From 7477bd87635568a5564cab3d22bb97943be538b6 Mon Sep 17 00:00:00 2001
From: brandonocasey <brandonocasey@gmail.com>
Date: Thu, 25 Mar 2021 15:10:50 -0400
Subject: [PATCH] fix: correct playlist end logic for live playlists

---
 src/playlist.js        | 16 +++++++++++-----
 src/sync-controller.js | 21 +++++++++++++++------
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/src/playlist.js b/src/playlist.js
index 59a236157..05f648cfb 100644
--- a/src/playlist.js
+++ b/src/playlist.js
@@ -37,6 +37,7 @@ const backwardDuration = function(playlist, endSequence) {
       };
     }
   }
+
   while (i--) {
     segment = playlist.segments[i];
     if (typeof segment.end !== 'undefined') {
@@ -104,7 +105,7 @@ const forwardDuration = function(playlist, endSequence) {
   */
 const intervalDuration = function(playlist, endSequence, expired) {
   if (typeof endSequence === 'undefined') {
-    endSequence = playlist.mediaSequence + playlist.segments.length;
+    endSequence = playlist.mediaSequence + (playlist.segments.length - 1);
   }
 
   if (endSequence < playlist.mediaSequence) {
@@ -293,13 +294,18 @@ export const playlistEnd = function(playlist, expired, useSafeLiveEnd, liveEdgeP
 
   expired = expired || 0;
 
-  const endSequence = useSafeLiveEnd ? safeLiveIndex(playlist, liveEdgePadding) : playlist.segments.length;
-
-  return intervalDuration(
+  let lastSegmentTime = intervalDuration(
     playlist,
-    playlist.mediaSequence + endSequence,
+    playlist.mediaSequence + playlist.segments.length - 1,
     expired
   );
+
+  if (useSafeLiveEnd) {
+    liveEdgePadding = typeof liveEdgePadding === 'number' ? liveEdgePadding : playlist.targetDuration * 3;
+    lastSegmentTime -= (playlist.targetDuration * 3);
+  }
+
+  return lastSegmentTime;
 };
 
 /**
diff --git a/src/sync-controller.js b/src/sync-controller.js
index 9c215b613..b90878e47 100644
--- a/src/sync-controller.js
+++ b/src/sync-controller.js
@@ -6,6 +6,12 @@ import {sumDurations} from './playlist';
 import videojs from 'video.js';
 import logger from './util/logger';
 
+const getSegmentIndex = (i, playlist, currentTime = 0) => {
+  const segments = playlist.segments;
+
+  return (playlist.endList || currentTime === 0) ? i : segments.length - (i + 1);
+};
+
 export const syncPointStrategies = [
   // Stategy "VOD": Handle the VOD-case where the sync-point is *always*
   //                the equivalence display-time 0 === segment-index 0
@@ -38,7 +44,8 @@ export const syncPointStrategies = [
       currentTime = currentTime || 0;
 
       for (let i = 0; i < segments.length; i++) {
-        const segment = segments[i];
+        const segmentIndex = getSegmentIndex(i, playlist, currentTime);
+        const segment = segments[segmentIndex];
         const datetimeMapping =
           syncController.timelineToDatetimeMappings[segment.timeline];
 
@@ -49,21 +56,23 @@ export const syncPointStrategies = [
         if (segment.dateTimeObject) {
           const segmentTime = segment.dateTimeObject.getTime() / 1000;
           const segmentStart = segmentTime + datetimeMapping;
+
           const distance = Math.abs(currentTime - segmentStart);
 
           // Once the distance begins to increase, or if distance is 0, we have passed
           // currentTime and can stop looking for better candidates
-          if (lastDistance !== null && (distance === 0 || lastDistance < distance)) {
+          if (lastDistance !== null && lastDistance < distance) {
             break;
           }
 
           lastDistance = distance;
           syncPoint = {
             time: segmentStart,
-            segmentIndex: i
+            segmentIndex
           };
         }
       }
+
       return syncPoint;
     }
   },
@@ -79,7 +88,8 @@ export const syncPointStrategies = [
       currentTime = currentTime || 0;
 
       for (let i = 0; i < segments.length; i++) {
-        const segment = segments[i];
+        const segmentIndex = getSegmentIndex(i, playlist, currentTime);
+        const segment = segments[segmentIndex];
 
         if (segment.timeline === currentTimeline &&
             typeof segment.start !== 'undefined') {
@@ -95,10 +105,9 @@ export const syncPointStrategies = [
             lastDistance = distance;
             syncPoint = {
               time: segment.start,
-              segmentIndex: i
+              segmentIndex
             };
           }
-
         }
       }
       return syncPoint;