feat: parse EXT-X-SKIP tags and attributes

dzianis-dashkevich · Oct 20, 2023 · 493e967 · 493e967
1 parent fdf9ead
commit 493e967
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Showing 4 changed files with 27 additions and 1 deletion.
diff --git a/packages/web-media-box/src/hls-parser/consts/tags.ts b/packages/web-media-box/src/hls-parser/consts/tags.ts
@@ -21,3 +21,4 @@ export const EXT_X_PROGRAM_DATE_TIME = 'EXT-X-PROGRAM-DATE-TIME';
 export const EXT_X_BITRATE = 'EXT-X-BITRATE';
 export const EXT_X_PART = 'EXT-X-PART';
 export const EXT_X_MEDIA = 'EXT_X_MEDIA';
+export const EXT_X_SKIP = 'EXT-X-SKIP';
diff --git a/packages/web-media-box/src/hls-parser/parse.ts b/packages/web-media-box/src/hls-parser/parse.ts
@@ -26,6 +26,7 @@ import {
   EXT_X_PART,
   EXT_X_PROGRAM_DATE_TIME,
   EXT_X_MEDIA,
+  EXT_X_SKIP,
 } from './consts/tags.ts';
 import type {
   CustomTagMap,
@@ -65,6 +66,7 @@ import {
   ExtXMap,
   ExtXPart,
   ExtXMedia,
+  ExtXSkip,
 } from './tags/tagWithAttributesProcessors.ts';
 
 const defaultSegment: Segment = {
@@ -142,6 +144,7 @@ class Parser {
       [EXT_X_MAP]: new ExtXMap(this.warnCallback),
       [EXT_X_PART]: new ExtXPart(this.warnCallback),
       [EXT_X_MEDIA]: new ExtXMedia(this.warnCallback),
+      [EXT_X_SKIP]: new ExtXSkip(this.warnCallback),
     };
   }
 

diff --git a/packages/web-media-box/src/hls-parser/tags/tagWithAttributesProcessors.ts b/packages/web-media-box/src/hls-parser/tags/tagWithAttributesProcessors.ts
@@ -1,7 +1,7 @@
 import type { ParsedPlaylist, PartialSegment, Segment, Rendition, RenditionType, RenditionGroups, GroupId } from '../types/parsedPlaylist';
 import { TagProcessor } from './base.ts';
 import { missingRequiredAttributeWarn } from '../utils/warn.ts';
-import { EXT_X_PART_INF, EXT_X_SERVER_CONTROL, EXT_X_START, EXT_X_KEY, EXT_X_MAP, EXT_X_PART, EXT_X_MEDIA } from '../consts/tags.ts';
+import { EXT_X_PART_INF, EXT_X_SERVER_CONTROL, EXT_X_START, EXT_X_KEY, EXT_X_MAP, EXT_X_PART, EXT_X_MEDIA, EXT_X_SKIP } from '../consts/tags.ts';
 import { parseBoolean } from '../utils/parse.ts';
 
 export abstract class TagWithAttributesProcessor extends TagProcessor {
@@ -240,3 +240,18 @@ export class ExtXMedia extends TagWithAttributesProcessor {
     playlist.renditionGroups[renditionTypeKey][rendition.groupId] = [rendition];
   }
 }
+
+export class ExtXSkip extends TagWithAttributesProcessor {
+  private static readonly SKIPPED_SEGMENTS = 'SKIPPED-SEGMENTS';
+  private static readonly RECENTLY_REMOVED_DATERANGES = 'RECENTLY-REMOVED-DATERANGES';
+
+  protected requiredAttributes = new Set([ExtXSkip.SKIPPED_SEGMENTS]);
+  protected readonly tag = EXT_X_SKIP;
+
+  protected safeProcess(tagAttributes: Record<string, string>, playlist: ParsedPlaylist): void {
+    playlist.skip = {
+      skippedSegments: Number(tagAttributes[ExtXSkip.SKIPPED_SEGMENTS]),
+      recentlyRemovedDateranges: tagAttributes[ExtXSkip.RECENTLY_REMOVED_DATERANGES].split('\t')
+    };
+  } 
+}
diff --git a/packages/web-media-box/src/hls-parser/types/parsedPlaylist.d.ts b/packages/web-media-box/src/hls-parser/types/parsedPlaylist.d.ts
@@ -81,6 +81,11 @@ export interface RenditionGroups {
   closedCaptions: Record<GroupId, RenditionGroup>;
 }
 
+export interface Skip {
+  skippedSegments: number;
+  recentlyRemovedDateranges?: Array<string>;
+}
+
 export type PlaylistType = 'EVENT' | 'VOD';
 
 export interface ParsedPlaylist {
@@ -117,4 +122,6 @@ export interface ParsedPlaylist {
   renditionGroups: RenditionGroups;
   // Used to persist EXT_X_BITRATE across segments
   currentBitrate?: number;
+  // https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis#section-4.4.5.2
+  skip?: Skip
 }