="horizontalSpacer_2">
+             <property name="orientation">
+              <enum>Qt::Horizontal</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>0</width>
+               <height>20</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+           <item>
+            <widget class="QSlider" name="sliderSpeed">
+             <property name="minimum">
+              <number>80</number>
+             </property>
+             <property name="maximum">
+              <number>120</number>
+             </property>
+             <property name="value">
+              <number>100</number>
+             </property>
+             <property name="orientation">
+              <enum>Qt::Vertical</enum>
+             </property>
+             <property name="tickPosition">
+              <enum>QSlider::TicksBothSides</enum>
+             </property>
+             <property name="tickInterval">
+              <number>10</number>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <spacer name="horizontalSpacer_3">
+             <property name="orientation">
+              <enum>Qt::Horizontal</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>0</width>
+               <height>20</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+          </layout>
+         </item>
+        </layout>
+       </item>
+      </layout>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QSlider" name="sliderVolume">
+     <property name="maximum">
+      <number>100</number>
+     </property>
+     <property name="value">
+      <number>100</number>
+     </property>
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+     <property name="tickPosition">
+      <enum>QSlider::TicksBothSides</enum>
+     </property>
+     <property name="tickInterval">
+      <number>25</number>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>PreviewWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/previewwidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>ScratchWidget</class>
+   <extends>QWidget</extends>
+   <header>widgets/scratchwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>