Fix file extension based on container

Jellyfin.Api/Controllers/VideosController.cs

@@ -458,8 +458,6 @@ public class VideosController : BaseJellyfinApiController
             return BadRequest($"Input protocol {state.InputProtocol} cannot be streamed statically");
         }
 
-        var outputPath = state.OutputFilePath;
-
         // Static stream
         if (@static.HasValue && @static.Value && !(state.MediaSource.VideoType == VideoType.BluRay || state.MediaSource.VideoType == VideoType.Dvd))
         {
@@ -478,7 +476,7 @@ public class VideosController : BaseJellyfinApiController
 
         // Need to start ffmpeg (because media can't be returned directly)
         var encodingOptions = _serverConfigurationManager.GetEncodingOptions();
-        var ffmpegCommandLineArguments = _encodingHelper.GetProgressiveVideoFullCommandLine(state, encodingOptions, outputPath, "superfast");
+        var ffmpegCommandLineArguments = _encodingHelper.GetProgressiveVideoFullCommandLine(state, encodingOptions, "superfast");
         return await FileStreamResponseHelpers.GetTranscodedFile(
             state,
             isHeadRequest,

Jellyfin.Api/Helpers/StreamingHelpers.cs

@@ -225,7 +225,7 @@ public static class StreamingHelpers
 
         var ext = string.IsNullOrWhiteSpace(state.OutputContainer)
             ? GetOutputFileExtension(state, mediaSource)
-            : ("." + state.OutputContainer);
+            : ("." + GetContainerFileExtension(state.OutputContainer));
 
         state.OutputFilePath = GetOutputFilePath(state, ext, serverConfigurationManager, streamingRequest.DeviceId, streamingRequest.PlaySessionId);
 
@@ -559,4 +559,23 @@ public static class StreamingHelpers
             }
         }
     }
+
+    /// <summary>
+    /// Parses the container into its file extension.
+    /// </summary>
+    /// <param name="container">The container.</param>
+    private static string? GetContainerFileExtension(string? container)
+    {
+        if (string.Equals(container, "mpegts", StringComparison.OrdinalIgnoreCase))
+        {
+            return "ts";
+        }
+
+        if (string.Equals(container, "matroska", StringComparison.OrdinalIgnoreCase))
+        {
+            return "mkv";
+        }
+
+        return container;
+    }
 }

MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

@@ -6541,13 +6541,14 @@ namespace MediaBrowser.Controller.MediaEncoding
             return " -codec:s:0 " + codec + " -disposition:s:0 default";
         }
 
-        public string GetProgressiveVideoFullCommandLine(EncodingJobInfo state, EncodingOptions encodingOptions, string outputPath, string defaultPreset)
+        public string GetProgressiveVideoFullCommandLine(EncodingJobInfo state, EncodingOptions encodingOptions, string defaultPreset)
         {
             // Get the output codec name
             var videoCodec = GetVideoEncoder(state, encodingOptions);
 
             var format = string.Empty;
             var keyFrame = string.Empty;
+            var outputPath = state.OutputFilePath;
 
             if (Path.GetExtension(outputPath.AsSpan()).Equals(".mp4", StringComparison.OrdinalIgnoreCase)
                 && state.BaseRequest.Context == EncodingContext.Streaming)