1 files changed, 54 insertions, 0 deletions
diff --git a/tests/Jellyfin.Model.Tests/Dlna/StreamBuilderTests.cs b/tests/Jellyfin.Model.Tests/Dlna/StreamBuilderTests.cs
index 0b103debad..16c586bcda 100644
--- a/tests/Jellyfin.Model.Tests/Dlna/StreamBuilderTests.cs
+++ b/tests/Jellyfin.Model.Tests/Dlna/StreamBuilderTests.cs
@@ -675,5 +675,59 @@ namespace Jellyfin.Model.Tests
 
             Assert.Equal(expectedMethod, result.Method);
         }
+
+        [Theory]
+        // External text subs embedded into MKV when transcoding (#16403)
+        [InlineData("srt", true, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        [InlineData("ass", true, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        // External graphical subs embedded into MKV when transcoding
+        [InlineData("pgssub", true, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        [InlineData("dvdsub", true, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        // External subs remain external when transcoding to non-MKV containers
+        [InlineData("srt", true, PlayMethod.Transcode, "mp4", MediaStreamProtocol.hls, SubtitleDeliveryMethod.External)]
+        [InlineData("srt", true, PlayMethod.Transcode, "ts", MediaStreamProtocol.hls, SubtitleDeliveryMethod.External)]
+        // External subs remain external during DirectPlay even with MKV
+        [InlineData("srt", true, PlayMethod.DirectPlay, "mkv", null, SubtitleDeliveryMethod.External)]
+        // Internal subs still embedded into MKV when transcoding (existing behavior)
+        [InlineData("srt", false, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        [InlineData("pgssub", false, PlayMethod.Transcode, "mkv", MediaStreamProtocol.http, SubtitleDeliveryMethod.Embed)]
+        public void GetSubtitleProfile_ReturnsExpectedDeliveryMethod(
+            string codec,
+            bool isExternal,
+            PlayMethod playMethod,
+            string outputContainer,
+            MediaStreamProtocol? transcodingSubProtocol,
+            SubtitleDeliveryMethod expectedMethod)
+        {
+            var mediaSource = new MediaSourceInfo();
+            var subtitleStream = new MediaStream
+            {
+                Codec = codec,
+                Language = "eng",
+                IsExternal = isExternal,
+                Type = MediaStreamType.Subtitle,
+                SupportsExternalStream = true
+            };
+
+            var subtitleProfiles = new[]
+            {
+                new SubtitleProfile { Format = codec, Method = SubtitleDeliveryMethod.Embed },
+                new SubtitleProfile { Format = codec, Method = SubtitleDeliveryMethod.External }
+            };
+
+            var transcoderSupport = new Mock<ITranscoderSupport>();
+            transcoderSupport.Setup(x => x.CanExtractSubtitles(It.IsAny<string>())).Returns(true);
+
+            var result = StreamBuilder.GetSubtitleProfile(
+                mediaSource,
+                subtitleStream,
+                subtitleProfiles,
+                playMethod,
+                transcoderSupport.Object,
+                outputContainer,
+                transcodingSubProtocol);
+
+            Assert.Equal(expectedMethod, result.Method);
+        }
     }
 }