Determine canSkip based on age of last playlist request

src/controller/base-playlist-controller.ts

@@ -1,6 +1,6 @@
 import type Hls from '../hls';
 import type { NetworkComponentAPI } from '../types/component-api';
-import { getSkipValue, HlsSkip, HlsUrlParameters, Level } from '../types/level';
+import { HlsSkip, HlsUrlParameters, Level } from '../types/level';
 import { computeReloadInterval, mergeDetails } from '../utils/level-helper';
 import { ErrorData } from '../types/events';
 import { getRetryDelay, isTimeoutError } from '../utils/error-helper';
@@ -310,7 +310,7 @@ export default class BasePlaylistController
     msn?: number,
     part?: number,
   ): HlsUrlParameters {
-    let skip = getSkipValue(details, msn);
+    let skip: HlsSkip | undefined;
     if (previousDeliveryDirectives?.skip && details.deltaUpdateFailed) {
       msn = previousDeliveryDirectives.msn;
       part = previousDeliveryDirectives.part;

src/controller/level-controller.ts

@@ -8,7 +8,12 @@ import {
   ManifestLoadingData,
   FragBufferedData,
 } from '../types/events';
-import { Level, VideoRangeValues, isVideoRange } from '../types/level';
+import {
+  Level,
+  VideoRangeValues,
+  isVideoRange,
+  getSkipValue,
+} from '../types/level';
 import { Events } from '../events';
 import { ErrorTypes, ErrorDetails } from '../errors';
 import {
@@ -575,9 +580,13 @@ export default class LevelController extends BasePlaylistController {
     const currentLevel = this.currentLevel;
 
     if (currentLevel && this.shouldLoadPlaylist(currentLevel)) {
+      const skipValue = currentLevel.details
+        ? getSkipValue(currentLevel.details)
+        : undefined;
       let url = currentLevel.uri;
       if (hlsUrlParameters) {
         try {
+          hlsUrlParameters.skip = skipValue;
           url = hlsUrlParameters.addDirectives(url);
         } catch (error) {
           this.warn(

src/types/level.ts

@@ -59,10 +59,13 @@ export const enum HlsSkip {
   v2 = 'v2',
 }
 
-export function getSkipValue(details: LevelDetails, msn?: number): HlsSkip {
-  const { canSkipUntil, canSkipDateRanges, endSN } = details;
-  const snChangeGoal = msn !== undefined ? msn - endSN : 0;
-  if (canSkipUntil && snChangeGoal < canSkipUntil) {
+export function getSkipValue(details: LevelDetails): HlsSkip {
+  const { canSkipUntil, canSkipDateRanges, age } = details;
+  // A Client SHOULD NOT request a Playlist Delta Update unless it already
+  // has a version of the Playlist that is no older than one-half of the Skip Boundary.
+  // @see: https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis#section-6.3.7
+  const playlistRecentEnough = age < canSkipUntil / 2;
+  if (canSkipUntil && playlistRecentEnough) {
     if (canSkipDateRanges) {
       return HlsSkip.v2;
     }