Make stream controllers wait for playlist updates before requesting segments from expired playlists

api-extractor/report/hls.js.api.md

@@ -556,6 +556,8 @@ export class BaseStreamController extends TaskLoop implements NetworkComponentAP
     protected unregisterListeners(): void;
     // (undocumented)
     protected waitForCdnTuneIn(details: LevelDetails): boolean | 0;
+    // (undocumented)
+    protected waitForLive(levelInfo: Level): boolean | undefined;
 }
 
 // Warning: (ae-missing-release-tag) "BaseTrack" is part of the package's API, but it is missing a release tag (@alpha, @beta, @public, or @internal)
@@ -3132,6 +3134,8 @@ export class LevelDetails {
     // (undocumented)
     endSN: number;
     // (undocumented)
+    get expired(): boolean;
+    // (undocumented)
     get fragmentEnd(): number;
     // (undocumented)
     fragmentHint?: MediaFragment;

src/controller/audio-stream-controller.ts

@@ -11,8 +11,8 @@ import { PlaylistContextType, PlaylistLevelType } from '../types/loader';
 import { ChunkMetadata } from '../types/transmuxer';
 import { alignMediaPlaylistByPDT } from '../utils/discontinuities';
 import { mediaAttributesIdentical } from '../utils/media-option-attributes';
-import type Hls from '../hls';
 import type { FragmentTracker } from './fragment-tracker';
+import type Hls from '../hls';
 import type { Fragment, MediaFragment, Part } from '../loader/fragment';
 import type KeyLoader from '../loader/key-loader';
 import type { LevelDetails } from '../loader/level-details';
@@ -207,8 +207,9 @@ class AudioStreamController
         break;
       case State.WAITING_TRACK: {
         const { levels, trackId } = this;
-        const details = levels?.[trackId]?.details;
-        if (details) {
+        const currenTrack = levels?.[trackId];
+        const details = currenTrack?.details;
+        if (details && !this.waitForLive(currenTrack)) {
           if (this.waitForCdnTuneIn(details)) {
             break;
           }
@@ -318,10 +319,11 @@ class AudioStreamController
     const trackDetails = levelInfo.details;
     if (
       !trackDetails ||
-      (trackDetails.live && this.levelLastLoaded !== levelInfo) ||
+      this.waitForLive(levelInfo) ||
       this.waitForCdnTuneIn(trackDetails)
     ) {
       this.state = State.WAITING_TRACK;
+      this.startFragRequested = false;
       return;
     }
 

src/controller/audio-track-controller.ts

@@ -425,8 +425,17 @@ class AudioTrackController extends BasePlaylistController {
         }
       }
       // track not retrieved yet, or live playlist we need to (re)load it
+      const details = audioTrack.details;
+      const age = details?.age;
       this.log(
-        `loading audio-track playlist ${id} "${audioTrack.name}" lang:${audioTrack.lang} group:${groupId}`,
+        `Loading audio-track ${id} "${audioTrack.name}" lang:${audioTrack.lang} group:${groupId}${
+          hlsUrlParameters?.msn !== undefined
+            ? ' at sn ' +
+              hlsUrlParameters.msn +
+              ' part ' +
+              hlsUrlParameters.part
+            : ''
+        }${age && details.live ? ' age ' + age.toFixed(1) + (details.type ? ' ' + details.type || '' : '') : ''} ${url}`,
       );
       this.clearTimer();
       this.hls.trigger(Events.AUDIO_TRACK_LOADING, {

src/controller/base-stream-controller.ts

@@ -601,6 +601,15 @@ export default class BaseStreamController
     }
   }
 
+  protected waitForLive(levelInfo: Level) {
+    const details = levelInfo.details;
+    return (
+      details?.live &&
+      details.type !== 'EVENT' &&
+      (this.levelLastLoaded !== levelInfo || details.expired)
+    );
+  }
+
   protected flushMainBuffer(
     startOffset: number,
     endOffset: number,
@@ -1077,7 +1086,7 @@ export default class BaseStreamController
     const { level: levelIndex, sn, part: partIndex } = chunkMeta;
     if (!levels?.[levelIndex]) {
       this.warn(
-        `Levels object was unset while buffering fragment ${sn} of level ${levelIndex}. The current chunk will not be buffered.`,
+        `Levels object was unset while buffering fragment ${sn} of ${this.playlistLabel()} ${levelIndex}. The current chunk will not be buffered.`,
       );
       return null;
     }
@@ -1643,6 +1652,7 @@ export default class BaseStreamController
         // Leave this.startPosition at -1, so that we can use `getInitialLiveFragment` logic when startPosition has
         // not been specified via the config or an as an argument to startLoad (#3736).
         startPosition = this.hls.liveSyncPosition || sliding;
+        this.startPosition = -1;
       } else {
         this.log(`setting startPosition to 0 by default`);
         this.startPosition = startPosition = 0;
@@ -1666,9 +1676,14 @@ export default class BaseStreamController
   }
 
   private handleFragLoadAborted(frag: Fragment, part: Part | undefined) {
-    if (this.transmuxer && isMediaFragment(frag) && frag.stats.aborted) {
+    if (
+      this.transmuxer &&
+      frag.type === this.playlistType &&
+      isMediaFragment(frag) &&
+      frag.stats.aborted
+    ) {
       this.warn(
-        `Fragment ${frag.sn}${part ? ' part ' + part.index : ''} of level ${
+        `Fragment ${frag.sn}${part ? ' part ' + part.index : ''} of ${this.playlistLabel()} ${
           frag.level
         } was aborted`,
       );
@@ -1861,7 +1876,7 @@ export default class BaseStreamController
 
   protected resetWhenMissingContext(chunkMeta: ChunkMetadata) {
     this.warn(
-      `The loading context changed while buffering fragment ${chunkMeta.sn} of level ${chunkMeta.level}. This chunk will not be buffered.`,
+      `The loading context changed while buffering fragment ${chunkMeta.sn} of ${this.playlistLabel()} ${chunkMeta.level}. This chunk will not be buffered.`,
     );
     this.removeUnbufferedFrags();
     this.resetStartWhenNotLoaded(this.levelLastLoaded);
@@ -1930,7 +1945,7 @@ export default class BaseStreamController
     );
     if (!parsed && this.transmuxer?.error === null) {
       const error = new Error(
-        `Found no media in fragment ${frag.sn} of level ${frag.level} resetting transmuxer to fallback to playlist timing`,
+        `Found no media in fragment ${frag.sn} of ${this.playlistLabel()} ${frag.level} resetting transmuxer to fallback to playlist timing`,
       );
       if (level.fragmentError === 0) {
         // Mark and track the odd empty segment as a gap to avoid reloading
@@ -1943,7 +1958,7 @@ export default class BaseStreamController
         fatal: false,
         error,
         frag,
-        reason: `Found no media in msn ${frag.sn} of level "${level.url}"`,
+        reason: `Found no media in msn ${frag.sn} of ${this.playlistLabel()} "${level.url}"`,
       });
       if (!this.hls) {
         return;

src/controller/level-controller.ts

@@ -648,6 +648,8 @@ export default class LevelController extends BasePlaylistController {
       }
 
       const pathwayId = currentLevel.attrs['PATHWAY-ID'];
+      const details = currentLevel.details;
+      const age = details?.age;
       this.log(
         `Loading level index ${currentLevelIndex}${
           hlsUrlParameters?.msn !== undefined
@@ -656,7 +658,7 @@ export default class LevelController extends BasePlaylistController {
               ' part ' +
               hlsUrlParameters.part
             : ''
-        } with${pathwayId ? ' Pathway ' + pathwayId : ''} ${url}`,
+        }${pathwayId ? ' Pathway ' + pathwayId : ''}${age && details.live ? ' age ' + age.toFixed(1) + (details.type ? ' ' + details.type || '' : '') : ''} ${url}`,
       );
 
       // console.log('Current audio track group ID:', this.hls.audioTracks[this.hls.audioTrack].groupId);

src/controller/stream-controller.ts

@@ -155,7 +155,11 @@ export default class StreamController
         this._hasEnoughToStart = false;
       }
       // if startPosition undefined but lastCurrentTime set, set startPosition to last currentTime
-      if (lastCurrentTime > 0 && startPosition === -1) {
+      if (
+        lastCurrentTime > 0 &&
+        startPosition === -1 &&
+        !skipSeekToStartPosition
+      ) {
         this.log(
           `Override startPosition with lastCurrentTime @${lastCurrentTime.toFixed(
             3,
@@ -186,7 +190,9 @@ export default class StreamController
         const details = currentLevel?.details;
         if (
           details &&
-          (!details.live || this.levelLastLoaded === currentLevel)
+          (!details.live ||
+            (this.levelLastLoaded === currentLevel &&
+              !this.waitForLive(currentLevel)))
         ) {
           if (this.waitForCdnTuneIn(details)) {
             break;
@@ -287,10 +293,11 @@ export default class StreamController
     if (
       !levelDetails ||
       this.state === State.WAITING_LEVEL ||
-      (levelDetails.live && this.levelLastLoaded !== levelInfo)
+      this.waitForLive(levelInfo)
     ) {
       this.level = level;
       this.state = State.WAITING_LEVEL;
+      this.startFragRequested = false;
       return;
     }
 
@@ -649,7 +656,8 @@ export default class StreamController
     const level = data.levelInfo;
     if (
       !level.details ||
-      (level.details.live && this.levelLastLoaded !== level) ||
+      (level.details.live &&
+        (this.levelLastLoaded !== level || level.details.expired)) ||
       this.waitForCdnTuneIn(level.details)
     ) {
       this.state = State.WAITING_LEVEL;

src/controller/subtitle-stream-controller.ts

@@ -18,8 +18,8 @@ import {
 } from '../utils/encryption-methods-util';
 import { addSliding } from '../utils/level-helper';
 import { subtitleOptionsIdentical } from '../utils/media-option-attributes';
-import type Hls from '../hls';
 import type { FragmentTracker } from './fragment-tracker';
+import type Hls from '../hls';
 import type KeyLoader from '../loader/key-loader';
 import type { LevelDetails } from '../loader/level-details';
 import type { NetworkComponentAPI } from '../types/component-api';
@@ -425,6 +425,9 @@ export class SubtitleStreamController
       if (!track || !levels.length || !track.details) {
         return;
       }
+      if (this.waitForLive(track)) {
+        return;
+      }
       const { config } = this;
       const currentTime = this.getLoadPosition();
       const bufferedInfo = BufferHelper.bufferedInfo(

src/controller/subtitle-track-controller.ts

@@ -447,7 +447,18 @@ class SubtitleTrackController extends BasePlaylistController {
           );
         }
       }
-      this.log(`Loading subtitle playlist for id ${id}`);
+      const details = currentTrack.details;
+      const age = details?.age;
+      this.log(
+        `Loading subtitle ${id} "${currentTrack.name}" lang:${currentTrack.lang} group:${groupId}${
+          hlsUrlParameters?.msn !== undefined
+            ? ' at sn ' +
+              hlsUrlParameters.msn +
+              ' part ' +
+              hlsUrlParameters.part
+            : ''
+        }${age && details.live ? ' age ' + age.toFixed(1) + (details.type ? ' ' + details.type || '' : '') : ''} ${url}`,
+      );
       this.hls.trigger(Events.SUBTITLE_TRACK_LOADING, {
         url,
         id,

src/loader/level-details.ts

@@ -160,4 +160,16 @@ export class LevelDetails {
     }
     return this.endSN;
   }
+
+  get expired(): boolean {
+    if (this.live && this.age) {
+      const playlistWindowDuration = this.partEnd - this.fragmentStart;
+      return (
+        this.age >
+        Math.max(playlistWindowDuration, this.totalduration) +
+          this.levelTargetDuration
+      );
+    }
+    return false;
+  }
 }

src/loader/playlist-loader.ts

@@ -240,17 +240,25 @@ class PlaylistLoader implements NetworkComponentAPI {
     // Check if a loader for this context already exists
     let loader = this.getInternalLoader(context);
     if (loader) {
+      const logger = this.hls.logger;
       const loaderContext = loader.context as PlaylistLoaderContext;
       if (
         loaderContext &&
-        loaderContext.url === context.url &&
-        loaderContext.levelOrTrack === context.levelOrTrack
+        loaderContext.levelOrTrack === context.levelOrTrack &&
+        (loaderContext.url === context.url ||
+          (loaderContext.deliveryDirectives && !context.deliveryDirectives))
       ) {
-        // same URL can't overlap
-        this.hls.logger.trace('[playlist-loader]: playlist request ongoing');
+        // same URL can't overlap, or wait for blocking request
+        if (loaderContext.url === context.url) {
+          logger.log(`[playlist-loader]: playlist request ongoing`);
+        } else {
+          logger.log(
+            `[playlist-loader]: ignore ${context.url} in favor of ${loaderContext.url}`,
+          );
+        }
         return;
       }
-      this.hls.logger.log(
+      logger.log(
         `[playlist-loader]: aborting previous loader for type: ${context.type}`,
       );
       loader.abort();