33 files changed, 547 insertions, 34 deletions

diff --git a/server/server/controllers/activitypub/client.ts b/server/server/controllers/activitypub/client.ts
index 5d5e43bf5..1d5d269a9 100644
--- a/server/server/controllers/activitypub/client.ts
+++ b/server/server/controllers/activitypub/client.ts
@@ -1,6 +1,13 @@
 import cors from 'cors'
 import express from 'express'
-import { VideoCommentObject, VideoPlaylistPrivacy, VideoPrivacy, VideoRateType } from '@peertube/peertube-models'
+import {
+  VideoChapterObject,
+  VideoChaptersObject,
+  VideoCommentObject,
+  VideoPlaylistPrivacy,
+  VideoPrivacy,
+  VideoRateType
+} from '@peertube/peertube-models'
 import { activityPubCollectionPagination } from '@server/lib/activitypub/collection.js'
 import { getContextFilter } from '@server/lib/activitypub/context.js'
 import { getServerActor } from '@server/models/application/application.js'
@@ -12,12 +19,18 @@ import { buildAnnounceWithVideoAudience, buildLikeActivity } from '../../lib/act
 import { buildCreateActivity } from '../../lib/activitypub/send/send-create.js'
 import { buildDislikeActivity } from '../../lib/activitypub/send/send-dislike.js'
 import {
+  getLocalVideoChaptersActivityPubUrl,
   getLocalVideoCommentsActivityPubUrl,
   getLocalVideoDislikesActivityPubUrl,
   getLocalVideoLikesActivityPubUrl,
   getLocalVideoSharesActivityPubUrl
 } from '../../lib/activitypub/url.js'
-import { cacheRoute } from '../../middlewares/cache/cache.js'
+import {
+  apVideoChaptersSetCacheKey,
+  buildAPVideoChaptersGroupsCache,
+  cacheRoute,
+  cacheRouteFactory
+} from '../../middlewares/cache/cache.js'
 import {
   activityPubRateLimiter,
   asyncMiddleware,
@@ -42,6 +55,8 @@ import { VideoCommentModel } from '../../models/video/video-comment.js'
 import { VideoPlaylistModel } from '../../models/video/video-playlist.js'
 import { VideoShareModel } from '../../models/video/video-share.js'
 import { activityPubResponse } from './utils.js'
+import { VideoChapterModel } from '@server/models/video/video-chapter.js'
+import { InternalEventEmitter } from '@server/lib/internal-event-emitter.js'
 
 const activityPubClientRouter = express.Router()
 activityPubClientRouter.use(cors())
@@ -145,6 +160,27 @@ activityPubClientRouter.get('/videos/watch/:videoId/comments/:commentId/activity
   asyncMiddleware(videoCommentController)
 )
 
+// ---------------------------------------------------------------------------
+
+const { middleware: chaptersCacheRouteMiddleware, instance: chaptersApiCache } = cacheRouteFactory()
+
+InternalEventEmitter.Instance.on('chapters-updated', ({ video }) => {
+  if (video.remote) return
+
+  chaptersApiCache.clearGroupSafe(buildAPVideoChaptersGroupsCache({ videoId: video.uuid }))
+})
+
+activityPubClientRouter.get('/videos/watch/:id/chapters',
+  executeIfActivityPub,
+  activityPubRateLimiter,
+  apVideoChaptersSetCacheKey,
+  chaptersCacheRouteMiddleware(ROUTE_CACHE_LIFETIME.ACTIVITY_PUB.VIDEOS),
+  asyncMiddleware(videosCustomGetValidator('only-video')),
+  asyncMiddleware(videoChaptersController)
+)
+
+// ---------------------------------------------------------------------------
+
 activityPubClientRouter.get(
   [ '/video-channels/:nameWithHost', '/video-channels/:nameWithHost/videos', '/c/:nameWithHost', '/c/:nameWithHost/videos' ],
   executeIfActivityPub,
@@ -390,6 +426,31 @@ async function videoCommentController (req: express.Request, res: express.Respon
   return activityPubResponse(activityPubContextify(videoCommentObject, 'Comment', getContextFilter()), res)
 }
 
+async function videoChaptersController (req: express.Request, res: express.Response) {
+  const video = res.locals.onlyVideo
+
+  if (redirectIfNotOwned(video.url, res)) return
+
+  const chapters = await VideoChapterModel.listChaptersOfVideo(video.id)
+
+  const hasPart: VideoChapterObject[] = []
+
+  if (chapters.length !== 0) {
+    for (let i = 0; i < chapters.length - 1; i++) {
+      hasPart.push(chapters[i].toActivityPubJSON({ video, nextChapter: chapters[i + 1] }))
+    }
+
+    hasPart.push(chapters[chapters.length - 1].toActivityPubJSON({ video: res.locals.onlyVideo, nextChapter: null }))
+  }
+
+  const chaptersObject: VideoChaptersObject = {
+    id: getLocalVideoChaptersActivityPubUrl(video),
+    hasPart
+  }
+
+  return activityPubResponse(activityPubContextify(chaptersObject, 'Chapters', getContextFilter()), res)
+}
+
 async function videoRedundancyController (req: express.Request, res: express.Response) {
   const videoRedundancy = res.locals.videoRedundancy
 
diff --git a/server/server/controllers/api/videos/chapters.ts b/server/server/controllers/api/videos/chapters.ts
new file mode 100644
index 000000000..f744a2b56
--- /dev/null
+++ b/server/server/controllers/api/videos/chapters.ts
@@ -0,0 +1,51 @@
+import express from 'express'
+import { asyncMiddleware, asyncRetryTransactionMiddleware, authenticate } from '../../../middlewares/index.js'
+import { updateVideoChaptersValidator, videosCustomGetValidator } from '../../../middlewares/validators/index.js'
+import { VideoChapterModel } from '@server/models/video/video-chapter.js'
+import { HttpStatusCode, VideoChapterUpdate } from '@peertube/peertube-models'
+import { sequelizeTypescript } from '@server/initializers/database.js'
+import { retryTransactionWrapper } from '@server/helpers/database-utils.js'
+import { federateVideoIfNeeded } from '@server/lib/activitypub/videos/federate.js'
+import { replaceChapters } from '@server/lib/video-chapters.js'
+
+const videoChaptersRouter = express.Router()
+
+videoChaptersRouter.get('/:id/chapters',
+  asyncMiddleware(videosCustomGetValidator('only-video')),
+  asyncMiddleware(listVideoChapters)
+)
+
+videoChaptersRouter.put('/:videoId/chapters',
+  authenticate,
+  asyncMiddleware(updateVideoChaptersValidator),
+  asyncRetryTransactionMiddleware(replaceVideoChapters)
+)
+
+// ---------------------------------------------------------------------------
+
+export {
+  videoChaptersRouter
+}
+
+// ---------------------------------------------------------------------------
+
+async function listVideoChapters (req: express.Request, res: express.Response) {
+  const chapters = await VideoChapterModel.listChaptersOfVideo(res.locals.onlyVideo.id)
+
+  return res.json({ chapters: chapters.map(c => c.toFormattedJSON()) })
+}
+
+async function replaceVideoChapters (req: express.Request, res: express.Response) {
+  const body = req.body as VideoChapterUpdate
+  const video = res.locals.videoAll
+
+  await retryTransactionWrapper(() => {
+    return sequelizeTypescript.transaction(async t => {
+      await replaceChapters({ video, chapters: body.chapters, transaction: t })
+
+      await federateVideoIfNeeded(video, false, t)
+    })
+  })
+
+  return res.sendStatus(HttpStatusCode.NO_CONTENT_204)
+}
diff --git a/server/server/controllers/api/videos/index.ts b/server/server/controllers/api/videos/index.ts
index f8e3d9cb5..508cbb7c5 100644
--- a/server/server/controllers/api/videos/index.ts
+++ b/server/server/controllers/api/videos/index.ts
@@ -49,6 +49,7 @@ import { transcodingRouter } from './transcoding.js'
 import { updateRouter } from './update.js'
 import { uploadRouter } from './upload.js'
 import { viewRouter } from './view.js'
+import { videoChaptersRouter } from './chapters.js'
 
 const auditLogger = auditLoggerFactory('videos')
 const videosRouter = express.Router()
@@ -73,6 +74,7 @@ videosRouter.use('/', tokenRouter)
 videosRouter.use('/', videoPasswordRouter)
 videosRouter.use('/', storyboardRouter)
 videosRouter.use('/', videoSourceRouter)
+videosRouter.use('/', videoChaptersRouter)
 
 videosRouter.get('/categories',
   openapiOperationDoc({ operationId: 'getCategories' }),
diff --git a/server/server/controllers/api/videos/update.ts b/server/server/controllers/api/videos/update.ts
index 491175d74..5adc5e8e5 100644
--- a/server/server/controllers/api/videos/update.ts
+++ b/server/server/controllers/api/videos/update.ts
@@ -22,6 +22,7 @@ import { autoBlacklistVideoIfNeeded } from '../../../lib/video-blacklist.js'
 import { asyncMiddleware, asyncRetryTransactionMiddleware, authenticate, videosUpdateValidator } from '../../../middlewares/index.js'
 import { ScheduleVideoUpdateModel } from '../../../models/video/schedule-video-update.js'
 import { VideoModel } from '../../../models/video/video.js'
+import { replaceChaptersFromDescriptionIfNeeded } from '@server/lib/video-chapters.js'
 
 const lTags = loggerTagsFactory('api', 'video')
 const auditLogger = auditLoggerFactory('videos')
@@ -67,6 +68,7 @@ async function updateVideo (req: express.Request, res: express.Response) {
       // Refresh video since thumbnails to prevent concurrent updates
       const video = await VideoModel.loadFull(videoFromReq.id, t)
 
+      const oldDescription = video.description
       const oldVideoChannel = video.VideoChannel
 
       const keysToUpdate: (keyof VideoUpdate & FilteredModelAttributes<VideoModel>)[] = [
@@ -127,6 +129,15 @@ async function updateVideo (req: express.Request, res: express.Response) {
       // Schedule an update in the future?
       await updateSchedule(videoInstanceUpdated, videoInfoToUpdate, t)
 
+      if (oldDescription !== video.description) {
+        await replaceChaptersFromDescriptionIfNeeded({
+          newDescription: videoInstanceUpdated.description,
+          transaction: t,
+          video,
+          oldDescription
+        })
+      }
+
       await autoBlacklistVideoIfNeeded({
         video: videoInstanceUpdated,
         user: res.locals.oauth.token.User,
diff --git a/server/server/controllers/api/videos/upload.ts b/server/server/controllers/api/videos/upload.ts
index 47f06e336..3d87deb1b 100644
--- a/server/server/controllers/api/videos/upload.ts
+++ b/server/server/controllers/api/videos/upload.ts
@@ -34,6 +34,8 @@ import {
 } from '../../../middlewares/index.js'
 import { ScheduleVideoUpdateModel } from '../../../models/video/schedule-video-update.js'
 import { VideoModel } from '../../../models/video/video.js'
+import { getChaptersFromContainer } from '@peertube/peertube-ffmpeg'
+import { replaceChapters, replaceChaptersFromDescriptionIfNeeded } from '@server/lib/video-chapters.js'
 
 const lTags = loggerTagsFactory('api', 'video')
 const auditLogger = auditLoggerFactory('videos')
@@ -143,6 +145,9 @@ async function addVideo (options: {
   const videoFile = await buildNewFile({ path: videoPhysicalFile.path, mode: 'web-video' })
   const originalFilename = videoPhysicalFile.originalname
 
+  const containerChapters = await getChaptersFromContainer(videoPhysicalFile.path)
+  logger.debug(`Got ${containerChapters.length} chapters from video "${video.name}" container`, { containerChapters, ...lTags(video.uuid) })
+
   // Move physical file
   const destination = VideoPathManager.Instance.getFSVideoFileOutputPath(video, videoFile)
   await move(videoPhysicalFile.path, destination)
@@ -188,6 +193,10 @@ async function addVideo (options: {
       }, sequelizeOptions)
     }
 
+    if (!await replaceChaptersFromDescriptionIfNeeded({ newDescription: video.description, video, transaction: t })) {
+      await replaceChapters({ video, chapters: containerChapters, transaction: t })
+    }
+
     await autoBlacklistVideoIfNeeded({
       video,
       user,
diff --git a/server/server/helpers/activity-pub-utils.ts b/server/server/helpers/activity-pub-utils.ts
index acc5c304b..cda40fdaa 100644
--- a/server/server/helpers/activity-pub-utils.ts
+++ b/server/server/helpers/activity-pub-utils.ts
@@ -79,6 +79,8 @@ const contextStore: { [ id in ContextType ]: (string | { [ id: string ]: string
 
     uploadDate: 'sc:uploadDate',
 
+    hasParts: 'sc:hasParts',
+
     views: {
       '@type': 'sc:Number',
       '@id': 'pt:views'
@@ -195,7 +197,14 @@ const contextStore: { [ id in ContextType ]: (string | { [ id: string ]: string
   Announce: buildContext(),
   Comment: buildContext(),
   Delete: buildContext(),
-  Rate: buildContext()
+  Rate: buildContext(),
+
+  Chapters: buildContext({
+    name: 'sc:name',
+    hasPart: 'sc:hasPart',
+    endOffset: 'sc:endOffset',
+    startOffset: 'sc:startOffset'
+  })
 }
 
 async function getContextData (type: ContextType, contextFilter: ContextFilter) {
diff --git a/server/server/helpers/custom-validators/activitypub/video-chapters.ts b/server/server/helpers/custom-validators/activitypub/video-chapters.ts
new file mode 100644
index 000000000..38009991b
--- /dev/null
+++ b/server/server/helpers/custom-validators/activitypub/video-chapters.ts
@@ -0,0 +1,15 @@
+import { isArray } from '../misc.js'
+import { isVideoChapterTitleValid, isVideoChapterTimecodeValid } from '../video-chapters.js'
+import { isActivityPubUrlValid } from './misc.js'
+import { VideoChaptersObject } from '@peertube/peertube-models'
+
+export function isVideoChaptersObjectValid (object: VideoChaptersObject) {
+  if (!object) return false
+  if (!isActivityPubUrlValid(object.id)) return false
+
+  if (!isArray(object.hasPart)) return false
+
+  return object.hasPart.every(part => {
+    return isVideoChapterTitleValid(part.name) && isVideoChapterTimecodeValid(part.startOffset)
+  })
+}
diff --git a/server/server/helpers/custom-validators/video-chapters.ts b/server/server/helpers/custom-validators/video-chapters.ts
new file mode 100644
index 000000000..8bdd2d7b8
--- /dev/null
+++ b/server/server/helpers/custom-validators/video-chapters.ts
@@ -0,0 +1,26 @@
+import { isArray } from './misc.js'
+import { VideoChapter, VideoChapterUpdate } from '@peertube/peertube-models'
+import { Unpacked } from '@peertube/peertube-typescript-utils'
+import { CONSTRAINTS_FIELDS } from '@server/initializers/constants.js'
+import validator from 'validator'
+
+export function areVideoChaptersValid (value: VideoChapter[]) {
+  if (!isArray(value)) return false
+  if (!value.every(v => isVideoChapterValid(v))) return false
+
+  const timecodes = value.map(c => c.timecode)
+
+  return new Set(timecodes).size === timecodes.length
+}
+
+export function isVideoChapterValid (value: Unpacked<VideoChapterUpdate['chapters']>) {
+  return isVideoChapterTimecodeValid(value.timecode) && isVideoChapterTitleValid(value.title)
+}
+
+export function isVideoChapterTitleValid (value: any) {
+  return validator.default.isLength(value + '', CONSTRAINTS_FIELDS.VIDEO_CHAPTERS.TITLE)
+}
+
+export function isVideoChapterTimecodeValid (value: any) {
+  return validator.default.isInt(value + '', { min: 0 })
+}
diff --git a/server/server/helpers/youtube-dl/youtube-dl-info-builder.ts b/server/server/helpers/youtube-dl/youtube-dl-info-builder.ts
index 0287f6183..66993d2ee 100644
--- a/server/server/helpers/youtube-dl/youtube-dl-info-builder.ts
+++ b/server/server/helpers/youtube-dl/youtube-dl-info-builder.ts
@@ -1,6 +1,7 @@
 import { CONSTRAINTS_FIELDS, VIDEO_CATEGORIES, VIDEO_LANGUAGES, VIDEO_LICENCES } from '../../initializers/constants.js'
 import { peertubeTruncate } from '../core-utils.js'
 import { isUrlValid } from '../custom-validators/activitypub/misc.js'
+import { isArray } from '../custom-validators/misc.js'
 
 export type YoutubeDLInfo = {
   name?: string
@@ -16,6 +17,11 @@ export type YoutubeDLInfo = {
   webpageUrl?: string
 
   urls?: string[]
+
+  chapters?: {
+    timecode: number
+    title: string
+  }[]
 }
 
 export class YoutubeDLInfoBuilder {
@@ -83,7 +89,10 @@ export class YoutubeDLInfoBuilder {
       urls: this.buildAvailableUrl(obj),
       originallyPublishedAtWithoutTime: this.buildOriginallyPublishedAt(obj),
       ext: obj.ext,
-      webpageUrl: obj.webpage_url
+      webpageUrl: obj.webpage_url,
+      chapters: isArray(obj.chapters)
+        ? obj.chapters.map((c: { start_time: number, title: string }) => ({ timecode: c.start_time, title: c.title }))
+        : []
     }
   }
 
diff --git a/server/server/initializers/constants.ts b/server/server/initializers/constants.ts
index 34392dbc8..027b927c2 100644
--- a/server/server/initializers/constants.ts
+++ b/server/server/initializers/constants.ts
@@ -465,6 +465,9 @@ const CONSTRAINTS_FIELDS = {
   },
   VIDEO_PASSWORD: {
     LENGTH: { min: 2, max: 100 }
+  },
+  VIDEO_CHAPTERS: {
+    TITLE: { min: 1, max: 100 } // Length
   }
 }
 
diff --git a/server/server/initializers/database.ts b/server/server/initializers/database.ts
index fe399a633..0294e2d29 100644
--- a/server/server/initializers/database.ts
+++ b/server/server/initializers/database.ts
@@ -59,6 +59,7 @@ import { VideoTagModel } from '../models/video/video-tag.js'
 import { VideoModel } from '../models/video/video.js'
 import { VideoViewModel } from '../models/view/video-view.js'
 import { CONFIG } from './config.js'
+import { VideoChapterModel } from '@server/models/video/video-chapter.js'
 
 pg.defaults.parseInt8 = true // Avoid BIGINT to be converted to string
 
@@ -137,6 +138,7 @@ async function initDatabaseModels (silent: boolean) {
     VideoShareModel,
     VideoFileModel,
     VideoSourceModel,
+    VideoChapterModel,
     VideoCaptionModel,
     VideoBlacklistModel,
     VideoTagModel,
diff --git a/server/server/lib/activitypub/url.ts b/server/server/lib/activitypub/url.ts
index 73f6f4849..aff104804 100644
--- a/server/server/lib/activitypub/url.ts
+++ b/server/server/lib/activitypub/url.ts
@@ -80,6 +80,10 @@ function getLocalVideoCommentsActivityPubUrl (video: MVideoUrl) {
   return video.url + '/comments'
 }
 
+function getLocalVideoChaptersActivityPubUrl (video: MVideoUrl) {
+  return video.url + '/chapters'
+}
+
 function getLocalVideoLikesActivityPubUrl (video: MVideoUrl) {
   return video.url + '/likes'
 }
@@ -167,6 +171,7 @@ export {
   getDeleteActivityPubUrl,
   getLocalVideoSharesActivityPubUrl,
   getLocalVideoCommentsActivityPubUrl,
+  getLocalVideoChaptersActivityPubUrl,
   getLocalVideoLikesActivityPubUrl,
   getLocalVideoDislikesActivityPubUrl,
   getLocalVideoViewerActivityPubUrl,
diff --git a/server/server/lib/activitypub/videos/shared/abstract-builder.ts b/server/server/lib/activitypub/videos/shared/abstract-builder.ts
index 4397e578f..2c0ad99ac 100644
--- a/server/server/lib/activitypub/videos/shared/abstract-builder.ts
+++ b/server/server/lib/activitypub/videos/shared/abstract-builder.ts
@@ -1,6 +1,12 @@
 import { CreationAttributes, Transaction } from 'sequelize'
-import { ActivityTagObject, ThumbnailType, VideoObject, VideoStreamingPlaylistType_Type } from '@peertube/peertube-models'
-import { deleteAllModels, filterNonExistingModels } from '@server/helpers/database-utils.js'
+import {
+  ActivityTagObject,
+  ThumbnailType,
+  VideoChaptersObject,
+  VideoObject,
+  VideoStreamingPlaylistType_Type
+} from '@peertube/peertube-models'
+import { deleteAllModels, filterNonExistingModels, retryTransactionWrapper } from '@server/helpers/database-utils.js'
 import { logger, LoggerTagsFn } from '@server/helpers/logger.js'
 import { updateRemoteVideoThumbnail } from '@server/lib/thumbnail.js'
 import { setVideoTags } from '@server/lib/video.js'
@@ -29,6 +35,10 @@ import {
   getThumbnailFromIcons
 } from './object-to-model-attributes.js'
 import { getTrackerUrls, setVideoTrackers } from './trackers.js'
+import { fetchAP } from '../../activity.js'
+import { isVideoChaptersObjectValid } from '@server/helpers/custom-validators/activitypub/video-chapters.js'
+import { sequelizeTypescript } from '@server/initializers/database.js'
+import { replaceChapters } from '@server/lib/video-chapters.js'
 
 export abstract class APVideoAbstractBuilder {
   protected abstract videoObject: VideoObject
@@ -44,7 +54,7 @@ export abstract class APVideoAbstractBuilder {
   protected async setThumbnail (video: MVideoThumbnail, t?: Transaction) {
     const miniatureIcon = getThumbnailFromIcons(this.videoObject)
     if (!miniatureIcon) {
-      logger.warn('Cannot find thumbnail in video object', { object: this.videoObject })
+      logger.warn('Cannot find thumbnail in video object', { object: this.videoObject, ...this.lTags() })
       return undefined
     }
 
@@ -138,6 +148,26 @@ export abstract class APVideoAbstractBuilder {
     video.VideoFiles = await Promise.all(upsertTasks)
   }
 
+  protected async updateChaptersOutsideTransaction (video: MVideoFullLight) {
+    if (!this.videoObject.hasParts || typeof this.videoObject.hasParts !== 'string') return
+
+    const { body } = await fetchAP<VideoChaptersObject>(this.videoObject.hasParts)
+    if (!isVideoChaptersObjectValid(body)) {
+      logger.warn('Chapters AP object is not valid, skipping', { body, ...this.lTags() })
+      return
+    }
+
+    logger.debug('Fetched chapters AP object', { body, ...this.lTags() })
+
+    return retryTransactionWrapper(() => {
+      return sequelizeTypescript.transaction(async t => {
+        const chapters = body.hasPart.map(p => ({ title: p.name, timecode: p.startOffset }))
+
+        await replaceChapters({ chapters, transaction: t, video })
+      })
+    })
+  }
+
   protected async setStreamingPlaylists (video: MVideoFullLight, t: Transaction) {
     const streamingPlaylistAttributes = getStreamingPlaylistAttributesFromObject(video, this.videoObject)
     const newStreamingPlaylists = streamingPlaylistAttributes.map(a => new VideoStreamingPlaylistModel(a))
diff --git a/server/server/lib/activitypub/videos/shared/creator.ts b/server/server/lib/activitypub/videos/shared/creator.ts
index 5a3a46282..35e537ccc 100644
--- a/server/server/lib/activitypub/videos/shared/creator.ts
+++ b/server/server/lib/activitypub/videos/shared/creator.ts
@@ -60,6 +60,8 @@ export class APVideoCreator extends APVideoAbstractBuilder {
       return { autoBlacklisted, videoCreated }
     })
 
+    await this.updateChaptersOutsideTransaction(videoCreated)
+
     return { autoBlacklisted, videoCreated }
   }
 }
diff --git a/server/server/lib/activitypub/videos/updater.ts b/server/server/lib/activitypub/videos/updater.ts
index 37bf7411a..f9c5b4040 100644
--- a/server/server/lib/activitypub/videos/updater.ts
+++ b/server/server/lib/activitypub/videos/updater.ts
@@ -77,6 +77,8 @@ export class APVideoUpdater extends APVideoAbstractBuilder {
 
       await runInReadCommittedTransaction(t => this.setCaptions(videoUpdated, t))
 
+      await this.updateChaptersOutsideTransaction(videoUpdated)
+
       await autoBlacklistVideoIfNeeded({
         video: videoUpdated,
         user: undefined,
diff --git a/server/server/lib/internal-event-emitter.ts b/server/server/lib/internal-event-emitter.ts
index 54f192982..db6e674d0 100644
--- a/server/server/lib/internal-event-emitter.ts
+++ b/server/server/lib/internal-event-emitter.ts
@@ -1,4 +1,4 @@
-import { MChannel, MVideo } from '@server/types/models/index.js'
+import { MChannel, MVideo, MVideoImmutable } from '@server/types/models/index.js'
 import { EventEmitter } from 'events'
 
 export interface PeerTubeInternalEvents {
@@ -9,6 +9,8 @@ export interface PeerTubeInternalEvents {
   'channel-created': (options: { channel: MChannel }) => void
   'channel-updated': (options: { channel: MChannel }) => void
   'channel-deleted': (options: { channel: MChannel }) => void
+
+  'chapters-updated': (options: { video: MVideoImmutable }) => void
 }
 
 declare interface InternalEventEmitter {
diff --git a/server/server/lib/job-queue/handlers/video-import.ts b/server/server/lib/job-queue/handlers/video-import.ts
index 7d5435a3b..09d974e90 100644
--- a/server/server/lib/job-queue/handlers/video-import.ts
+++ b/server/server/lib/job-queue/handlers/video-import.ts
@@ -32,6 +32,7 @@ import { MVideoImport, MVideoImportDefault, MVideoImportDefaultFiles, MVideoImpo
 import { getLowercaseExtension } from '@peertube/peertube-node-utils'
 import {
   ffprobePromise,
+  getChaptersFromContainer,
   getVideoStreamDimensionsInfo,
   getVideoStreamDuration,
   getVideoStreamFPS,
@@ -49,6 +50,7 @@ import { federateVideoIfNeeded } from '../../activitypub/videos/index.js'
 import { Notifier } from '../../notifier/index.js'
 import { generateLocalVideoMiniature } from '../../thumbnail.js'
 import { JobQueue } from '../job-queue.js'
+import { replaceChaptersIfNotExist } from '@server/lib/video-chapters.js'
 
 async function processVideoImport (job: Job): Promise<VideoImportPreventExceptionResult> {
   const payload = job.data as VideoImportPayload
@@ -150,6 +152,8 @@ async function processFile (downloader: () => Promise<string>, videoImport: MVid
     const fps = await getVideoStreamFPS(tempVideoPath, probe)
     const duration = await getVideoStreamDuration(tempVideoPath, probe)
 
+    const containerChapters = await getChaptersFromContainer(tempVideoPath, probe)
+
     // Prepare video file object for creation in database
     const fileExt = getLowercaseExtension(tempVideoPath)
     const videoFileData = {
@@ -228,6 +232,8 @@ async function processFile (downloader: () => Promise<string>, videoImport: MVid
           if (thumbnailModel) await video.addAndSaveThumbnail(thumbnailModel, t)
           if (previewModel) await video.addAndSaveThumbnail(previewModel, t)
 
+          await replaceChaptersIfNotExist({ video, chapters: containerChapters, transaction: t })
+
           // Now we can federate the video (reload from database, we need more attributes)
           const videoForFederation = await VideoModel.loadFull(video.uuid, t)
           await federateVideoIfNeeded(videoForFederation, true, t)
diff --git a/server/server/lib/video-chapters.ts b/server/server/lib/video-chapters.ts
new file mode 100644
index 000000000..c2b091356
--- /dev/null
+++ b/server/server/lib/video-chapters.ts
@@ -0,0 +1,99 @@
+import { parseChapters, sortBy } from '@peertube/peertube-core-utils'
+import { VideoChapter } from '@peertube/peertube-models'
+import { logger, loggerTagsFactory } from '@server/helpers/logger.js'
+import { VideoChapterModel } from '@server/models/video/video-chapter.js'
+import { MVideoImmutable } from '@server/types/models/index.js'
+import { Transaction } from 'sequelize'
+import { InternalEventEmitter } from './internal-event-emitter.js'
+
+const lTags = loggerTagsFactory('video', 'chapters')
+
+export async function replaceChapters (options: {
+  video: MVideoImmutable
+  chapters: VideoChapter[]
+  transaction: Transaction
+}) {
+  const { chapters, transaction, video } = options
+
+  await VideoChapterModel.deleteChapters(video.id, transaction)
+
+  await createChapters({ videoId: video.id, chapters, transaction })
+
+  InternalEventEmitter.Instance.emit('chapters-updated', { video })
+}
+
+export async function replaceChaptersIfNotExist (options: {
+  video: MVideoImmutable
+  chapters: VideoChapter[]
+  transaction: Transaction
+}) {
+  const { chapters, transaction, video } = options
+
+  if (await VideoChapterModel.hasVideoChapters(video.id, transaction)) return
+
+  await createChapters({ videoId: video.id, chapters, transaction })
+
+  InternalEventEmitter.Instance.emit('chapters-updated', { video })
+}
+
+export async function replaceChaptersFromDescriptionIfNeeded (options: {
+  oldDescription?: string
+  newDescription: string
+  video: MVideoImmutable
+  transaction: Transaction
+}) {
+  const { transaction, video, newDescription, oldDescription = '' } = options
+
+  const chaptersFromOldDescription = sortBy(parseChapters(oldDescription), 'timecode')
+  const existingChapters = await VideoChapterModel.listChaptersOfVideo(video.id, transaction)
+
+  logger.debug(
+    'Check if we replace chapters from description',
+    { oldDescription, chaptersFromOldDescription, newDescription, existingChapters, ...lTags(video.uuid) }
+  )
+
+  // Then we can update chapters from the new description
+  if (areSameChapters(chaptersFromOldDescription, existingChapters)) {
+    const chaptersFromNewDescription = sortBy(parseChapters(newDescription), 'timecode')
+    if (chaptersFromOldDescription.length === 0 && chaptersFromNewDescription.length === 0) return false
+
+    await replaceChapters({ video, chapters: chaptersFromNewDescription, transaction })
+
+    logger.info('Replaced chapters of video ' + video.uuid, { chaptersFromNewDescription, ...lTags(video.uuid) })
+
+    return true
+  }
+
+  return false
+}
+
+// ---------------------------------------------------------------------------
+// Private
+// ---------------------------------------------------------------------------
+
+async function createChapters (options: {
+  videoId: number
+  chapters: VideoChapter[]
+  transaction: Transaction
+}) {
+  const { chapters, transaction, videoId } = options
+
+  for (const chapter of chapters) {
+    await VideoChapterModel.create({
+      title: chapter.title,
+      timecode: chapter.timecode,
+      videoId
+    }, { transaction })
+  }
+}
+
+function areSameChapters (chapters1: VideoChapter[], chapters2: VideoChapter[]) {
+  if (chapters1.length !== chapters2.length) return false
+
+  for (let i = 0; i < chapters1.length; i++) {
+    if (chapters1[i].timecode !== chapters2[i].timecode) return false
+    if (chapters1[i].title !== chapters2[i].title) return false
+  }
+
+  return true
+}
diff --git a/server/server/lib/video-pre-import.ts b/server/server/lib/video-pre-import.ts
index 0298e121e..447ea341d 100644
--- a/server/server/lib/video-pre-import.ts
+++ b/server/server/lib/video-pre-import.ts
@@ -39,6 +39,7 @@ import {
 } from '@server/types/models/index.js'
 import { getLocalVideoActivityPubUrl } from './activitypub/url.js'
 import { updateLocalVideoMiniatureFromExisting, updateLocalVideoMiniatureFromUrl } from './thumbnail.js'
+import { replaceChapters, replaceChaptersFromDescriptionIfNeeded } from './video-chapters.js'
 
 class YoutubeDlImportError extends Error {
   code: YoutubeDlImportError.CODE
@@ -227,6 +228,29 @@ async function buildYoutubeDLImport (options: {
     videoPasswords: importDataOverride.videoPasswords
   })
 
+  await sequelizeTypescript.transaction(async transaction => {
+    // Priority to explicitely set description
+    if (importDataOverride?.description) {
+      const inserted = await replaceChaptersFromDescriptionIfNeeded({ newDescription: importDataOverride.description, video, transaction })
+      if (inserted) return
+    }
+
+    // Then priority to youtube-dl chapters
+    if (youtubeDLInfo.chapters.length !== 0) {
+      logger.info(
+        `Inserting chapters in video ${video.uuid} from youtube-dl`,
+        { chapters: youtubeDLInfo.chapters, tags: [ 'chapters', video.uuid ] }
+      )
+
+      await replaceChapters({ video, chapters: youtubeDLInfo.chapters, transaction })
+      return
+    }
+
+    if (video.description) {
+      await replaceChaptersFromDescriptionIfNeeded({ newDescription: video.description, video, transaction })
+    }
+  })
+
   // Get video subtitles
   await processYoutubeSubtitles(youtubeDL, targetUrl, video.id)
 
diff --git a/server/server/middlewares/cache/cache.ts b/server/server/middlewares/cache/cache.ts
index 6cf37e322..e615fc353 100644
--- a/server/server/middlewares/cache/cache.ts
+++ b/server/server/middlewares/cache/cache.ts
@@ -1,3 +1,4 @@
+import express from 'express'
 import { HttpStatusCode } from '@peertube/peertube-models'
 import { ApiCache, APICacheOptions } from './shared/index.js'
 
@@ -8,13 +9,13 @@ const defaultOptions: APICacheOptions = {
   ]
 }
 
-function cacheRoute (duration: string) {
+export function cacheRoute (duration: string) {
   const instance = new ApiCache(defaultOptions)
 
   return instance.buildMiddleware(duration)
 }
 
-function cacheRouteFactory (options: APICacheOptions) {
+export function cacheRouteFactory (options: APICacheOptions = {}) {
   const instance = new ApiCache({ ...defaultOptions, ...options })
 
   return { instance, middleware: instance.buildMiddleware.bind(instance) }
@@ -22,17 +23,36 @@ function cacheRouteFactory (options: APICacheOptions) {
 
 // ---------------------------------------------------------------------------
 
-function buildPodcastGroupsCache (options: {
+export function buildPodcastGroupsCache (options: {
   channelId: number
 }) {
   return 'podcast-feed-' + options.channelId
 }
 
-// ---------------------------------------------------------------------------
+export function buildAPVideoChaptersGroupsCache (options: {
+  videoId: number | string
+}) {
+  return 'ap-video-chapters-' + options.videoId
+}
 
-export {
-  cacheRoute,
-  cacheRouteFactory,
+// ---------------------------------------------------------------------------
 
-  buildPodcastGroupsCache
-}
+export const videoFeedsPodcastSetCacheKey = [
+  (req: express.Request, res: express.Response, next: express.NextFunction) => {
+    if (req.query.videoChannelId) {
+      res.locals.apicacheGroups = [ buildPodcastGroupsCache({ channelId: req.query.videoChannelId }) ]
+    }
+
+    return next()
+  }
+]
+
+export const apVideoChaptersSetCacheKey = [
+  (req: express.Request, res: express.Response, next: express.NextFunction) => {
+    if (req.params.id) {
+      res.locals.apicacheGroups = [ buildAPVideoChaptersGroupsCache({ videoId: req.params.id }) ]
+    }
+
+    return next()
+  }
+]
diff --git a/server/server/middlewares/validators/feeds.ts b/server/server/middlewares/validators/feeds.ts
index ec99b6920..895dd35ba 100644
--- a/server/server/middlewares/validators/feeds.ts
+++ b/server/server/middlewares/validators/feeds.ts
@@ -3,7 +3,6 @@ import { param, query } from 'express-validator'
 import { HttpStatusCode } from '@peertube/peertube-models'
 import { isValidRSSFeed } from '../../helpers/custom-validators/feeds.js'
 import { exists, isIdOrUUIDValid, isIdValid, toCompleteUUID } from '../../helpers/custom-validators/misc.js'
-import { buildPodcastGroupsCache } from '../cache/index.js'
 import {
   areValidationErrors,
   checkCanSeeVideo,
@@ -114,15 +113,6 @@ const videoFeedsPodcastValidator = [
   }
 ]
 
-const videoFeedsPodcastSetCacheKey = [
-  (req: express.Request, res: express.Response, next: express.NextFunction) => {
-    if (req.query.videoChannelId) {
-      res.locals.apicacheGroups = [ buildPodcastGroupsCache({ channelId: req.query.videoChannelId }) ]
-    }
-
-    return next()
-  }
-]
 // ---------------------------------------------------------------------------
 
 const videoSubscriptionFeedsValidator = [
@@ -173,6 +163,5 @@ export {
   feedsAccountOrChannelFiltersValidator,
   videoFeedsPodcastValidator,
   videoSubscriptionFeedsValidator,
-  videoFeedsPodcastSetCacheKey,
   videoCommentsFeedsValidator
 }
diff --git a/server/server/middlewares/validators/videos/index.ts b/server/server/middlewares/validators/videos/index.ts
index 05c6659ae..eed4f35d4 100644
--- a/server/server/middlewares/validators/videos/index.ts
+++ b/server/server/middlewares/validators/videos/index.ts
@@ -2,6 +2,7 @@ export * from './video-blacklist.js'
 export * from './video-captions.js'
 export * from './video-channel-sync.js'
 export * from './video-channels.js'
+export * from './video-chapters.js'
 export * from './video-comments.js'
 export * from './video-files.js'
 export * from './video-imports.js'
diff --git a/server/server/middlewares/validators/videos/video-chapters.ts b/server/server/middlewares/validators/videos/video-chapters.ts
new file mode 100644
index 000000000..5097e6380
--- /dev/null
+++ b/server/server/middlewares/validators/videos/video-chapters.ts
@@ -0,0 +1,34 @@
+import express from 'express'
+import { body } from 'express-validator'
+import { HttpStatusCode, UserRight } from '@peertube/peertube-models'
+import {
+  areValidationErrors, checkUserCanManageVideo, doesVideoExist,
+  isValidVideoIdParam
+} from '../shared/index.js'
+import { areVideoChaptersValid } from '@server/helpers/custom-validators/video-chapters.js'
+
+export const updateVideoChaptersValidator = [
+  isValidVideoIdParam('videoId'),
+
+  body('chapters')
+    .custom(areVideoChaptersValid)
+    .withMessage('Chapters must have a valid title and timecode, and each timecode must be unique'),
+
+  async (req: express.Request, res: express.Response, next: express.NextFunction) => {
+    if (areValidationErrors(req, res)) return
+    if (!await doesVideoExist(req.params.videoId, res)) return
+
+    if (res.locals.videoAll.isLive) {
+      return res.fail({
+        status: HttpStatusCode.BAD_REQUEST_400,
+        message: 'You cannot add chapters to a live video'
+      })
+    }
+
+    // Check if the user who did the request is able to update video chapters (same right as updating the video)
+    const user = res.locals.oauth.token.User
+    if (!checkUserCanManageVideo(user, res.locals.videoAll, UserRight.UPDATE_ANY_VIDEO, res)) return
+
+    return next()
+  }
+]
diff --git a/server/server/models/video/formatter/video-activity-pub-format.ts b/server/server/models/video/formatter/video-activity-pub-format.ts
index 759e6dbbc..d19bb1880 100644
--- a/server/server/models/video/formatter/video-activity-pub-format.ts
+++ b/server/server/models/video/formatter/video-activity-pub-format.ts
@@ -13,6 +13,7 @@ import {
 } from '@peertube/peertube-models'
 import { MIMETYPES, WEBSERVER } from '../../../initializers/constants.js'
 import {
+  getLocalVideoChaptersActivityPubUrl,
   getLocalVideoCommentsActivityPubUrl,
   getLocalVideoDislikesActivityPubUrl,
   getLocalVideoLikesActivityPubUrl,
@@ -95,6 +96,7 @@ export function videoModelToActivityPubObject (video: MVideoAP): VideoObject {
     dislikes: getLocalVideoDislikesActivityPubUrl(video),
     shares: getLocalVideoSharesActivityPubUrl(video),
     comments: getLocalVideoCommentsActivityPubUrl(video),
+    hasParts: getLocalVideoChaptersActivityPubUrl(video),
 
     attributedTo: [
       {
diff --git a/server/server/models/video/video-chapter.ts b/server/server/models/video/video-chapter.ts
new file mode 100644
index 000000000..6e59abec9
--- /dev/null
+++ b/server/server/models/video/video-chapter.ts
@@ -0,0 +1,95 @@
+import { AllowNull, BelongsTo, Column, CreatedAt, ForeignKey, Model, Table, UpdatedAt } from 'sequelize-typescript'
+import { MVideo, MVideoChapter } from '@server/types/models/index.js'
+import { VideoChapter, VideoChapterObject } from '@peertube/peertube-models'
+import { AttributesOnly } from '@peertube/peertube-typescript-utils'
+import { VideoModel } from './video.js'
+import { Transaction } from 'sequelize'
+import { getSort } from '../shared/sort.js'
+
+@Table({
+  tableName: 'videoChapter',
+  indexes: [
+    {
+      fields: [ 'videoId', 'timecode' ],
+      unique: true
+    }
+  ]
+})
+export class VideoChapterModel extends Model<Partial<AttributesOnly<VideoChapterModel>>> {
+
+  @AllowNull(false)
+  @Column
+  timecode: number
+
+  @AllowNull(false)
+  @Column
+  title: string
+
+  @ForeignKey(() => VideoModel)
+  @Column
+  videoId: number
+
+  @BelongsTo(() => VideoModel, {
+    foreignKey: {
+      allowNull: false
+    },
+    onDelete: 'CASCADE'
+  })
+  Video: Awaited<VideoModel>
+
+  @CreatedAt
+  createdAt: Date
+
+  @UpdatedAt
+  updatedAt: Date
+
+  static deleteChapters (videoId: number, transaction: Transaction) {
+    const query = {
+      where: {
+        videoId
+      },
+      transaction
+    }
+
+    return VideoChapterModel.destroy(query)
+  }
+
+  static listChaptersOfVideo (videoId: number, transaction?: Transaction) {
+    const query = {
+      where: {
+        videoId
+      },
+      order: getSort('timecode'),
+      transaction
+    }
+
+    return VideoChapterModel.findAll<MVideoChapter>(query)
+  }
+
+  static hasVideoChapters (videoId: number, transaction: Transaction) {
+    return VideoChapterModel.findOne({
+      where: { videoId },
+      transaction
+    }).then(c => !!c)
+  }
+
+  toActivityPubJSON (this: MVideoChapter, options: {
+    video: MVideo
+    nextChapter: MVideoChapter
+  }): VideoChapterObject {
+    return {
+      name: this.title,
+      startOffset: this.timecode,
+      endOffset: options.nextChapter
+        ? options.nextChapter.timecode
+        : options.video.duration
+    }
+  }
+
+  toFormattedJSON (this: MVideoChapter): VideoChapter {
+    return {
+      timecode: this.timecode,
+      title: this.title
+    }
+  }
+}
diff --git a/server/server/types/models/account/account.ts b/server/server/types/models/account/account.ts
index 4a5e80725..a8ff058ed 100644
--- a/server/server/types/models/account/account.ts
+++ b/server/server/types/models/account/account.ts
@@ -14,7 +14,7 @@ import {
   MActorSummaryFormattable,
   MActorUrl
 } from '../actor/index.js'
-import { MChannelDefault } from '../video/video-channels.js'
+import { MChannelDefault } from '../video/video-channel.js'
 import { MAccountBlocklistId } from './account-blocklist.js'
 
 type Use<K extends keyof AccountModel, M> = PickWith<AccountModel, K, M>
diff --git a/server/server/types/models/user/user.ts b/server/server/types/models/user/user.ts
index 4a655c792..3d0bee1aa 100644
--- a/server/server/types/models/user/user.ts
+++ b/server/server/types/models/user/user.ts
@@ -11,7 +11,7 @@ import {
   MAccountIdActorId,
   MAccountUrl
 } from '../account/index.js'
-import { MChannelFormattable } from '../video/video-channels.js'
+import { MChannelFormattable } from '../video/video-channel.js'
 import { MNotificationSetting, MNotificationSettingFormattable } from './user-notification-setting.js'
 
 type Use<K extends keyof UserModel, M> = PickWith<UserModel, K, M>
diff --git a/server/server/types/models/video/index.ts b/server/server/types/models/video/index.ts
index f88198b67..0eeb7aad2 100644
--- a/server/server/types/models/video/index.ts
+++ b/server/server/types/models/video/index.ts
@@ -10,7 +10,8 @@ export * from './video-blacklist.js'
 export * from './video-caption.js'
 export * from './video-change-ownership.js'
 export * from './video-channel-sync.js'
-export * from './video-channels.js'
+export * from './video-channel.js'
+export * from './video-chapter.js'
 export * from './video-comment.js'
 export * from './video-file.js'
 export * from './video-import.js'
diff --git a/server/server/types/models/video/video-channel-sync.ts b/server/server/types/models/video/video-channel-sync.ts
index 2b3a3930f..7e4f9373b 100644
--- a/server/server/types/models/video/video-channel-sync.ts
+++ b/server/server/types/models/video/video-channel-sync.ts
@@ -1,6 +1,6 @@
 import { VideoChannelSyncModel } from '@server/models/video/video-channel-sync.js'
 import { FunctionProperties, PickWith } from '@peertube/peertube-typescript-utils'
-import { MChannelAccountDefault, MChannelFormattable } from './video-channels.js'
+import { MChannelAccountDefault, MChannelFormattable } from './video-channel.js'
 
 type Use<K extends keyof VideoChannelSyncModel, M> = PickWith<VideoChannelSyncModel, K, M>
 
diff --git a/server/server/types/models/video/video-channels.ts b/server/server/types/models/video/video-channel.ts
index e8cb9cb26..e8cb9cb26 100644
--- a/server/server/types/models/video/video-channels.ts
+++ b/server/server/types/models/video/video-channel.ts
diff --git a/server/server/types/models/video/video-chapter.ts b/server/server/types/models/video/video-chapter.ts
new file mode 100644
index 000000000..377cf213a
--- /dev/null
+++ b/server/server/types/models/video/video-chapter.ts
@@ -0,0 +1,3 @@
+import { VideoChapterModel } from '@server/models/video/video-chapter.js'
+
+export type MVideoChapter = Omit<VideoChapterModel, 'Video'>
diff --git a/server/server/types/models/video/video-playlist.ts b/server/server/types/models/video/video-playlist.ts
index 3d99bf4e5..152904d22 100644
--- a/server/server/types/models/video/video-playlist.ts
+++ b/server/server/types/models/video/video-playlist.ts
@@ -3,7 +3,7 @@ import { PickWith } from '@peertube/peertube-typescript-utils'
 import { VideoPlaylistModel } from '../../../models/video/video-playlist.js'
 import { MAccount, MAccountDefault, MAccountSummary, MAccountSummaryFormattable } from '../account/index.js'
 import { MThumbnail } from './thumbnail.js'
-import { MChannelDefault, MChannelSummary, MChannelSummaryFormattable, MChannelUrl } from './video-channels.js'
+import { MChannelDefault, MChannelSummary, MChannelSummaryFormattable, MChannelUrl } from './video-channel.js'
 
 type Use<K extends keyof VideoPlaylistModel, M> = PickWith<VideoPlaylistModel, K, M>
 
diff --git a/server/server/types/models/video/video.ts b/server/server/types/models/video/video.ts
index b7f8652be..f9141681b 100644
--- a/server/server/types/models/video/video.ts
+++ b/server/server/types/models/video/video.ts
@@ -16,7 +16,7 @@ import {
   MChannelFormattable,
   MChannelHostOnly,
   MChannelUserId
-} from './video-channels.js'
+} from './video-channel.js'
 import { MVideoFile, MVideoFileRedundanciesAll, MVideoFileRedundanciesOpt } from './video-file.js'
 import { MVideoLive } from './video-live.js'
 import {