feat(playback): report Embedded MPV file chapters on the timeline (#1771)

.changes/playback-mpv-file-chapters.md

@@ -0,0 +1,6 @@
+---
+type: feature
+area: playback
+---
+
+With the Embedded MPV frame-copy engine, a movie's or episode's own chapters now appear as sections on the timeline, with their titles in the hover label. When an episode has a closing-credits chapter, the "Up next" card appears as the credits start.

apps/electron-backend-e2e/src/embedded-mpv-chapters.e2e.ts

@@ -0,0 +1,129 @@
+import { readFileSync, writeFileSync } from 'fs';
+import { join } from 'path';
+import {
+    channelItemByTitle,
+    closeElectronApp,
+    expect,
+    goToDashboard,
+    importM3uPlaylistFromNativeDialog,
+    launchElectronApp,
+    openSettings,
+    openSettingsSection,
+    saveSettings,
+    test,
+    workspaceRoot,
+    type LaunchedElectronApp,
+} from './electron-test-fixtures';
+import {
+    createLocalMediaServer,
+    installEmbeddedMpvSessionCapture,
+} from './embedded-mpv-frame-copy-packaged-fixtures';
+
+/**
+ * mpv's `chapter-list` must reach the shared controls: the chaptered fixture
+ * (Intro 0 s, Episode 5 s, Credits 24 s of 30 s) is drawn as three titled
+ * timeline segments. Frame-copy is the Embedded MPV engine that mounts
+ * `app-player-controls`; the test skips where that runtime is unavailable.
+ */
+test('@playback @electron @embedded-mpv frame-copy draws file chapters on the timeline', async ({
+    dataDir,
+}) => {
+    const media = await createLocalMediaServer({
+        body: readFileSync(
+            join(
+                workspaceRoot,
+                'apps/web-e2e/src/fixtures/playback/episode-chapters.webm'
+            )
+        ),
+        resourcePath: '/episode-chapters.webm',
+        contentType: 'video/webm',
+    });
+    // The launch sits inside the cleanup scope: a failed launch must still
+    // close the media server.
+    let app: LaunchedElectronApp | undefined;
+    try {
+        const launched = await launchElectronApp(dataDir, {
+            env: {
+                IPTVNATOR_ENABLE_EMBEDDED_MPV_EXPERIMENT: '1',
+                IPTVNATOR_ENABLE_EMBEDDED_MPV_FRAME_COPY: '1',
+                IPTVNATOR_EMBEDDED_MPV_ALLOW_HOMEBREW: '1',
+            },
+        });
+        app = launched;
+        const support = await launched.mainWindow.evaluate(() =>
+            window.electron.getEmbeddedMpvSupport()
+        );
+        test.skip(
+            !support.supported || support.engine !== 'frame-copy',
+            `Frame-copy runtime unavailable: ${JSON.stringify(support)}`
+        );
+        await openSettings(launched.mainWindow);
+        await openSettingsSection(launched.mainWindow, 'playback');
+        await launched.mainWindow.getByTestId('select-video-player').click();
+        await launched.mainWindow.getByTestId('embedded-mpv').click();
+        await saveSettings(launched.mainWindow);
+        await goToDashboard(launched.mainWindow);
+
+        const playlist = join(dataDir, 'chapters.m3u');
+        writeFileSync(
+            playlist,
+            `#EXTM3U\n#EXTINF:-1,Chaptered fixture\n${media.url}\n`
+        );
+        await installEmbeddedMpvSessionCapture(launched);
+        await importM3uPlaylistFromNativeDialog(launched, playlist);
+        await channelItemByTitle(launched.mainWindow, 'Chaptered fixture')
+            .first()
+            .click();
+
+        // The local frame-copy runtime can fail a frame-view initialization,
+        // and the failure can surface at any point while the session starts;
+        // a user Retry recovers it (see player-theme). Retry whenever the
+        // stalled state shows until mpv's chapters arrive.
+        const stalled = launched.mainWindow.locator(
+            '.embedded-mpv-player__stalled'
+        );
+        await expect(async () => {
+            if (await stalled.isVisible()) {
+                await stalled.getByRole('button', { name: 'Retry' }).click();
+            }
+            expect(
+                await launched.mainWindow.evaluate(
+                    () =>
+                        window.__packagedEmbeddedMpvSessions?.at(-1)
+                            ?.chapters ?? []
+                )
+            ).toEqual([
+                { timeSeconds: 0, title: 'Intro' },
+                { timeSeconds: 5, title: 'Episode' },
+                { timeSeconds: 24, title: 'Credits' },
+            ]);
+        }).toPass({ timeout: 30000 });
+
+        const segments = launched.mainWindow.locator(
+            'app-player-controls .player-controls__timeline-segment'
+        );
+        await expect(segments).toHaveCount(3);
+        await expect
+            .poll(() =>
+                segments.evaluateAll((elements) =>
+                    elements.map((element) => ({
+                        title: element.getAttribute('data-segment-title'),
+                        left: Math.round(parseFloat(element.style.left)),
+                    }))
+                )
+            )
+            .toEqual([
+                { title: 'Intro', left: 0 },
+                { title: 'Episode', left: 17 },
+                { title: 'Credits', left: 80 },
+            ]);
+    } finally {
+        try {
+            if (app) {
+                await closeElectronApp(app);
+            }
+        } finally {
+            await media.close();
+        }
+    }
+});

apps/electron-backend-e2e/src/embedded-mpv-frame-copy-packaged.e2e.ts

@@ -360,12 +360,23 @@ test.describe('Packaged Linux embedded MPV frame-copy runtime', () => {
                 resourcePath: '/stream-stats-switch.webm',
                 contentType: 'video/webm',
             });
+            const chapteredMedia = await createLocalMediaServer({
+                body: readFileSync(
+                    join(
+                        __dirname,
+                        '../../web-e2e/src/fixtures/playback/episode-chapters.webm'
+                    )
+                ),
+                resourcePath: '/chapters.webm',
+                contentType: 'video/webm',
+            });
             media = {
                 url: mediaServer.url,
                 close: async () => {
                     await Promise.all([
                         mediaServer.close(),
                         alternateMedia.close(),
+                        chapteredMedia.close(),
                     ]);
                 },
             };
@@ -415,6 +426,33 @@ test.describe('Packaged Linux embedded MPV frame-copy runtime', () => {
                     });
             }
 
+            // mpv's `chapter-list` reaches the renderer session (it draws the
+            // timeline segments and times the Up next card), and the next
+            // file starts without the previous file's chapters.
+            await launchedFrameCopyApp.mainWindow.evaluate(
+                async ({ sessionId, streamUrl }) => {
+                    await window.electron.loadEmbeddedMpvPlayback(sessionId, {
+                        streamUrl,
+                        title: 'Chaptered episode',
+                        isLive: false,
+                    });
+                },
+                { sessionId: created.id, streamUrl: chapteredMedia.url }
+            );
+            await expect
+                .poll(
+                    () => getLatestSession(launchedFrameCopyApp, created.id),
+                    { timeout: 15000 }
+                )
+                .toMatchObject({
+                    streamUrl: chapteredMedia.url,
+                    chapters: [
+                        { timeSeconds: 0, title: 'Intro' },
+                        { timeSeconds: 5, title: 'Episode' },
+                        { timeSeconds: 24, title: 'Credits' },
+                    ],
+                });
+
             // Audio-only replacements must not retain the previous video size.
             await launchedFrameCopyApp.mainWindow.evaluate(
                 async ({ sessionId, streamUrl }) => {
@@ -433,6 +471,7 @@ test.describe('Packaged Linux embedded MPV frame-copy runtime', () => {
                 )
                 .toMatchObject({
                     streamUrl: audioMedia.url,
+                    chapters: [],
                     videoWidth: 0,
                     videoHeight: 0,
                     stats: {

apps/electron-backend/native/helper/mpv_frame_helper.cpp

@@ -55,6 +55,12 @@ struct TrackInfo {
     bool forced = false;
 };
 
+/* One entry of mpv's `chapter-list`: start time and optional title. */
+struct ChapterInfo {
+    double timeSeconds = 0;
+    std::string title;
+};
+
 struct SnapshotState {
     std::string status = "idle";
     double positionSeconds = 0;
@@ -118,6 +124,7 @@ struct SnapshotState {
     int64_t selectedAudioTrackId = -1;
     std::vector<TrackInfo> subtitleTracks;
     int64_t selectedSubtitleTrackId = -1;
+    std::vector<ChapterInfo> chapters;
     double playbackSpeed = 1;
     std::string aspectOverride = "no";
     bool recordingActive = false;
@@ -187,6 +194,21 @@ std::string tracksJson(const std::vector<TrackInfo>& tracks,
     return out;
 }
 
+std::string chaptersJson(const std::vector<ChapterInfo>& chapters) {
+    std::string out = "[";
+    bool first = true;
+    for (const ChapterInfo& chapter : chapters) {
+        JsonWriter writer;
+        writer.num("timeSeconds", chapter.timeSeconds);
+        if (!chapter.title.empty()) writer.str("title", chapter.title);
+        if (!first) out += ',';
+        first = false;
+        out += writer.finish();
+    }
+    out += ']';
+    return out;
+}
+
 /* Compose the `stats` object of the snapshot event. Always emitted, even when
  * empty: the adapter merges snapshot events field by field, so an omitted key
  * would leave the previous stream's numbers in place across a channel switch.
@@ -262,6 +284,9 @@ std::string composeSnapshotLocked() {
     } else {
         writer.nullValue("selectedSubtitleTrackId");
     }
+    /* Always emitted: the adapter merges snapshot events field by field, so
+     * an omitted key would keep the previous file's chapters. */
+    writer.raw("chapters", chaptersJson(s.chapters));
     writer.num("playbackSpeed", s.playbackSpeed);
     writer.str("aspectOverride", s.aspectOverride);
     writer.raw("stats", composeStatsJsonLocked());
@@ -383,6 +408,63 @@ void updateTracksFromNode(const mpv_node& trackListNode) {
     g_state.snapshot.subtitleTracks = std::move(subs);
 }
 
+/* Snapshots repeat the chapter list on every emit, so a file with thousands
+ * of chapters or a huge title must not inflate every snapshot. Beyond these
+ * bounds a timeline cannot draw anything useful anyway. */
+constexpr size_t kMaxChapters = 256;
+constexpr size_t kMaxChapterTitleBytes = 256;
+
+/* Cut to at most `maxBytes` without splitting a UTF-8 sequence. */
+std::string truncateUtf8(const char* value, size_t maxBytes) {
+    std::string text = value ? value : "";
+    if (text.size() <= maxBytes) return text;
+    size_t end = maxBytes;
+    while (end > 0 &&
+           (static_cast<unsigned char>(text[end]) & 0xC0) == 0x80) {
+        end--;
+    }
+    text.resize(end);
+    return text;
+}
+
+/* mpv `chapter-list`: an array of { time, title? } maps in file order. */
+void updateChaptersFromNode(const mpv_node& chapterListNode) {
+    std::vector<ChapterInfo> chapters;
+    if (chapterListNode.format == MPV_FORMAT_NODE_ARRAY &&
+        chapterListNode.u.list) {
+        for (int i = 0; i < chapterListNode.u.list->num &&
+                        chapters.size() < kMaxChapters;
+             i++) {
+            const mpv_node& entry = chapterListNode.u.list->values[i];
+            if (entry.format != MPV_FORMAT_NODE_MAP || !entry.u.list) continue;
+            ChapterInfo chapter;
+            bool hasTime = false;
+            const mpv_node_list& map = *entry.u.list;
+            for (int k = 0; k < map.num; k++) {
+                const char* key = map.keys[k];
+                const mpv_node& value = map.values[k];
+                if (!key) continue;
+                if (std::strcmp(key, "time") == 0 &&
+                    value.format == MPV_FORMAT_DOUBLE) {
+                    chapter.timeSeconds = value.u.double_;
+                    hasTime = std::isfinite(chapter.timeSeconds);
+                } else if (std::strcmp(key, "time") == 0 &&
+                           value.format == MPV_FORMAT_INT64) {
+                    chapter.timeSeconds = (double)value.u.int64;
+                    hasTime = true;
+                } else if (std::strcmp(key, "title") == 0 &&
+                           value.format == MPV_FORMAT_STRING &&
+                           value.u.string) {
+                    chapter.title =
+                        truncateUtf8(value.u.string, kMaxChapterTitleBytes);
+                }
+            }
+            if (hasTime) chapters.push_back(std::move(chapter));
+        }
+    }
+    g_state.snapshot.chapters = std::move(chapters);
+}
+
 bool parseTrackSelection(const char* value, int64_t& out) {
     if (!value) return false;
     char* end = nullptr;
@@ -436,6 +518,9 @@ void handlePropertyChange(const mpv_event_property& property) {
     } else if (name == "track-list" && property.format == MPV_FORMAT_NODE &&
                property.data) {
         updateTracksFromNode(*static_cast<mpv_node*>(property.data));
+    } else if (name == "chapter-list" &&
+               property.format == MPV_FORMAT_NODE && property.data) {
+        updateChaptersFromNode(*static_cast<mpv_node*>(property.data));
     } else if (name == "aid" && property.format == MPV_FORMAT_STRING &&
                property.data) {
         int64_t selected = -1;
@@ -536,6 +621,7 @@ void runMpvEventLoop() {
                     s.selectedAudioTrackId = -1;
                     s.subtitleTracks.clear();
                     s.selectedSubtitleTrackId = -1;
+                    s.chapters.clear();
                     g_state.loadedPath = false;
                     markDirtyLocked();
                     break;
@@ -1115,6 +1201,8 @@ int main(int argc, char** argv) {
                          MPV_FORMAT_STRING);
     mpv_observe_property(g_state.mpv, 24, "audio-params/samplerate",
                          MPV_FORMAT_INT64);
+    /* File chapters draw the timeline segments and mark closing credits. */
+    mpv_observe_property(g_state.mpv, 25, "chapter-list", MPV_FORMAT_NODE);
 
     g_state.pipeline.onGenerationChanged = [](const std::string& name,
                                               int width, int height,

apps/electron-backend/native/src/embedded_mpv.mm

@@ -91,6 +91,12 @@ struct AudioTrack {
     bool forced = false;
 };
 
+// One entry of mpv's `chapter-list`: start time and optional title.
+struct Chapter {
+    double timeSeconds = 0.0;
+    std::string title;
+};
+
 struct SessionSnapshot {
     SessionStatus status = SessionStatus::Idle;
     double positionSeconds = 0.0;
@@ -108,6 +114,7 @@ struct SessionSnapshot {
     int64_t selectedAudioTrackId = -1;
     std::vector<AudioTrack> subtitleTracks;
     int64_t selectedSubtitleTrackId = -1;
+    std::vector<Chapter> chapters;
     double playbackSpeed = 1.0;
     std::string aspectOverride = "no";
     // Stream diagnostics for the player's info popover. Sentinels mean "mpv
@@ -1087,6 +1094,67 @@ void updateAudioTracksFromNode(SessionSnapshot& snapshot, const mpv_node& node)
     );
 }
 
+// Snapshots repeat the chapter list on every emit, so a file with thousands
+// of chapters or a huge title must not inflate every snapshot. Beyond these
+// bounds a timeline cannot draw anything useful anyway.
+constexpr size_t kMaxChapters = 256;
+constexpr size_t kMaxChapterTitleBytes = 256;
+
+// Cut to at most `maxBytes` without splitting a UTF-8 sequence.
+std::string truncateUtf8(const std::string& value, size_t maxBytes)
+{
+    std::string text = value;
+    if (text.size() <= maxBytes) return text;
+    size_t end = maxBytes;
+    while (end > 0 &&
+           (static_cast<unsigned char>(text[end]) & 0xC0) == 0x80) {
+        end--;
+    }
+    text.resize(end);
+    return text;
+}
+
+// mpv `chapter-list`: an array of { time, title? } maps in file order.
+void updateChaptersFromNode(SessionSnapshot& snapshot, const mpv_node& node)
+{
+    snapshot.chapters.clear();
+    if (node.format != MPV_FORMAT_NODE_ARRAY ||
+        !node.u.list ||
+        !node.u.list->values) {
+        return;
+    }
+
+    for (int index = 0;
+         index < node.u.list->num && snapshot.chapters.size() < kMaxChapters;
+         index += 1) {
+        const mpv_node& chapterNode = node.u.list->values[index];
+        if (chapterNode.format != MPV_FORMAT_NODE_MAP) {
+            continue;
+        }
+
+        const mpv_node* timeNode = getNodeMapValue(chapterNode, "time");
+        if (!timeNode) {
+            continue;
+        }
+        Chapter chapter;
+        if (timeNode->format == MPV_FORMAT_DOUBLE) {
+            chapter.timeSeconds = timeNode->u.double_;
+        } else if (timeNode->format == MPV_FORMAT_INT64) {
+            chapter.timeSeconds = static_cast<double>(timeNode->u.int64);
+        } else {
+            continue;
+        }
+        if (!std::isfinite(chapter.timeSeconds)) {
+            continue;
+        }
+        if (const mpv_node* titleNode = getNodeMapValue(chapterNode, "title")) {
+            chapter.title =
+                truncateUtf8(readNodeString(*titleNode), kMaxChapterTitleBytes);
+        }
+        snapshot.chapters.push_back(chapter);
+    }
+}
+
 void updateSubtitleTracksFromNode(SessionSnapshot& snapshot, const mpv_node& node)
 {
     updateTracksFromNode(
@@ -1228,6 +1296,7 @@ void runEventLoop(const std::shared_ptr<Session>& session)
                 session->snapshot.selectedAudioTrackId = -1;
                 session->snapshot.subtitleTracks.clear();
                 session->snapshot.selectedSubtitleTrackId = -1;
+                session->snapshot.chapters.clear();
                 session->loadedPath = false;
                 break;
             case MPV_EVENT_FILE_LOADED:
@@ -1354,6 +1423,16 @@ void runEventLoop(const std::shared_ptr<Session>& session)
                     break;
                 }
 
+                if (propertyName == "chapter-list" &&
+                    property->format == MPV_FORMAT_NODE &&
+                    property->data) {
+                    updateChaptersFromNode(
+                        session->snapshot,
+                        *static_cast<mpv_node*>(property->data)
+                    );
+                    break;
+                }
+
                 if (propertyName == "aid" &&
                     property->format == MPV_FORMAT_STRING &&
                     property->data) {
@@ -1993,6 +2072,8 @@ Napi::Value CreateSession(const Napi::CallbackInfo& info)
         "audio-params/samplerate",
         MPV_FORMAT_INT64
     );
+    // File chapters draw the timeline segments and mark closing credits.
+    mpv_observe_property(session->handle, 23, "chapter-list", MPV_FORMAT_NODE);
 
     session->running.store(true);
     session->eventThread = std::thread(runEventLoop, session);
@@ -2818,6 +2899,21 @@ Napi::Value GetSessionSnapshot(const Napi::CallbackInfo& info)
     }
     result.Set("subtitleTracks", subtitleTracks);
 
+    auto chapters = Napi::Array::New(env, snapshot.chapters.size());
+    for (size_t index = 0; index < snapshot.chapters.size(); index += 1) {
+        const Chapter& chapter = snapshot.chapters[index];
+        auto chapterObject = Napi::Object::New(env);
+        chapterObject.Set(
+            "timeSeconds",
+            Napi::Number::New(env, chapter.timeSeconds)
+        );
+        if (!chapter.title.empty()) {
+            chapterObject.Set("title", Napi::String::New(env, chapter.title));
+        }
+        chapters.Set(index, chapterObject);
+    }
+    result.Set("chapters", chapters);
+
     result.Set(
         "playbackSpeed",
         Napi::Number::New(env, snapshot.playbackSpeed)

apps/electron-backend/native/src/embedded_mpv_wid_common.h

@@ -112,6 +112,12 @@ struct AudioTrack {
     bool forced = false;
 };
 
+/** One entry of mpv's `chapter-list`: start time and optional title. */
+struct Chapter {
+    double timeSeconds = 0.0;
+    std::string title;
+};
+
 struct SessionSnapshot {
     SessionStatus status = SessionStatus::Idle;
     double positionSeconds = 0.0;
@@ -125,6 +131,8 @@ struct SessionSnapshot {
     int64_t selectedAudioTrackId = -1;
     std::vector<AudioTrack> subtitleTracks;
     int64_t selectedSubtitleTrackId = -1;
+    /** libmpv backend only; the Linux `--wid` poller does not read it. */
+    std::vector<Chapter> chapters;
     double playbackSpeed = 1.0;
     std::string aspectOverride = "no";
     /** Stream diagnostics for the player's info popover. Sentinels mean "not
@@ -1400,6 +1408,65 @@ void updateAudioTracksFromNode(SessionSnapshot& snapshot, const mpv_node& node)
     }
 }
 
+/* Snapshots repeat the chapter list on every emit, so a file with thousands
+ * of chapters or a huge title must not inflate every snapshot. Beyond these
+ * bounds a timeline cannot draw anything useful anyway. */
+constexpr size_t kMaxChapters = 256;
+constexpr size_t kMaxChapterTitleBytes = 256;
+
+/* Cut to at most `maxBytes` without splitting a UTF-8 sequence. */
+std::string truncateUtf8(const std::string& value, size_t maxBytes)
+{
+    std::string text = value;
+    if (text.size() <= maxBytes) return text;
+    size_t end = maxBytes;
+    while (end > 0 &&
+           (static_cast<unsigned char>(text[end]) & 0xC0) == 0x80) {
+        end--;
+    }
+    text.resize(end);
+    return text;
+}
+
+/** mpv `chapter-list`: an array of { time, title? } maps in file order. */
+void updateChaptersFromNode(SessionSnapshot& snapshot, const mpv_node& node)
+{
+    snapshot.chapters.clear();
+    if (node.format != MPV_FORMAT_NODE_ARRAY || !node.u.list ||
+        !node.u.list->values) {
+        return;
+    }
+
+    for (int index = 0;
+         index < node.u.list->num && snapshot.chapters.size() < kMaxChapters;
+         index += 1) {
+        const mpv_node& chapterNode = node.u.list->values[index];
+        if (chapterNode.format != MPV_FORMAT_NODE_MAP) {
+            continue;
+        }
+        const mpv_node* timeNode = getNodeMapValue(chapterNode, "time");
+        if (!timeNode) {
+            continue;
+        }
+        Chapter chapter;
+        if (timeNode->format == MPV_FORMAT_DOUBLE) {
+            chapter.timeSeconds = timeNode->u.double_;
+        } else if (timeNode->format == MPV_FORMAT_INT64) {
+            chapter.timeSeconds = static_cast<double>(timeNode->u.int64);
+        } else {
+            continue;
+        }
+        if (!std::isfinite(chapter.timeSeconds)) {
+            continue;
+        }
+        if (const mpv_node* titleNode = getNodeMapValue(chapterNode, "title")) {
+            chapter.title =
+                truncateUtf8(readNodeString(*titleNode), kMaxChapterTitleBytes);
+        }
+        snapshot.chapters.push_back(chapter);
+    }
+}
+
 void updateSubtitleTracksFromNode(SessionSnapshot& snapshot, const mpv_node& node)
 {
     snapshot.subtitleTracks = readTracksOfType(node, "sub");
@@ -1498,6 +1565,7 @@ void runEventLoop(std::shared_ptr<Session> session)
                 session->snapshot.status = SessionStatus::Loading;
                 session->snapshot.error.clear();
                 session->snapshot.clearStreamStats();
+                session->snapshot.chapters.clear();
                 break;
             case MPV_EVENT_FILE_LOADED:
                 session->snapshot.status =
@@ -1580,6 +1648,10 @@ void runEventLoop(std::shared_ptr<Session> session)
                         *static_cast<mpv_node*>(property->data);
                     updateAudioTracksFromNode(session->snapshot, node);
                     updateSubtitleTracksFromNode(session->snapshot, node);
+                } else if (name == "chapter-list" && property->format == MPV_FORMAT_NODE) {
+                    updateChaptersFromNode(
+                        session->snapshot,
+                        *static_cast<mpv_node*>(property->data));
                 } else if (name == "aid") {
                     const char* rawValue = property->format == MPV_FORMAT_STRING
                         ? *static_cast<char**>(property->data)
@@ -1918,6 +1990,8 @@ Napi::Value CreateSession(const Napi::CallbackInfo& info)
         session->handle, 21, "audio-params/channels", MPV_FORMAT_STRING);
     mpv_observe_property(
         session->handle, 22, "audio-params/samplerate", MPV_FORMAT_INT64);
+    /* File chapters draw the timeline segments and mark closing credits. */
+    mpv_observe_property(session->handle, 23, "chapter-list", MPV_FORMAT_NODE);
 
     session->running.store(true);
     session->eventThread = std::thread(runEventLoop, session);
@@ -2624,6 +2698,17 @@ Napi::Value GetSessionSnapshot(const Napi::CallbackInfo& info)
         result.Set("selectedSubtitleTrackId", env.Null());
     }
     writeTracks(env, result, "subtitleTracks", snapshot.subtitleTracks);
+    auto chapters = Napi::Array::New(env, snapshot.chapters.size());
+    for (size_t index = 0; index < snapshot.chapters.size(); index += 1) {
+        const Chapter& chapter = snapshot.chapters[index];
+        auto chapterObject = Napi::Object::New(env);
+        chapterObject.Set("timeSeconds", Napi::Number::New(env, chapter.timeSeconds));
+        if (!chapter.title.empty()) {
+            chapterObject.Set("title", Napi::String::New(env, chapter.title));
+        }
+        chapters.Set(index, chapterObject);
+    }
+    result.Set("chapters", chapters);
     result.Set("playbackSpeed", Napi::Number::New(env, snapshot.playbackSpeed));
     result.Set("aspectOverride", Napi::String::New(env, snapshot.aspectOverride));
     writeStreamStats(env, result, snapshot);

apps/electron-backend/src/app/services/embedded-mpv-chapters.util.spec.ts

@@ -0,0 +1,61 @@
+import {
+    MAX_EMBEDDED_MPV_CHAPTERS,
+    MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH,
+    normalizeEmbeddedMpvChapters,
+} from './embedded-mpv-chapters.util';
+
+describe('normalizeEmbeddedMpvChapters', () => {
+    it('keeps valid chapters and trims titles', () => {
+        expect(
+            normalizeEmbeddedMpvChapters([
+                { timeSeconds: 0, title: ' Intro ' },
+                { timeSeconds: 12.5 },
+                { timeSeconds: 40, title: '' },
+            ])
+        ).toEqual([
+            { timeSeconds: 0, title: 'Intro' },
+            { timeSeconds: 12.5 },
+            { timeSeconds: 40 },
+        ]);
+    });
+
+    it('drops malformed entries', () => {
+        expect(
+            normalizeEmbeddedMpvChapters([
+                null,
+                'chapter',
+                { title: 'No time' },
+                { timeSeconds: -1 },
+                { timeSeconds: Number.NaN },
+                { timeSeconds: '10' },
+                { timeSeconds: 5, title: 7 },
+            ])
+        ).toEqual([{ timeSeconds: 5 }]);
+    });
+
+    it('bounds the chapter count and title length', () => {
+        const chapters = normalizeEmbeddedMpvChapters(
+            Array.from({ length: MAX_EMBEDDED_MPV_CHAPTERS + 50 }, (_, i) => ({
+                timeSeconds: i,
+                title: '😀'.repeat(MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH + 5),
+            }))
+        );
+
+        expect(chapters).toHaveLength(MAX_EMBEDDED_MPV_CHAPTERS);
+        expect(chapters.at(-1)?.timeSeconds).toBe(
+            MAX_EMBEDDED_MPV_CHAPTERS - 1
+        );
+        // Cut by code point, so no surrogate pair is split.
+        expect(Array.from(chapters[0].title ?? '')).toHaveLength(
+            MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH
+        );
+        expect(chapters[0].title).toBe(
+            '😀'.repeat(MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH)
+        );
+    });
+
+    it('treats a missing field from an older binary as no chapters', () => {
+        expect(normalizeEmbeddedMpvChapters(undefined)).toEqual([]);
+        expect(normalizeEmbeddedMpvChapters({})).toEqual([]);
+    });
+});

apps/electron-backend/src/app/services/embedded-mpv-chapters.util.ts

@@ -0,0 +1,51 @@
+import type { EmbeddedMpvChapter } from '@iptvnator/shared/interfaces';
+
+/**
+ * Every session update repeats the list, so a chapter-heavy file must not
+ * inflate each IPC payload; the native parsers apply the same bounds.
+ */
+export const MAX_EMBEDDED_MPV_CHAPTERS = 256;
+export const MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH = 256;
+
+/**
+ * Validate the addon's or helper's `chapters` snapshot field before it
+ * reaches the renderer: an older binary omits it, and a malformed entry must
+ * not draw a segment; the list and each title are bounded. Order is left to the renderer's timeline mapping.
+ */
+export function normalizeEmbeddedMpvChapters(
+    value: unknown
+): EmbeddedMpvChapter[] {
+    if (!Array.isArray(value)) {
+        return [];
+    }
+    const chapters: EmbeddedMpvChapter[] = [];
+    for (const entry of value) {
+        if (chapters.length >= MAX_EMBEDDED_MPV_CHAPTERS) {
+            break;
+        }
+        if (!entry || typeof entry !== 'object') {
+            continue;
+        }
+        const { timeSeconds, title } = entry as Record<string, unknown>;
+        if (
+            typeof timeSeconds !== 'number' ||
+            !Number.isFinite(timeSeconds) ||
+            timeSeconds < 0
+        ) {
+            continue;
+        }
+        const trimmedTitle =
+            typeof title === 'string'
+                ? Array.from(title.trim())
+                      .slice(0, MAX_EMBEDDED_MPV_CHAPTER_TITLE_LENGTH)
+                      .join('')
+                      .trim()
+                : '';
+        chapters.push(
+            trimmedTitle
+                ? { timeSeconds, title: trimmedTitle }
+                : { timeSeconds }
+        );
+    }
+    return chapters;
+}

apps/electron-backend/src/app/services/embedded-mpv-frame-copy-protocol.ts

@@ -53,6 +53,7 @@ export function createInitialSnapshot(): NativeEmbeddedMpvSessionSnapshot {
         selectedAudioTrackId: null,
         subtitleTracks: [],
         selectedSubtitleTrackId: null,
+        chapters: [],
         playbackSpeed: 1,
         aspectOverride: 'no',
         recording: { active: false },

apps/electron-backend/src/app/services/embedded-mpv-native.service.spec.ts

@@ -83,6 +83,7 @@ interface MockSnapshot {
     streamUrl: string;
     audioTracks?: never[];
     selectedAudioTrackId?: number | null;
+    chapters?: Array<{ timeSeconds: number; title?: string }>;
     stats?: {
         fps?: number;
         videoBitrateBps?: number;
@@ -580,6 +581,24 @@ describe('EmbeddedMpvNativeService power blocker', () => {
         });
     });
 
+    it('passes validated file chapters through to the renderer session', () => {
+        startSession('s1', snapshot('playing'));
+        addon.getSessionSnapshot.mockReturnValue(
+            snapshot('playing', {
+                chapters: [
+                    { timeSeconds: 0, title: 'Intro' },
+                    { timeSeconds: Number.NaN, title: 'Broken' },
+                    { timeSeconds: 1320, title: 'Credits' },
+                ],
+            })
+        );
+
+        expect(service.setVolume('s1', 1)?.chapters).toEqual([
+            { timeSeconds: 0, title: 'Intro' },
+            { timeSeconds: 1320, title: 'Credits' },
+        ]);
+    });
+
     it('omits the stats key entirely when the engine reports none', () => {
         // An empty object would make the renderer render an empty popover
         // instead of hiding the info button.

apps/electron-backend/src/app/services/embedded-mpv-native.service.ts

@@ -14,6 +14,7 @@ import App from '../app';
 import {
     EmbeddedMpvAudioTrack,
     EmbeddedMpvBounds,
+    EmbeddedMpvChapter,
     EmbeddedMpvCapabilities,
     EmbeddedMpvRecordingStartOptions,
     EmbeddedMpvRecordingState,
@@ -56,6 +57,7 @@ import {
     resolveFrameCopyHelperPath,
 } from './embedded-mpv-frame-copy-platform.util';
 import type { EmbeddedMpvFrameCopyRuntimeMode } from './embedded-mpv-frame-copy-runtime';
+import { normalizeEmbeddedMpvChapters } from './embedded-mpv-chapters.util';
 import {
     EMBEDDED_MPV_EXPERIMENT_ENV,
     isEmbeddedMpvFeatureEnabled,
@@ -71,6 +73,7 @@ export interface NativeEmbeddedMpvSessionSnapshot {
     selectedAudioTrackId?: number | null;
     subtitleTracks?: EmbeddedMpvSubtitleTrack[];
     selectedSubtitleTrackId?: number | null;
+    chapters?: EmbeddedMpvChapter[];
     playbackSpeed?: number;
     aspectOverride?: string;
     videoWidth?: number;
@@ -1237,6 +1240,7 @@ export class EmbeddedMpvNativeService {
                 typeof snapshot.selectedSubtitleTrackId === 'number'
                     ? snapshot.selectedSubtitleTrackId
                     : null,
+            chapters: normalizeEmbeddedMpvChapters(snapshot.chapters),
             playbackSpeed:
                 typeof snapshot.playbackSpeed === 'number'
                     ? snapshot.playbackSpeed

docs/architecture/embedded-mpv-native.md

@@ -487,6 +487,8 @@ Audio tracks are discovered from MPV's `track-list` property. The selected track
 
 Subtitle tracks mirror the audio-track contract: same `track-list` source, same parsing pipeline, but selected through MPV's `sid` property. A `trackId` of `-1` from the renderer is interpreted as "disable subtitles" and translated to `sid=no` at the addon boundary. Playback speed is observed and set through MPV's `speed` property, clamped at the addon to `[0.25, 4.0]`. Aspect override uses MPV's `video-aspect-override` property as a passthrough string ("no", "16:9", "4:3", "21:9", "2.35:1"). All four properties (`sid`, `speed`, `video-aspect-override`, plus `aid`) are observed at session init so renderer state stays in sync with the native side without needing extra round-trips.
 
+File chapters come from MPV's `chapter-list` property, observed as a node next to `track-list` by the macOS and Windows addons and the frame-copy helper, and cleared on every `START_FILE` so a replacement file never shows the previous one's chapters. Each snapshot carries `chapters: [{ timeSeconds, title? }]` (the helper always emits the key, because the adapter merges snapshot events field by field); `EmbeddedMpvNativeService` validates it with `normalizeEmbeddedMpvChapters` into `EmbeddedMpvSession.chapters`, and an older binary without the field yields `[]`. The Linux `mpv --wid` poller does not read chapters. The renderer maps them to timeline segments — see "Timeline segments" in the [player controls contract](player-controls-contract.md).
+
 The renderer learns which features the loaded addon binary supports through the `EmbeddedMpvSupport.capabilities` field returned from `getEmbeddedMpvSupport()`. The service probes `typeof addon.<method> === 'function'` for each optional native export. Older addon binaries with the original audio-only surface return `capabilities: { subtitles: false, playbackSpeed: false, aspectOverride: false, screenshot: false, recording: false }`, and the renderer hides the corresponding controls instead of throwing at runtime. Linux intentionally does not export libmpv-only optional controls while it uses the process-isolated `mpv --wid` backend.
 
 Linux audio-track discovery works differently from macOS/Windows because the hand-rolled JSON IPC reply parser only understands scalar `data` values: the poll loop reads `track-list/count` every tick and walks the scalar `track-list/N/{type,id,title,lang,default,forced}` sub-properties only when the count changes. The selected track is reconciled from the scalar `aid` property on every tick (`aid` reads back non-numeric when audio is disabled, which maps to "no selection"). Track switching still goes through `set_property aid` over the same socket.

docs/architecture/player-controls-contract.md

@@ -366,7 +366,23 @@ always covers `[0, duration]`. Without segments — live playback, VOD and
 series — the row is one untitled segment, which is the plain bar.
 `ControlsTimeline` owns the normalized list and the per-segment fill for the
 current scrub or playback value; the hover label becomes `Chapter 2 · 12:40`
-over a titled segment. mpv's chapter list is not a producer yet.
+over a titled segment.
+
+**Chapter producer.** Embedded MPV reports the file's own chapters: the
+addons and the frame-copy helper observe mpv `chapter-list` and publish it
+as `EmbeddedMpvSession.chapters` (`{ timeSeconds, title? }`, validated in
+main by `normalizeEmbeddedMpvChapters`). `buildChapterTimelineSegments`
+(`chapter-timeline-segments.ts`) runs each chapter from its start to the
+next one's, the last to the duration, orders them and drops repeated or
+out-of-range starts; an untitled chapter becomes an untitled segment, and
+no chapters or no finite duration yields `null`.
+`EmbeddedMpvPlayerComponent.controlsTimelineSegments`
+(`embeddedMpvTimelineSegments`) passes the host's segments when it
+supplies any and the chapter segments otherwise, so catch-up programmes
+always win; `sameTimelineSegments` keeps a re-polled, unchanged list from
+counting as a change. The Linux native-view `mpv --wid` backend reads no
+chapters, and the web engines report none (streamed HLS/DASH carries no
+chapter track), so their VOD and series stay one plain bar.
 
 **Catch-up producer.** Archive playback of a live channel passes the EPG
 programmes overlapping its archive window.
@@ -413,8 +429,9 @@ episode: `upNextThresholdSeconds` is 4% of the duration clamped to
 `timelineSegments` carry a closing-credits chapter in the last third
 (`creditsStartSeconds`: "Credits", "Outro", "Ending", an anime `ED`, and a
 few localized names), the card appears when it starts instead, at most
-5 min before the end. No engine reports file chapters today, so in practice
-the adaptive lead applies. The countdown shows whole minutes, and seconds
+5 min before the end. Embedded MPV under the frame-copy engine supplies
+file chapters (see the chapter producer above); every other engine, and a
+file without a credits chapter, uses the adaptive lead. The countdown shows whole minutes, and seconds
 in the last minute. A
 still that fails to load falls back to the label tile. A
 click emits `nextEpisodeRequested` directly — not through the

libs/shared/interfaces/src/lib/embedded-mpv-session.interface.ts

@@ -84,6 +84,13 @@ export interface EmbeddedMpvAudioTrack {
 
 export type EmbeddedMpvSubtitleTrack = EmbeddedMpvAudioTrack;
 
+/** One entry of mpv's `chapter-list`, in file order. */
+export interface EmbeddedMpvChapter {
+    /** Chapter start, in media seconds. */
+    timeSeconds: number;
+    title?: string;
+}
+
 export interface EmbeddedMpvRecordingState {
     active: boolean;
     targetPath?: string;
@@ -142,6 +149,11 @@ export interface EmbeddedMpvSession {
     selectedSubtitleTrackId: number | null;
     playbackSpeed: number;
     aspectOverride: string;
+    /**
+     * The file's chapters (mpv `chapter-list`). Absent from an addon built
+     * before chapters were observed and from the Linux `--wid` backend.
+     */
+    chapters?: EmbeddedMpvChapter[];
     /** Source video size (mpv dwidth/dheight); frame-copy engine only. */
     videoWidth?: number;
     videoHeight?: number;

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-chapter-segments.spec.ts

@@ -0,0 +1,58 @@
+import type { EmbeddedMpvSession } from '@iptvnator/shared/interfaces';
+import { embeddedMpvTimelineSegments } from './embedded-mpv-chapter-segments';
+
+function session(
+    overrides: Partial<EmbeddedMpvSession> = {}
+): EmbeddedMpvSession {
+    return {
+        id: 'session-1',
+        title: 'Episode',
+        streamUrl: 'https://example.test/episode.mkv',
+        status: 'playing',
+        positionSeconds: 0,
+        durationSeconds: 1500,
+        volume: 1,
+        audioTracks: [],
+        selectedAudioTrackId: null,
+        subtitleTracks: [],
+        selectedSubtitleTrackId: null,
+        playbackSpeed: 1,
+        aspectOverride: 'no',
+        startedAt: '2026-09-30T10:00:00Z',
+        updatedAt: '2026-09-30T10:00:00Z',
+        chapters: [
+            { timeSeconds: 0, title: 'Opening' },
+            { timeSeconds: 1410, title: 'Ending' },
+        ],
+        ...overrides,
+    };
+}
+
+describe('embeddedMpvTimelineSegments', () => {
+    it('maps mpv chapters when the host passes no segments', () => {
+        const expected = [
+            { startSeconds: 0, endSeconds: 1410, title: 'Opening' },
+            { startSeconds: 1410, endSeconds: 1500, title: 'Ending' },
+        ];
+        expect(embeddedMpvTimelineSegments(null, session())).toEqual(expected);
+        expect(embeddedMpvTimelineSegments([], session())).toEqual(expected);
+    });
+
+    it('keeps catch-up programmes ahead of file chapters', () => {
+        const catchup = [{ startSeconds: 0, endSeconds: 1800, title: 'News' }];
+        expect(embeddedMpvTimelineSegments(catchup, session())).toBe(catchup);
+    });
+
+    it('draws nothing without chapters or a known duration', () => {
+        expect(embeddedMpvTimelineSegments(null, null)).toBeNull();
+        expect(
+            embeddedMpvTimelineSegments(null, session({ chapters: undefined }))
+        ).toBeNull();
+        expect(
+            embeddedMpvTimelineSegments(
+                null,
+                session({ durationSeconds: null })
+            )
+        ).toBeNull();
+    });
+});

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-chapter-segments.ts

@@ -0,0 +1,23 @@
+import type { EmbeddedMpvSession } from '@iptvnator/shared/interfaces';
+import { buildChapterTimelineSegments } from '../player-controls/chapter-timeline-segments';
+import type { PlayerTimelineSegment } from '../player-controls/player-controls.model';
+
+/**
+ * The segments `app-player-controls` draws for an Embedded MPV session: the
+ * host's catch-up programmes when it passes any, otherwise the file's own
+ * chapters from mpv's `chapter-list`, which also lets a closing-credits
+ * chapter time the "Up next" card.
+ */
+export function embeddedMpvTimelineSegments(
+    hostSegments: readonly PlayerTimelineSegment[] | null,
+    session: EmbeddedMpvSession | null
+): readonly PlayerTimelineSegment[] | null {
+    if (hostSegments?.length) {
+        return hostSegments;
+    }
+    const chapters = session?.chapters?.map((chapter) => ({
+        startSeconds: chapter.timeSeconds,
+        title: chapter.title ?? null,
+    }));
+    return buildChapterTimelineSegments(chapters, session?.durationSeconds);
+}

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-player.component.html

@@ -104,7 +104,7 @@
             [fullscreenTarget]="fullscreenTarget()"
             [mediaTitle]="mediaTitle()"
             [upNext]="upNext()"
-            [timelineSegments]="timelineSegments()"
+            [timelineSegments]="controlsTimelineSegments()"
             [showControls]="showControls()"
             [shortcutsEnabled]="sharedShortcutsEnabled()"
             (previousEpisodeRequested)="requestPreviousEpisode()"

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-player.component.shared-controls.spec.ts

@@ -220,6 +220,66 @@ describe('EmbeddedMpvPlayerComponent shared controls host', () => {
         expect(next).toHaveBeenCalledTimes(1);
     });
 
+    describe('file chapters', () => {
+        const EPISODE: EmbeddedMpvSession = {
+            ...READY_SESSION,
+            durationSeconds: 3000,
+            positionSeconds: 2750,
+            chapters: [
+                { timeSeconds: 0, title: 'Episode' },
+                { timeSeconds: 2700, title: 'Credits' },
+            ],
+        };
+        const UP_NEXT = { label: 'S01E02', title: 'Next', thumbnailUrl: null };
+
+        function upNextCard(
+            fixture: ComponentFixture<EmbeddedMpvPlayerComponent>
+        ): Element | null {
+            return fixture.nativeElement.querySelector(
+                '[data-test-id="player-controls-up-next"]'
+            );
+        }
+
+        function play(session: EmbeddedMpvSession) {
+            const rendered = render();
+            rendered.fixture.componentRef.setInput('upNext', UP_NEXT);
+            rendered.controller.session.set(session);
+            rendered.fixture.detectChanges();
+            return rendered;
+        }
+
+        it('draws mpv chapters on the shared timeline', () => {
+            const { fixture } = play(EPISODE);
+
+            expect(sharedControls(fixture)?.timelineSegments()).toEqual([
+                { startSeconds: 0, endSeconds: 2700, title: 'Episode' },
+                { startSeconds: 2700, endSeconds: 3000, title: 'Credits' },
+            ]);
+        });
+
+        it('keeps host catch-up segments ahead of file chapters', () => {
+            const { fixture } = play(EPISODE);
+            const catchup = [
+                { startSeconds: 0, endSeconds: 3000, title: 'Programme' },
+            ];
+            fixture.componentRef.setInput('timelineSegments', catchup);
+            fixture.detectChanges();
+
+            expect(sharedControls(fixture)?.timelineSegments()).toEqual(
+                catchup
+            );
+        });
+
+        it('shows Up next when the closing-credits chapter starts', () => {
+            // 250 s left: past the credits start, but before the adaptive
+            // lead (4% of 50 min = 2 min) would bring the card up.
+            expect(upNextCard(play(EPISODE).fixture)).not.toBeNull();
+            expect(
+                upNextCard(play({ ...EPISODE, chapters: [] }).fixture)
+            ).toBeNull();
+        });
+    });
+
     it('syncs bounds on fullscreen changes without revealing legacy state', () => {
         const { fixture, component, controller } = render();
         const triggerBoundsSync = jest.spyOn(controller, 'triggerBoundsSync');

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-player.component.ts

@@ -25,6 +25,7 @@ import {
     RecordingStoppedEvent,
     ResolvedPortalPlayback,
 } from '@iptvnator/shared/interfaces';
+import { sameTimelineSegments } from '../player-controls/chapter-timeline-segments';
 import { PlayerControlsComponent } from '../player-controls/player-controls.component';
 import type {
     PlayerMediaTitle,
@@ -32,6 +33,7 @@ import type {
     PlayerTimelineSegment,
 } from '../player-controls/player-controls.model';
 import type { SeriesPlaybackNavigation } from '../portal-inline-player/series-playback-navigation';
+import { embeddedMpvTimelineSegments } from './embedded-mpv-chapter-segments';
 import { EmbeddedMpvControlsAdapter } from './embedded-mpv-controls.adapter';
 import { EmbeddedMpvDockPanelComponent } from './embedded-mpv-dock-panel.component';
 import { EmbeddedMpvDockPanelState } from './embedded-mpv-dock-panels';
@@ -88,7 +90,7 @@ export class EmbeddedMpvPlayerComponent implements OnDestroy {
     readonly seriesNavigation = input<SeriesPlaybackNavigation | null>(null);
     readonly mediaTitle = input<PlayerMediaTitle | null>(null);
     readonly upNext = input<PlayerUpNextItem | null>(null);
-    /** Catch-up programmes drawn as track segments; null draws one. */
+    /** Catch-up programmes drawn as track segments; they outrank chapters. */
     readonly timelineSegments = input<readonly PlayerTimelineSegment[] | null>(
         null
     );
@@ -143,6 +145,12 @@ export class EmbeddedMpvPlayerComponent implements OnDestroy {
 
     readonly support = this.controller.support;
     readonly session = this.controller.session;
+    /** Catch-up programmes first, else the file's chapters; see the helper. */
+    readonly controlsTimelineSegments = computed(
+        () =>
+            embeddedMpvTimelineSegments(this.timelineSegments(), this.session()),
+        { equal: sameTimelineSegments }
+    );
     readonly stalled = this.controller.stalled;
 
     readonly volume = signal(readStoredVolume());

libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-factory.ts

@@ -26,6 +26,7 @@ function baseSession(
         selectedAudioTrackId: null,
         subtitleTracks: [],
         selectedSubtitleTrackId: null,
+        chapters: [],
         playbackSpeed: 1,
         aspectOverride: 'no',
         recording: { active: false },

libs/ui/playback/src/lib/player-controls/chapter-timeline-segments.spec.ts

@@ -0,0 +1,97 @@
+import {
+    buildChapterTimelineSegments,
+    sameTimelineSegments,
+} from './chapter-timeline-segments';
+
+describe('buildChapterTimelineSegments', () => {
+    it('runs each chapter to the next start and the last one to the end', () => {
+        expect(
+            buildChapterTimelineSegments(
+                [
+                    { startSeconds: 0, title: 'Intro' },
+                    { startSeconds: 90.5, title: 'Episode' },
+                    { startSeconds: 2640, title: 'Credits' },
+                ],
+                2700
+            )
+        ).toEqual([
+            { startSeconds: 0, endSeconds: 90.5, title: 'Intro' },
+            { startSeconds: 90.5, endSeconds: 2640, title: 'Episode' },
+            { startSeconds: 2640, endSeconds: 2700, title: 'Credits' },
+        ]);
+    });
+
+    it('orders chapters and drops repeated or out-of-range starts', () => {
+        expect(
+            buildChapterTimelineSegments(
+                [
+                    { startSeconds: 600, title: 'B' },
+                    { startSeconds: 0, title: 'A' },
+                    { startSeconds: 600, title: 'B again' },
+                    { startSeconds: -1, title: 'Before' },
+                    { startSeconds: 1200, title: 'At the end' },
+                    { startSeconds: Number.NaN, title: 'Broken' },
+                ],
+                1200
+            )
+        ).toEqual([
+            { startSeconds: 0, endSeconds: 600, title: 'A' },
+            { startSeconds: 600, endSeconds: 1200, title: 'B' },
+        ]);
+    });
+
+    it('keeps untitled and blank-titled chapters as untitled segments', () => {
+        expect(
+            buildChapterTimelineSegments(
+                [
+                    { startSeconds: 0 },
+                    { startSeconds: 10, title: '   ' },
+                    { startSeconds: 20, title: ' Outro ' },
+                ],
+                30
+            )
+        ).toEqual([
+            { startSeconds: 0, endSeconds: 10, title: null },
+            { startSeconds: 10, endSeconds: 20, title: null },
+            { startSeconds: 20, endSeconds: 30, title: 'Outro' },
+        ]);
+    });
+
+    it.each([
+        ['no chapters', [], 100],
+        ['null chapters', null, 100],
+        ['an unknown duration', [{ startSeconds: 0 }], null],
+        ['a zero duration', [{ startSeconds: 0 }], 0],
+        ['an infinite duration', [{ startSeconds: 0 }], Infinity],
+        ['only unusable chapters', [{ startSeconds: 500 }], 100],
+    ])('returns null for %s', (_label, chapters, duration) => {
+        expect(buildChapterTimelineSegments(chapters, duration)).toBeNull();
+    });
+});
+
+describe('sameTimelineSegments', () => {
+    const segments = [
+        { startSeconds: 0, endSeconds: 10, title: 'A' },
+        { startSeconds: 10, endSeconds: 20, title: null },
+    ];
+
+    it('compares by value', () => {
+        expect(
+            sameTimelineSegments(
+                segments,
+                segments.map((segment) => ({ ...segment }))
+            )
+        ).toBe(true);
+        expect(sameTimelineSegments(null, null)).toBe(true);
+        expect(sameTimelineSegments(segments, null)).toBe(false);
+        expect(sameTimelineSegments(segments, segments.slice(0, 1))).toBe(
+            false
+        );
+        expect(
+            sameTimelineSegments(segments, [
+                segments[0],
+                { ...segments[1], title: 'B' },
+            ])
+        ).toBe(false);
+    });
+});

libs/ui/playback/src/lib/player-controls/chapter-timeline-segments.ts

@@ -0,0 +1,68 @@
+import type { PlayerTimelineSegment } from './player-controls.model';
+
+/** A file chapter as an engine reports it: its start and optional title. */
+export interface PlayerChapter {
+    startSeconds: number;
+    title?: string | null;
+}
+
+/**
+ * Turns an engine's chapter list into timeline segments: each chapter runs
+ * from its start to the next chapter's start, the last one to the end of the
+ * media. Chapters outside `[0, duration)` and repeated start times are
+ * dropped. Without a finite duration or any usable chapter there is nothing
+ * to draw, so the result is null and the track stays one plain bar.
+ */
+export function buildChapterTimelineSegments(
+    chapters: readonly PlayerChapter[] | null | undefined,
+    durationSeconds: number | null | undefined
+): PlayerTimelineSegment[] | null {
+    if (
+        !chapters?.length ||
+        typeof durationSeconds !== 'number' ||
+        !Number.isFinite(durationSeconds) ||
+        durationSeconds <= 0
+    ) {
+        return null;
+    }
+    const starts = chapters
+        .filter(
+            (chapter) =>
+                Number.isFinite(chapter.startSeconds) &&
+                chapter.startSeconds >= 0 &&
+                chapter.startSeconds < durationSeconds
+        )
+        .sort((a, b) => a.startSeconds - b.startSeconds)
+        .filter(
+            (chapter, index, sorted) =>
+                index === 0 ||
+                chapter.startSeconds !== sorted[index - 1].startSeconds
+        );
+    if (starts.length === 0) {
+        return null;
+    }
+    return starts.map((chapter, index) => ({
+        startSeconds: chapter.startSeconds,
+        endSeconds: starts[index + 1]?.startSeconds ?? durationSeconds,
+        title: chapter.title?.trim() || null,
+    }));
+}
+
+/** Value equality, so a re-polled but unchanged chapter list is no update. */
+export function sameTimelineSegments(
+    a: readonly PlayerTimelineSegment[] | null,
+    b: readonly PlayerTimelineSegment[] | null
+): boolean {
+    if (a === b) {
+        return true;
+    }
+    if (!a || !b || a.length !== b.length) {
+        return false;
+    }
+    return a.every(
+        (segment, index) =>
+            segment.startSeconds === b[index].startSeconds &&
+            segment.endSeconds === b[index].endSeconds &&
+            segment.title === b[index].title
+    );
+}

libs/ui/playback/src/lib/player-controls/index.ts

@@ -14,6 +14,7 @@ export * from './legacy-player-shortcuts';
 export * from './controls-surface';
 export * from './pointer-focus-release';
 export * from './catchup-timeline-segments';
+export * from './chapter-timeline-segments';
 export * from './controls-timeline';
 export * from './controls-view-model';
 export * from './controls-visibility';