From 7dc6544d3441187f73393dac54dc358b3ceb98ed Mon Sep 17 00:00:00 2001
From: klizas <klizas@users.noreply.github.com>
Date: Mon, 5 Oct 2026 19:18:45 -0400
Subject: Backport pull request #18186 from jellyfin/release-12.z

Fix segment cleaner deleting segments ahead of playback when remuxing MKV

Original-merge: 3acc9c8443d7ee445c4fe015f2977a47d4ea57ac

Merged-by: crobibero <cody@robibe.ro>

Backported-by: Cody Robibero <cody@robibe.ro>
---
 .../MediaEncoding/TranscodingJob.cs                | 36 ++++++++++++++++++++++
 1 file changed, 36 insertions(+)

(limited to 'MediaBrowser.Controller/MediaEncoding/TranscodingJob.cs')

diff --git a/MediaBrowser.Controller/MediaEncoding/TranscodingJob.cs b/MediaBrowser.Controller/MediaEncoding/TranscodingJob.cs
index 5045030b9b..12600af384 100644
--- a/MediaBrowser.Controller/MediaEncoding/TranscodingJob.cs
+++ b/MediaBrowser.Controller/MediaEncoding/TranscodingJob.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Threading;
 using MediaBrowser.Model.Dto;
@@ -14,6 +15,7 @@ public sealed class TranscodingJob : IDisposable
     private readonly ILogger<TranscodingJob> _logger;
     private readonly Lock _processLock = new();
     private readonly Lock _timerLock = new();
+    private readonly ConcurrentDictionary<int, long> _segmentEndPositionTicks = new();
 
     private int _activeRequestCount;
     private Timer? _killTimer;
@@ -156,6 +158,40 @@ public sealed class TranscodingJob : IDisposable
     /// </summary>
     public int PingTimeout { get; set; }
 
+    /// <summary>
+    /// Records the end position of a served segment.
+    /// </summary>
+    /// <param name="segmentIndex">The segment index.</param>
+    /// <param name="segmentEndPositionTicks">The segment end position ticks.</param>
+    public void ReportSegmentDownloaded(int segmentIndex, long segmentEndPositionTicks)
+    {
+        if (segmentIndex < 0)
+        {
+            return;
+        }
+
+        _segmentEndPositionTicks[segmentIndex] = segmentEndPositionTicks;
+    }
+
+    /// <summary>
+    /// Gets the highest index among served segments whose end position is at or before the given position.
+    /// </summary>
+    /// <param name="positionTicks">The position ticks.</param>
+    /// <returns>The segment index, or <c>null</c> if there is none.</returns>
+    public int? GetHighestServedSegmentIndexEndingAtOrBefore(long positionTicks)
+    {
+        int? result = null;
+        foreach (var (index, endPositionTicks) in _segmentEndPositionTicks)
+        {
+            if (endPositionTicks <= positionTicks && (result is null || index > result))
+            {
+                result = index;
+            }
+        }
+
+        return result;
+    }
+
     /// <summary>
     /// Increments the active request count.
     /// </summary>
-- 
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