Add "Audio Language" selection

Add a selection for the preferred audio language.
The existing "Language" setting is used for the menu language
but was until this fix also used as preferred audio language.
When there is no "Audio Language" preference specified
then the "Language" setting is used so users do not need
to configure anything to keep the current behavior.
Note that TVs sold in Europe generally have separate
settings for "Menu Language" and "Audio Language".

mythtv/libs/libmythbase/mythcorecontext.cpp

@@ -94,6 +94,7 @@ class MythCoreContextPrivate : public QObject
 
     MythLocale *m_locale { nullptr };
     QString m_language;
+    QString m_audioLanguage;
 
     MythScheduler *m_scheduler { nullptr };
 
@@ -1792,6 +1793,40 @@ void MythCoreContext::ResetLanguage(void)
     d->m_language.clear();
 }
 
+/**
+ *  \brief Returns two character ISO-639 language descriptor for audio language.
+ *  \sa iso639_get_language_list()
+ */
+QString MythCoreContext::GetAudioLanguage(void)
+{
+    return GetAudioLanguageAndVariant().left(2);
+}
+
+/**
+ *  \brief Returns the user-set audio language and variant.
+ *
+ *   The string has the form ll or ll_vv, where ll is the two character
+ *   ISO-639 language code, and vv (which may not exist) is the variant.
+ *   Examples include en_AU, en_CA, en_GB, en_US, fr_CH, fr_DE, pt_BR, pt_PT.
+ */
+QString MythCoreContext::GetAudioLanguageAndVariant(void)
+{
+    if (d->m_audioLanguage.isEmpty())
+    {
+        auto menuLanguage = GetLanguageAndVariant();
+        d->m_audioLanguage = GetSetting("AudioLanguage", menuLanguage).toLower();
+
+        LOG(VB_AUDIO, LOG_DEBUG, LOC + QString("audio language:%1 menu language:%2")
+            .arg(d->m_audioLanguage).arg(menuLanguage));
+    }
+    return d->m_audioLanguage;
+}
+
+void MythCoreContext::ResetAudioLanguage(void)
+{
+    d->m_audioLanguage.clear();
+}
+
 void MythCoreContext::ResetSockets(void)
 {
     QMutexLocker locker(&d->m_sockLock);

mythtv/libs/libmythbase/mythcorecontext.h

@@ -236,6 +236,9 @@ class MBASE_PUBLIC MythCoreContext : public QObject, public MythObservable, publ
     QString GetLanguage(void);
     QString GetLanguageAndVariant(void);
     void ResetLanguage(void);
+    QString GetAudioLanguage(void);
+    QString GetAudioLanguageAndVariant(void);
+    void ResetAudioLanguage(void);
     void ResetSockets(void);
 
     using PlaybackStartCb = void (QObject::*)(void);

mythtv/libs/libmythtv/decoders/avformatdecoder.cpp

@@ -4394,8 +4394,8 @@ int AvFormatDecoder::AutoSelectAudioTrack(void)
                 ftype.push_back(i);
         }
 
-        // try to get the language track matching the frontend language.
-        QString language_key_convert = iso639_str2_to_str3(gCoreContext->GetLanguage());
+        // Try to get the language track for the preferred language for audio
+        QString language_key_convert = iso639_str2_to_str3(gCoreContext->GetAudioLanguage());
         uint language_key = iso639_str3_to_key(language_key_convert);
         uint canonical_key = iso639_key_to_canonical_key(language_key);
 
@@ -4422,8 +4422,8 @@ int AvFormatDecoder::AutoSelectAudioTrack(void)
         if (selTrack < 0)
             selTrack = filter_max_ch(m_ic, atracks, flang);
 
-        // try to get best track for most preferred language
-        // Set by the "Guide Data" language prefs in Appearance.
+        // Try to get best track for most preferred language for audio.
+        // Set by the "Guide Data" "Audio Language" preference in Appearance.
         if (selTrack < 0)
         {
             auto it = m_languagePreference.begin();
@@ -4457,8 +4457,8 @@ int AvFormatDecoder::AutoSelectAudioTrack(void)
             }
         }
 
-        // could not select track based on user preferences (language)
-        // try to select the default track
+        // Could not select track based on user preferences (audio language)
+        // Try to select the default track
         if (selTrack < 0)
         {
             LOG(VB_AUDIO, LOG_INFO, LOC + "Trying to select default track");
@@ -4472,7 +4472,7 @@ int AvFormatDecoder::AutoSelectAudioTrack(void)
             }
         }
 
-        // try to get best track for any language
+        // Try to get best track for any language
         if (selTrack < 0)
         {
             LOG(VB_AUDIO, LOG_INFO, LOC +

mythtv/libs/libmythui/mythmainwindow.cpp

@@ -634,6 +634,7 @@ bool MythMainWindow::event(QEvent *Event)
 void MythMainWindow::LoadQtConfig()
 {
     gCoreContext->ResetLanguage();
+    gCoreContext->ResetAudioLanguage();
     GetMythUI()->ClearThemeCacheDir();
     QApplication::setStyle("Windows");
 }

mythtv/programs/mythfrontend/globalsettings.cpp

@@ -3214,7 +3214,7 @@ static GlobalComboBoxSetting *MythLanguage()
 {
     auto *gc = new GlobalComboBoxSetting("Language");
 
-    gc->setLabel(AppearanceSettings::tr("Language"));
+    gc->setLabel(AppearanceSettings::tr("Menu Language"));
 
     QMap<QString, QString> langMap = MythTranslation::getLanguages();
     QStringList langs = langMap.values();
@@ -3237,6 +3237,36 @@ static GlobalComboBoxSetting *MythLanguage()
     return gc;
 }
 
+static GlobalComboBoxSetting *AudioLanguage()
+{
+    auto *gc = new GlobalComboBoxSetting("AudioLanguage");
+
+    gc->setLabel(AppearanceSettings::tr("Audio Language"));
+
+    QMap<QString, QString> langMap = MythTranslation::getLanguages();
+    QStringList langs = langMap.values();
+    langs.sort();
+    QString langCode = gCoreContext->GetSetting("AudioLanguage").toLower();
+
+    if (langCode.isEmpty())
+    {
+        auto menuLangCode = gCoreContext->GetSetting("Language").toLower();
+        langCode = menuLangCode.isEmpty() ? "en_US" : menuLangCode;
+    }
+
+    gc->clearSelections();
+
+    for (const auto & label : qAsConst(langs))
+    {
+        QString value = langMap.key(label);
+        gc->addSelection(label, value, (value.toLower() == langCode));
+    }
+
+    gc->setHelpText(AppearanceSettings::tr("Preferred language for the "
+                                           "audio track."));
+    return gc;
+}
+
 static void ISO639_fill_selections(MythUIComboBoxSetting *widget, uint i)
 {
     widget->clearSelections();
@@ -4784,6 +4814,7 @@ AppearanceSettings::AppearanceSettings()
     dates->setLabel(tr("Localization"));
 
     dates->addChild(MythLanguage());
+    dates->addChild(AudioLanguage());
     dates->addChild(ISO639PreferredLanguage(0));
     dates->addChild(ISO639PreferredLanguage(1));
     dates->addChild(MythDateFormatCB());