Implement EXT-X-DEFINE Variable Substitution

Add support EXT-X-START in Multi-Variant Playlist
Add Content-Steering Multi-Variant Playlist parsing (#5074)

.eslintrc.js

@@ -14,6 +14,8 @@ module.exports = {
     __USE_ALT_AUDIO__: true,
     __USE_EME_DRM__: true,
     __USE_CMCD__: true,
+    __USE_CONTENT_STEERING__: true,
+    __USE_VARIABLE_SUBSTITUTION__: true,
   },
   // see https://github.com/standard/eslint-config-standard
   // 'prettier' (https://github.com/prettier/eslint-config-prettier) must be last

README.md

@@ -65,23 +65,26 @@ HLS.js is written in [ECMAScript6] (`*.js`) and [TypeScript] (`*.ts`) (strongly
   - Retry mechanism embedded in the library
   - Recovery actions can be triggered fix fatal media or network errors
 - [Redundant/Failover Playlists](https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/StreamingMediaGuide/UsingHTTPLiveStreaming/UsingHTTPLiveStreaming.html#//apple_ref/doc/uid/TP40008332-CH102-SW22)
+- HLS Variable Substitution
 
-### Supported M3U8 tags
+### Supported HLS tags
 
-For details on the HLS format and these tags' meanings, see https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-08
+For details on the HLS format and these tags' meanings, see https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis
 
-#### Manifest tags
+#### Multi-Variant Playlist tags
 
 - `#EXT-X-STREAM-INF:<attribute-list>`
   `<URI>`
 - `#EXT-X-MEDIA:<attribute-list>`
 - `#EXT-X-SESSION-DATA:<attribute-list>`
+- `#EXT-X-START:TIME-OFFSET=<n>`
+- `#EXT-X-DEFINE` Variable Substitution
 
 The following properties are added to their respective variants' attribute list but are not implemented in their selection and playback.
 
 - `VIDEO-RANGE` and `HDCP-LEVEL` (See [#2489](https://github.com/video-dev/hls.js/issues/2489))
 
-#### Playlist tags
+#### Media Playlist tags
 
 - `#EXTM3U`
 - `#EXT-X-VERSION=<n>`
@@ -99,24 +102,30 @@ The following properties are added to their respective variants' attribute list
 - `#EXT-X-SERVER-CONTROL:<attribute-list>`
 - `#EXT-X-PART-INF:PART-TARGET=<n>`
 - `#EXT-X-PART:<attribute-list>`
-- `#EXT-X-PRELOAD-HINT:<attribute-list>`
-- `#EXT-X-SKIP:<attribute-list>`
+- `#EXT-X-SKIP:<attribute-list>` Delta Playlists
 - `#EXT-X-RENDITION-REPORT:<attribute-list>`
-- `#EXT-X-DATERANGE:<attribute-list>`
+- `#EXT-X-DATERANGE:<attribute-list>` Metadata
+- `#EXT-X-DEFINE` Variable Substitution
 
 The following tags are added to their respective fragment's attribute list but are not implemented in streaming and playback.
 
 - `#EXT-X-BITRATE` (Not used in ABR controller)
 - `#EXT-X-GAP` (Not implemented. See [#2940](https://github.com/video-dev/hls.js/issues/2940))
 
+Parsed but missing feature support
+
+- `#EXT-X-CONTENT-STEERING:<attribute-list>` (See [#3988](https://github.com/video-dev/hls.js/issues/3988))
+  - #3988
+- `#EXT-X-PRELOAD-HINT:<attribute-list>` (See [#5074](https://github.com/video-dev/hls.js/issues/3988))
+  - #5074
+
 ### Not Supported
 
 For a complete list of issues, see ["Top priorities" in the Release Planning and Backlog project tab](https://github.com/video-dev/hls.js/projects/6). Codec support is dependent on the runtime environment (for example, not all browsers on the same OS support HEVC).
 
 - Advanced variant selection based on runtime media capabilities (See issues labeled [`media-capabilities`](https://github.com/video-dev/hls.js/labels/media-capabilities))
 - HLS Content Steering
 - HLS Interstitials
-- `#EXT-X-DEFINE` variable substitution
 - `#EXT-X-GAP` filling [#2940](https://github.com/video-dev/hls.js/issues/2940)
 - `#EXT-X-I-FRAME-STREAM-INF` I-frame Media Playlist files
 - `SAMPLE-AES` with fmp4, aac, mp3, vtt... segments (MPEG-2 TS only)

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

@@ -482,6 +482,8 @@ export enum ErrorDetails {
     // (undocumented)
     LEVEL_LOAD_TIMEOUT = "levelLoadTimeOut",
     // (undocumented)
+    LEVEL_PARSING_ERROR = "levelParsingError",
+    // (undocumented)
     LEVEL_SWITCH_ERROR = "levelSwitchError",
     // (undocumented)
     MANIFEST_INCOMPATIBLE_CODECS_ERROR = "manifestIncompatibleCodecsError",
@@ -1502,6 +1504,8 @@ export class LevelDetails {
     // (undocumented)
     partTarget: number;
     // (undocumented)
+    playlistParsingError: Error | null;
+    // (undocumented)
     preloadHint?: AttrList;
     // (undocumented)
     PTSKnown: boolean;
@@ -1532,6 +1536,8 @@ export class LevelDetails {
     // (undocumented)
     url: string;
     // (undocumented)
+    variableList: VariableMap | null;
+    // (undocumented)
     version: number | null;
 }
 
@@ -1860,6 +1866,8 @@ export interface ManifestLoadedData {
     // (undocumented)
     captions?: MediaPlaylist[];
     // (undocumented)
+    contentSteering: Object | null;
+    // (undocumented)
     levels: LevelParsed[];
     // (undocumented)
     networkDetails: any;
@@ -1868,11 +1876,15 @@ export interface ManifestLoadedData {
     // (undocumented)
     sessionKeys: LevelKey[] | null;
     // (undocumented)
+    startTimeOffset: number | null;
+    // (undocumented)
     stats: LoaderStats;
     // (undocumented)
     subtitles?: MediaPlaylist[];
     // (undocumented)
     url: string;
+    // (undocumented)
+    variableList: VariableMap | null;
 }
 
 // Warning: (ae-missing-release-tag) "ManifestLoadingData" is part of the package's API, but it is missing a release tag (@alpha, @beta, @public, or @internal)
@@ -2312,6 +2324,11 @@ export interface UserdataSample {
     uuid?: string;
 }
 
+// Warning: (ae-missing-release-tag) "VariableMap" is part of the package's API, but it is missing a release tag (@alpha, @beta, @public, or @internal)
+//
+// @public (undocumented)
+export type VariableMap = Record<string, string>;
+
 // Warnings were encountered during analysis:
 //
 // src/config.ts:90:3 - (ae-forgotten-export) The symbol "MediaKeySessionContext" needs to be exported by the entry point hls.d.ts

docs/API.md

@@ -1722,6 +1722,8 @@ Full list of errors is described below:
   - data: { type : `NETWORK_ERROR`, details : `Hls.ErrorDetails.LEVEL_LOAD_ERROR`, fatal : `true`, url : level URL, response : { code: error code, text: error text }, loader : URL loader }
 - `Hls.ErrorDetails.LEVEL_LOAD_TIMEOUT` - raised when level loading fails because of a timeout
   - data: { type : `NETWORK_ERROR`, details : `Hls.ErrorDetails.LEVEL_LOAD_TIMEOUT`, fatal : `false`, url : level URL, loader : URL loader }
+- `Hls.ErrorDetails.LEVEL_PARSING_ERROR` - raised when level parsing failed or found invalid content
+  - data: { type : `NETWORK_ERROR`, details : `Hls.ErrorDetails.LEVEL_PARSING_ERROR`, fatal : `false`, url : level URL, error: Error }
 - `Hls.ErrorDetails.AUDIO_TRACK_LOAD_ERROR` - raised when audio playlist loading fails because of a network error
   - data: { type : `NETWORK_ERROR`, details : `Hls.ErrorDetails.AUDIO_TRACK_LOAD_ERROR`, fatal : `false`, url : audio URL, response : { code: error code, text: error text }, loader : URL loader }
 - `Hls.ErrorDetails.AUDIO_TRACK_LOAD_TIMEOUT` - raised when audio playlist loading fails because of a timeout

src/controller/base-stream-controller.ts

@@ -37,6 +37,7 @@ import type {
   MediaAttachingData,
   BufferFlushingData,
   LevelSwitchingData,
+  ManifestLoadedData,
 } from '../types/events';
 import type { FragmentTracker } from './fragment-tracker';
 import type { Level } from '../types/level';
@@ -82,6 +83,7 @@ export default class BaseStreamController
   protected lastCurrentTime: number = 0;
   protected nextLoadPosition: number = 0;
   protected startPosition: number = 0;
+  protected startTimeOffset: number | null = null;
   protected loadedmetadata: boolean = false;
   protected fragLoadError: number = 0;
   protected retryDate: number = 0;
@@ -115,6 +117,7 @@ export default class BaseStreamController
     this.fragmentTracker = fragmentTracker;
     this.config = hls.config;
     this.decrypter = new Decrypter(hls.config);
+    hls.on(Events.MANIFEST_LOADED, this.onManifestLoaded, this);
     hls.on(Events.LEVEL_SWITCHING, this.onLevelSwitching, this);
   }
 
@@ -283,6 +286,13 @@ export default class BaseStreamController
     this.startPosition = this.lastCurrentTime = 0;
   }
 
+  protected onManifestLoaded(
+    event: Events.MANIFEST_LOADED,
+    data: ManifestLoadedData
+  ): void {
+    this.startTimeOffset = data.startTimeOffset;
+  }
+
   protected onLevelSwitching(
     event: Events.LEVEL_SWITCHING,
     data: LevelSwitchingData
@@ -1254,9 +1264,13 @@ export default class BaseStreamController
       startPosition = -1;
     }
     if (startPosition === -1 || this.lastCurrentTime === -1) {
-      // first, check if start time offset has been set in playlist, if yes, use this value
-      const startTimeOffset = details.startTimeOffset!;
-      if (Number.isFinite(startTimeOffset)) {
+      // Use Playlist EXT-X-START:TIME-OFFSET when set
+      // Prioritize Multi-Variant Playlist offset so that main, audio, and subtitle stream-controller start times match
+      const offsetInMultiVariantPlaylist = this.startTimeOffset !== null;
+      const startTimeOffset = offsetInMultiVariantPlaylist
+        ? this.startTimeOffset
+        : details.startTimeOffset;
+      if (startTimeOffset !== null && Number.isFinite(startTimeOffset)) {
         startPosition = sliding + startTimeOffset;
         if (startTimeOffset < 0) {
           startPosition += details.totalduration;
@@ -1266,7 +1280,9 @@ export default class BaseStreamController
           sliding + details.totalduration
         );
         this.log(
-          `Start time offset ${startTimeOffset} found in playlist, adjust startPosition to ${startPosition}`
+          `Start time offset ${startTimeOffset} found in ${
+            offsetInMultiVariantPlaylist ? 'multi-variant' : 'media'
+          } playlist, adjust startPosition to ${startPosition}`
         );
         this.startPosition = startPosition;
       } else if (details.live) {

src/controller/level-controller.ts

@@ -407,6 +407,7 @@ export default class LevelController extends BasePlaylistController {
         break;
       case ErrorDetails.LEVEL_LOAD_ERROR:
       case ErrorDetails.LEVEL_LOAD_TIMEOUT:
+      case ErrorDetails.LEVEL_PARSING_ERROR:
         // Do not perform level switch if an error occurred using delivery directives
         // Attempt to reload level without directives first
         if (context) {

src/controller/stream-controller.ts

@@ -871,6 +871,7 @@ export default class StreamController
         break;
       case ErrorDetails.LEVEL_LOAD_ERROR:
       case ErrorDetails.LEVEL_LOAD_TIMEOUT:
+      case ErrorDetails.LEVEL_PARSING_ERROR:
         if (this.state !== State.ERROR) {
           if (data.fatal) {
             // if fatal error, stop processing

src/define-plugin.d.ts

@@ -5,3 +5,5 @@ declare const __USE_ALT_AUDIO__: boolean;
 declare const __USE_EME_DRM__: boolean;
 declare const __USE_SUBTITLES__: boolean;
 declare const __USE_CMCD__: boolean;
+declare const __USE_CONTENT_STEERING__: boolean;
+declare const __USE_VARIABLE_SUBSTITUTION__: boolean;

src/errors.ts

@@ -40,6 +40,8 @@ export enum ErrorDetails {
   LEVEL_LOAD_ERROR = 'levelLoadError',
   // Identifier for a level load timeout - data: { url : faulty URL, response : { code: error code, text: error text }}
   LEVEL_LOAD_TIMEOUT = 'levelLoadTimeOut',
+  // Identifier for a level parse error - data: { url : faulty URL, error: Error, reason: error message }
+  LEVEL_PARSING_ERROR = 'levelParsingError',
   // Identifier for a level switch error - data: { level : faulty level Id, event : error description}
   LEVEL_SWITCH_ERROR = 'levelSwitchError',
   // Identifier for an audio track load error - data: { url : faulty URL, response : { code: error code, text: error text }}

src/hls.ts

@@ -23,7 +23,7 @@ import type SubtitleTrackController from './controller/subtitle-track-controller
 import type { ComponentAPI, NetworkComponentAPI } from './types/component-api';
 import type { MediaPlaylist } from './types/media-playlist';
 import type { HlsConfig } from './config';
-import { HdcpLevel, HdcpLevels, Level } from './types/level';
+import { HdcpLevel, HdcpLevels, Level, VariableMap } from './types/level';
 import type { Fragment } from './loader/fragment';
 import { BufferInfo } from './utils/buffer-helper';
 
@@ -909,6 +909,7 @@ export type {
   HlsUrlParameters,
   LevelAttributes,
   LevelParsed,
+  VariableMap,
 } from './types/level';
 export type {
   PlaylistLevelType,

src/loader/fragment-loader.ts

@@ -314,8 +314,8 @@ function createLoaderContext(
 
 export class LoadError extends Error {
   public readonly data: FragLoadFailResult;
-  constructor(data: FragLoadFailResult, ...params) {
-    super(...params);
+  constructor(data: FragLoadFailResult, message?: string) {
+    super(message);
     this.data = data;
   }
 }

src/loader/key-loader.ts

@@ -68,16 +68,19 @@ export default class KeyLoader implements ComponentAPI {
   createKeyLoadError(
     frag: Fragment,
     details: ErrorDetails = ErrorDetails.KEY_LOAD_ERROR,
-    networkDetails?: any,
-    message?: string
+    message: string,
+    networkDetails?: any
   ): LoadError {
-    return new LoadError({
-      type: ErrorTypes.NETWORK_ERROR,
-      details,
-      fatal: false,
-      frag,
-      networkDetails,
-    });
+    return new LoadError(
+      {
+        type: ErrorTypes.NETWORK_ERROR,
+        details,
+        fatal: false,
+        frag,
+        networkDetails,
+      },
+      message
+    );
   }
 
   loadClear(
@@ -127,12 +130,7 @@ export default class KeyLoader implements ComponentAPI {
         ? `Expected frag.decryptdata to be defined after setting format ${keySystemFormat}`
         : 'Missing decryption data on fragment in onKeyLoading';
       return Promise.reject(
-        this.createKeyLoadError(
-          frag,
-          ErrorDetails.KEY_LOAD_ERROR,
-          null,
-          errorMessage
-        )
+        this.createKeyLoadError(frag, ErrorDetails.KEY_LOAD_ERROR, errorMessage)
       );
     }
     const uri = decryptdata.uri;
@@ -141,7 +139,6 @@ export default class KeyLoader implements ComponentAPI {
         this.createKeyLoadError(
           frag,
           ErrorDetails.KEY_LOAD_ERROR,
-          null,
           `Invalid key URI: "${uri}"`
         )
       );
@@ -190,7 +187,6 @@ export default class KeyLoader implements ComponentAPI {
           this.createKeyLoadError(
             frag,
             ErrorDetails.KEY_LOAD_ERROR,
-            null,
             `Key supplied with unsupported METHOD: "${decryptdata.method}"`
           )
         );
@@ -256,8 +252,8 @@ export default class KeyLoader implements ComponentAPI {
               this.createKeyLoadError(
                 frag,
                 ErrorDetails.KEY_LOAD_ERROR,
-                networkDetails,
-                'after key load, decryptdata unset or changed'
+                'after key load, decryptdata unset or changed',
+                networkDetails
               )
             );
           }
@@ -282,6 +278,7 @@ export default class KeyLoader implements ComponentAPI {
             this.createKeyLoadError(
               frag,
               ErrorDetails.KEY_LOAD_ERROR,
+              'error loading key',
               networkDetails
             )
           );
@@ -297,6 +294,7 @@ export default class KeyLoader implements ComponentAPI {
             this.createKeyLoadError(
               frag,
               ErrorDetails.KEY_LOAD_TIMEOUT,
+              'key loading timed out',
               networkDetails
             )
           );
@@ -312,6 +310,7 @@ export default class KeyLoader implements ComponentAPI {
             this.createKeyLoadError(
               frag,
               ErrorDetails.INTERNAL_ABORTED,
+              'key loading aborted',
               networkDetails
             )
           );

src/loader/level-details.ts

@@ -2,6 +2,7 @@ import { Part } from './fragment';
 import type { Fragment } from './fragment';
 import type { AttrList } from '../utils/attr-list';
 import type { DateRange } from './date-range';
+import type { VariableMap } from '../types/level';
 
 const DEFAULT_TARGET_DURATION = 10;
 
@@ -48,6 +49,8 @@ export class LevelDetails {
   public driftStart: number = 0;
   public driftEnd: number = 0;
   public encryptedFragments: Fragment[];
+  public playlistParsingError: Error | null = null;
+  public variableList: VariableMap | null = null;
 
   constructor(baseUrl) {
     this.fragments = [];