feat: translate subtitles with an OpenAI-compatible LLM

src/mpv/mpvitem.cpp

@@ -185,6 +185,24 @@ void MpvItem::addSubtitleFile(const QUrl &url)
     commandAsync(QStringList{QStringLiteral("sub-add"), localPathOrUrl(url), QStringLiteral("select")});
 }
 
+void MpvItem::showSecondarySubtitleFile(const QUrl &url, const QString &title)
+{
+    if (!url.isValid()) {
+        return;
+    }
+    const QString path = localPathOrUrl(url);
+    for (const QVariant &entry : std::as_const(m_subtitleTracks)) {
+        const QVariantMap track = entry.toMap();
+        if (track.value(QStringLiteral("externalFilename")).toString() == path) {
+            setSecondarySubtitleId(track.value(QStringLiteral("id")).toInt());
+            return;
+        }
+    }
+    // "auto" adds the track without selecting it; updateTracks() selects it as secondary.
+    m_pendingSecondaryPath = path;
+    commandAsync(QStringList{QStringLiteral("sub-add"), path, QStringLiteral("auto"), title});
+}
+
 void MpvItem::showText(const QString &text)
 {
     commandAsync(QStringList{QStringLiteral("show-text"), text});
@@ -241,7 +259,13 @@ void MpvItem::updateTracks(const QVariantList &trackList)
             {QStringLiteral("codec"), track.value(QStringLiteral("codec")).toString()},
             {QStringLiteral("external"), track.value(QStringLiteral("external")).toBool()},
             {QStringLiteral("externalFilename"), track.value(QStringLiteral("external-filename")).toString()},
+            {QStringLiteral("ffIndex"), track.value(QStringLiteral("ff-index"), -1).toInt()},
         });
+
+        if (!m_pendingSecondaryPath.isEmpty() && track.value(QStringLiteral("external-filename")).toString() == m_pendingSecondaryPath) {
+            m_pendingSecondaryPath.clear();
+            setSecondarySubtitleId(id);
+        }
     }
 
     m_subtitleTracks = subtitles;