22 files changed, 274 insertions, 45 deletions

diff --git a/server/controllers/api/config.ts b/server/controllers/api/config.ts
index 821ed4ad3..376143cb8 100644
--- a/server/controllers/api/config.ts
+++ b/server/controllers/api/config.ts
@@ -237,6 +237,9 @@ function customConfig (): CustomConfig {
     live: {
       enabled: CONFIG.LIVE.ENABLED,
       allowReplay: CONFIG.LIVE.ALLOW_REPLAY,
+      latencySetting: {
+        enabled: CONFIG.LIVE.LATENCY_SETTING.ENABLED
+      },
       maxDuration: CONFIG.LIVE.MAX_DURATION,
       maxInstanceLives: CONFIG.LIVE.MAX_INSTANCE_LIVES,
       maxUserLives: CONFIG.LIVE.MAX_USER_LIVES,
diff --git a/server/controllers/api/videos/live.ts b/server/controllers/api/videos/live.ts
index 49cabb6f3..c6f038079 100644
--- a/server/controllers/api/videos/live.ts
+++ b/server/controllers/api/videos/live.ts
@@ -1,4 +1,5 @@
 import express from 'express'
+import { exists } from '@server/helpers/custom-validators/misc'
 import { createReqFiles } from '@server/helpers/express-utils'
 import { ASSETS_PATH, MIMETYPES } from '@server/initializers/constants'
 import { getLocalVideoActivityPubUrl } from '@server/lib/activitypub/url'
@@ -9,7 +10,7 @@ import { videoLiveAddValidator, videoLiveGetValidator, videoLiveUpdateValidator
 import { VideoLiveModel } from '@server/models/video/video-live'
 import { MVideoDetails, MVideoFullLight } from '@server/types/models'
 import { buildUUID, uuidToShort } from '@shared/extra-utils'
-import { HttpStatusCode, LiveVideoCreate, LiveVideoUpdate, VideoState } from '@shared/models'
+import { HttpStatusCode, LiveVideoCreate, LiveVideoLatencyMode, LiveVideoUpdate, VideoState } from '@shared/models'
 import { logger } from '../../../helpers/logger'
 import { sequelizeTypescript } from '../../../initializers/database'
 import { updateVideoMiniatureFromExisting } from '../../../lib/thumbnail'
@@ -60,8 +61,9 @@ async function updateLiveVideo (req: express.Request, res: express.Response) {
   const video = res.locals.videoAll
   const videoLive = res.locals.videoLive
 
-  videoLive.saveReplay = body.saveReplay || false
-  videoLive.permanentLive = body.permanentLive || false
+  if (exists(body.saveReplay)) videoLive.saveReplay = body.saveReplay
+  if (exists(body.permanentLive)) videoLive.permanentLive = body.permanentLive
+  if (exists(body.latencyMode)) videoLive.latencyMode = body.latencyMode
 
   video.VideoLive = await videoLive.save()
 
@@ -87,6 +89,7 @@ async function addLiveVideo (req: express.Request, res: express.Response) {
   const videoLive = new VideoLiveModel()
   videoLive.saveReplay = videoInfo.saveReplay || false
   videoLive.permanentLive = videoInfo.permanentLive || false
+  videoLive.latencyMode = videoInfo.latencyMode || LiveVideoLatencyMode.DEFAULT
   videoLive.streamKey = buildUUID()
 
   const [ thumbnailModel, previewModel ] = await buildVideoThumbnailsFromReq({
diff --git a/server/helpers/activitypub.ts b/server/helpers/activitypub.ts
index cbba2f51c..d0bcc6785 100644
--- a/server/helpers/activitypub.ts
+++ b/server/helpers/activitypub.ts
@@ -50,6 +50,10 @@ function getContextData (type: ContextType) {
           '@type': 'sc:Boolean',
           '@id': 'pt:permanentLive'
         },
+        latencyMode: {
+          '@type': 'sc:Number',
+          '@id': 'pt:latencyMode'
+        },
 
         Infohash: 'pt:Infohash',
         Playlist: 'pt:Playlist',
diff --git a/server/helpers/custom-validators/activitypub/videos.ts b/server/helpers/custom-validators/activitypub/videos.ts
index a41d37810..80a321117 100644
--- a/server/helpers/custom-validators/activitypub/videos.ts
+++ b/server/helpers/custom-validators/activitypub/videos.ts
@@ -1,10 +1,11 @@
 import validator from 'validator'
 import { logger } from '@server/helpers/logger'
 import { ActivityTrackerUrlObject, ActivityVideoFileMetadataUrlObject } from '@shared/models'
-import { VideoState } from '../../../../shared/models/videos'
+import { LiveVideoLatencyMode, VideoState } from '../../../../shared/models/videos'
 import { ACTIVITY_PUB, CONSTRAINTS_FIELDS } from '../../../initializers/constants'
 import { peertubeTruncate } from '../../core-utils'
 import { exists, isArray, isBooleanValid, isDateValid, isUUIDValid } from '../misc'
+import { isLiveLatencyModeValid } from '../video-lives'
 import {
   isVideoDurationValid,
   isVideoNameValid,
@@ -65,6 +66,7 @@ function sanitizeAndCheckVideoTorrentObject (video: any) {
   if (!isBooleanValid(video.isLiveBroadcast)) video.isLiveBroadcast = false
   if (!isBooleanValid(video.liveSaveReplay)) video.liveSaveReplay = false
   if (!isBooleanValid(video.permanentLive)) video.permanentLive = false
+  if (!isLiveLatencyModeValid(video.latencyMode)) video.latencyMode = LiveVideoLatencyMode.DEFAULT
 
   return isActivityPubUrlValid(video.id) &&
     isVideoNameValid(video.name) &&
diff --git a/server/helpers/custom-validators/video-lives.ts b/server/helpers/custom-validators/video-lives.ts
new file mode 100644
index 000000000..69d08ae68
--- /dev/null
+++ b/server/helpers/custom-validators/video-lives.ts
@@ -0,0 +1,11 @@
+import { LiveVideoLatencyMode } from '@shared/models'
+
+function isLiveLatencyModeValid (value: any) {
+  return [ LiveVideoLatencyMode.DEFAULT, LiveVideoLatencyMode.SMALL_LATENCY, LiveVideoLatencyMode.HIGH_LATENCY ].includes(value)
+}
+
+// ---------------------------------------------------------------------------
+
+export {
+  isLiveLatencyModeValid
+}
diff --git a/server/helpers/ffmpeg/ffmpeg-live.ts b/server/helpers/ffmpeg/ffmpeg-live.ts
index ff571626c..fd20971eb 100644
--- a/server/helpers/ffmpeg/ffmpeg-live.ts
+++ b/server/helpers/ffmpeg/ffmpeg-live.ts
@@ -1,7 +1,7 @@
 import { FfmpegCommand, FilterSpecification } from 'fluent-ffmpeg'
 import { join } from 'path'
 import { VIDEO_LIVE } from '@server/initializers/constants'
-import { AvailableEncoders } from '@shared/models'
+import { AvailableEncoders, LiveVideoLatencyMode } from '@shared/models'
 import { logger, loggerTagsFactory } from '../logger'
 import { buildStreamSuffix, getFFmpeg, getScaleFilter, StreamType } from './ffmpeg-commons'
 import { getEncoderBuilderResult } from './ffmpeg-encoders'
@@ -15,6 +15,7 @@ async function getLiveTranscodingCommand (options: {
 
   outPath: string
   masterPlaylistName: string
+  latencyMode: LiveVideoLatencyMode
 
   resolutions: number[]
 
@@ -26,7 +27,7 @@ async function getLiveTranscodingCommand (options: {
   availableEncoders: AvailableEncoders
   profile: string
 }) {
-  const { inputUrl, outPath, resolutions, fps, bitrate, availableEncoders, profile, masterPlaylistName, ratio } = options
+  const { inputUrl, outPath, resolutions, fps, bitrate, availableEncoders, profile, masterPlaylistName, ratio, latencyMode } = options
 
   const command = getFFmpeg(inputUrl, 'live')
 
@@ -120,14 +121,21 @@ async function getLiveTranscodingCommand (options: {
 
   command.complexFilter(complexFilter)
 
-  addDefaultLiveHLSParams(command, outPath, masterPlaylistName)
+  addDefaultLiveHLSParams({ command, outPath, masterPlaylistName, latencyMode })
 
   command.outputOption('-var_stream_map', varStreamMap.join(' '))
 
   return command
 }
 
-function getLiveMuxingCommand (inputUrl: string, outPath: string, masterPlaylistName: string) {
+function getLiveMuxingCommand (options: {
+  inputUrl: string
+  outPath: string
+  masterPlaylistName: string
+  latencyMode: LiveVideoLatencyMode
+}) {
+  const { inputUrl, outPath, masterPlaylistName, latencyMode } = options
+
   const command = getFFmpeg(inputUrl, 'live')
 
   command.outputOption('-c:v copy')
@@ -135,22 +143,39 @@ function getLiveMuxingCommand (inputUrl: string, outPath: string, masterPlaylist
   command.outputOption('-map 0:a?')
   command.outputOption('-map 0:v?')
 
-  addDefaultLiveHLSParams(command, outPath, masterPlaylistName)
+  addDefaultLiveHLSParams({ command, outPath, masterPlaylistName, latencyMode })
 
   return command
 }
 
+function getLiveSegmentTime (latencyMode: LiveVideoLatencyMode) {
+  if (latencyMode === LiveVideoLatencyMode.SMALL_LATENCY) {
+    return VIDEO_LIVE.SEGMENT_TIME_SECONDS.SMALL_LATENCY
+  }
+
+  return VIDEO_LIVE.SEGMENT_TIME_SECONDS.DEFAULT_LATENCY
+}
+
 // ---------------------------------------------------------------------------
 
 export {
+  getLiveSegmentTime,
+
   getLiveTranscodingCommand,
   getLiveMuxingCommand
 }
 
 // ---------------------------------------------------------------------------
 
-function addDefaultLiveHLSParams (command: FfmpegCommand, outPath: string, masterPlaylistName: string) {
-  command.outputOption('-hls_time ' + VIDEO_LIVE.SEGMENT_TIME_SECONDS)
+function addDefaultLiveHLSParams (options: {
+  command: FfmpegCommand
+  outPath: string
+  masterPlaylistName: string
+  latencyMode: LiveVideoLatencyMode
+}) {
+  const { command, outPath, masterPlaylistName, latencyMode } = options
+
+  command.outputOption('-hls_time ' + getLiveSegmentTime(latencyMode))
   command.outputOption('-hls_list_size ' + VIDEO_LIVE.SEGMENTS_LIST_SIZE)
   command.outputOption('-hls_flags delete_segments+independent_segments')
   command.outputOption(`-hls_segment_filename ${join(outPath, '%v-%06d.ts')}`)
diff --git a/server/initializers/checker-before-init.ts b/server/initializers/checker-before-init.ts
index 10dd98f43..fa311f708 100644
--- a/server/initializers/checker-before-init.ts
+++ b/server/initializers/checker-before-init.ts
@@ -49,8 +49,8 @@ function checkMissedConfig () {
     'peertube.check_latest_version.enabled', 'peertube.check_latest_version.url',
     'search.remote_uri.users', 'search.remote_uri.anonymous', 'search.search_index.enabled', 'search.search_index.url',
     'search.search_index.disable_local_search', 'search.search_index.is_default_search',
-    'live.enabled', 'live.allow_replay', 'live.max_duration', 'live.max_user_lives', 'live.max_instance_lives',
-    'live.rtmp.enabled', 'live.rtmp.port', 'live.rtmp.hostname',
+    'live.enabled', 'live.allow_replay', 'live.latency_setting.enabled', 'live.max_duration',
+    'live.max_user_lives', 'live.max_instance_lives', 'live.rtmp.enabled', 'live.rtmp.port', 'live.rtmp.hostname',
     'live.rtmps.enabled', 'live.rtmps.port', 'live.rtmps.hostname', 'live.rtmps.key_file', 'live.rtmps.cert_file',
     'live.transcoding.enabled', 'live.transcoding.threads', 'live.transcoding.profile',
     'live.transcoding.resolutions.144p', 'live.transcoding.resolutions.240p', 'live.transcoding.resolutions.360p',
diff --git a/server/initializers/config.ts b/server/initializers/config.ts
index 7a13a1368..6dcca9b67 100644
--- a/server/initializers/config.ts
+++ b/server/initializers/config.ts
@@ -4,9 +4,9 @@ import { dirname, join } from 'path'
 import { decacheModule } from '@server/helpers/decache'
 import { VideoRedundancyConfigFilter } from '@shared/models/redundancy/video-redundancy-config-filter.type'
 import { BroadcastMessageLevel } from '@shared/models/server'
+import { buildPath, root } from '../../shared/core-utils'
 import { VideoPrivacy, VideosRedundancyStrategy } from '../../shared/models'
 import { NSFWPolicyType } from '../../shared/models/videos/nsfw-policy.type'
-import { buildPath, root } from '../../shared/core-utils'
 import { parseBytes, parseDurationToMs } from '../helpers/core-utils'
 
 // Use a variable to reload the configuration if we need
@@ -296,6 +296,10 @@ const CONFIG = {
 
     get ALLOW_REPLAY () { return config.get<boolean>('live.allow_replay') },
 
+    LATENCY_SETTING: {
+      get ENABLED () { return config.get<boolean>('live.latency_setting.enabled') }
+    },
+
     RTMP: {
       get ENABLED () { return config.get<boolean>('live.rtmp.enabled') },
       get PORT () { return config.get<number>('live.rtmp.port') },
diff --git a/server/initializers/constants.ts b/server/initializers/constants.ts
index 7bc2877aa..1c849b561 100644
--- a/server/initializers/constants.ts
+++ b/server/initializers/constants.ts
@@ -24,7 +24,7 @@ import { CONFIG, registerConfigChangedHandler } from './config'
 
 // ---------------------------------------------------------------------------
 
-const LAST_MIGRATION_VERSION = 685
+const LAST_MIGRATION_VERSION = 690
 
 // ---------------------------------------------------------------------------
 
@@ -700,7 +700,10 @@ const RESUMABLE_UPLOAD_SESSION_LIFETIME = SCHEDULER_INTERVALS_MS.REMOVE_DANGLING
 const VIDEO_LIVE = {
   EXTENSION: '.ts',
   CLEANUP_DELAY: 1000 * 60 * 5, // 5 minutes
-  SEGMENT_TIME_SECONDS: 4, // 4 seconds
+  SEGMENT_TIME_SECONDS: {
+    DEFAULT_LATENCY: 4, // 4 seconds
+    SMALL_LATENCY: 2 // 2 seconds
+  },
   SEGMENTS_LIST_SIZE: 15, // 15 maximum segments in live playlist
   REPLAY_DIRECTORY: 'replay',
   EDGE_LIVE_DELAY_SEGMENTS_NOTIFICATION: 4,
@@ -842,7 +845,8 @@ if (isTestInstance() === true) {
   PLUGIN_EXTERNAL_AUTH_TOKEN_LIFETIME = 5000
 
   VIDEO_LIVE.CLEANUP_DELAY = 5000
-  VIDEO_LIVE.SEGMENT_TIME_SECONDS = 2
+  VIDEO_LIVE.SEGMENT_TIME_SECONDS.DEFAULT_LATENCY = 2
+  VIDEO_LIVE.SEGMENT_TIME_SECONDS.SMALL_LATENCY = 1
   VIDEO_LIVE.EDGE_LIVE_DELAY_SEGMENTS_NOTIFICATION = 1
 }
 
diff --git a/server/initializers/migrations/0690-live-latency-mode.ts b/server/initializers/migrations/0690-live-latency-mode.ts
new file mode 100644
index 000000000..c31a61364
--- /dev/null
+++ b/server/initializers/migrations/0690-live-latency-mode.ts
@@ -0,0 +1,35 @@
+import { LiveVideoLatencyMode } from '@shared/models'
+import * as Sequelize from 'sequelize'
+
+async function up (utils: {
+  transaction: Sequelize.Transaction
+  queryInterface: Sequelize.QueryInterface
+  sequelize: Sequelize.Sequelize
+  db: any
+}): Promise<void> {
+  await utils.queryInterface.addColumn('videoLive', 'latencyMode', {
+    type: Sequelize.INTEGER,
+    defaultValue: null,
+    allowNull: true
+  }, { transaction: utils.transaction })
+
+  {
+    const query = `UPDATE "videoLive" SET "latencyMode" = ${LiveVideoLatencyMode.DEFAULT}`
+    await utils.sequelize.query(query, { type: Sequelize.QueryTypes.UPDATE, transaction: utils.transaction })
+  }
+
+  await utils.queryInterface.changeColumn('videoLive', 'latencyMode', {
+    type: Sequelize.INTEGER,
+    defaultValue: null,
+    allowNull: false
+  }, { transaction: utils.transaction })
+}
+
+function down () {
+  throw new Error('Not implemented.')
+}
+
+export {
+  up,
+  down
+}
diff --git a/server/lib/activitypub/videos/shared/object-to-model-attributes.ts b/server/lib/activitypub/videos/shared/object-to-model-attributes.ts
index 1e1479869..c97217669 100644
--- a/server/lib/activitypub/videos/shared/object-to-model-attributes.ts
+++ b/server/lib/activitypub/videos/shared/object-to-model-attributes.ts
@@ -151,6 +151,7 @@ function getLiveAttributesFromObject (video: MVideoId, videoObject: VideoObject)
   return {
     saveReplay: videoObject.liveSaveReplay,
     permanentLive: videoObject.permanentLive,
+    latencyMode: videoObject.latencyMode,
     videoId: video.id
   }
 }
diff --git a/server/lib/live/live-manager.ts b/server/lib/live/live-manager.ts
index 21c34a9a4..920d3a5ec 100644
--- a/server/lib/live/live-manager.ts
+++ b/server/lib/live/live-manager.ts
@@ -5,9 +5,10 @@ import { createServer as createServerTLS, Server as ServerTLS } from 'tls'
 import {
   computeLowerResolutionsToTranscode,
   ffprobePromise,
+  getLiveSegmentTime,
   getVideoStreamBitrate,
-  getVideoStreamFPS,
-  getVideoStreamDimensionsInfo
+  getVideoStreamDimensionsInfo,
+  getVideoStreamFPS
 } from '@server/helpers/ffmpeg'
 import { logger, loggerTagsFactory } from '@server/helpers/logger'
 import { CONFIG, registerConfigChangedHandler } from '@server/initializers/config'
@@ -353,7 +354,7 @@ class LiveManager {
           .catch(err => logger.error('Cannot federate live video %s.', video.url, { err, ...localLTags }))
 
         PeerTubeSocket.Instance.sendVideoLiveNewState(video)
-      }, VIDEO_LIVE.SEGMENT_TIME_SECONDS * 1000 * VIDEO_LIVE.EDGE_LIVE_DELAY_SEGMENTS_NOTIFICATION)
+      }, getLiveSegmentTime(live.latencyMode) * 1000 * VIDEO_LIVE.EDGE_LIVE_DELAY_SEGMENTS_NOTIFICATION)
     } catch (err) {
       logger.error('Cannot save/federate live video %d.', videoId, { err, ...localLTags })
     }
diff --git a/server/lib/live/shared/muxing-session.ts b/server/lib/live/shared/muxing-session.ts
index f5f473039..a703f5b5f 100644
--- a/server/lib/live/shared/muxing-session.ts
+++ b/server/lib/live/shared/muxing-session.ts
@@ -125,6 +125,8 @@ class MuxingSession extends EventEmitter {
         outPath,
         masterPlaylistName: this.streamingPlaylist.playlistFilename,
 
+        latencyMode: this.videoLive.latencyMode,
+
         resolutions: this.allResolutions,
         fps: this.fps,
         bitrate: this.bitrate,
@@ -133,7 +135,12 @@ class MuxingSession extends EventEmitter {
         availableEncoders: VideoTranscodingProfilesManager.Instance.getAvailableEncoders(),
         profile: CONFIG.LIVE.TRANSCODING.PROFILE
       })
-      : getLiveMuxingCommand(this.inputUrl, outPath, this.streamingPlaylist.playlistFilename)
+      : getLiveMuxingCommand({
+        inputUrl: this.inputUrl,
+        outPath,
+        masterPlaylistName: this.streamingPlaylist.playlistFilename,
+        latencyMode: this.videoLive.latencyMode
+      })
 
     logger.info('Running live muxing/transcoding for %s.', this.videoUUID, this.lTags())
 
diff --git a/server/lib/server-config-manager.ts b/server/lib/server-config-manager.ts
index 43ca2332b..744186cfc 100644
--- a/server/lib/server-config-manager.ts
+++ b/server/lib/server-config-manager.ts
@@ -137,6 +137,10 @@ class ServerConfigManager {
         enabled: CONFIG.LIVE.ENABLED,
 
         allowReplay: CONFIG.LIVE.ALLOW_REPLAY,
+        latencySetting: {
+          enabled: CONFIG.LIVE.LATENCY_SETTING.ENABLED
+        },
+
         maxDuration: CONFIG.LIVE.MAX_DURATION,
         maxInstanceLives: CONFIG.LIVE.MAX_INSTANCE_LIVES,
         maxUserLives: CONFIG.LIVE.MAX_USER_LIVES,
diff --git a/server/middlewares/validators/videos/video-live.ts b/server/middlewares/validators/videos/video-live.ts
index 6c7601e05..8e52c953f 100644
--- a/server/middlewares/validators/videos/video-live.ts
+++ b/server/middlewares/validators/videos/video-live.ts
@@ -1,12 +1,21 @@
 import express from 'express'
 import { body } from 'express-validator'
+import { isLiveLatencyModeValid } from '@server/helpers/custom-validators/video-lives'
 import { CONSTRAINTS_FIELDS } from '@server/initializers/constants'
 import { isLocalLiveVideoAccepted } from '@server/lib/moderation'
 import { Hooks } from '@server/lib/plugins/hooks'
 import { VideoModel } from '@server/models/video/video'
 import { VideoLiveModel } from '@server/models/video/video-live'
-import { HttpStatusCode, ServerErrorCode, UserRight, VideoState } from '@shared/models'
-import { isBooleanValid, isIdValid, toBooleanOrNull, toIntOrNull } from '../../../helpers/custom-validators/misc'
+import {
+  HttpStatusCode,
+  LiveVideoCreate,
+  LiveVideoLatencyMode,
+  LiveVideoUpdate,
+  ServerErrorCode,
+  UserRight,
+  VideoState
+} from '@shared/models'
+import { exists, isBooleanValid, isIdValid, toBooleanOrNull, toIntOrNull } from '../../../helpers/custom-validators/misc'
 import { isVideoNameValid } from '../../../helpers/custom-validators/videos'
 import { cleanUpReqFiles } from '../../../helpers/express-utils'
 import { logger } from '../../../helpers/logger'
@@ -67,6 +76,12 @@ const videoLiveAddValidator = getCommonVideoEditAttributes().concat([
     .customSanitizer(toBooleanOrNull)
     .custom(isBooleanValid).withMessage('Should have a valid permanentLive attribute'),
 
+  body('latencyMode')
+    .optional()
+    .customSanitizer(toIntOrNull)
+    .custom(isLiveLatencyModeValid)
+    .withMessage('Should have a valid latency mode attribute'),
+
   async (req: express.Request, res: express.Response, next: express.NextFunction) => {
     logger.debug('Checking videoLiveAddValidator parameters', { parameters: req.body })
 
@@ -82,7 +97,9 @@ const videoLiveAddValidator = getCommonVideoEditAttributes().concat([
       })
     }
 
-    if (CONFIG.LIVE.ALLOW_REPLAY !== true && req.body.saveReplay === true) {
+    const body: LiveVideoCreate = req.body
+
+    if (hasValidSaveReplay(body) !== true) {
       cleanUpReqFiles(req)
 
       return res.fail({
@@ -92,14 +109,23 @@ const videoLiveAddValidator = getCommonVideoEditAttributes().concat([
       })
     }
 
-    if (req.body.permanentLive && req.body.saveReplay) {
+    if (hasValidLatencyMode(body) !== true) {
+      cleanUpReqFiles(req)
+
+      return res.fail({
+        status: HttpStatusCode.FORBIDDEN_403,
+        message: 'Custom latency mode is not allowed by this instance'
+      })
+    }
+
+    if (body.permanentLive && body.saveReplay) {
       cleanUpReqFiles(req)
 
       return res.fail({ message: 'Cannot set this live as permanent while saving its replay' })
     }
 
     const user = res.locals.oauth.token.User
-    if (!await doesVideoChannelOfAccountExist(req.body.channelId, user, res)) return cleanUpReqFiles(req)
+    if (!await doesVideoChannelOfAccountExist(body.channelId, user, res)) return cleanUpReqFiles(req)
 
     if (CONFIG.LIVE.MAX_INSTANCE_LIVES !== -1) {
       const totalInstanceLives = await VideoModel.countLocalLives()
@@ -141,19 +167,34 @@ const videoLiveUpdateValidator = [
     .customSanitizer(toBooleanOrNull)
     .custom(isBooleanValid).withMessage('Should have a valid saveReplay attribute'),
 
+  body('latencyMode')
+    .optional()
+    .customSanitizer(toIntOrNull)
+    .custom(isLiveLatencyModeValid)
+    .withMessage('Should have a valid latency mode attribute'),
+
   (req: express.Request, res: express.Response, next: express.NextFunction) => {
     logger.debug('Checking videoLiveUpdateValidator parameters', { parameters: req.body })
 
     if (areValidationErrors(req, res)) return
 
-    if (req.body.permanentLive && req.body.saveReplay) {
+    const body: LiveVideoUpdate = req.body
+
+    if (body.permanentLive && body.saveReplay) {
       return res.fail({ message: 'Cannot set this live as permanent while saving its replay' })
     }
 
-    if (CONFIG.LIVE.ALLOW_REPLAY !== true && req.body.saveReplay === true) {
+    if (hasValidSaveReplay(body) !== true) {
       return res.fail({
         status: HttpStatusCode.FORBIDDEN_403,
-        message: 'Saving live replay is not allowed instance'
+        message: 'Saving live replay is not allowed by this instance'
+      })
+    }
+
+    if (hasValidLatencyMode(body) !== true) {
+      return res.fail({
+        status: HttpStatusCode.FORBIDDEN_403,
+        message: 'Custom latency mode is not allowed by this instance'
       })
     }
 
@@ -203,3 +244,19 @@ async function isLiveVideoAccepted (req: express.Request, res: express.Response)
 
   return true
 }
+
+function hasValidSaveReplay (body: LiveVideoUpdate | LiveVideoCreate) {
+  if (CONFIG.LIVE.ALLOW_REPLAY !== true && body.saveReplay === true) return false
+
+  return true
+}
+
+function hasValidLatencyMode (body: LiveVideoUpdate | LiveVideoCreate) {
+  if (
+    CONFIG.LIVE.LATENCY_SETTING.ENABLED !== true &&
+    exists(body.latencyMode) &&
+    body.latencyMode !== LiveVideoLatencyMode.DEFAULT
+  ) return false
+
+  return true
+}
diff --git a/server/models/video/formatter/video-format-utils.ts b/server/models/video/formatter/video-format-utils.ts
index 7456f37c5..611edf0b9 100644
--- a/server/models/video/formatter/video-format-utils.ts
+++ b/server/models/video/formatter/video-format-utils.ts
@@ -411,15 +411,6 @@ function videoModelToActivityPubObject (video: MVideoAP): VideoObject {
     views: video.views,
     sensitive: video.nsfw,
     waitTranscoding: video.waitTranscoding,
-    isLiveBroadcast: video.isLive,
-
-    liveSaveReplay: video.isLive
-      ? video.VideoLive.saveReplay
-      : null,
-
-    permanentLive: video.isLive
-      ? video.VideoLive.permanentLive
-      : null,
 
     state: video.state,
     commentsEnabled: video.commentsEnabled,
@@ -431,10 +422,13 @@ function videoModelToActivityPubObject (video: MVideoAP): VideoObject {
       : null,
 
     updated: video.updatedAt.toISOString(),
+
     mediaType: 'text/markdown',
     content: video.description,
     support: video.support,
+
     subtitleLanguage,
+
     icon: icons.map(i => ({
       type: 'Image',
       url: i.getFileUrl(video),
@@ -442,11 +436,14 @@ function videoModelToActivityPubObject (video: MVideoAP): VideoObject {
       width: i.width,
       height: i.height
     })),
+
     url,
+
     likes: getLocalVideoLikesActivityPubUrl(video),
     dislikes: getLocalVideoDislikesActivityPubUrl(video),
     shares: getLocalVideoSharesActivityPubUrl(video),
     comments: getLocalVideoCommentsActivityPubUrl(video),
+
     attributedTo: [
       {
         type: 'Person',
@@ -456,7 +453,9 @@ function videoModelToActivityPubObject (video: MVideoAP): VideoObject {
         type: 'Group',
         id: video.VideoChannel.Actor.url
       }
-    ]
+    ],
+
+    ...buildLiveAPAttributes(video)
   }
 }
 
@@ -500,3 +499,23 @@ export {
   getPrivacyLabel,
   getStateLabel
 }
+
+// ---------------------------------------------------------------------------
+
+function buildLiveAPAttributes (video: MVideoAP) {
+  if (!video.isLive) {
+    return {
+      isLiveBroadcast: false,
+      liveSaveReplay: null,
+      permanentLive: null,
+      latencyMode: null
+    }
+  }
+
+  return {
+    isLiveBroadcast: true,
+    liveSaveReplay: video.VideoLive.saveReplay,
+    permanentLive: video.VideoLive.permanentLive,
+    latencyMode: video.VideoLive.latencyMode
+  }
+}
diff --git a/server/models/video/sql/video/shared/video-table-attributes.ts b/server/models/video/sql/video/shared/video-table-attributes.ts
index f4d9e99fd..e2c1c0f6d 100644
--- a/server/models/video/sql/video/shared/video-table-attributes.ts
+++ b/server/models/video/sql/video/shared/video-table-attributes.ts
@@ -158,6 +158,7 @@ export class VideoTableAttributes {
       'streamKey',
       'saveReplay',
       'permanentLive',
+      'latencyMode',
       'videoId',
       'createdAt',
       'updatedAt'
diff --git a/server/models/video/video-live.ts b/server/models/video/video-live.ts
index e3fdcc0ba..904f712b4 100644
--- a/server/models/video/video-live.ts
+++ b/server/models/video/video-live.ts
@@ -1,11 +1,11 @@
 import { AllowNull, BelongsTo, Column, CreatedAt, DataType, DefaultScope, ForeignKey, Model, Table, UpdatedAt } from 'sequelize-typescript'
+import { CONFIG } from '@server/initializers/config'
 import { WEBSERVER } from '@server/initializers/constants'
 import { MVideoLive, MVideoLiveVideo } from '@server/types/models'
+import { LiveVideo, LiveVideoLatencyMode, VideoState } from '@shared/models'
 import { AttributesOnly } from '@shared/typescript-utils'
-import { LiveVideo, VideoState } from '@shared/models'
 import { VideoModel } from './video'
 import { VideoBlacklistModel } from './video-blacklist'
-import { CONFIG } from '@server/initializers/config'
 
 @DefaultScope(() => ({
   include: [
@@ -44,6 +44,10 @@ export class VideoLiveModel extends Model<Partial<AttributesOnly<VideoLiveModel>
   @Column
   permanentLive: boolean
 
+  @AllowNull(false)
+  @Column
+  latencyMode: LiveVideoLatencyMode
+
   @CreatedAt
   createdAt: Date
 
@@ -113,7 +117,8 @@ export class VideoLiveModel extends Model<Partial<AttributesOnly<VideoLiveModel>
 
       streamKey: this.streamKey,
       permanentLive: this.permanentLive,
-      saveReplay: this.saveReplay
+      saveReplay: this.saveReplay,
+      latencyMode: this.latencyMode
     }
   }
 }
diff --git a/server/tests/api/check-params/config.ts b/server/tests/api/check-params/config.ts
index ce067a892..900f642c2 100644
--- a/server/tests/api/check-params/config.ts
+++ b/server/tests/api/check-params/config.ts
@@ -125,6 +125,9 @@ describe('Test config API validators', function () {
       enabled: true,
 
       allowReplay: false,
+      latencySetting: {
+        enabled: false
+      },
       maxDuration: 30,
       maxInstanceLives: -1,
       maxUserLives: 50,
diff --git a/server/tests/api/check-params/live.ts b/server/tests/api/check-params/live.ts
index 8aee6164c..b253f5e20 100644
--- a/server/tests/api/check-params/live.ts
+++ b/server/tests/api/check-params/live.ts
@@ -3,7 +3,7 @@
 import 'mocha'
 import { omit } from 'lodash'
 import { buildAbsoluteFixturePath } from '@shared/core-utils'
-import { HttpStatusCode, VideoCreateResult, VideoPrivacy } from '@shared/models'
+import { HttpStatusCode, LiveVideoLatencyMode, VideoCreateResult, VideoPrivacy } from '@shared/models'
 import {
   cleanupTests,
   createSingleServer,
@@ -38,6 +38,9 @@ describe('Test video lives API validator', function () {
       newConfig: {
         live: {
           enabled: true,
+          latencySetting: {
+            enabled: false
+          },
           maxInstanceLives: 20,
           maxUserLives: 20,
           allowReplay: true
@@ -81,7 +84,8 @@ describe('Test video lives API validator', function () {
         privacy: VideoPrivacy.PUBLIC,
         channelId,
         saveReplay: false,
-        permanentLive: false
+        permanentLive: false,
+        latencyMode: LiveVideoLatencyMode.DEFAULT
       }
     })
 
@@ -214,6 +218,18 @@ describe('Test video lives API validator', function () {
       await makePostBodyRequest({ url: server.url, path, token: server.accessToken, fields })
     })
 
+    it('Should fail with bad latency setting', async function () {
+      const fields = { ...baseCorrectParams, latencyMode: 42 }
+
+      await makePostBodyRequest({ url: server.url, path, token: server.accessToken, fields })
+    })
+
+    it('Should fail to set latency if the server does not allow it', async function () {
+      const fields = { ...baseCorrectParams, latencyMode: LiveVideoLatencyMode.HIGH_LATENCY }
+
+      await makePostBodyRequest({ url: server.url, path, token: server.accessToken, fields, expectedStatus: HttpStatusCode.FORBIDDEN_403 })
+    })
+
     it('Should succeed with the correct parameters', async function () {
       this.timeout(30000)
 
@@ -393,6 +409,18 @@ describe('Test video lives API validator', function () {
       await command.update({ videoId: video.id, fields, expectedStatus: HttpStatusCode.BAD_REQUEST_400 })
     })
 
+    it('Should fail with bad latency setting', async function () {
+      const fields = { latencyMode: 42 }
+
+      await command.update({ videoId: video.id, fields, expectedStatus: HttpStatusCode.BAD_REQUEST_400 })
+    })
+
+    it('Should fail to set latency if the server does not allow it', async function () {
+      const fields = { latencyMode: LiveVideoLatencyMode.HIGH_LATENCY }
+
+      await command.update({ videoId: video.id, fields, expectedStatus: HttpStatusCode.FORBIDDEN_403 })
+    })
+
     it('Should succeed with the correct params', async function () {
       await command.update({ videoId: video.id, fields: { saveReplay: false } })
       await command.update({ videoId: video.uuid, fields: { saveReplay: false } })
diff --git a/server/tests/api/live/live.ts b/server/tests/api/live/live.ts
index d756a02c1..aeb039696 100644
--- a/server/tests/api/live/live.ts
+++ b/server/tests/api/live/live.ts
@@ -10,6 +10,7 @@ import {
   HttpStatusCode,
   LiveVideo,
   LiveVideoCreate,
+  LiveVideoLatencyMode,
   VideoDetails,
   VideoPrivacy,
   VideoState,
@@ -52,6 +53,9 @@ describe('Test live', function () {
         live: {
           enabled: true,
           allowReplay: true,
+          latencySetting: {
+            enabled: true
+          },
           transcoding: {
             enabled: false
           }
@@ -85,6 +89,7 @@ describe('Test live', function () {
         commentsEnabled: false,
         downloadEnabled: false,
         saveReplay: true,
+        latencyMode: LiveVideoLatencyMode.SMALL_LATENCY,
         privacy: VideoPrivacy.PUBLIC,
         previewfile: 'video_short1-preview.webm.jpg',
         thumbnailfile: 'video_short1.webm.jpg'
@@ -131,6 +136,7 @@ describe('Test live', function () {
         }
 
         expect(live.saveReplay).to.be.true
+        expect(live.latencyMode).to.equal(LiveVideoLatencyMode.SMALL_LATENCY)
       }
     })
 
@@ -175,7 +181,7 @@ describe('Test live', function () {
     it('Should update the live', async function () {
       this.timeout(10000)
 
-      await commands[0].update({ videoId: liveVideoUUID, fields: { saveReplay: false } })
+      await commands[0].update({ videoId: liveVideoUUID, fields: { saveReplay: false, latencyMode: LiveVideoLatencyMode.DEFAULT } })
       await waitJobs(servers)
     })
 
@@ -192,6 +198,7 @@ describe('Test live', function () {
         }
 
         expect(live.saveReplay).to.be.false
+        expect(live.latencyMode).to.equal(LiveVideoLatencyMode.DEFAULT)
       }
     })
 
diff --git a/server/tests/api/server/config.ts b/server/tests/api/server/config.ts
index 565b2953a..5028b65e6 100644
--- a/server/tests/api/server/config.ts
+++ b/server/tests/api/server/config.ts
@@ -82,6 +82,7 @@ function checkInitialConfig (server: PeerTubeServer, data: CustomConfig) {
 
   expect(data.live.enabled).to.be.false
   expect(data.live.allowReplay).to.be.false
+  expect(data.live.latencySetting.enabled).to.be.true
   expect(data.live.maxDuration).to.equal(-1)
   expect(data.live.maxInstanceLives).to.equal(20)
   expect(data.live.maxUserLives).to.equal(3)
@@ -185,6 +186,7 @@ function checkUpdatedConfig (data: CustomConfig) {
 
   expect(data.live.enabled).to.be.true
   expect(data.live.allowReplay).to.be.true
+  expect(data.live.latencySetting.enabled).to.be.false
   expect(data.live.maxDuration).to.equal(5000)
   expect(data.live.maxInstanceLives).to.equal(-1)
   expect(data.live.maxUserLives).to.equal(10)
@@ -326,6 +328,9 @@ const newCustomConfig: CustomConfig = {
   live: {
     enabled: true,
     allowReplay: true,
+    latencySetting: {
+      enabled: false
+    },
     maxDuration: 5000,
     maxInstanceLives: -1,
     maxUserLives: 10,