From cafe603694b47b4e4096648681dfe01721eedbaf Mon Sep 17 00:00:00 2001
From: aquilescanta <aquilescanta@google.com>
Date: Fri, 18 Nov 2016 03:30:44 -0800
Subject: [PATCH] Allow regressing media sequence numbers in HLS media
 playlists

This is techically not allowed by the spec[1] but might still occur in
certain scenarios. New playlists with older media sequence numbers are
ignored.

[1]: HLS draft version 20, section-6.2.1

Issue:#2059

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139564889
---
 .../exoplayer2/source/hls/playlist/HlsPlaylistTracker.java    | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java b/library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java
index abad300f70..e368b1c37f 100644
--- a/library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java
+++ b/library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java
@@ -311,6 +311,10 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
       // Playlist has not changed.
       return oldPlaylist;
     }
+    if (mediaSequenceOffset < 0) {
+      // Playlist has changed but media sequence has regressed.
+      return oldPlaylist;
+    }
     if (mediaSequenceOffset <= oldPlaylistSize) {
       // We can extrapolate the start time of new segments from the segments of the old snapshot.
       ArrayList<HlsMediaPlaylist.Segment> newSegments = new ArrayList<>(newPlaylistSize);