feat(translate): translate a whole playlist

autotests/CMakeLists.txt

@@ -34,3 +34,8 @@ ecm_add_test(mediainfotest.cpp
     TEST_NAME mediainfotest
     LINK_LIBRARIES qtpotato_core Qt6::Test
 )
+
+ecm_add_test(subtitleextractortest.cpp
+    TEST_NAME subtitleextractortest
+    LINK_LIBRARIES qtpotato_core Qt6::Test
+)

autotests/subtitleextractortest.cpp

@@ -0,0 +1,97 @@
+// SPDX-FileCopyrightText: 2026 Tri Vo Khac
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "subtitleextractor.h"
+
+#include <QFile>
+#include <QProcess>
+#include <QStandardPaths>
+#include <QTemporaryDir>
+#include <QTest>
+
+using namespace Qt::Literals::StringLiterals;
+
+class SubtitleExtractorTest : public QObject
+{
+    Q_OBJECT
+
+private:
+    // Makes \a name in \a dir with a German audio track plus \a subtitleLanguages as
+    // SRT subtitle tracks, in that order.
+    static QString makeSample(const QTemporaryDir &dir, const QString &name, const QStringList &subtitleLanguages)
+    {
+        const QString ffmpeg = QStandardPaths::findExecutable(u"ffmpeg"_s);
+        const QString srt = dir.filePath(u"line.srt"_s);
+        QFile file(srt);
+        if (!file.open(QIODevice::WriteOnly) || file.write("1\n00:00:00,000 --> 00:00:01,000\nHello\n") < 0) {
+            return {};
+        }
+        file.close();
+
+        QStringList args{u"-v"_s, u"error"_s, u"-f"_s, u"lavfi"_s, u"-i"_s, u"sine=duration=1"_s};
+        for (qsizetype i = 0; i < subtitleLanguages.size(); ++i) {
+            args << u"-i"_s << srt;
+        }
+        args << u"-map"_s << u"0:a"_s << u"-metadata:s:a:0"_s << u"language=ger"_s;
+        for (qsizetype i = 0; i < subtitleLanguages.size(); ++i) {
+            args << u"-map"_s << u"%1:s"_s.arg(i + 1) << u"-metadata:s:s:%1"_s.arg(i) << u"language=%1"_s.arg(subtitleLanguages.at(i));
+        }
+        const QString path = dir.filePath(name);
+        args << u"-c:s"_s << u"srt"_s << path;
+        QProcess process;
+        process.start(ffmpeg, args);
+        if (!process.waitForFinished() || process.exitCode() != 0) {
+            qWarning() << process.readAllStandardError();
+            return {};
+        }
+        return path;
+    }
+
+private Q_SLOTS:
+    void initTestCase()
+    {
+        if (QStandardPaths::findExecutable(u"ffmpeg"_s).isEmpty()) {
+            QSKIP("ffmpeg is needed to make sample files");
+        }
+    }
+
+    void findTranslationSourcePrefersEnglish()
+    {
+        QTemporaryDir dir;
+        const QString path = makeSample(dir, u"episode.mkv"_s, {u"fre"_s, u"eng"_s});
+        QVERIFY(!path.isEmpty());
+        const Subtitles::SourceResult result = Subtitles::findTranslationSource(path);
+        QVERIFY2(result.error.isEmpty(), qPrintable(result.error));
+        // Stream 0 is the audio, 1 French, 2 English.
+        QCOMPARE(result.streamIndex, 2);
+
+        std::atomic_bool cancelled = false;
+        const Subtitles::ExtractResult cues = Subtitles::extractEmbedded(path, result.streamIndex, cancelled);
+        QCOMPARE(cues.cues.size(), 1);
+        QCOMPARE(cues.cues.first().text, u"Hello"_s);
+    }
+
+    void findTranslationSourceFallsBackToTheAudioLanguage()
+    {
+        QTemporaryDir dir;
+        const QString path = makeSample(dir, u"episode.mkv"_s, {u"fre"_s, u"ger"_s});
+        QVERIFY(!path.isEmpty());
+        QCOMPARE(Subtitles::findTranslationSource(path).streamIndex, 2);
+    }
+
+    void findTranslationSourceWithoutSubtitles()
+    {
+        QTemporaryDir dir;
+        const QString path = makeSample(dir, u"episode.mkv"_s, {});
+        QVERIFY(!path.isEmpty());
+        const Subtitles::SourceResult result = Subtitles::findTranslationSource(path);
+        QVERIFY(result.error.isEmpty());
+        QCOMPARE(result.streamIndex, -1);
+
+        QVERIFY(!Subtitles::findTranslationSource(dir.filePath(u"missing.mkv"_s)).error.isEmpty());
+    }
+};
+
+QTEST_GUILESS_MAIN(SubtitleExtractorTest)
+
+#include "subtitleextractortest.moc"

src/playlist/playlistmodel.cpp

@@ -278,6 +278,11 @@ QUrl PlaylistModel::urlAt(int index) const
     return m_urls.value(index);
 }
 
+QList<QUrl> PlaylistModel::urls() const
+{
+    return m_urls;
+}
+
 void PlaylistModel::setPlayingIndex(int index)
 {
     if (index == m_playingIndex) {

src/playlist/playlistmodel.h

@@ -59,6 +59,7 @@ public:
     Q_INVOKABLE void move(int from, int to);
     Q_INVOKABLE void clear();
     Q_INVOKABLE QUrl urlAt(int index) const;
+    Q_INVOKABLE QList<QUrl> urls() const;
 
     // Media files directly inside \a folder, sorted the way a file manager does
     // ("Episode 2" before "Episode 10").

src/qml/Actions.qml

@@ -38,6 +38,7 @@ Item {
     signal headerToggleRequested()
     signal contextMenuRequested()
     signal translateRequested()
+    signal translatePlaylistRequested()
     signal editGlossaryRequested()
 
     function seekBy(seconds: real) {
@@ -396,6 +397,13 @@ Item {
         onTriggered: root.translateRequested()
     }
 
+    property Action translatePlaylist: Action {
+        enabled: root.shortcutsEnabled && root.playlist.count > 1 && !root.translator.busy
+        text: KI18n.i18nc("@action", "Translate Whole Playlist into %1", QtPotatoSettings.targetLanguage)
+        icon.name: "translate"
+        onTriggered: root.translatePlaylistRequested()
+    }
+
     property Action editGlossary: Action {
         enabled: root.shortcutsEnabled && root.hasFile && root.mpv.currentUrl.toString().startsWith("file:")
         text: KI18n.i18nc("@action", "Edit Translation Glossary…")

src/qml/Header.qml

@@ -103,6 +103,7 @@ ToolBar {
 
                 MenuSeparator {}
                 AppMenuItem { action: root.actions.translateSubtitle }
+                AppMenuItem { action: root.actions.translatePlaylist }
                 AppMenuItem { action: root.actions.addSubtitle }
             }
         }

src/qml/Main.qml

@@ -49,7 +49,8 @@ ApplicationWindow {
         return KI18n.i18nc("@item:inlistbox subtitle track, %1 is a language", "%1 (translated)", QtPotatoSettings.targetLanguage)
     }
 
-    function translateCurrentSubtitle() {
+    // The subtitle of the current video to translate, or undefined when it has no text one.
+    function translationSourceTrack() {
         let track = video.subtitleTracks.find(track => track.id === video.subtitleId)
         // Translate the original again, not the translation on screen.
         if (track && video.isTranslatedSubtitle(track.id)) {
@@ -60,6 +61,11 @@ ApplicationWindow {
             const sourceId = video.translationSourceId()
             track = video.subtitleTracks.find(track => track.id === sourceId)
         }
+        return track
+    }
+
+    function translateCurrentSubtitle() {
+        const track = translationSourceTrack()
         if (track) {
             lastTranslationTrack = track
             lastTranslationVideo = video.currentUrl
@@ -128,6 +134,14 @@ ApplicationWindow {
         onPlaylistToggleRequested: playlistPanel.toggle()
         onContextMenuRequested: contextMenu.popup()
         onTranslateRequested: appWindow.translateCurrentSubtitle()
+        onTranslatePlaylistRequested: {
+            const track = appWindow.translationSourceTrack()
+            if (track) {
+                appWindow.lastTranslationTrack = track
+                appWindow.lastTranslationVideo = video.currentUrl
+            }
+            translationService.translatePlaylist(playlistModel.urls(), track ?? {}, video.mediaTitle)
+        }
         onEditGlossaryRequested: {
             translationService.loadGlossary(video.currentUrl)
             glossaryDialog.open()
@@ -173,20 +187,28 @@ ApplicationWindow {
 
     TranslationService {
         id: translationService
+        currentVideo: video.currentUrl
         onTranslated: (subtitleUrl, fromCache) => {
             video.showTranslatedSubtitleFile(subtitleUrl, appWindow.translatedTrackTitle())
             osdItem.message(fromCache
                 ? KI18n.i18nc("@info:osd", "Loaded the saved translation")
                 : KI18n.i18nc("@info:osd", "Translation ready"))
         }
+        onPlaylistTranslated: (translatedCount, alreadyTranslatedCount, problemCount) => {
+            // Skipped episodes are listed in the error message.
+            if (translatedCount > 0) {
+                osdItem.message(KI18n.i18ncp("@info:osd", "Translated %1 episode", "Translated %1 episodes", translatedCount))
+            } else if (problemCount === 0) {
+                osdItem.message(KI18n.i18nc("@info:osd", "Every episode is already translated"))
+            }
+        }
     }
 
     MpvVideo {
         id: video
 
+        // TranslationService follows the video itself (currentVideo).
         onCurrentUrlChanged: {
-            translationService.cancel()
-            translationService.forgetTranslation()
             appWindow.lastTranslationTrack = null
             appWindow.lastTranslationVideo = ""
             glossaryDialog.close()
@@ -246,6 +268,7 @@ ApplicationWindow {
         playlist: playlistModel
         mpv: video
         mainWindowWidth: appWindow.width
+        translateAction: appActions.translatePlaylist
         fullscreen: appWindow.isFullScreen
         height: video.height
         onAddFilesRequested: addToPlaylistDialog.open()

src/qml/Playlist.qml

@@ -17,6 +17,8 @@ Page {
     required property PlaylistModel playlist
     required property MpvItem mpv
     required property int mainWindowWidth
+    // Translates the subtitles of every entry.
+    required property Action translateAction
     property bool fullscreen: false
 
     readonly property int edge: QtPotatoSettings.playlistPosition === "left" ? Qt.LeftEdge : Qt.RightEdge
@@ -67,6 +69,18 @@ Page {
                 onClicked: root.addFilesRequested()
             }
 
+            ToolButton {
+                action: root.translateAction
+                icon.width: root.buttonSize
+                icon.height: root.buttonSize
+                display: AbstractButton.IconOnly
+                focusPolicy: Qt.TabFocus
+
+                ToolTip.text: text
+                ToolTip.visible: hovered
+                ToolTip.delay: Kirigami.Units.toolTipDelay
+            }
+
             ToolButton {
                 text: KI18n.i18nc("@action:button", "Scroll to Playing Item")
                 icon.name: "go-jump"

src/qml/SubtitlesMenu.qml

@@ -28,6 +28,7 @@ AppMenu {
     }
     MenuSeparator {}
     AppMenuItem { action: root.actions.translateSubtitle }
+    AppMenuItem { action: root.actions.translatePlaylist }
     AppMenuItem { action: root.actions.editGlossary }
     AppMenuItem { action: root.actions.cancelTranslation }
     MenuSeparator {}

src/subtitles/subtitleextractor.cpp

@@ -1,5 +1,7 @@
 #include "subtitleextractor.h"
 
+#include "trackselection.h"
+
 #include <KLocalizedString>
 
 #include <memory>
@@ -138,4 +140,39 @@ ExtractResult extractEmbedded(const QString &path, int streamIndex, const std::a
     }
     return result;
 }
+
+SourceResult findTranslationSource(const QString &path)
+{
+    AVFormatContext *rawFormat = nullptr;
+    if (const int ret = avformat_open_input(&rawFormat, path.toUtf8().constData(), nullptr, nullptr); ret < 0) {
+        return {-1, i18n("Could not open %1: %2", path, ffmpegError(ret))};
+    }
+    std::unique_ptr<AVFormatContext, FormatContextDeleter> format(rawFormat);
+
+    const auto language = [](const AVStream *stream) {
+        const AVDictionaryEntry *tag = av_dict_get(stream->metadata, "language", nullptr, 0);
+        return tag ? QString::fromUtf8(tag->value) : QString();
+    };
+    // Track ids start at 1, since 0 means "none"; id - 1 is the stream index.
+    QList<TrackSelection::Track> subtitles;
+    QString audioLanguage;
+    bool audioIsDefault = false;
+    for (unsigned i = 0; i < format->nb_streams; ++i) {
+        const AVStream *stream = format->streams[i];
+        const bool isDefault = stream->disposition & AV_DISPOSITION_DEFAULT;
+        if (stream->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
+            if (audioLanguage.isEmpty() || (isDefault && !audioIsDefault)) {
+                audioLanguage = language(stream);
+                audioIsDefault = isDefault;
+            }
+        } else if (stream->codecpar->codec_type == AVMEDIA_TYPE_SUBTITLE) {
+            subtitles.append({static_cast<int>(i) + 1,
+                              language(stream),
+                              QString::fromUtf8(avcodec_get_name(stream->codecpar->codec_id)),
+                              bool(stream->disposition & AV_DISPOSITION_FORCED),
+                              isDefault});
+        }
+    }
+    return {TrackSelection::pickTranslationSource(subtitles, {QStringLiteral("en"), audioLanguage}, 0) - 1, {}};
+}
 }

src/subtitles/subtitleextractor.h

@@ -14,4 +14,15 @@ struct ExtractResult {
 // Decodes a text subtitle stream of a media file with FFmpeg. \a streamIndex is the
 // FFmpeg stream index (mpv reports it as "ff-index"). Blocking; run it off the GUI thread.
 ExtractResult extractEmbedded(const QString &path, int streamIndex, const std::atomic_bool &cancelled);
+
+struct SourceResult {
+    // FFmpeg stream index of the subtitle to translate, or -1 when the file has no
+    // text subtitle.
+    int streamIndex = -1;
+    QString error;
+};
+
+// The embedded subtitle of a file that is not open in mpv to translate, chosen like
+// MpvItem::translationSourceId(): English first, then the audio language. Blocking.
+SourceResult findTranslationSource(const QString &path);
 }

src/translate/translationservice.cpp

@@ -1,6 +1,7 @@
 #include "translationservice.h"
 
 #include "apikeystore.h"
+#include "mediainfo.h"
 #include "qtpotatosettings.h"
 #include "translationpresets.h"
 #include "translationstore.h"
@@ -69,6 +70,10 @@ struct TranslationService::Job {
     std::atomic_bool cancelled = false;
     std::unique_ptr<LlmClient> client;
     QString mediaTitle;
+    bool playlist = false;
+    // In a playlist: the episode being translated (from 0) and how many there are.
+    int episode = 0;
+    int episodes = 0;
 };
 
 struct TranslationService::Batches {
@@ -160,6 +165,25 @@ QString TranslationService::glossaryError() const
     return m_glossaryError;
 }
 
+QUrl TranslationService::currentVideo() const
+{
+    return m_currentVideo;
+}
+
+void TranslationService::setCurrentVideo(const QUrl &url)
+{
+    if (url == m_currentVideo) {
+        return;
+    }
+    m_currentVideo = url;
+    forgetTranslation();
+    // A playlist translation is meant to go on while the episodes play.
+    if (m_job && !m_job->playlist) {
+        cancel();
+    }
+    Q_EMIT currentVideoChanged();
+}
+
 void TranslationService::loadGlossary(const QUrl &videoUrl)
 {
     const QString directory = videoUrl.isLocalFile() ? QFileInfo(videoUrl.toLocalFile()).absolutePath() : QString();
@@ -323,7 +347,25 @@ void TranslationService::translate(const QUrl &videoUrl, const QVariantMap &trac
     cancel();
     m_job = std::make_shared<Job>();
     m_job->mediaTitle = mediaTitle;
-    run(videoUrl, track);
+    run(m_job, videoUrl, track);
+}
+
+void TranslationService::translatePlaylist(const QList<QUrl> &urls, const QVariantMap &currentTrack, const QString &currentTitle)
+{
+    cancel();
+    // Start with the episode playing, then the ones after it, which are watched next.
+    QList<QUrl> ordered;
+    const qsizetype current = std::max<qsizetype>(0, urls.indexOf(m_currentVideo));
+    for (qsizetype i = 0; i < urls.size(); ++i) {
+        const QUrl &url = urls.at((current + i) % urls.size());
+        if (!ordered.contains(url)) {
+            ordered.append(url);
+        }
+    }
+    m_job = std::make_shared<Job>();
+    m_job->playlist = true;
+    m_job->episodes = ordered.size();
+    runPlaylist(m_job, ordered, currentTrack, currentTitle);
 }
 
 void TranslationService::cancel()
@@ -408,10 +450,8 @@ QCoro::Task<Subtitles::ExtractResult> TranslationService::loadCues(std::shared_p
     });
 }
 
-QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
+QCoro::Task<std::optional<LlmClient::Config>> TranslationService::startJob(std::shared_ptr<Job> job)
 {
-    const std::shared_ptr<Job> job = m_job;
-
     setErrorText({});
     setProgress(0);
     setBusy(true);
@@ -419,29 +459,123 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
 
     auto [config, configError] = co_await loadConfig();
     if (job->cancelled) {
-        co_return;
+        co_return std::nullopt;
+    }
+    if (configError.isEmpty() && config.model.isEmpty()) {
+        configError = i18n("Choose a model in Settings first.");
     }
     if (!configError.isEmpty()) {
         fail(job, configError);
-        co_return;
+        co_return std::nullopt;
-    }
-    if (config.model.isEmpty()) {
-        fail(job, i18n("Choose a model in Settings first."));
-        co_return;
     }
+    co_return config;
+}
 
-    Subtitles::ExtractResult source = co_await loadCues(job, videoUrl, track);
+QCoro::Task<> TranslationService::run(std::shared_ptr<Job> job, QUrl videoUrl, QVariantMap track)
+{
+    const std::optional<LlmClient::Config> config = co_await startJob(job);
+    if (!config) {
+        co_return;
+    }
+    const Outcome outcome = co_await translateVideo(job, *config, videoUrl, track);
     if (job->cancelled) {
         co_return;
     }
-    if (!source.error.isEmpty()) {
+    const QString error = outcome.error.isEmpty() ? publish(job, videoUrl, outcome) : outcome.error;
-        fail(job, source.error);
+    if (!error.isEmpty()) {
+        fail(job, error);
         co_return;
     }
+    endJob(job);
+}
+
+QCoro::Task<> TranslationService::runPlaylist(std::shared_ptr<Job> job, QList<QUrl> urls, QVariantMap currentTrack, QString currentTitle)
+{
+    const std::optional<LlmClient::Config> config = co_await startJob(job);
+    if (!config) {
+        co_return;
+    }
+
+    int translatedCount = 0;
+    int alreadyTranslatedCount = 0;
+    QStringList problems;
+    for (qsizetype i = 0; i < urls.size(); ++i) {
+        const QUrl videoUrl = urls.at(i);
+        const QString name = videoUrl.fileName();
+        job->episode = int(i);
+        setJobProgress(*job, 0);
+        setJobStatus(*job, i18n("Reading subtitles…"));
+        if (!savedTranslation(videoUrl).isEmpty()) {
+            ++alreadyTranslatedCount;
+            continue;
+        }
+
+        QVariantMap track = currentTrack;
+        job->mediaTitle = currentTitle;
+        if (videoUrl != m_currentVideo || currentTrack.isEmpty()) {
+            if (!videoUrl.isLocalFile()) {
+                problems.append(i18nc("@info %1 is a file name", "%1: only subtitles of local files can be translated", name));
+                continue;
+            }
+            const QString path = videoUrl.toLocalFile();
+            const Subtitles::SourceResult source = co_await QtConcurrent::run([path] {
+                return Subtitles::findTranslationSource(path);
+            });
+            if (job->cancelled) {
+                co_return;
+            }
+            if (!source.error.isEmpty() || source.streamIndex < 0) {
+                problems.append(source.error.isEmpty() ? i18nc("@info %1 is a file name", "%1: no text subtitle", name)
+                                                       : i18nc("@info %1 is a file name, %2 an error", "%1: %2", name, source.error));
+                continue;
+            }
+            track = QVariantMap{{u"ffIndex"_s, source.streamIndex}};
+            job->mediaTitle = MediaInfo::cleanTitle(name);
+        }
+
+        const Outcome outcome = co_await translateVideo(job, *config, videoUrl, track);
+        if (job->cancelled) {
+            co_return;
+        }
+        if (!outcome.error.isEmpty() && !outcome.skippable) {
+            // Errors from the API or the disk would repeat for every episode.
+            fail(job, i18nc("@info %1 is a file name, %2 an error", "Stopped translating the playlist at %1: %2", name, outcome.error));
+            co_return;
+        }
+        const QString error = outcome.error.isEmpty() ? publish(job, videoUrl, outcome) : outcome.error;
+        if (error.isEmpty()) {
+            ++translatedCount;
+        } else {
+            problems.append(i18nc("@info %1 is a file name, %2 an error", "%1: %2", name, error));
+        }
+    }
+
+    endJob(job);
+    if (!problems.isEmpty()) {
+        setErrorText(i18np("Translated %2 of %3 episodes. Skipped one:\n%4",
+                           "Translated %2 of %3 episodes. Skipped %1:\n%4",
+                           problems.size(),
+                           translatedCount + alreadyTranslatedCount,
+                           urls.size(),
+                           problems.join(u'\n')));
+    }
+    Q_EMIT playlistTranslated(translatedCount, alreadyTranslatedCount, int(problems.size()));
+}
+
+QCoro::Task<TranslationService::Outcome> TranslationService::translateVideo(std::shared_ptr<Job> job, LlmClient::Config config, QUrl videoUrl, QVariantMap track)
+{
+    setJobProgress(*job, 0);
+    setJobStatus(*job, i18n("Reading subtitles…"));
+    Subtitles::ExtractResult source = co_await loadCues(job, videoUrl, track);
+    if (job->cancelled) {
+        co_return Outcome{};
+    }
+    if (!source.error.isEmpty()) {
+        co_return Outcome::failed(source.error, true);
+    }
     const QList<SubtitleCue> cues = Subtitles::mergeRepeated(source.cues);
     if (cues.isEmpty()) {
-        fail(job, i18n("This subtitle track has no text to translate."));
+        co_return Outcome::failed(i18n("This subtitle track has no text to translate."), true);
-        co_return;
     }
 
     // Episodes in one folder share a glossary. Streams have no folder, so they get none.
@@ -449,24 +583,30 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     const bool useGlossary = !seriesDirectory.isEmpty();
     GlossaryStore::Glossary glossary = useGlossary ? GlossaryStore::load(seriesDirectory) : GlossaryStore::Glossary{};
     const QString episode = videoUrl.isLocalFile() ? QFileInfo(videoUrl.toLocalFile()).completeBaseName() : job->mediaTitle;
-    const auto saveGlossaryGroups = [&]() {
+    // Returns an error message.
+    const auto saveGlossaryGroups = [&]() -> QString {
         QString error;
         if (!GlossaryStore::save(glossary, &error)) {
-            fail(job, i18n("Could not save the translation glossary: %1", error));
+            return i18n("Could not save the translation glossary: %1", error);
-            return false;
         }
-        m_glossary = glossary;
+        // Another episode of the playlist only updates the terms of the open series.
-        m_glossaryEpisode = episode;
+        if (!job->playlist || videoUrl == m_currentVideo) {
-        Q_EMIT glossaryChanged();
+            m_glossary = glossary;
-        return true;
+            m_glossaryEpisode = episode;
+            Q_EMIT glossaryChanged();
+        } else if (m_glossary.directory == glossary.directory) {
+            m_glossary = glossary;
+            Q_EMIT glossaryChanged();
+        }
+        return {};
     };
     if (useGlossary) {
         // New terms belong to the episode being translated. Migrate legacy or
         // imported entries without provenance to this first episode too. This
         // happens before the cache shortcut and never changes translation text.
         glossary = GlossaryStore::assignUnassigned(glossary, episode);
-        if (!saveGlossaryGroups()) {
+        if (const QString error = saveGlossaryGroups(); !error.isEmpty()) {
-            co_return;
+            co_return Outcome::failed(error);
         }
     }
     const QString sourceSrt = Subtitles::toSrt(cues);
@@ -488,12 +628,11 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     QString outputPath = TranslationStore::cachePath(cacheDir(), videoUrl, configKey, suffix);
 
     if (QFileInfo::exists(outputPath)) {
-        finish(job, videoUrl, suffix, configKey, outputPath, true);
+        co_return Outcome::ready(outputPath, suffix, configKey, true);
-        co_return;
     }
 
     if (useGlossary && QtPotatoSettings::self()->autoBuildGlossary()) {
-        setStatusText(i18n("Building glossary…"));
+        setJobStatus(*job, i18n("Building glossary…"));
         QStringList extractionLines;
         QHash<QString, bool> seen;
         for (const SubtitleCue &cue : cues) {
@@ -518,7 +657,7 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
         job->client = std::make_unique<LlmClient>(m_network, config);
         const LlmClient::BatchResult extracted = co_await job->client->extractGlossary(sampled, job->mediaTitle);
         if (job->cancelled) {
-            co_return;
+            co_return Outcome{};
         }
         if (extracted.error.isEmpty()) {
             QList<GlossaryStore::Entry> additions;
@@ -529,17 +668,16 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
             // Suggestions extracted while translating this episode belong to
             // this episode. Existing terms keep their original ownership.
             glossary = GlossaryStore::merge(glossary, additions, episode);
-            if (!saveGlossaryGroups()) {
+            if (const QString error = saveGlossaryGroups(); !error.isEmpty()) {
-                co_return;
+                co_return Outcome::failed(error);
             }
         } else {
-            setStatusText(i18n("Glossary unavailable; translating without it."));
+            setJobStatus(*job, i18n("Glossary unavailable; translating without it."));
         }
         configKey = configKeyFor(glossary);
         outputPath = TranslationStore::cachePath(cacheDir(), videoUrl, configKey, suffix);
         if (QFileInfo::exists(outputPath)) {
-            finish(job, videoUrl, suffix, configKey, outputPath, true);
+            co_return Outcome::ready(outputPath, suffix, configKey, true);
-            co_return;
         }
     }
 
@@ -567,7 +705,7 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     batches->lines = uniqueLines;
     batches->translations.resize(uniqueLines.size());
     batches->batchSize = QtPotatoSettings::self()->batchSize();
-    setStatusText(i18n("Translating… %1 of %2 lines", 0, uniqueLines.size()));
+    setLinesStatus(*job, 0, uniqueLines.size());
 
     // Tasks start running as soon as they are created; awaiting them just waits for the end.
     std::vector<QCoro::Task<>> workers;
@@ -578,11 +716,10 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
         co_await std::move(worker);
     }
     if (job->cancelled) {
-        co_return;
+        co_return Outcome{};
     }
     if (!batches->error.isEmpty()) {
-        fail(job, batches->error);
+        co_return Outcome::failed(batches->error);
-        co_return;
     }
 
     QList<SubtitleCue> output = cues;
@@ -593,36 +730,64 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
     QDir().mkpath(QFileInfo(outputPath).absolutePath());
     QSaveFile file(outputPath);
     if (!file.open(QIODevice::WriteOnly) || file.write(Subtitles::toSrt(output).toUtf8()) < 0 || !file.commit()) {
-        fail(job, i18n("Could not save the translation to %1: %2", outputPath, file.errorString()));
+        co_return Outcome::failed(i18n("Could not save the translation to %1: %2", outputPath, file.errorString()));
-        co_return;
     }
-
+    co_return Outcome::ready(outputPath, suffix, configKey, false);
-    finish(job, videoUrl, suffix, configKey, outputPath, false);
 }
 
-void TranslationService::finish(const std::shared_ptr<Job> &job,
+QString TranslationService::publish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const Outcome &outcome)
-                                const QUrl &videoUrl,
-                                const QString &suffix,
-                                const QString &configKey,
-                                const QString &cacheFile,
-                                bool fromCache)
 {
-    QFile file(cacheFile);
+    QFile file(outcome.cacheFile);
     if (!file.open(QIODevice::ReadOnly)) {
-        fail(job, i18n("Could not read the translation from %1: %2", cacheFile, file.errorString()));
+        return i18n("Could not read the translation from %1: %2", outcome.cacheFile, file.errorString());
-        return;
     }
     // The cache keeps every version; the published copy is the one players load.
     const QString registryFile = TranslationStore::registryFile();
     TranslationStore::Registry registry = TranslationStore::load(registryFile);
-    const TranslationStore::PublishResult published = TranslationStore::publish(registry, videoUrl, suffix, configKey, file.readAll(), cacheFile);
+    const TranslationStore::PublishResult published =
+        TranslationStore::publish(registry, videoUrl, outcome.suffix, outcome.configKey, file.readAll(), outcome.cacheFile);
     TranslationStore::save(registryFile, registry);
 
+    // Other episodes of a playlist load their translation when they are opened.
+    if (!job->playlist || videoUrl == m_currentVideo) {
+        m_lastTranslationPath = published.path;
+        Q_EMIT translated(QUrl::fromLocalFile(published.path), outcome.fromCache);
+    }
+    return {};
+}
+
+void TranslationService::endJob(const std::shared_ptr<Job> &job)
+{
+    if (m_job != job) {
+        return;
+    }
     m_job.reset();
-    m_lastTranslationPath = published.path;
     setBusy(false);
     setStatusText({});
-    Q_EMIT translated(QUrl::fromLocalFile(published.path), fromCache);
+}
+
+void TranslationService::setJobStatus(const Job &job, const QString &text)
+{
+    if (!job.playlist) {
+        setStatusText(text);
+        return;
+    }
+    setStatusText(i18nc("@info:status %1 and %2 are numbers, %3 is what is being done",
+                        "Episode %1 of %2: %3",
+                        job.episode + 1,
+                        job.episodes,
+                        text));
+}
+
+void TranslationService::setLinesStatus(const Job &job, qsizetype done, qsizetype total)
+{
+    // The line count would not fit after the episode number; the progress bar shows it.
+    setJobStatus(job, job.playlist ? i18n("Translating…") : i18n("Translating… %1 of %2 lines", done, total));
+}
+
+void TranslationService::setJobProgress(const Job &job, double episodeProgress)
+{
+    setProgress(job.playlist ? (job.episode + episodeProgress) / job.episodes : episodeProgress);
 }
 
 QString TranslationService::savedTranslation(const QUrl &videoUrl) const
@@ -716,8 +881,8 @@ QCoro::Task<> TranslationService::translateBatches(std::shared_ptr<Job> job, std
             batches->translations[start + i] = result.translations.at(i);
         }
         batches->doneLines += result.translations.size();
-        setProgress(double(batches->doneLines) / batches->lines.size());
+        setJobProgress(*job, double(batches->doneLines) / batches->lines.size());
-        setStatusText(i18n("Translating… %1 of %2 lines", batches->doneLines, batches->lines.size()));
+        setLinesStatus(*job, batches->doneLines, batches->lines.size());
     }
 }
 

src/translate/translationservice.h

@@ -15,6 +15,7 @@
 
 #include <atomic>
 #include <memory>
+#include <optional>
 
 class QNetworkAccessManager;
 
@@ -37,6 +38,9 @@ class TranslationService : public QObject
     Q_PROPERTY(QString glossaryEpisode READ glossaryEpisode NOTIFY glossaryChanged)
     Q_PROPERTY(QStringList glossaryEpisodes READ glossaryEpisodes NOTIFY glossaryChanged)
     Q_PROPERTY(QString glossaryError READ glossaryError NOTIFY glossaryErrorChanged)
+    // The video playing. Its translations are shown when ready; others are only saved.
+    // Opening another video stops a single translation but not a playlist one.
+    Q_PROPERTY(QUrl currentVideo READ currentVideo WRITE setCurrentVideo NOTIFY currentVideoChanged)
 
 public:
     explicit TranslationService(QObject *parent = nullptr);
@@ -54,9 +58,15 @@ public:
     QString glossaryEpisode() const;
     QStringList glossaryEpisodes() const;
     QString glossaryError() const;
+    QUrl currentVideo() const;
+    void setCurrentVideo(const QUrl &url);
 
     // \a track is an entry of MpvItem::subtitleTracks.
     Q_INVOKABLE void translate(const QUrl &videoUrl, const QVariantMap &track, const QString &mediaTitle);
+    // Translates every video in \a urls that has no saved translation yet, one after
+    // another, starting at the current video. The current one uses \a currentTrack when
+    // set; the others use the embedded subtitle findTranslationSource() picks.
+    Q_INVOKABLE void translatePlaylist(const QList<QUrl> &urls, const QVariantMap &currentTrack, const QString &currentTitle);
     Q_INVOKABLE void cancel();
     // Asks the API configured in the settings for its models.
     Q_INVOKABLE void fetchModels();
@@ -83,12 +93,46 @@ Q_SIGNALS:
     void glossaryChanged();
     void glossaryErrorChanged();
     void translated(const QUrl &subtitleUrl, bool fromCache);
+    void currentVideoChanged();
+    // A playlist translation ended without being cancelled. Problems are in errorText.
+    void playlistTranslated(int translatedCount, int alreadyTranslatedCount, int problemCount);
 
 private:
     struct Job;
     struct Batches;
+    // Where translateVideo() left a translation, or why it could not make one.
+    struct Outcome {
+        QString cacheFile;
+        QString suffix;
+        QString configKey;
+        bool fromCache = false;
+        QString error;
+        // The error is about this video's subtitles; other videos may still work.
+        bool skippable = false;
 
-    QCoro::Task<> run(QUrl videoUrl, QVariantMap track);
+        static Outcome ready(const QString &cacheFile, const QString &suffix, const QString &configKey, bool fromCache)
+        {
+            Outcome outcome;
+            outcome.cacheFile = cacheFile;
+            outcome.suffix = suffix;
+            outcome.configKey = configKey;
+            outcome.fromCache = fromCache;
+            return outcome;
+        }
+        static Outcome failed(const QString &error, bool skippable = false)
+        {
+            Outcome outcome;
+            outcome.error = error;
+            outcome.skippable = skippable;
+            return outcome;
+        }
+    };
+
+    QCoro::Task<> run(std::shared_ptr<Job> job, QUrl videoUrl, QVariantMap track);
+    QCoro::Task<> runPlaylist(std::shared_ptr<Job> job, QList<QUrl> urls, QVariantMap currentTrack, QString currentTitle);
+    // Reads the settings and the API key for \a job; nothing (after failing it) when they are not usable.
+    QCoro::Task<std::optional<LlmClient::Config>> startJob(std::shared_ptr<Job> job);
+    QCoro::Task<Outcome> translateVideo(std::shared_ptr<Job> job, LlmClient::Config config, QUrl videoUrl, QVariantMap track);
     QCoro::Task<> runFetchModels();
     // Translates \a lines, retrying failures and asking again for lines the model skipped.
     QCoro::Task<LlmClient::BatchResult> translateLines(std::shared_ptr<Job> job, QStringList lines, QStringList context);
@@ -100,8 +144,14 @@ private:
     // something is missing.
     QCoro::Task<std::pair<LlmClient::Config, QString>> loadConfig();
     void fail(const std::shared_ptr<Job> &job, const QString &error);
-    // Saves the translation in \a cacheFile where players find it and announces it.
+    // Saves the translation where players find it and, for the current video, shows it.
-    void finish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const QString &suffix, const QString &configKey, const QString &cacheFile, bool fromCache);
+    // Returns an error message on failure.
+    QString publish(const std::shared_ptr<Job> &job, const QUrl &videoUrl, const Outcome &outcome);
+    void endJob(const std::shared_ptr<Job> &job);
+    // In a playlist, prefixes the episode number and counts finished episodes in the progress.
+    void setJobStatus(const Job &job, const QString &text);
+    void setJobProgress(const Job &job, double episodeProgress);
+    void setLinesStatus(const Job &job, qsizetype done, qsizetype total);
 
     void setBusy(bool busy);
     void setProgress(double progress);
@@ -122,4 +172,5 @@ private:
     GlossaryStore::Glossary m_glossary;
     QString m_glossaryEpisode;
     QString m_lastTranslationPath;
+    QUrl m_currentVideo;
 };