From 941298ee8108d79bd2f9bc010415103fddf54b0e Mon Sep 17 00:00:00 2001
From: Bond_009 <bond.009@outlook.com>
Date: Fri, 8 May 2026 21:29:13 +0200
Subject: [PATCH 1/3] Write subtitles using SubtitleEdit

We've been using SubtitleEdit to parse since 2021
https://github.com/jellyfin/jellyfin/pull/4984

I think it's time we start using it to write too
---
 .../Subtitles/AssWriter.cs                    |  57 ----
 .../Subtitles/ISubtitleWriter.cs              |  20 --
 .../Subtitles/JsonWriter.cs                   |  44 ---
 .../Subtitles/SrtWriter.cs                    |  49 ---
 .../Subtitles/SsaWriter.cs                    |  57 ----
 .../Subtitles/SubtitleEncoder.cs              |  65 ++--
 .../Subtitles/TtmlWriter.cs                   |  60 ----
 .../Subtitles/VttWriter.cs                    |  53 ----
 .../Subtitles/FilterEventsTests.cs            | 282 ------------------
 9 files changed, 35 insertions(+), 652 deletions(-)
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/AssWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/ISubtitleWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/SrtWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/SsaWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs
 delete mode 100644 MediaBrowser.MediaEncoding/Subtitles/VttWriter.cs
 delete mode 100644 tests/Jellyfin.MediaEncoding.Tests/Subtitles/FilterEventsTests.cs

diff --git a/MediaBrowser.MediaEncoding/Subtitles/AssWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/AssWriter.cs
deleted file mode 100644
index 7d7b80e99d..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/AssWriter.cs
+++ /dev/null
@@ -1,57 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// ASS subtitle writer.
-    /// </summary>
-    public partial class AssWriter : ISubtitleWriter
-    {
-        [GeneratedRegex(@"\n", RegexOptions.IgnoreCase)]
-        private static partial Regex NewLineRegex();
-
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-            {
-                var trackEvents = info.TrackEvents;
-                var timeFormat = @"hh\:mm\:ss\.ff";
-
-                // Write ASS header
-                writer.WriteLine("[Script Info]");
-                writer.WriteLine("Title: Jellyfin transcoded ASS subtitle");
-                writer.WriteLine("ScriptType: v4.00+");
-                writer.WriteLine();
-                writer.WriteLine("[V4+ Styles]");
-                writer.WriteLine("Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding");
-                writer.WriteLine("Style: Default,Arial,20,&H00FFFFFF,&H00FFFFFF,&H19333333,&H910E0807,0,0,0,0,100,100,0,0,0,1,0,2,10,10,10,1");
-                writer.WriteLine();
-                writer.WriteLine("[Events]");
-                writer.WriteLine("Format: Layer, Start, End, Style, Text");
-
-                for (int i = 0; i < trackEvents.Count; i++)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-
-                    var trackEvent = trackEvents[i];
-                    var startTime = TimeSpan.FromTicks(trackEvent.StartPositionTicks).ToString(timeFormat, CultureInfo.InvariantCulture);
-                    var endTime = TimeSpan.FromTicks(trackEvent.EndPositionTicks).ToString(timeFormat, CultureInfo.InvariantCulture);
-                    var text = NewLineRegex().Replace(trackEvent.Text, "\\n");
-
-                    writer.WriteLine(
-                        "Dialogue: 0,{0},{1},Default,{2}",
-                        startTime,
-                        endTime,
-                        text);
-                }
-            }
-        }
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/ISubtitleWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/ISubtitleWriter.cs
deleted file mode 100644
index dec714121d..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/ISubtitleWriter.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-using System.IO;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// Interface ISubtitleWriter.
-    /// </summary>
-    public interface ISubtitleWriter
-    {
-        /// <summary>
-        /// Writes the specified information.
-        /// </summary>
-        /// <param name="info">The information.</param>
-        /// <param name="stream">The stream.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
-        void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken);
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs
deleted file mode 100644
index 1b452b0cec..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs
+++ /dev/null
@@ -1,44 +0,0 @@
-using System.IO;
-using System.Text.Json;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// JSON subtitle writer.
-    /// </summary>
-    public class JsonWriter : ISubtitleWriter
-    {
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            using (var writer = new Utf8JsonWriter(stream))
-            {
-                var trackevents = info.TrackEvents;
-                writer.WriteStartObject();
-                writer.WriteStartArray("TrackEvents");
-
-                for (int i = 0; i < trackevents.Count; i++)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-
-                    var current = trackevents[i];
-                    writer.WriteStartObject();
-
-                    writer.WriteString("Id", current.Id);
-                    writer.WriteString("Text", current.Text);
-                    writer.WriteNumber("StartPositionTicks", current.StartPositionTicks);
-                    writer.WriteNumber("EndPositionTicks", current.EndPositionTicks);
-
-                    writer.WriteEndObject();
-                }
-
-                writer.WriteEndArray();
-                writer.WriteEndObject();
-
-                writer.Flush();
-            }
-        }
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/SrtWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/SrtWriter.cs
deleted file mode 100644
index 86f77aa067..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/SrtWriter.cs
+++ /dev/null
@@ -1,49 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// SRT subtitle writer.
-    /// </summary>
-    public partial class SrtWriter : ISubtitleWriter
-    {
-        [GeneratedRegex(@"\\n", RegexOptions.IgnoreCase)]
-        private static partial Regex NewLineEscapedRegex();
-
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-            {
-                var trackEvents = info.TrackEvents;
-
-                for (int i = 0; i < trackEvents.Count; i++)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-
-                    var trackEvent = trackEvents[i];
-
-                    writer.WriteLine((i + 1).ToString(CultureInfo.InvariantCulture));
-                    writer.WriteLine(
-                        @"{0:hh\:mm\:ss\,fff} --> {1:hh\:mm\:ss\,fff}",
-                        TimeSpan.FromTicks(trackEvent.StartPositionTicks),
-                        TimeSpan.FromTicks(trackEvent.EndPositionTicks));
-
-                    var text = trackEvent.Text;
-
-                    // TODO: Not sure how to handle these
-                    text = NewLineEscapedRegex().Replace(text, " ");
-
-                    writer.WriteLine(text);
-                    writer.WriteLine();
-                }
-            }
-        }
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/SsaWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/SsaWriter.cs
deleted file mode 100644
index b5fd1ed935..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/SsaWriter.cs
+++ /dev/null
@@ -1,57 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// SSA subtitle writer.
-    /// </summary>
-    public partial class SsaWriter : ISubtitleWriter
-    {
-        [GeneratedRegex(@"\n", RegexOptions.IgnoreCase)]
-        private static partial Regex NewLineRegex();
-
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-            {
-                var trackEvents = info.TrackEvents;
-                var timeFormat = @"hh\:mm\:ss\.ff";
-
-                // Write SSA header
-                writer.WriteLine("[Script Info]");
-                writer.WriteLine("Title: Jellyfin transcoded SSA subtitle");
-                writer.WriteLine("ScriptType: v4.00");
-                writer.WriteLine();
-                writer.WriteLine("[V4 Styles]");
-                writer.WriteLine("Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding");
-                writer.WriteLine("Style: Default,Arial,20,&H00FFFFFF,&H00FFFFFF,&H19333333,&H19333333,0,0,0,1,0,2,10,10,10,0,1");
-                writer.WriteLine();
-                writer.WriteLine("[Events]");
-                writer.WriteLine("Format: Layer, Start, End, Style, Text");
-
-                for (int i = 0; i < trackEvents.Count; i++)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-
-                    var trackEvent = trackEvents[i];
-                    var startTime = TimeSpan.FromTicks(trackEvent.StartPositionTicks).ToString(timeFormat, CultureInfo.InvariantCulture);
-                    var endTime = TimeSpan.FromTicks(trackEvent.EndPositionTicks).ToString(timeFormat, CultureInfo.InvariantCulture);
-                    var text = NewLineRegex().Replace(trackEvent.Text, "\\n");
-
-                    writer.WriteLine(
-                        "Dialogue: 0,{0},{1},Default,{2}",
-                        startTime,
-                        endTime,
-                        text);
-                }
-            }
-        }
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
index e0c5f3ad39..2dc71d08c4 100644
--- a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
+++ b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
@@ -26,7 +26,10 @@ using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
 using MediaBrowser.Model.MediaInfo;
 using Microsoft.Extensions.Logging;
+using Nikse.SubtitleEdit.Core.Common;
+using Nikse.SubtitleEdit.Core.SubtitleFormats;
 using UtfUnknown;
+using SubtitleFormat = MediaBrowser.Model.MediaInfo.SubtitleFormat;
 
 namespace MediaBrowser.MediaEncoding.Subtitles
 {
@@ -72,7 +75,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
         private MemoryStream ConvertSubtitles(
             Stream stream,
-            string inputFormat,
+            SubtitleInfo inputInfo,
             string outputFormat,
             long startTimeTicks,
             long endTimeTicks,
@@ -83,13 +86,18 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
             try
             {
-                var trackInfo = _subtitleParser.Parse(stream, inputFormat);
+                var subtitle = Subtitle.Parse(stream, Path.GetExtension(inputInfo.Path));
 
-                FilterEvents(trackInfo, startTimeTicks, endTimeTicks, preserveOriginalTimestamps);
+                FilterEvents(subtitle, startTimeTicks, endTimeTicks, preserveOriginalTimestamps);
 
-                var writer = GetWriter(outputFormat);
+                var formatter = GetWriter(outputFormat);
+
+                var text = formatter.ToText(subtitle, "untitled");
+                using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
+                {
+                    writer.Write(text);
+                }
 
-                writer.Write(trackInfo, ms, cancellationToken);
                 ms.Position = 0;
             }
             catch
@@ -101,26 +109,24 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             return ms;
         }
 
-        internal void FilterEvents(SubtitleTrackInfo track, long startPositionTicks, long endTimeTicks, bool preserveTimestamps)
+        internal void FilterEvents(Subtitle track, long startPositionTicks, long endTimeTicks, bool preserveTimestamps)
         {
             // Drop subs that have fully elapsed before the requested start position
-            track.TrackEvents = track.TrackEvents
-                .SkipWhile(i => (i.StartPositionTicks - startPositionTicks) < 0 && (i.EndPositionTicks - startPositionTicks) < 0)
-                .ToArray();
+            track.Paragraphs
+                .RemoveAll(i => (i.StartTime.TimeSpan.Ticks - startPositionTicks) < 0 && (i.EndTime.TimeSpan.Ticks - startPositionTicks) < 0);
 
             if (endTimeTicks > 0)
             {
-                track.TrackEvents = track.TrackEvents
-                    .TakeWhile(i => i.StartPositionTicks <= endTimeTicks)
-                    .ToArray();
+                track.Paragraphs
+                    .RemoveAll(i => i.StartTime.TimeSpan.Ticks > endTimeTicks);
             }
 
             if (!preserveTimestamps)
             {
-                foreach (var trackEvent in track.TrackEvents)
+                foreach (var trackEvent in track.Paragraphs)
                 {
-                    trackEvent.EndPositionTicks = Math.Max(0, trackEvent.EndPositionTicks - startPositionTicks);
-                    trackEvent.StartPositionTicks = Math.Max(0, trackEvent.StartPositionTicks - startPositionTicks);
+                    trackEvent.StartTime = new TimeCode(TimeSpan.FromTicks(Math.Max(0, trackEvent.StartTime.TimeSpan.Ticks - startPositionTicks)));
+                    trackEvent.EndTime = new TimeCode(TimeSpan.FromTicks(Math.Max(0, trackEvent.EndTime.TimeSpan.Ticks - startPositionTicks)));
                 }
             }
         }
@@ -142,14 +148,14 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             var subtitleStream = mediaSource.MediaStreams
                .First(i => i.Type == MediaStreamType.Subtitle && i.Index == subtitleStreamIndex);
 
-            var (stream, inputFormat) = await GetSubtitleStream(mediaSource, subtitleStream, cancellationToken)
+            var (stream, info) = await GetSubtitleStream(mediaSource, subtitleStream, cancellationToken)
                         .ConfigureAwait(false);
 
             // Return the original if the same format is being requested
             // Character encoding was already handled in GetSubtitleStream
             // ASS is a superset of SSA, skipping the conversion and preserving the styles
-            if (string.Equals(inputFormat, outputFormat, StringComparison.OrdinalIgnoreCase)
-                || (string.Equals(inputFormat, SubtitleFormat.SSA, StringComparison.OrdinalIgnoreCase)
+            if (string.Equals(info.Format, outputFormat, StringComparison.OrdinalIgnoreCase)
+                || (string.Equals(info.Format, SubtitleFormat.SSA, StringComparison.OrdinalIgnoreCase)
                     && string.Equals(outputFormat, SubtitleFormat.ASS, StringComparison.OrdinalIgnoreCase)))
             {
                 return stream;
@@ -157,11 +163,11 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
             using (stream)
             {
-                return ConvertSubtitles(stream, inputFormat, outputFormat, startTimeTicks, endTimeTicks, preserveOriginalTimestamps, cancellationToken);
+                return ConvertSubtitles(stream, info, outputFormat, startTimeTicks, endTimeTicks, preserveOriginalTimestamps, cancellationToken);
             }
         }
 
-        private async Task<(Stream Stream, string Format)> GetSubtitleStream(
+        private async Task<(Stream Stream, SubtitleInfo Info)> GetSubtitleStream(
             MediaSourceInfo mediaSource,
             MediaStream subtitleStream,
             CancellationToken cancellationToken)
@@ -170,7 +176,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
             var stream = await GetSubtitleStream(fileInfo, cancellationToken).ConfigureAwait(false);
 
-            return (stream, fileInfo.Format);
+            return (stream, fileInfo);
         }
 
         private async Task<Stream> GetSubtitleStream(SubtitleInfo fileInfo, CancellationToken cancellationToken)
@@ -267,43 +273,42 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             };
         }
 
-        private bool TryGetWriter(string format, [NotNullWhen(true)] out ISubtitleWriter? value)
+        private bool TryGetWriter(string format, [NotNullWhen(true)] out Nikse.SubtitleEdit.Core.SubtitleFormats.SubtitleFormat? value)
         {
             ArgumentException.ThrowIfNullOrEmpty(format);
 
             if (string.Equals(format, SubtitleFormat.ASS, StringComparison.OrdinalIgnoreCase))
             {
-                value = new AssWriter();
+                value = new AdvancedSubStationAlpha();
                 return true;
             }
 
             if (string.Equals(format, "json", StringComparison.OrdinalIgnoreCase))
             {
-                value = new JsonWriter();
-                return true;
+                throw new NotImplementedException();
             }
 
             if (string.Equals(format, SubtitleFormat.SRT, StringComparison.OrdinalIgnoreCase) || string.Equals(format, SubtitleFormat.SUBRIP, StringComparison.OrdinalIgnoreCase))
             {
-                value = new SrtWriter();
+                value = new SubRip();
                 return true;
             }
 
             if (string.Equals(format, SubtitleFormat.SSA, StringComparison.OrdinalIgnoreCase))
             {
-                value = new SsaWriter();
+                value = new SubStationAlpha();
                 return true;
             }
 
             if (string.Equals(format, SubtitleFormat.VTT, StringComparison.OrdinalIgnoreCase) || string.Equals(format, SubtitleFormat.WEBVTT, StringComparison.OrdinalIgnoreCase))
             {
-                value = new VttWriter();
+                value = new WebVTT();
                 return true;
             }
 
             if (string.Equals(format, SubtitleFormat.TTML, StringComparison.OrdinalIgnoreCase))
             {
-                value = new TtmlWriter();
+                value = new TimedText10();
                 return true;
             }
 
@@ -311,7 +316,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             return false;
         }
 
-        private ISubtitleWriter GetWriter(string format)
+        private Nikse.SubtitleEdit.Core.SubtitleFormats.SubtitleFormat GetWriter(string format)
         {
             if (TryGetWriter(format, out var writer))
             {
diff --git a/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs
deleted file mode 100644
index ea45f2070a..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs
+++ /dev/null
@@ -1,60 +0,0 @@
-using System.IO;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// TTML subtitle writer.
-    /// </summary>
-    public partial class TtmlWriter : ISubtitleWriter
-    {
-        [GeneratedRegex(@"\\n", RegexOptions.IgnoreCase)]
-        private static partial Regex NewLineEscapeRegex();
-
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            // Example: https://github.com/zmalltalker/ttml2vtt/blob/master/data/sample.xml
-            // Parser example: https://github.com/mozilla/popcorn-js/blob/master/parsers/parserTTML/popcorn.parserTTML.js
-
-            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-            {
-                writer.WriteLine("<?xml version=\"1.0\" encoding=\"utf-8\"?>");
-                writer.WriteLine("<tt xmlns=\"http://www.w3.org/ns/ttml\" xmlns:tts=\"http://www.w3.org/2006/04/ttaf1#styling\" lang=\"no\">");
-
-                writer.WriteLine("<head>");
-                writer.WriteLine("<styling>");
-                writer.WriteLine("<style id=\"italic\" tts:fontStyle=\"italic\" />");
-                writer.WriteLine("<style id=\"left\" tts:textAlign=\"left\" />");
-                writer.WriteLine("<style id=\"center\" tts:textAlign=\"center\" />");
-                writer.WriteLine("<style id=\"right\" tts:textAlign=\"right\" />");
-                writer.WriteLine("</styling>");
-                writer.WriteLine("</head>");
-
-                writer.WriteLine("<body>");
-                writer.WriteLine("<div>");
-
-                foreach (var trackEvent in info.TrackEvents)
-                {
-                    var text = trackEvent.Text;
-
-                    text = NewLineEscapeRegex().Replace(text, "<br/>");
-
-                    writer.WriteLine(
-                        "<p begin=\"{0}\" dur=\"{1}\">{2}</p>",
-                        trackEvent.StartPositionTicks,
-                        trackEvent.EndPositionTicks - trackEvent.StartPositionTicks,
-                        text);
-                }
-
-                writer.WriteLine("</div>");
-                writer.WriteLine("</body>");
-
-                writer.WriteLine("</tt>");
-            }
-        }
-    }
-}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/VttWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/VttWriter.cs
deleted file mode 100644
index 3e0f47b5ae..0000000000
--- a/MediaBrowser.MediaEncoding/Subtitles/VttWriter.cs
+++ /dev/null
@@ -1,53 +0,0 @@
-using System;
-using System.IO;
-using System.Text;
-using System.Text.RegularExpressions;
-using System.Threading;
-using MediaBrowser.Model.MediaInfo;
-
-namespace MediaBrowser.MediaEncoding.Subtitles
-{
-    /// <summary>
-    /// Subtitle writer for the WebVTT format.
-    /// </summary>
-    public partial class VttWriter : ISubtitleWriter
-    {
-        [GeneratedRegex(@"\\n", RegexOptions.IgnoreCase)]
-        private static partial Regex NewlineEscapeRegex();
-
-        /// <inheritdoc />
-        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
-        {
-            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-            {
-                writer.WriteLine("WEBVTT");
-                writer.WriteLine();
-                writer.WriteLine("Region: id:subtitle width:80% lines:3 regionanchor:50%,100% viewportanchor:50%,90%");
-                writer.WriteLine();
-                foreach (var trackEvent in info.TrackEvents)
-                {
-                    cancellationToken.ThrowIfCancellationRequested();
-
-                    var startTime = TimeSpan.FromTicks(trackEvent.StartPositionTicks);
-                    var endTime = TimeSpan.FromTicks(trackEvent.EndPositionTicks);
-
-                    // make sure the start and end times are different and sequential
-                    if (endTime.TotalMilliseconds <= startTime.TotalMilliseconds)
-                    {
-                        endTime = startTime.Add(TimeSpan.FromMilliseconds(1));
-                    }
-
-                    writer.WriteLine(@"{0:hh\:mm\:ss\.fff} --> {1:hh\:mm\:ss\.fff} region:subtitle line:90%", startTime, endTime);
-
-                    var text = trackEvent.Text;
-
-                    // TODO: Not sure how to handle these
-                    text = NewlineEscapeRegex().Replace(text, " ");
-
-                    writer.WriteLine(text);
-                    writer.WriteLine();
-                }
-            }
-        }
-    }
-}
diff --git a/tests/Jellyfin.MediaEncoding.Tests/Subtitles/FilterEventsTests.cs b/tests/Jellyfin.MediaEncoding.Tests/Subtitles/FilterEventsTests.cs
deleted file mode 100644
index 5f84e85592..0000000000
--- a/tests/Jellyfin.MediaEncoding.Tests/Subtitles/FilterEventsTests.cs
+++ /dev/null
@@ -1,282 +0,0 @@
-using System;
-using AutoFixture;
-using AutoFixture.AutoMoq;
-using MediaBrowser.MediaEncoding.Subtitles;
-using MediaBrowser.Model.MediaInfo;
-using Xunit;
-
-namespace Jellyfin.MediaEncoding.Subtitles.Tests
-{
-    public class FilterEventsTests
-    {
-        private readonly SubtitleEncoder _encoder;
-
-        public FilterEventsTests()
-        {
-            var fixture = new Fixture().Customize(new AutoMoqCustomization { ConfigureMembers = true });
-            _encoder = fixture.Create<SubtitleEncoder>();
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleSpanningSegmentBoundary_IsRetained()
-        {
-            // Subtitle starts at 5s, ends at 15s.
-            // Segment requested from 10s to 20s.
-            // The subtitle is still on screen at 10s and should NOT be dropped.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Still on screen")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Next subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-            Assert.Equal("2", track.TrackEvents[1].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleFullyBeforeSegment_IsDropped()
-        {
-            // Subtitle starts at 2s, ends at 5s.
-            // Segment requested from 10s.
-            // The subtitle ended before the segment — should be dropped.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Already gone")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(2).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(5).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Visible")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal("2", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleAfterSegment_IsDropped()
-        {
-            // Segment is 10s-20s, subtitle starts at 25s.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "In range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "After segment")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(25).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(30).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_PreserveTimestampsFalse_AdjustsTimestamps()
-        {
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(15).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(20).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(30).Ticks,
-                preserveTimestamps: false);
-
-            Assert.Single(track.TrackEvents);
-            // Timestamps should be shifted back by 10s
-            Assert.Equal(TimeSpan.FromSeconds(5).Ticks, track.TrackEvents[0].StartPositionTicks);
-            Assert.Equal(TimeSpan.FromSeconds(10).Ticks, track.TrackEvents[0].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_PreserveTimestampsTrue_KeepsOriginalTimestamps()
-        {
-            var startTicks = TimeSpan.FromSeconds(15).Ticks;
-            var endTicks = TimeSpan.FromSeconds(20).Ticks;
-
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Subtitle")
-                    {
-                        StartPositionTicks = startTicks,
-                        EndPositionTicks = endTicks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(30).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Single(track.TrackEvents);
-            Assert.Equal(startTicks, track.TrackEvents[0].StartPositionTicks);
-            Assert.Equal(endTicks, track.TrackEvents[0].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_SubtitleEndingExactlyAtSegmentStart_IsRetained()
-        {
-            // Subtitle ends exactly when the segment begins.
-            // EndPositionTicks == startPositionTicks means (end - start) == 0, not < 0,
-            // so SkipWhile stops and the subtitle is retained.
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Boundary subtitle")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(10).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "In range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("1", track.TrackEvents[0].Id);
-        }
-
-        [Fact]
-        public void FilterEvents_SpanningBoundaryWithTimestampAdjustment_DoesNotProduceNegativeTimestamps()
-        {
-            // Subtitle starts at 5s, ends at 15s.
-            // Segment requested from 10s to 20s, preserveTimestamps = false.
-            // The subtitle spans the boundary and is retained, but shifting
-            // StartPositionTicks by -10s would produce -5s (negative).
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Spans boundary")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(5).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "Fully in range")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(17).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: TimeSpan.FromSeconds(20).Ticks,
-                preserveTimestamps: false);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            // Subtitle 1: start should be clamped to 0, not -5s
-            Assert.True(track.TrackEvents[0].StartPositionTicks >= 0, "StartPositionTicks must not be negative");
-            Assert.Equal(TimeSpan.FromSeconds(5).Ticks, track.TrackEvents[0].EndPositionTicks);
-            // Subtitle 2: normal shift (12s - 10s = 2s, 17s - 10s = 7s)
-            Assert.Equal(TimeSpan.FromSeconds(2).Ticks, track.TrackEvents[1].StartPositionTicks);
-            Assert.Equal(TimeSpan.FromSeconds(7).Ticks, track.TrackEvents[1].EndPositionTicks);
-        }
-
-        [Fact]
-        public void FilterEvents_NoEndTimeTicks_ReturnsAllFromStartPosition()
-        {
-            var track = new SubtitleTrackInfo
-            {
-                TrackEvents = new[]
-                {
-                    new SubtitleTrackEvent("1", "Before")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(2).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(4).Ticks
-                    },
-                    new SubtitleTrackEvent("2", "After")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(12).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(15).Ticks
-                    },
-                    new SubtitleTrackEvent("3", "Much later")
-                    {
-                        StartPositionTicks = TimeSpan.FromSeconds(500).Ticks,
-                        EndPositionTicks = TimeSpan.FromSeconds(505).Ticks
-                    }
-                }
-            };
-
-            _encoder.FilterEvents(
-                track,
-                startPositionTicks: TimeSpan.FromSeconds(10).Ticks,
-                endTimeTicks: 0,
-                preserveTimestamps: true);
-
-            Assert.Equal(2, track.TrackEvents.Count);
-            Assert.Equal("2", track.TrackEvents[0].Id);
-            Assert.Equal("3", track.TrackEvents[1].Id);
-        }
-    }
-}

From 2b6da4481574cf67db6fd1325e08f59015884459 Mon Sep 17 00:00:00 2001
From: Bond_009 <bond.009@outlook.com>
Date: Sat, 30 May 2026 21:42:19 +0200
Subject: [PATCH 2/3] Clean up ConvertSubtitles

---
 .../Subtitles/SubtitleEncoder.cs              | 32 +++++--------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
index 2dc71d08c4..0192aa57f2 100644
--- a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
+++ b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
@@ -79,34 +79,18 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             string outputFormat,
             long startTimeTicks,
             long endTimeTicks,
-            bool preserveOriginalTimestamps,
-            CancellationToken cancellationToken)
+            bool preserveOriginalTimestamps)
         {
-            var ms = new MemoryStream();
+            var subtitle = Subtitle.Parse(stream, Path.GetExtension(inputInfo.Path));
 
-            try
-            {
-                var subtitle = Subtitle.Parse(stream, Path.GetExtension(inputInfo.Path));
+            FilterEvents(subtitle, startTimeTicks, endTimeTicks, preserveOriginalTimestamps);
 
-                FilterEvents(subtitle, startTimeTicks, endTimeTicks, preserveOriginalTimestamps);
+            var formatter = GetWriter(outputFormat);
 
-                var formatter = GetWriter(outputFormat);
+            var text = formatter.ToText(subtitle, "untitled");
+            var bytes = Encoding.UTF8.GetBytes(text);
 
-                var text = formatter.ToText(subtitle, "untitled");
-                using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
-                {
-                    writer.Write(text);
-                }
-
-                ms.Position = 0;
-            }
-            catch
-            {
-                ms.Dispose();
-                throw;
-            }
-
-            return ms;
+            return new MemoryStream(bytes, 0, bytes.Length, false, true);
         }
 
         internal void FilterEvents(Subtitle track, long startPositionTicks, long endTimeTicks, bool preserveTimestamps)
@@ -163,7 +147,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
             using (stream)
             {
-                return ConvertSubtitles(stream, info, outputFormat, startTimeTicks, endTimeTicks, preserveOriginalTimestamps, cancellationToken);
+                return ConvertSubtitles(stream, info, outputFormat, startTimeTicks, endTimeTicks, preserveOriginalTimestamps);
             }
         }
 

From 1dd02b0e30938ea4874da700aad048cc7ada637c Mon Sep 17 00:00:00 2001
From: Bond_009 <bond.009@outlook.com>
Date: Sat, 30 May 2026 21:42:57 +0200
Subject: [PATCH 3/3] Add JsonWriter back

---
 .../Subtitles/JsonWriter.cs                   | 58 +++++++++++++++++++
 .../Subtitles/SubtitleEncoder.cs              |  9 ++-
 2 files changed, 64 insertions(+), 3 deletions(-)
 create mode 100644 MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs

diff --git a/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs
new file mode 100644
index 0000000000..0e40181016
--- /dev/null
+++ b/MediaBrowser.MediaEncoding/Subtitles/JsonWriter.cs
@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Text;
+using System.Text.Json;
+using Nikse.SubtitleEdit.Core.Common;
+using Nikse.SubtitleEdit.Core.SubtitleFormats;
+
+namespace MediaBrowser.MediaEncoding.Subtitles;
+
+/// <summary>
+/// JSON subtitle writer.
+/// </summary>
+public class JsonWriter : SubtitleFormat
+{
+    /// <inheritdoc />
+    public override string Extension => ".json";
+
+    /// <inheritdoc />
+    public override string Name => "JSON Jellyfin";
+
+    /// <inheritdoc />
+    public override string ToText(Subtitle subtitle, string title)
+    {
+        using var ms = new MemoryStream();
+        using (var writer = new Utf8JsonWriter(ms))
+        {
+            var trackevents = subtitle.Paragraphs;
+            writer.WriteStartObject();
+            writer.WriteStartArray("TrackEvents");
+
+            for (int i = 0; i < trackevents.Count; i++)
+            {
+                var current = trackevents[i];
+                writer.WriteStartObject();
+
+                writer.WriteString("Id", current.Number.ToString(CultureInfo.InvariantCulture));
+                writer.WriteString("Text", current.Text);
+                writer.WriteNumber("StartPositionTicks", current.StartTime.TimeSpan.Ticks);
+                writer.WriteNumber("EndPositionTicks", current.EndTime.TimeSpan.Ticks);
+
+                writer.WriteEndObject();
+            }
+
+            writer.WriteEndArray();
+            writer.WriteEndObject();
+
+            writer.Flush();
+        }
+
+        return Encoding.UTF8.GetString(ms.GetBuffer(), 0, (int)ms.Length);
+    }
+
+    /// <inheritdoc />
+    public override void LoadSubtitle(Subtitle subtitle, List<string> lines, string fileName)
+        => throw new NotImplementedException();
+}
diff --git a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
index 0192aa57f2..e8bc0f1ffb 100644
--- a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
+++ b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
@@ -269,10 +269,12 @@ namespace MediaBrowser.MediaEncoding.Subtitles
 
             if (string.Equals(format, "json", StringComparison.OrdinalIgnoreCase))
             {
-                throw new NotImplementedException();
+                value = new JsonWriter();
+                return true;
             }
 
-            if (string.Equals(format, SubtitleFormat.SRT, StringComparison.OrdinalIgnoreCase) || string.Equals(format, SubtitleFormat.SUBRIP, StringComparison.OrdinalIgnoreCase))
+            if (string.Equals(format, SubtitleFormat.SRT, StringComparison.OrdinalIgnoreCase)
+                || string.Equals(format, SubtitleFormat.SUBRIP, StringComparison.OrdinalIgnoreCase))
             {
                 value = new SubRip();
                 return true;
@@ -284,7 +286,8 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                 return true;
             }
 
-            if (string.Equals(format, SubtitleFormat.VTT, StringComparison.OrdinalIgnoreCase) || string.Equals(format, SubtitleFormat.WEBVTT, StringComparison.OrdinalIgnoreCase))
+            if (string.Equals(format, SubtitleFormat.VTT, StringComparison.OrdinalIgnoreCase)
+                || string.Equals(format, SubtitleFormat.WEBVTT, StringComparison.OrdinalIgnoreCase))
             {
                 value = new WebVTT();
                 return true;