BackendSettingsPage: add "EBU R 128 loudness normalization"-related settings

Change `Use Replay Gain metadata if it is available` checkbox
into a radio button and add button to disable any loudness normalization.

Add second group(+radio button), for EBU R 128 loudness normalization.

There is only one tunable: Target Level,
defaulting to EBU R 128-recommended `-23 LUFS`.

Care should be taken when changing Target Level!
You probably don't want to go outside of `-30..-16` range!

At least as implemented, there is only support for per-song normalization,
i.e. no per-album normalization.

We do not do anything with loudness range,
although i have some further thoughts about compression.

We do not do anything about clipping / peak level.

NOTE: we do not need `libebur128` to *perform* the audio normalization,
      only for the initial analysis.


Co-authored-by: Jonas Kvinge <jonas@jkvinge.net>

src/settings/backendsettingspage.cpp

@@ -74,6 +74,8 @@ BackendSettingsPage::BackendSettingsPage(SettingsDialog *dialog, QWidget *parent
   ui_->label_replaygainpreamp->setMinimumWidth(QFontMetrics(ui_->label_replaygainpreamp->font()).horizontalAdvance("-WW.W dB"));
   ui_->label_replaygainfallbackgain->setMinimumWidth(QFontMetrics(ui_->label_replaygainfallbackgain->font()).horizontalAdvance("-WW.W dB"));
 
+  ui_->label_ebur128_target_level->setMinimumWidth(QFontMetrics(ui_->label_ebur128_target_level->font()).horizontalAdvance("-WW.W LUFS"));
+
   QObject::connect(ui_->combobox_engine, QOverload<int>::of(&QComboBox::currentIndexChanged), this, &BackendSettingsPage::EngineChanged);
   QObject::connect(ui_->combobox_output, QOverload<int>::of(&QComboBox::currentIndexChanged), this, &BackendSettingsPage::OutputChanged);
   QObject::connect(ui_->combobox_device, QOverload<int>::of(&QComboBox::currentIndexChanged), this, &BackendSettingsPage::DeviceSelectionChanged);
@@ -85,6 +87,9 @@ BackendSettingsPage::BackendSettingsPage(SettingsDialog *dialog, QWidget *parent
 #endif
   QObject::connect(ui_->stickyslider_replaygainpreamp, &StickySlider::valueChanged, this, &BackendSettingsPage::RgPreampChanged);
   QObject::connect(ui_->stickyslider_replaygainfallbackgain, &StickySlider::valueChanged, this, &BackendSettingsPage::RgFallbackGainChanged);
+#ifdef HAVE_GSTREAMER
+  QObject::connect(ui_->stickyslider_ebur128_target_level, &StickySlider::valueChanged, this, &BackendSettingsPage::EbuR128TargetLevelChanged);
+#endif
   QObject::connect(ui_->checkbox_fadeout_stop, &QCheckBox::toggled, this, &BackendSettingsPage::FadingOptionsChanged);
   QObject::connect(ui_->checkbox_fadeout_cross, &QCheckBox::toggled, this, &BackendSettingsPage::FadingOptionsChanged);
   QObject::connect(ui_->checkbox_fadeout_auto, &QCheckBox::toggled, this, &BackendSettingsPage::FadingOptionsChanged);
@@ -161,12 +166,21 @@ void BackendSettingsPage::Load() {
   ui_->spinbox_low_watermark->setValue(s.value("bufferlowwatermark", kDefaultBufferLowWatermark).toDouble());
   ui_->spinbox_high_watermark->setValue(s.value("bufferhighwatermark", kDefaultBufferHighWatermark).toDouble());
 
-  ui_->checkbox_replaygain->setChecked(s.value("rgenabled", false).toBool());
+  ui_->radiobutton_replaygain->setChecked(s.value("rgenabled", false).toBool());
   ui_->combobox_replaygainmode->setCurrentIndex(s.value("rgmode", 0).toInt());
   ui_->stickyslider_replaygainpreamp->setValue(static_cast<int>(s.value("rgpreamp", 0.0).toDouble() * 10 + 600));
   ui_->checkbox_replaygaincompression->setChecked(s.value("rgcompression", true).toBool());
   ui_->stickyslider_replaygainfallbackgain->setValue(static_cast<int>(s.value("rgfallbackgain", 0.0).toDouble() * 10 + 600));
 
+#ifdef HAVE_GSTREAMER
+  ui_->groupbox_ebur128->show();
+#else
+  ui_->groupbox_ebur128->hide();
+#endif
+
+  ui_->radiobutton_ebur128_loudness_normalization->setChecked(s.value("ebur128_loudness_normalization", false).toBool());
+  ui_->stickyslider_ebur128_target_level->setValue(static_cast<int>(s.value("ebur128_target_level_lufs", -23.0).toDouble() * 10));
+
 #ifdef HAVE_ALSA
   bool fade_default = false;
 #else
@@ -197,6 +211,10 @@ void BackendSettingsPage::Load() {
   RgPreampChanged(ui_->stickyslider_replaygainpreamp->value());
   RgFallbackGainChanged(ui_->stickyslider_replaygainfallbackgain->value());
 
+#ifdef HAVE_GSTREAMER
+  EbuR128TargetLevelChanged(ui_->stickyslider_ebur128_target_level->value());
+#endif
+
   Init(ui_->layout_backendsettingspage->parentWidget());
   if (!QSettings().childGroups().contains(kSettingsGroup)) set_changed();
 
@@ -251,6 +269,7 @@ void BackendSettingsPage::Load_Engine(const EngineBase::Type enginetype) {
   ui_->lineedit_device->clear();
 
   ui_->groupbox_replaygain->setEnabled(false);
+  ui_->groupbox_ebur128->setEnabled(false);
 
   if (engine()->type() != enginetype) {
     qLog(Debug) << "Switching engine.";
@@ -304,10 +323,12 @@ void BackendSettingsPage::Load_Output(QString output, QVariant device) {
   if (engine()->type() == EngineBase::Type::GStreamer) {
     ui_->groupbox_buffer->setEnabled(true);
     ui_->groupbox_replaygain->setEnabled(true);
+    ui_->groupbox_ebur128->setEnabled(true);
   }
   else {
     ui_->groupbox_buffer->setEnabled(false);
     ui_->groupbox_replaygain->setEnabled(false);
+    ui_->groupbox_ebur128->setEnabled(false);
   }
 
   if (ui_->combobox_output->count() >= 1) Load_Device(output, device);
@@ -474,12 +495,15 @@ void BackendSettingsPage::Save() {
   s.setValue("bufferlowwatermark", ui_->spinbox_low_watermark->value());
   s.setValue("bufferhighwatermark", ui_->spinbox_high_watermark->value());
 
-  s.setValue("rgenabled", ui_->checkbox_replaygain->isChecked());
+  s.setValue("rgenabled", ui_->radiobutton_replaygain->isChecked());
   s.setValue("rgmode", ui_->combobox_replaygainmode->currentIndex());
   s.setValue("rgpreamp", static_cast<double>(ui_->stickyslider_replaygainpreamp->value()) / 10 - 60);
   s.setValue("rgfallbackgain", static_cast<double>(ui_->stickyslider_replaygainfallbackgain->value()) / 10 - 60);
   s.setValue("rgcompression", ui_->checkbox_replaygaincompression->isChecked());
 
+  s.setValue("ebur128_loudness_normalization", ui_->radiobutton_ebur128_loudness_normalization->isChecked());
+  s.setValue("ebur128_target_level_lufs", static_cast<double>(ui_->stickyslider_ebur128_target_level->value()) / 10);
+
   s.setValue("FadeoutEnabled", ui_->checkbox_fadeout_stop->isChecked());
   s.setValue("CrossfadeEnabled", ui_->checkbox_fadeout_cross->isChecked());
   s.setValue("AutoCrossfadeEnabled", ui_->checkbox_fadeout_auto->isChecked());
@@ -638,6 +662,16 @@ void BackendSettingsPage::RgFallbackGainChanged(const int value) {
 
 }
 
+#ifdef HAVE_GSTREAMER
+void BackendSettingsPage::EbuR128TargetLevelChanged(const int value) {
+
+  double db = static_cast<double>(value) / 10;
+  QString db_str = QString::asprintf("%+.1f LUFS", db);
+  ui_->label_ebur128_target_level->setText(db_str);
+
+}
+#endif
+
 #ifdef HAVE_ALSA
 void BackendSettingsPage::SwitchALSADevices(const ALSAPluginType alsa_plugin_type) {
 

src/settings/backendsettingspage.h

@@ -68,6 +68,9 @@ class BackendSettingsPage : public SettingsPage {
   void DeviceStringChanged();
   void RgPreampChanged(const int value);
   void RgFallbackGainChanged(const int value);
+#ifdef HAVE_GSTREAMER
+  void EbuR128TargetLevelChanged(const int value);
+#endif
   void radiobutton_alsa_hw_clicked(const bool checked);
   void radiobutton_alsa_plughw_clicked(const bool checked);
   void radiobutton_alsa_pcm_clicked(const bool checked);

src/settings/backendsettingspage.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>583</width>
-    <height>1097</height>
+    <width>717</width>
+    <height>1245</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -409,131 +409,235 @@
     </widget>
    </item>
    <item>
-    <widget class="QGroupBox" name="groupbox_replaygain">
-     <property name="enabled">
-      <bool>true</bool>
-     </property>
+    <widget class="QGroupBox" name="groupBox_2">
      <property name="title">
-      <string>Replay Gain</string>
+      <string>Audio normalization</string>
      </property>
-     <layout class="QVBoxLayout" name="layout_replay_gain">
+     <layout class="QVBoxLayout" name="verticalLayout_3">
       <item>
-       <widget class="QCheckBox" name="checkbox_replaygain">
-        <property name="enabled">
+       <widget class="QRadioButton" name="radiobutton_no_audio_normalization">
+        <property name="text">
+         <string>No audio normalization</string>
+        </property>
+        <property name="checked">
          <bool>true</bool>
         </property>
-        <property name="text">
-         <string>Use Replay Gain metadata if it is available</string>
-        </property>
+        <attribute name="buttonGroup">
+         <string notr="true">buttonGroup_audio_normalization</string>
+        </attribute>
        </widget>
       </item>
       <item>
-       <widget class="QWidget" name="widget_replaygain" native="true">
+       <widget class="QGroupBox" name="groupbox_replaygain">
         <property name="enabled">
-         <bool>false</bool>
+         <bool>true</bool>
         </property>
-        <layout class="QFormLayout" name="formLayout_4">
-         <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 row="0" column="0">
-          <widget class="QLabel" name="label_regainmode">
-           <property name="text">
-            <string>Replay Gain mode</string>
+        <property name="title">
+         <string>Replay Gain</string>
+        </property>
+        <layout class="QVBoxLayout" name="layout_replay_gain">
+         <item>
+          <widget class="QRadioButton" name="radiobutton_replaygain">
+           <property name="enabled">
+            <bool>true</bool>
            </property>
+           <property name="text">
+            <string>Use Replay Gain metadata if it is available</string>
+           </property>
+           <attribute name="buttonGroup">
+            <string notr="true">buttonGroup_audio_normalization</string>
+           </attribute>
           </widget>
          </item>
-         <item row="0" column="1">
-          <widget class="QComboBox" name="combobox_replaygainmode">
-           <item>
-            <property name="text">
-             <string>Radio (equal loudness for all tracks)</string>
+         <item>
+          <widget class="QWidget" name="widget_replaygain" native="true">
+           <property name="enabled">
+            <bool>false</bool>
+           </property>
+           <layout class="QFormLayout" name="formLayout_4">
+            <property name="leftMargin">
+             <number>0</number>
             </property>
-           </item>
-           <item>
-            <property name="text">
-             <string>Album (ideal loudness for all tracks)</string>
+            <property name="topMargin">
+             <number>0</number>
             </property>
-           </item>
+            <property name="rightMargin">
+             <number>0</number>
+            </property>
+            <property name="bottomMargin">
+             <number>0</number>
+            </property>
+            <item row="0" column="0">
+             <widget class="QLabel" name="label_regainmode">
+              <property name="text">
+               <string>Replay Gain mode</string>
+              </property>
+             </widget>
+            </item>
+            <item row="0" column="1">
+             <widget class="QComboBox" name="combobox_replaygainmode">
+              <item>
+               <property name="text">
+                <string>Radio (equal loudness for all tracks)</string>
+               </property>
+              </item>
+              <item>
+               <property name="text">
+                <string>Album (ideal loudness for all tracks)</string>
+               </property>
+              </item>
+             </widget>
+            </item>
+            <item row="1" column="0">
+             <widget class="QLabel" name="label_preamp">
+              <property name="text">
+               <string>Pre-amp</string>
+              </property>
+             </widget>
+            </item>
+            <item row="1" column="1">
+             <layout class="QHBoxLayout" name="layout_replayagainpreamp">
+              <item>
+               <widget class="QLabel" name="label_replaygainpreamp"/>
+              </item>
+              <item>
+               <widget class="StickySlider" name="stickyslider_replaygainpreamp">
+                <property name="maximum">
+                 <number>1200</number>
+                </property>
+                <property name="value">
+                 <number>600</number>
+                </property>
+                <property name="orientation">
+                 <enum>Qt::Horizontal</enum>
+                </property>
+                <property name="sticky_center" stdset="0">
+                 <number>600</number>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+            <item row="4" column="0" colspan="2">
+             <widget class="QCheckBox" name="checkbox_replaygaincompression">
+              <property name="text">
+               <string>Apply compression to prevent clipping</string>
+              </property>
+             </widget>
+            </item>
+            <item row="2" column="1">
+             <layout class="QHBoxLayout" name="layout_replaygainfallbackgain">
+              <item>
+               <widget class="QLabel" name="label_replaygainfallbackgain"/>
+              </item>
+              <item>
+               <widget class="StickySlider" name="stickyslider_replaygainfallbackgain">
+                <property name="minimum">
+                 <number>0</number>
+                </property>
+                <property name="maximum">
+                 <number>1200</number>
+                </property>
+                <property name="value">
+                 <number>600</number>
+                </property>
+                <property name="orientation">
+                 <enum>Qt::Horizontal</enum>
+                </property>
+                <property name="sticky_center" stdset="0">
+                 <number>600</number>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+            <item row="2" column="0">
+             <widget class="QLabel" name="label_fallbackgain">
+              <property name="text">
+               <string>Fallback-gain</string>
+              </property>
+             </widget>
+            </item>
+           </layout>
           </widget>
          </item>
-         <item row="1" column="0">
-          <widget class="QLabel" name="label_preamp">
-           <property name="text">
-            <string>Pre-amp</string>
+        </layout>
+       </widget>
+      </item>
+      <item>
+       <widget class="QGroupBox" name="groupbox_ebur128">
+        <property name="enabled">
+         <bool>true</bool>
+        </property>
+        <property name="title">
+         <string>EBU R 128 Loudness Normalization</string>
+        </property>
+        <layout class="QVBoxLayout" name="layout_ebur128">
+         <item>
+          <widget class="QRadioButton" name="radiobutton_ebur128_loudness_normalization">
+           <property name="enabled">
+            <bool>true</bool>
            </property>
+           <property name="text">
+            <string>Perform track loudness normalization</string>
+           </property>
+           <attribute name="buttonGroup">
+            <string notr="true">buttonGroup_audio_normalization</string>
+           </attribute>
           </widget>
          </item>
-         <item row="1" column="1">
-          <layout class="QHBoxLayout" name="layout_replayagainpreamp">
-           <item>
-            <widget class="QLabel" name="label_replaygainpreamp"/>
-           </item>
-           <item>
-            <widget class="StickySlider" name="stickyslider_replaygainpreamp">
-             <property name="maximum">
-              <number>1200</number>
-             </property>
-             <property name="value">
-              <number>600</number>
-             </property>
-             <property name="orientation">
-              <enum>Qt::Horizontal</enum>
-             </property>
-             <property name="sticky_center" stdset="0">
-              <number>600</number>
-             </property>
-            </widget>
-           </item>
-          </layout>
-         </item>
-         <item row="4" column="0" colspan="2">
-          <widget class="QCheckBox" name="checkbox_replaygaincompression">
-           <property name="text">
-            <string>Apply compression to prevent clipping</string>
-           </property>
-          </widget>
-         </item>
-         <item row="2" column="1">
-          <layout class="QHBoxLayout" name="layout_replaygainfallbackgain">
-           <item>
-            <widget class="QLabel" name="label_replaygainfallbackgain"/>
-           </item>
-           <item>
-            <widget class="StickySlider" name="stickyslider_replaygainfallbackgain">
-             <property name="minimum">
-              <number>0</number>
-             </property>
-             <property name="maximum">
-              <number>1200</number>
-             </property>
-             <property name="value">
-              <number>600</number>
-             </property>
-             <property name="orientation">
-              <enum>Qt::Horizontal</enum>
-             </property>
-             <property name="sticky_center" stdset="0">
-              <number>600</number>
-             </property>
-            </widget>
-           </item>
-          </layout>
-         </item>
-         <item row="2" column="0">
-          <widget class="QLabel" name="label_fallbackgain">
-           <property name="text">
-            <string>Fallback-gain</string>
+         <item>
+          <widget class="QWidget" name="widget_ebur128" native="true">
+           <property name="enabled">
+            <bool>false</bool>
            </property>
+           <layout class="QFormLayout" name="formLayout_ebur128">
+            <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 row="0" column="0">
+             <widget class="QLabel" name="label_ebur128_target_level_label">
+              <property name="text">
+               <string>Target Level</string>
+              </property>
+             </widget>
+            </item>
+            <item row="0" column="1">
+             <layout class="QHBoxLayout" name="layout_ebur128_target_level">
+              <item>
+               <widget class="QLabel" name="label_ebur128_target_level"/>
+              </item>
+              <item>
+               <widget class="StickySlider" name="stickyslider_ebur128_target_level">
+                <property name="minimum">
+                 <number>-480</number>
+                </property>
+                <property name="maximum">
+                 <number>0</number>
+                </property>
+                <property name="value">
+                 <number>-230</number>
+                </property>
+                <property name="orientation">
+                 <enum>Qt::Horizontal</enum>
+                </property>
+                <property name="sticky_center" stdset="0">
+                 <number>-230</number>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+           </layout>
           </widget>
          </item>
         </layout>
@@ -735,7 +839,7 @@
   <tabstop>spinbox_low_watermark</tabstop>
   <tabstop>spinbox_high_watermark</tabstop>
   <tabstop>button_buffer_defaults</tabstop>
-  <tabstop>checkbox_replaygain</tabstop>
+  <tabstop>radiobutton_replaygain</tabstop>
   <tabstop>combobox_replaygainmode</tabstop>
   <tabstop>stickyslider_replaygainpreamp</tabstop>
   <tabstop>stickyslider_replaygainfallbackgain</tabstop>
@@ -751,20 +855,43 @@
  <resources/>
  <connections>
   <connection>
-   <sender>checkbox_replaygain</sender>
+   <sender>radiobutton_ebur128_loudness_normalization</sender>
+   <signal>toggled(bool)</signal>
+   <receiver>widget_ebur128</receiver>
+   <slot>setEnabled(bool)</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>429</x>
+     <y>835</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>429</x>
+     <y>890</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>radiobutton_replaygain</sender>
    <signal>toggled(bool)</signal>
    <receiver>widget_replaygain</receiver>
    <slot>setEnabled(bool)</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>110</x>
-     <y>465</y>
+     <x>429</x>
+     <y>640</y>
     </hint>
     <hint type="destinationlabel">
-     <x>164</x>
-     <y>573</y>
+     <x>429</x>
+     <y>717</y>
     </hint>
    </hints>
   </connection>
  </connections>
+ <buttongroups>
+  <buttongroup name="buttonGroup_audio_normalization">
+   <property name="exclusive">
+    <bool>true</bool>
+   </property>
+  </buttongroup>
+ </buttongroups>
 </ui>