PLAYLIST_UNCHANGED_ERROR should not be fatal so that playback is allowed to reach the end of the playlist

src/controller/base-playlist-controller.ts

@@ -150,6 +150,7 @@ export default class BasePlaylistController
     previousDetails?: LevelDetails,
   ) {
     const { details, stats } = data;
+    const fragments = details.fragments;
 
     // Set last updated date-time
     const now = self.performance.now();
@@ -163,8 +164,8 @@ export default class BasePlaylistController
     if (timelineOffset !== details.appliedTimelineOffset) {
       const offset = Math.max(timelineOffset || 0, 0);
       details.appliedTimelineOffset = offset;
-      details.fragments.forEach((frag) => {
-        frag.setStart(frag.playlistOffset + offset);
+      fragments.forEach((frag) => {
+        frag?.setStart(frag.playlistOffset + offset);
       });
     }
 
@@ -172,11 +173,12 @@ export default class BasePlaylistController
     if (details.live || previousDetails?.live) {
       const levelOrTrack = 'levelInfo' in data ? data.levelInfo : data.track;
       details.reloaded(previousDetails);
+      const parent = fragments[fragments.length - 1]?.type;
 
       // TODO: consider a separate flow for low-latency blocking reload requests with delivery directives
       if (details.misses >= this.hls.config.liveMaxUnchangedPlaylistRefresh) {
         const error = new Error(
-          `levelOrTrack (${levelOrTrack.id}) hits max allowed unchanged reloads.`,
+          `${parent} playlist ${levelOrTrack.id} hit max allowed unchanged reloads.`,
         );
         this.warn(error);
         const { networkDetails, context } = data;
@@ -187,8 +189,8 @@ export default class BasePlaylistController
           url: details.url,
           error,
           reason: error.message,
-          level: (data as LevelLoadedData).level ?? undefined,
-          parent: details.fragments[0]?.type,
+          level: (data as LevelLoadedData).level,
+          parent,
           context,
           networkDetails,
           stats,
@@ -197,7 +199,7 @@ export default class BasePlaylistController
       }
 
       // Merge live playlists to adjust fragment starts and fill in delta playlist skipped segments
-      if (previousDetails && details.fragments.length > 0) {
+      if (previousDetails) {
         mergeDetails(previousDetails, details, this);
         const error = details.playlistParsingError;
         if (error) {
@@ -212,8 +214,8 @@ export default class BasePlaylistController
               url: details.url,
               error,
               reason: error.message,
-              level: (data as any).level || undefined,
-              parent: details.fragments[0]?.type,
+              level: (data as LevelLoadedData).level,
+              parent,
               networkDetails,
               stats,
             });

src/controller/base-stream-controller.ts

@@ -2341,7 +2341,7 @@ export default class BaseStreamController
   }
 
   private playlistLabel() {
-    return this.playlistType === PlaylistLevelType.MAIN ? 'level' : 'track';
+    return `${this.playlistType} playlist`;
   }
 
   private fragInfo(

src/controller/buffer-controller.ts

@@ -1013,8 +1013,8 @@ transfer tracks: ${stringify(transferredTracks, (key, value) => (key === 'initSe
     };
     this.log(
       `queuing "${type}" append sn: ${sn}${part ? ' p: ' + part.index : ''} of ${
-        parent === PlaylistLevelType.MAIN ? 'level' : 'track'
-      } ${frag.level} cc: ${cc} offset: ${offset} bytes: ${data.byteLength}`,
+        parent
+      } playlist ${frag.level} cc: ${cc} offset: ${offset} bytes: ${data.byteLength}`,
     );
     this.append(operation, type, this.isPending(this.tracks[type]));
   }

src/controller/error-controller.ts

@@ -481,7 +481,8 @@ export default class ErrorController
         this.sendAlternateToPenaltyBox(data);
         if (
           !data.errorAction.resolved &&
-          data.details !== ErrorDetails.FRAG_GAP
+          data.details !== ErrorDetails.FRAG_GAP &&
+          data.details !== ErrorDetails.PLAYLIST_UNCHANGED_ERROR
         ) {
           data.fatal = true;
         }

src/demux/transmuxer-interface.ts

@@ -12,7 +12,6 @@ import Transmuxer, {
 } from '../demux/transmuxer';
 import { ErrorDetails, ErrorTypes } from '../errors';
 import { Events } from '../events';
-import { PlaylistLevelType } from '../types/loader';
 import { getM2TSSupportedAudioTypes } from '../utils/codecs';
 import { stringify } from '../utils/safe-json-stringify';
 import type { WorkerContext } from './inject-worker';
@@ -20,6 +19,7 @@ import type { HlsEventEmitter, HlsListeners } from '../events';
 import type Hls from '../hls';
 import type { MediaFragment, Part } from '../loader/fragment';
 import type { ErrorData, FragDecryptedData } from '../types/events';
+import type { PlaylistLevelType } from '../types/loader';
 import type { ChunkMetadata, TransmuxerResult } from '../types/transmuxer';
 import type { TimestampOffset } from '../utils/timescale-conversion';
 
@@ -237,7 +237,7 @@ export default class TransmuxerInterface {
       this.hls.logger
         .log(`[transmuxer-interface]: Starting new transmux session for ${frag.type} sn: ${chunkMeta.sn}${
         chunkMeta.part > -1 ? ' part: ' + chunkMeta.part : ''
-      } ${this.id === PlaylistLevelType.MAIN ? 'level' : 'track'}: ${chunkMeta.level} id: ${chunkMeta.id}
+      } ${this.id} playlist: ${chunkMeta.level} id: ${chunkMeta.id}
         discontinuity: ${discontinuity}
         trackSwitch: ${trackSwitch}
         contiguous: ${contiguous}

src/demux/transmuxer.ts

@@ -8,7 +8,6 @@ import { ErrorDetails, ErrorTypes } from '../errors';
 import { Events } from '../events';
 import MP4Remuxer from '../remux/mp4-remuxer';
 import PassThroughRemuxer from '../remux/passthrough-remuxer';
-import { PlaylistLevelType } from '../types/loader';
 import {
   getAesModeFromFullSegmentMethod,
   isFullSegmentEncryption,
@@ -17,6 +16,7 @@ import type { HlsConfig } from '../config';
 import type { HlsEventEmitter } from '../events';
 import type { DecryptData } from '../loader/level-key';
 import type { Demuxer, DemuxerResult, KeyData } from '../types/demuxer';
+import type { PlaylistLevelType } from '../types/loader';
 import type { Remuxer } from '../types/remuxer';
 import type { ChunkMetadata, TransmuxerResult } from '../types/transmuxer';
 import type { TypeSupported } from '../utils/codecs';
@@ -287,7 +287,7 @@ export default class Transmuxer {
     this.logger.log(
       `[transmuxer.ts]: Flushed ${this.id} sn: ${chunkMeta.sn}${
         chunkMeta.part > -1 ? ' part: ' + chunkMeta.part : ''
-      } of ${this.id === PlaylistLevelType.MAIN ? 'level' : 'track'} ${chunkMeta.level}`,
+      } of ${this.id} playlist ${chunkMeta.level}`,
     );
     const remuxResult = this.remuxer!.remux(
       audioTrack,

tests/unit/controller/error-controller.ts

@@ -457,12 +457,12 @@ segment101.ts`;
         expect(data.details).to.equal(ErrorDetails.PLAYLIST_UNCHANGED_ERROR);
         expect(data.fatal).to.equal(false, 'Error should not be fatal');
         expect(data.error.message).to.include(
-          'hits max allowed unchanged reloads',
+          'hit max allowed unchanged reloads',
         );
       });
     });
 
-    it('PLAYLIST_UNCHANGED_ERROR becomes fatal when no alternate levels are available', function () {
+    it('PLAYLIST_UNCHANGED_ERROR is not fatal when no alternate levels are available', function () {
       (hls.config as any).liveMaxUnchangedPlaylistRefresh = 2;
 
       server.respondWith('singleLevelMultivariant.m3u8', [
@@ -502,13 +502,12 @@ segment101.ts`;
       }).then((data: ErrorData) => {
         expect(data.details).to.equal(ErrorDetails.PLAYLIST_UNCHANGED_ERROR);
         expect(data.fatal).to.equal(
-          true,
-          'Error should be fatal with no alternates',
+          false,
+          'Error should not be fatal with no alternates',
         );
         expect(data.error.message).to.include(
-          'hits max allowed unchanged reloads',
+          'hit max allowed unchanged reloads',
         );
-        expect(hls.stopLoad).to.have.been.called;
       });
     });
 
@@ -572,7 +571,7 @@ audio101.ts`;
         expect(data.details).to.equal(ErrorDetails.PLAYLIST_UNCHANGED_ERROR);
         expect(data.fatal).to.equal(false, 'Error should not be fatal');
         expect(data.error.message).to.include(
-          'hits max allowed unchanged reloads',
+          'hit max allowed unchanged reloads',
         );
       });
     });