From e53a6d3e6ae29cb05c55c7b8edf2d237a1f75c16 Mon Sep 17 00:00:00 2001
From: Speenah <speenah@pm.me>
Date: Tue, 13 Oct 2026 13:43:53 -0400
Subject: Merge pull request #17299 from Speenah/fix/hls-subtitle-timing

Fix fMP4 HLS subtitle timestamp map offset
---
 .../Controllers/SubtitleControllerTests.cs         | 40 ++++++++++++++++++++++
 .../Helpers/DynamicHlsHelperTests.cs               | 26 ++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 tests/Jellyfin.Api.Tests/Helpers/DynamicHlsHelperTests.cs

(limited to 'tests')

diff --git a/tests/Jellyfin.Api.Tests/Controllers/SubtitleControllerTests.cs b/tests/Jellyfin.Api.Tests/Controllers/SubtitleControllerTests.cs
index 77321f0b05..36b4e7156e 100644
--- a/tests/Jellyfin.Api.Tests/Controllers/SubtitleControllerTests.cs
+++ b/tests/Jellyfin.Api.Tests/Controllers/SubtitleControllerTests.cs
@@ -134,4 +134,44 @@ public class SubtitleControllerTests
             fileSystem.Object,
             NullLogger<SubtitleController>.Instance);
     }
+
+    [Theory]
+    [MemberData(nameof(GetVttTimestampMap_Success_TestData))]
+    public static void GetVttTimestampMap_Success(long mpegTimestamp, string expected)
+    {
+        Assert.Equal(expected, SubtitleController.GetVttTimestampMap(mpegTimestamp));
+    }
+
+    public static TheoryData<long, string> GetVttTimestampMap_Success_TestData()
+    {
+        var data = new TheoryData<long, string>();
+        data.Add(900000, "X-TIMESTAMP-MAP=MPEGTS:900000,LOCAL:00:00:00.000");
+        data.Add(0, "X-TIMESTAMP-MAP=MPEGTS:0,LOCAL:00:00:00.000");
+        return data;
+    }
+
+    [Theory]
+    [MemberData(nameof(GetSubtitleSegmentUrl_Success_TestData))]
+    public static void GetSubtitleSegmentUrl_Success(long positionTicks, long endPositionTicks, string accessToken, long vttTimestampMapMpegts, string expected)
+    {
+        Assert.Equal(expected, SubtitleController.GetSubtitleSegmentUrl(positionTicks, endPositionTicks, accessToken, vttTimestampMapMpegts));
+    }
+
+    public static TheoryData<long, long, string, long, string> GetSubtitleSegmentUrl_Success_TestData()
+    {
+        var data = new TheoryData<long, long, string, long, string>();
+        data.Add(
+            0,
+            300000000,
+            "abc123",
+            0,
+            "stream.vtt?CopyTimestamps=true&AddVttTimeMap=true&StartPositionTicks=0&EndPositionTicks=300000000&ApiKey=abc123&VttTimestampMapMpegts=0");
+        data.Add(
+            300000000,
+            600000000,
+            "abc123",
+            900000,
+            "stream.vtt?CopyTimestamps=true&AddVttTimeMap=true&StartPositionTicks=300000000&EndPositionTicks=600000000&ApiKey=abc123&VttTimestampMapMpegts=900000");
+        return data;
+    }
 }
diff --git a/tests/Jellyfin.Api.Tests/Helpers/DynamicHlsHelperTests.cs b/tests/Jellyfin.Api.Tests/Helpers/DynamicHlsHelperTests.cs
new file mode 100644
index 0000000000..d17ce0f896
--- /dev/null
+++ b/tests/Jellyfin.Api.Tests/Helpers/DynamicHlsHelperTests.cs
@@ -0,0 +1,26 @@
+using Jellyfin.Api.Helpers;
+using Xunit;
+
+namespace Jellyfin.Api.Tests.Helpers
+{
+    public static class DynamicHlsHelperTests
+    {
+        [Theory]
+        [MemberData(nameof(GetVttTimestampMapMpegts_Success_TestData))]
+        public static void GetVttTimestampMapMpegts_Success(string? segmentContainer, long expected)
+        {
+            Assert.Equal(expected, DynamicHlsHelper.GetVttTimestampMapMpegts(segmentContainer));
+        }
+
+        public static TheoryData<string?, long> GetVttTimestampMapMpegts_Success_TestData()
+        {
+            var data = new TheoryData<string?, long>();
+            data.Add(null, 900000);
+            data.Add(string.Empty, 900000);
+            data.Add("ts", 900000);
+            data.Add("mp4", 0);
+            data.Add("MP4", 0);
+            return data;
+        }
+    }
+}
-- 
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