From e2f2f240a30530257a674f32017dee066ca42fa9 Mon Sep 17 00:00:00 2001
From: Rob Walch <rwalch@apple.com>
Date: Mon, 24 Oct 2022 10:27:26 -0700
Subject: [PATCH] Reload live stream using last segment length when distance to
 playlist end is less than or equal to four target durations (Reload is
 scheduled on update. With a default live sync of 3 target durations, without
 interruption, a distance of 3x-4x is most likely.)

---
 src/controller/level-helper.ts        | 7 +++++--
 tests/unit/controller/level-helper.ts | 4 ++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/controller/level-helper.ts b/src/controller/level-helper.ts
index d8fd96952e2..18ce16264a1 100644
--- a/src/controller/level-helper.ts
+++ b/src/controller/level-helper.ts
@@ -7,7 +7,6 @@ import { logger } from '../utils/logger';
 import { Fragment, Part } from '../loader/fragment';
 import { LevelDetails } from '../loader/level-details';
 import type { Level } from '../types/level';
-import type { LoaderStats } from '../types/loader';
 import type { MediaPlaylist } from '../types/media-playlist';
 import { DateRange } from '../loader/date-range';
 
@@ -441,7 +440,11 @@ export function computeReloadInterval(
   if (newDetails.updated) {
     // Use last segment duration when shorter than target duration and near live edge
     const fragments = newDetails.fragments;
-    if (fragments.length && reloadInterval * 3 > distanceToLiveEdgeMs) {
+    const liveEdgeMaxTargetDurations = 4;
+    if (
+      fragments.length &&
+      reloadInterval * liveEdgeMaxTargetDurations > distanceToLiveEdgeMs
+    ) {
       const lastSegmentDuration =
         fragments[fragments.length - 1].duration * 1000;
       if (lastSegmentDuration < reloadInterval) {
diff --git a/tests/unit/controller/level-helper.ts b/tests/unit/controller/level-helper.ts
index d548cd6f8b8..5c70a739b30 100644
--- a/tests/unit/controller/level-helper.ts
+++ b/tests/unit/controller/level-helper.ts
@@ -307,11 +307,11 @@ expect: ${JSON.stringify(merged.fragments[i])}`
       expect(actual).to.equal(2500);
     });
 
-    it('returns the last fragment duration when distance to live edge is less than three target durations', function () {
+    it('returns the last fragment duration when distance to live edge is less than or equal to four target durations', function () {
       const newPlaylist = generatePlaylist([3, 4], 0, 2);
       newPlaylist.targetduration = 5;
       newPlaylist.updated = true;
-      const actual = computeReloadInterval(newPlaylist, 15000);
+      const actual = computeReloadInterval(newPlaylist, 20000);
       expect(actual).to.equal(5000);
       const actualLow = computeReloadInterval(newPlaylist, 14000);
       expect(actualLow).to.equal(2000);