diff --git a/DrumMachine.pro b/DrumMachine.pro
index ae307ef..ddd8080 100755
--- a/DrumMachine.pro
+++ b/DrumMachine.pro
@@ -14,7 +14,10 @@ SOURCES += \
     audiodecoder.cpp \
     audioformat.cpp \
     audioplayer.cpp \
+    djwidget.cpp \
     filesmodel.cpp \
+    flatfilesystemmodel.cpp \
+    graphrenderer.cpp \
     jsonconverters.cpp \
     main.cpp \
     mainwindow.cpp \
@@ -23,15 +26,22 @@ SOURCES += \
     presetdetailwidget.cpp \
     presets.cpp \
     presetsmodel.cpp \
+    previewwidget.cpp \
     sampleswidget.cpp \
     samplewidget.cpp \
-    sequencerwidget.cpp
+    scratchwidget.cpp \
+    sequencerwidget.cpp \
+    synthisizer.cpp \
+    trackdeck.cpp
 
 HEADERS += \
     audiodecoder.h \
     audioformat.h \
     audioplayer.h \
+    djwidget.h \
     filesmodel.h \
+    flatfilesystemmodel.h \
+    graphrenderer.h \
     jsonconverters.h \
     mainwindow.h \
     midicontainers.h \
@@ -39,16 +49,22 @@ HEADERS += \
     presetdetailwidget.h \
     presets.h \
     presetsmodel.h \
+    previewwidget.h \
     sampleswidget.h \
     samplewidget.h \
-    sequencerwidget.h
+    scratchwidget.h \
+    sequencerwidget.h \
+    synthisizer.h \
+    trackdeck.h
 
 FORMS += \
+    djwidget.ui \
     mainwindow.ui \
     presetdetailwidget.ui \
     sampleswidget.ui \
     samplewidget.ui \
-    sequencerwidget.ui
+    sequencerwidget.ui \
+    trackdeck.ui
 
 RESOURCES += \
     resources.qrc
diff --git a/audiodecoder.cpp b/audiodecoder.cpp
index f64899f..d13ad42 100644
--- a/audiodecoder.cpp
+++ b/audiodecoder.cpp
@@ -22,10 +22,19 @@ AudioDecoder::AudioDecoder(QObject *parent) :
     m_decoder.setAudioFormat(audioFormat());
 }
 
-void AudioDecoder::startDecoding(std::shared_ptr<QIODevice> device)
+void AudioDecoder::startDecodingFilename(const QString &filename)
 {
-    qDebug() << "called" << device.get();
+    if (m_decoder.state() == QAudioDecoder::DecodingState)
+        m_decoder.stop();
 
+    m_decoder.setSourceFilename(filename);
+    m_device = nullptr;
+    m_bytearray.clear();
+    m_decoder.start();
+}
+
+void AudioDecoder::startDecodingDevice(std::shared_ptr<QIODevice> device)
+{
     if (m_decoder.state() == QAudioDecoder::DecodingState)
         m_decoder.stop();
 
@@ -42,7 +51,6 @@ void AudioDecoder::error(const QAudioDecoder::Error error)
 
 void AudioDecoder::finished()
 {
-    qDebug() << "called";
     emit decodingFinished(QAudioBuffer{std::move(m_bytearray), audioFormat()});
 }
 
@@ -71,7 +79,6 @@ void AudioDecoder::durationChanged(const qint64 duration)
     const auto &format = m_decoder.audioFormat();
     const auto reserve = (format.sampleSize()/8) * format.sampleRate() * format.channelCount() * (duration + 1000) / 1000;
     m_bytearray.reserve(reserve);
-    qDebug() << "duration:" << duration << reserve;
 }
 
 namespace {
diff --git a/audiodecoder.h b/audiodecoder.h
index 6282a56..21357c0 100644
--- a/audiodecoder.h
+++ b/audiodecoder.h
@@ -22,7 +22,8 @@ signals:
     void decodingFinished(const QAudioBuffer &buffer);
 
 public slots:
-    void startDecoding(std::shared_ptr<QIODevice> device);
+    void startDecodingFilename(const QString &filename);
+    void startDecodingDevice(std::shared_ptr<QIODevice> device);
 
 private slots:
     void error(const QAudioDecoder::Error error);
diff --git a/audioplayer.cpp b/audioplayer.cpp
index eba50ba..edeea4a 100644
--- a/audioplayer.cpp
+++ b/audioplayer.cpp
@@ -19,7 +19,14 @@ void AudioPlayer::writeSamples(frame_t *begin, frame_t *end)
     if (!m_playing)
         return;
 
-    const auto frames = std::min<size_t>(std::distance(begin, end), m_buffer.frameCount()-m_position);
+    // thread safe copies
+    auto position = m_position;
+    const auto speed = m_speed;
+    const auto buffer = m_buffer;
+    const auto volume = m_volume;
+    const auto &data = buffer.constData<frame_t>();
+
+    const auto frames = std::min<size_t>(std::distance(begin, end), buffer.frameCount()-position);
 
     if (!frames)
     {
@@ -28,25 +35,80 @@ void AudioPlayer::writeSamples(frame_t *begin, frame_t *end)
         return;
     }
 
-    std::transform(static_cast<const frame_t *>(begin), static_cast<const frame_t *>(begin+frames), m_buffer.constData<frame_t>() + m_position, begin,
-                   [](const frame_t &frame, const frame_t &frame2)->frame_t{
-        frame_t newFrame;
-        std::transform(std::begin(frame), std::end(frame), std::begin(frame2), std::begin(newFrame),
-                       [](const sample_t &left, const sample_t &right) { return left + right; });
-        return newFrame;
+    bool ended{};
+    std::transform(static_cast<const frame_t *>(begin), static_cast<const frame_t *>(begin+frames), begin,
+                   [&](frame_t frame)->frame_t{
+        if (ended)
+            return frame;
+
+        const auto index = std::size_t(position);
+        if (index >= buffer.frameCount())
+        {
+            ended = true;
+            return frame;
+        }
+
+        const frame_t &frame2 = data[index];
+        position += speed;
+
+        std::transform(std::cbegin(frame), std::cend(frame), std::begin(frame2), std::begin(frame),
+                       [&volume](const sample_t &left, const sample_t &right) { return left + (right*volume); });
+
+        return frame;
     });
 
-    m_position += frames;
+    m_position = position;
+    const auto now = QDateTime::currentDateTime();
+    if (m_lastPositionUpdate.isNull() || m_lastPositionUpdate.msecsTo(now) > 100)
+        emit positionChanged(m_position);
+
+    if (ended)
+        emit playingChanged(m_playing = false);
+}
+
+void AudioPlayer::setPlaying(bool playing)
+{
+    m_playing = playing;
+    emit playingChanged(playing);
+}
+
+void AudioPlayer::setPosition(double position)
+{
+    m_position = position;
+    emit positionChanged(position);
+}
+
+void AudioPlayer::setSpeed(float speed)
+{
+    m_speed = speed;
+    emit speedChanged(speed);
+}
+
+void AudioPlayer::setVolume(float volume)
+{
+    m_volume = volume;
+    emit volumeChanged(volume);
+}
+
+void AudioPlayer::setBuffer(const QAudioBuffer &buffer)
+{
+    stop();
+    emit bufferChanged(m_buffer = buffer);
+}
+
+void AudioPlayer::togglePlaying()
+{
+    emit playingChanged(m_playing = !m_playing);
 }
 
 void AudioPlayer::restart()
 {
-    setPosition(0);
+    setPosition(0.);
     setPlaying(true);
 }
 
 void AudioPlayer::stop()
 {
-    setPosition(0);
+    setPosition(0.);
     setPlaying(false);
 }
diff --git a/audioplayer.h b/audioplayer.h
index 8fed489..f9f82a4 100644
--- a/audioplayer.h
+++ b/audioplayer.h
@@ -20,25 +20,36 @@ public:
     void writeSamples(frame_t *begin, frame_t *end);
 
     bool playing() const { return m_playing; }
-    void setPlaying(bool playing) { m_playing = playing; emit playingChanged(playing); }
+    void setPlaying(bool playing);
 
-    std::size_t position() const { return m_position; }
-    void setPosition(std::size_t position) { m_position = position; emit positionChanged(position); }
+    double position() const { return m_position; }
+    void setPosition(double position);
+
+    float speed() const { return m_speed; }
+    void setSpeed(float speed);
+
+    float volume() const { return m_volume; }
+    void setVolume(float volume);
 
     const QAudioBuffer &buffer() const { return m_buffer; }
-    void setBuffer(const QAudioBuffer &buffer) { emit bufferChanged(m_buffer = buffer); }
+    void setBuffer(const QAudioBuffer &buffer);
 
+    void togglePlaying();
     void restart();
     void stop();
 
 signals:
     void playingChanged(bool playing);
-    void positionChanged(std::size_t position);
+    void positionChanged(double position);
+    void speedChanged(float speed);
+    void volumeChanged(float volume);
     void bufferChanged(const QAudioBuffer &buffer);
 
 private:
     bool m_playing{false};
-    std::size_t m_position{};
+    double m_position{};
+    float m_speed{1.f};
+    float m_volume{1.f};
     QAudioBuffer m_buffer;
 
     QDateTime m_lastPositionUpdate;
diff --git a/djwidget.cpp b/djwidget.cpp
new file mode 100644
index 0000000..46d94ab
--- /dev/null
+++ b/djwidget.cpp
@@ -0,0 +1,83 @@
+#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(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::AllEntries|QDir::NoDotAndDotDot);
+    m_ui->treeViewFiles->setModel(&m_filesModel);
+
+    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_filesModel.m_root_path = rootIndex;
+        m_ui->treeViewFiles->setRootIndex(rootIndex);
+    }
+}
+
+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::directorySelected()
+{
+    const auto selected = m_ui->treeViewDirectories->currentIndex();
+    if (selected.isValid())
+    {
+        const auto rootIndex = m_filesModel.setRootPath(m_directoryModel.filePath(selected));
+        m_filesModel.m_root_path = rootIndex;
+        m_ui->treeViewFiles->setRootIndex(rootIndex);
+    }
+}
diff --git a/djwidget.h b/djwidget.h
new file mode 100644
index 0000000..6a519f1
--- /dev/null
+++ b/djwidget.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <QWidget>
+#include <QFileSystemModel>
+
+#include <memory>
+
+#include "audioformat.h"
+#include "flatfilesystemmodel.h"
+
+namespace Ui { class DjWidget; }
+
+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);
+
+private slots:
+    void directorySelected();
+
+private:
+    const std::unique_ptr<Ui::DjWidget> m_ui;
+
+    QFileSystemModel m_directoryModel;
+    FlatFileSystemModel m_filesModel;
+};
diff --git a/djwidget.ui b/djwidget.ui
new file mode 100644
index 0000000..0d48128
--- /dev/null
+++ b/djwidget.ui
@@ -0,0 +1,145 @@
+<?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="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>
+         <property name="rootIsDecorated">
+          <bool>false</bool>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>TrackDeck</class>
+   <extends>QWidget</extends>
+   <header>trackdeck.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>
diff --git a/flatfilesystemmodel.cpp b/flatfilesystemmodel.cpp
new file mode 100644
index 0000000..835f076
--- /dev/null
+++ b/flatfilesystemmodel.cpp
@@ -0,0 +1 @@
+#include "flatfilesystemmodel.h"
diff --git a/flatfilesystemmodel.h b/flatfilesystemmodel.h
new file mode 100644
index 0000000..99cc3b7
--- /dev/null
+++ b/flatfilesystemmodel.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <QFileSystemModel>
+
+class FlatFileSystemModel : public QFileSystemModel
+{
+public:
+    bool hasChildren(const QModelIndex &parent = QModelIndex()) const override { return (parent == m_root_path) ? QFileSystemModel::hasChildren(parent) : false; };
+    bool canFetchMore(const QModelIndex &parent) const override { return (parent == m_root_path) ? QFileSystemModel::canFetchMore(parent) : false; };
+    void fetchMore(const QModelIndex &parent) override { if ((parent == m_root_path)) QFileSystemModel::fetchMore(parent); };
+
+public:
+    QModelIndex m_root_path;
+};
diff --git a/graphrenderer.cpp b/graphrenderer.cpp
new file mode 100644
index 0000000..a1f1c25
--- /dev/null
+++ b/graphrenderer.cpp
@@ -0,0 +1,59 @@
+#include "graphrenderer.h"
+
+#include <iterator>
+
+#include <QPixmap>
+#include <QPainter>
+#include <QPalette>
+
+QPixmap GraphRenderer::render(const QSize &size, const frame_t *frameBegin, const frame_t *frameEnd, const QPalette &palette)
+{
+    QPixmap pixmap{size};
+
+    QPainter painter;
+    painter.begin(&pixmap);
+
+    painter.fillRect(pixmap.rect(), palette.base());
+
+    painter.setPen(Qt::white);
+    painter.setBrush(Qt::black);
+
+    painter.drawRect(QRect({}, size));
+
+    render(size, frameBegin, frameEnd, painter, palette);
+    painter.end();
+    return pixmap;
+}
+
+void GraphRenderer::render(const QSize &size, const frame_t *frameBegin, const frame_t *frameEnd, QPainter &painter, const QPalette &palette)
+{
+    if (frameEnd == frameBegin)
+        return;
+
+    painter.setPen(QPen{palette.color(QPalette::Text)});
+    painter.setBrush(palette.text());
+
+    const auto framesPerPixel = std::distance(frameBegin, frameEnd) / size.width();
+
+    for (int x = 0; x < size.width(); x++)
+    {
+        const frame_t *begin = frameBegin + (x * framesPerPixel);
+        const frame_t *end = begin + framesPerPixel;
+
+        frame_t min{1.f, 1.f}, max{-1.f, -1.f};
+        for (auto iter = begin; iter != end; iter++)
+        {
+            if ((*iter)[0] < min[0])
+                min[0] = (*iter)[0];
+            if ((*iter)[1] < min[1])
+                min[1] = (*iter)[1];
+            if ((*iter)[0] > max[0])
+                max[0] = (*iter)[0];
+            if ((*iter)[1] > max[1])
+                max[1] = (*iter)[1];
+        }
+
+        painter.drawLine(x, (size.height() / 2) - (min[0] * (size.height() / 2)),
+                         x, (size.height() / 2) + (max[0] * (size.height() / 2)));
+    }
+}
diff --git a/graphrenderer.h b/graphrenderer.h
new file mode 100644
index 0000000..71eef46
--- /dev/null
+++ b/graphrenderer.h
@@ -0,0 +1,14 @@
+#pragma once
+
+class QPixmap;
+class QSize;
+class QPainter;
+class QPalette;
+
+#include "audioformat.h"
+
+namespace GraphRenderer
+{
+    QPixmap render(const QSize &size, const frame_t *frameBegin, const frame_t *frameEnd, const QPalette &palette);
+    void render(const QSize &size, const frame_t *frameBegin, const frame_t *frameEnd, QPainter &painter, const QPalette &palette);
+}
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 2d5d4ac..8bd00e9 100755
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -1,6 +1,7 @@
 #include "mainwindow.h"
 #include "ui_mainwindow.h"
 
+#include <QEventLoop>
 #include <QMetaEnum>
 #include <QMessageBox>
 #include <QTimer>
@@ -53,7 +54,7 @@ int paCallback(const void *inputBuffer, void *outputBuffer,
 MainWindow::MainWindow(const presets::PresetsConfig &presetsConfig, QWidget *parent) :
     QMainWindow{parent},
     m_ui{std::make_unique<Ui::MainWindow>()},
-    m_paStream(nullptr, DummyDeleter),
+    m_paStream{nullptr, DummyDeleter},
     m_presetsModel{*presetsConfig.presets}
 {
     m_ui->setupUi(this);
@@ -61,6 +62,16 @@ MainWindow::MainWindow(const presets::PresetsConfig &presetsConfig, QWidget *par
 
     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->samplesWidget->injectDecodingThread(m_decoderThread);
+    m_ui->djWidget->injectDecodingThread(m_decoderThread);
+
     connect(m_ui->sequencerWidget, &SequencerWidget::triggerSample, m_ui->samplesWidget, &SamplesWidget::sequencerTriggerSample);
 
     updateMidiDevices();
@@ -75,6 +86,7 @@ MainWindow::MainWindow(const presets::PresetsConfig &presetsConfig, QWidget *par
                 m_midiIn.openPort(index);
         }
 
+        m_ui->comboBoxMidiController->setDisabled(m_midiIn.isPortOpen());
         m_ui->pushButtonMidiController->setText(m_midiIn.isPortOpen() ? tr("Close") : tr("Open"));
     });
 
@@ -99,7 +111,11 @@ MainWindow::MainWindow(const presets::PresetsConfig &presetsConfig, QWidget *par
     connect(m_ui->presetsView->selectionModel(), &QItemSelectionModel::currentRowChanged, this, &MainWindow::currentRowChanged);
 }
 
-MainWindow::~MainWindow() = default;
+MainWindow::~MainWindow()
+{
+    m_decoderThread.exit();
+    m_decoderThread.wait();
+}
 
 void MainWindow::selectFirstPreset()
 {
@@ -119,6 +135,15 @@ void MainWindow::writeSamples(frame_t *begin, frame_t *end)
     std::fill(begin, end, frame_t{0.,0.});
 
     m_ui->samplesWidget->writeSamples(begin, end);
+    m_ui->djWidget->writeSamples(begin, end);
+    m_synthisizer.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;
+    });
 }
 
 void MainWindow::openAudioDevice()
@@ -126,6 +151,8 @@ 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
@@ -169,6 +196,8 @@ void MainWindow::openAudioDevice()
         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"));
     }
 }
@@ -179,7 +208,10 @@ void MainWindow::messageReceived(const midi::MidiMessage &message)
                                  .arg(message.flag?"true":"false", QMetaEnum::fromType<midi::Command>().valueToKey(int(message.cmd)))
                                  .arg(message.channel).arg(message.note).arg(message.velocity), 1000);
 
-    m_ui->samplesWidget->messageReceived(message);
+    if (m_ui->comboBoxMidiType->currentIndex() == 0)
+        m_ui->samplesWidget->messageReceived(message);
+    else if (m_ui->comboBoxMidiType->currentIndex() == 1)
+        m_synthisizer.messageReceived(message);
 }
 
 void MainWindow::currentRowChanged(const QModelIndex &current)
diff --git a/mainwindow.h b/mainwindow.h
index 6103851..883d6d5 100755
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -4,6 +4,7 @@
 
 #include <QMainWindow>
 #include <QSortFilterProxyModel>
+#include <QThread>
 
 #include "portaudio.h"
 
@@ -11,6 +12,7 @@
 #include "presetsmodel.h"
 #include "filesmodel.h"
 #include "midiinwrapper.h"
+#include "synthisizer.h"
 
 namespace Ui { class MainWindow; }
 namespace presets { struct PresetsConfig; }
@@ -43,6 +45,10 @@ private:
 
     MidiInWrapper m_midiIn;
 
+    QThread m_decoderThread;
+
+    Synthisizer m_synthisizer;
+
     PresetsModel m_presetsModel;
     QSortFilterProxyModel m_presetsProxyModel;
 
diff --git a/mainwindow.ui b/mainwindow.ui
index 506e6b1..dfdc9c4 100755
--- a/mainwindow.ui
+++ b/mainwindow.ui
@@ -101,6 +101,19 @@
       <item>
        <widget class="QComboBox" name="comboBoxMidiController"/>
       </item>
+      <item>
+       <widget class="QPushButton" name="pushButtonRefreshMidiControllers">
+        <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="pushButtonMidiController">
         <property name="text">
@@ -108,6 +121,20 @@
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="QComboBox" name="comboBoxMidiType">
+        <item>
+         <property name="text">
+          <string>Samples</string>
+         </property>
+        </item>
+        <item>
+         <property name="text">
+          <string>Synthisizer</string>
+         </property>
+        </item>
+       </widget>
+      </item>
       <item>
        <spacer name="horizontalSpacer">
         <property name="orientation">
@@ -124,6 +151,19 @@
       <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">
@@ -186,28 +226,38 @@
           </layout>
          </item>
          <item>
-          <widget class="QTreeView" name="presetsView">
-           <property name="rootIsDecorated">
-            <bool>false</bool>
-           </property>
-           <property name="sortingEnabled">
-            <bool>true</bool>
+          <widget class="QSplitter" name="splitter">
+           <property name="orientation">
+            <enum>Qt::Horizontal</enum>
            </property>
+           <widget class="QTreeView" name="presetsView">
+            <property name="rootIsDecorated">
+             <bool>false</bool>
+            </property>
+            <property name="sortingEnabled">
+             <bool>true</bool>
+            </property>
+           </widget>
+           <widget class="QTabWidget" name="tabWidget">
+            <widget class="PresetDetailWidget" name="presetDetailWidget">
+             <attribute name="title">
+              <string/>
+             </attribute>
+            </widget>
+            <widget class="QTreeView" name="filesView">
+             <property name="rootIsDecorated">
+              <bool>false</bool>
+             </property>
+             <attribute name="title">
+              <string/>
+             </attribute>
+            </widget>
+           </widget>
           </widget>
          </item>
         </layout>
        </widget>
-       <widget class="QSplitter" name="splitter_3">
-        <property name="orientation">
-         <enum>Qt::Horizontal</enum>
-        </property>
-        <widget class="PresetDetailWidget" name="presetDetailWidget"/>
-        <widget class="QTreeView" name="filesView">
-         <property name="rootIsDecorated">
-          <bool>false</bool>
-         </property>
-        </widget>
-       </widget>
+       <widget class="DjWidget" name="djWidget" native="true"/>
       </widget>
       <widget class="QWidget" name="layoutWidget">
        <layout class="QVBoxLayout" stretch="1,0">
@@ -254,6 +304,12 @@
    <header>sequencerwidget.h</header>
    <container>1</container>
   </customwidget>
+  <customwidget>
+   <class>DjWidget</class>
+   <extends>QWidget</extends>
+   <header>djwidget.h</header>
+   <container>1</container>
+  </customwidget>
  </customwidgets>
  <resources/>
  <connections/>
diff --git a/presetdetailwidget.cpp b/presetdetailwidget.cpp
index 1813739..bca3f02 100755
--- a/presetdetailwidget.cpp
+++ b/presetdetailwidget.cpp
@@ -12,5 +12,5 @@ PresetDetailWidget::~PresetDetailWidget() = default;
 
 void PresetDetailWidget::setPreset(const presets::Preset &preset)
 {
-
+    // TODO
 }
diff --git a/previewwidget.cpp b/previewwidget.cpp
new file mode 100644
index 0000000..d353424
--- /dev/null
+++ b/previewwidget.cpp
@@ -0,0 +1,88 @@
+#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());
+
+        if (m_buffer.isValid())
+            GraphRenderer::render(size(), m_buffer.constData<frame_t>(), m_buffer.constData<frame_t>() + m_buffer.frameCount(), painter, palette());
+
+        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);
+}
diff --git a/previewwidget.h b/previewwidget.h
new file mode 100644
index 0000000..52f371e
--- /dev/null
+++ b/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;
+};
diff --git a/sampleswidget.cpp b/sampleswidget.cpp
index 5e0f560..5e32a81 100755
--- a/sampleswidget.cpp
+++ b/sampleswidget.cpp
@@ -16,13 +16,6 @@ SamplesWidget::SamplesWidget(QWidget *parent) :
     m_cache.setCacheDirectory("cache");
     m_networkAccessManager.setCache(&m_cache);
 
-    {
-        QEventLoop eventLoop;
-        connect(&m_decoderThread, &QThread::started, &eventLoop, &QEventLoop::quit);
-        m_decoderThread.start(QThread::HighestPriority);
-        eventLoop.exec();
-    }
-
     connect(m_ui->checkBox, &QCheckBox::toggled, this, &SamplesWidget::updateWidgets);
 
     connect(m_ui->pushButtonStopAll, &QAbstractButton::pressed, this, &SamplesWidget::stopAll);
@@ -30,7 +23,6 @@ SamplesWidget::SamplesWidget(QWidget *parent) :
     for (const auto &ref : getWidgets())
     {
         ref.get().injectNetworkAccessManager(m_networkAccessManager);
-        ref.get().injectDecodingThread(m_decoderThread);
         connect(&ref.get(), &SampleWidget::chokeTriggered, this, &SamplesWidget::chokeTriggered);
     }
 
@@ -52,11 +44,7 @@ SamplesWidget::SamplesWidget(QWidget *parent) :
     m_ui->sampleWidget_24->setNote(72);
 }
 
-SamplesWidget::~SamplesWidget()
-{
-    m_decoderThread.exit();
-    m_decoderThread.wait();
-}
+SamplesWidget::~SamplesWidget() = default;
 
 void SamplesWidget::setPreset(const presets::Preset &preset)
 {
@@ -94,6 +82,12 @@ void SamplesWidget::writeSamples(frame_t *begin, frame_t *end)
         ref.get().writeSamples(begin, end);
 }
 
+void SamplesWidget::injectDecodingThread(QThread &thread)
+{
+    for (const auto &ref : getWidgets())
+        ref.get().injectDecodingThread(thread);
+}
+
 void SamplesWidget::sequencerTriggerSample(int index)
 {
     const auto widgets = getWidgets();
diff --git a/sampleswidget.h b/sampleswidget.h
index 1bdb79b..d5ffda8 100755
--- a/sampleswidget.h
+++ b/sampleswidget.h
@@ -7,7 +7,6 @@
 #include <QWidget>
 #include <QNetworkAccessManager>
 #include <QNetworkDiskCache>
-#include <QThread>
 
 #include "audioformat.h"
 #include "presets.h"
@@ -30,6 +29,8 @@ public:
 
     void writeSamples(frame_t *begin, frame_t *end);
 
+    void injectDecodingThread(QThread &thread);
+
 public slots:
     void sequencerTriggerSample(int index);
 
@@ -46,7 +47,5 @@ private:
     QNetworkDiskCache m_cache;
     QNetworkAccessManager m_networkAccessManager;
 
-    QThread m_decoderThread;
-
     presets::Preset m_preset;
 };
diff --git a/samplewidget.cpp b/samplewidget.cpp
index 3104725..86f6f07 100755
--- a/samplewidget.cpp
+++ b/samplewidget.cpp
@@ -23,6 +23,9 @@ SampleWidget::SampleWidget(QWidget *parent) :
 {
     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); });
@@ -38,6 +41,8 @@ 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){
@@ -84,6 +89,26 @@ void SampleWidget::setNote(quint8 note)
     m_ui->noteSpinBox->setValue(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)
@@ -121,10 +146,10 @@ 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::startDecoding);
+        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->startDecoding(m_reply);
+            m_decoder->startDecodingDevice(m_reply);
     });
 }
 
@@ -136,7 +161,7 @@ void SampleWidget::writeSamples(frame_t *begin, frame_t *end)
 void SampleWidget::updateStatus()
 {
     QPalette pal;
-    if (m_file && m_file->color)
+    if (m_file && m_file->color && m_player.buffer().isValid())
     {
         const auto bright = m_player.playing() ? 255 : 155;
         const auto dark = m_player.playing() ?
@@ -183,7 +208,6 @@ void SampleWidget::updateStatus()
 
 void SampleWidget::requestFinished()
 {
-    qDebug() << "called" << m_reply->error() << m_reply->attribute(QNetworkRequest::SourceIsFromCacheAttribute);
     if (m_reply->error() == QNetworkReply::NoError)
     {
         emit startDecoding(m_reply);
@@ -193,9 +217,10 @@ void SampleWidget::requestFinished()
 
 void SampleWidget::decodingFinished(const QAudioBuffer &buffer)
 {
-    qDebug() << "called";
     m_reply = nullptr;
     m_player.setBuffer(buffer);
+    setSpeed(100);
+    setVolume(100);
     updateStatus();
 }
 
diff --git a/samplewidget.h b/samplewidget.h
index 8270f3a..d458a98 100755
--- a/samplewidget.h
+++ b/samplewidget.h
@@ -30,6 +30,12 @@ public:
     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);
diff --git a/samplewidget.ui b/samplewidget.ui
index 9016064..6472c87 100755
--- a/samplewidget.ui
+++ b/samplewidget.ui
@@ -24,7 +24,7 @@
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
-    <layout class="QHBoxLayout" name="horizontalLayout_3">
+    <layout class="QHBoxLayout" name="horizontalLayout_5">
      <item>
       <widget class="QLabel" name="statusLabel">
        <property name="text">
@@ -32,21 +32,65 @@
        </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>
-    <widget class="QProgressBar" name="progressBar">
-     <property name="value">
-      <number>24</number>
-     </property>
-    </widget>
-   </item>
-   <item>
-    <widget class="QPushButton" name="pushButton">
-     <property name="text">
-      <string>PushButton</string>
-     </property>
-    </widget>
+    <layout class="QHBoxLayout" name="horizontalLayout_4">
+     <item>
+      <widget class="QPushButton" name="pushButton">
+       <property name="text">
+        <string>PushButton</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">
diff --git a/scratchwidget.cpp b/scratchwidget.cpp
new file mode 100644
index 0000000..2e30543
--- /dev/null
+++ b/scratchwidget.cpp
@@ -0,0 +1,45 @@
+#include "scratchwidget.h"
+
+#include <QPainter>
+
+#include "graphrenderer.h"
+
+ScratchWidget::ScratchWidget(QWidget *parent) :
+    QWidget{parent}
+{
+}
+
+void ScratchWidget::paintEvent(QPaintEvent *event)
+{
+    QPainter painter;
+    painter.begin(this);
+
+    painter.setPen({});
+    painter.setBrush(palette().window());
+    painter.drawRect(rect());
+
+    {
+        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)
+{
+
+}
+
+void ScratchWidget::mouseReleaseEvent(QMouseEvent *event)
+{
+
+}
+
+void ScratchWidget::mouseMoveEvent(QMouseEvent *event)
+{
+
+}
diff --git a/scratchwidget.h b/scratchwidget.h
new file mode 100644
index 0000000..d95ea7f
--- /dev/null
+++ b/scratchwidget.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <vector>
+
+#include <QWidget>
+#include <QAudioBuffer>
+
+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(); }
+
+    double position() const { return m_position; }
+    void setPosition(double position) { m_position = position; repaint(); }
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+    void mouseReleaseEvent(QMouseEvent *event) override;
+    void mouseMoveEvent(QMouseEvent *event) override;
+
+private:
+    QAudioBuffer m_buffer;
+    double m_position{};
+    std::vector<QPixmap> m_graphCache;
+};
diff --git a/synthisizer.cpp b/synthisizer.cpp
new file mode 100644
index 0000000..d6cdcc9
--- /dev/null
+++ b/synthisizer.cpp
@@ -0,0 +1,33 @@
+#include "synthisizer.h"
+
+#include <cmath>
+
+#include "midicontainers.h"
+
+constexpr double pi = std::acos(-1);
+
+void Synthisizer::writeSamples(frame_t *begin, frame_t *end)
+{
+    if (m_frequency)
+        std::transform(begin, end, begin, [&](frame_t frame){
+            std::transform(std::cbegin(frame), std::cend(frame), std::begin(frame),
+                           [value=std::sin(m_phase)](const sample_t &sample) { return sample + value; });
+
+            m_phase += pi*2./sampleRate*m_frequency;
+            if (m_phase >= pi*2.)
+                m_phase -= pi*2.;
+
+            return frame;
+        });
+}
+
+void Synthisizer::messageReceived(const midi::MidiMessage &message)
+{
+    if (message.cmd == midi::Command::NoteOn)
+        m_frequency = 440.*std::pow(std::pow(2., 1./12.), message.note-48);
+    else if (message.cmd == midi::Command::NoteOff)
+    {
+        if (m_frequency == int16_t(440.*std::pow(std::pow(2., 1./12.), message.note-48)))
+            m_frequency = 0;
+    }
+}
diff --git a/synthisizer.h b/synthisizer.h
new file mode 100644
index 0000000..9d867e0
--- /dev/null
+++ b/synthisizer.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "audioformat.h"
+
+namespace midi { class MidiMessage; }
+
+class Synthisizer
+{
+public:
+    void setFrequency(int16_t frequency) { m_frequency = frequency; }
+
+    void writeSamples(frame_t *begin, frame_t *end);
+
+    void messageReceived(const midi::MidiMessage &message);
+
+private:
+    int16_t m_frequency{};
+    double m_phase{};
+};
diff --git a/trackdeck.cpp b/trackdeck.cpp
new file mode 100644
index 0000000..3e4e0ea
--- /dev/null
+++ b/trackdeck.cpp
@@ -0,0 +1,145 @@
+#include "trackdeck.h"
+#include "ui_trackdeck.h"
+
+#include <QAbstractEventDispatcher>
+#include <QDragEnterEvent>
+#include <QDragLeaveEvent>
+#include <QDropEvent>
+#include <QMimeData>
+#include <QTextStream>
+#include <QUrl>
+#include <QFileInfo>
+#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();
+
+    connect(m_ui->pushButtonPlay, &QAbstractButton::pressed, &m_player, &AudioPlayer::togglePlaying);
+    connect(m_ui->pushButtonStop, &QAbstractButton::pressed, &m_player, &AudioPlayer::stop);
+
+    connect(m_ui->verticalSliderVolume, &QAbstractSlider::valueChanged, &m_player, [&player=m_player](int value){ player.setVolume(float(value)/100.f); });
+
+    connect(m_ui->horizontalSliderSpeed, &QAbstractSlider::valueChanged, &m_player, [&player=m_player](int value){ player.setSpeed(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_player, &AudioPlayer::positionChanged, m_ui->scratchWidget, &ScratchWidget::setPosition);
+    connect(&m_player, &AudioPlayer::playingChanged, m_ui->pushButtonPlay, [&button=*m_ui->pushButtonPlay](bool playing){ button.setText(playing ? tr("▮▮") : tr("▶")); });
+}
+
+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->previewWidget->setBuffer(buffer);
+    m_ui->scratchWidget->setBuffer(buffer);
+    m_ui->progressBar->hide();
+}
diff --git a/trackdeck.h b/trackdeck.h
new file mode 100644
index 0000000..d7e8db7
--- /dev/null
+++ b/trackdeck.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include <QWidget>
+
+#include <memory>
+
+#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);
+
+private:
+    const std::unique_ptr<Ui::TrackDeck> m_ui;
+
+    std::unique_ptr<AudioDecoder> m_decoder;
+
+    AudioPlayer m_player;
+
+    QString m_filename;
+};
diff --git a/trackdeck.ui b/trackdeck.ui
new file mode 100644
index 0000000..b98a0aa
--- /dev/null
+++ b/trackdeck.ui
@@ -0,0 +1,195 @@
+<?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>400</width>
+    <height>300</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">
+     <item>
+      <widget class="QLabel" name="labelTitle">
+       <property name="font">
+        <font>
+         <pointsize>20</pointsize>
+        </font>
+       </property>
+       <property name="text">
+        <string>Track</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <layout class="QHBoxLayout" name="horizontalLayout">
+       <item>
+        <widget class="QProgressBar" name="progressBar">
+         <property name="value">
+          <number>24</number>
+         </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="horizontalSliderSpeed">
+         <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::Horizontal</enum>
+         </property>
+         <property name="tickPosition">
+          <enum>QSlider::TicksBothSides</enum>
+         </property>
+         <property name="tickInterval">
+          <number>10</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>
+      <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>
+    </layout>
+   </item>
+   <item>
+    <widget class="QSlider" name="verticalSliderVolume">
+     <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>previewwidget.h</header>
+   <container>1</container>
+  </customwidget>
+  <customwidget>
+   <class>ScratchWidget</class>
+   <extends>QWidget</extends>
+   <header>scratchwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>