From 82d2a8af4539e75f434fbfb6869dd0b009a9e8db Mon Sep 17 00:00:00 2001
From: toneloke <tony@digimart.space>
Date: Tue, 9 Mar 2021 10:01:45 -0800
Subject: [PATCH] added: cherry picked code from WEBTECH-6432

---
 src/controller/subtitle-stream-controller.js | 24 ++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/controller/subtitle-stream-controller.js b/src/controller/subtitle-stream-controller.js
index cc67c2c3d82..d3b77181009 100644
--- a/src/controller/subtitle-stream-controller.js
+++ b/src/controller/subtitle-stream-controller.js
@@ -204,6 +204,30 @@ export class SubtitleStreamController extends BaseStreamController {
         if (!foundFrag) {
           foundFrag = findFragmentByPTS(fragPrevious, fragments, bufferEnd, maxFragLookUpTolerance);
         }
+        if (!foundFrag && trackDetails.live && fragPrevious && fragPrevious.start < fragments[0].start) {
+          /*
+          below is a real world example of what can happen in production.
+
+          fragPrevious  s:04:08:44.000Z, e:04:08:49.000Z -- was found by PDT
+
+          # response on subtitle/en/playlist.m3u8 on Nth call
+          fragments[0]: s:04:08:24.000Z, e:04:08:29.000Z -- s:4532.900002, e:4537.900002
+          fragments[1]: s:04:08:29.000Z, e:04:08:34.000Z -- s:4537.900002, e:4542.900002
+          fragments[2]: s:04:08:34.000Z, e:04:08:39.000Z -- s:4542.900002, e:4547.900002
+          fragments[3]: s:04:08:39.000Z, e:04:08:44.000Z -- s:4547.900002, e:4552.900002
+          fragments[4]: s:04:08:44.000Z, e:04:08:49.000Z -- s:4552.900002, e:4557.900002
+          # response on subtitle/en/playlist.m3u8 on (N+1)th call
+          fragments[0]: s:04:08:54.000Z, e:04:08:59.000Z -- s:4562.900002, e:4567.900002
+          fragments[1]: s:04:08:59.000Z, e:04:09:04.000Z -- s:4567.900002, e:4572.900002
+          fragments[2]: s:04:09:04.000Z, e:04:09:09.000Z -- s:4572.900002, e:4577.900002
+          fragments[3]: s:04:09:09.000Z, e:04:09:14.000Z -- s:4577.900002, e:4582.900002
+          fragments[4]: s:04:09:14.000Z, e:04:09:19.000Z -- s:4582.900002, e:4587.900002
+          # notice the gap from e:04:08:49.000Z to s:04:08:54.000Z, code below is to fix this issue
+          */
+
+          foundFrag = fragments[0];
+          logger.warn(`Gap detected in live subtitle playlist, using next available fragment {start: ${foundFrag.start}}`);
+        }
       } else {
         foundFrag = fragments[fragLen - 1];
       }