support subtitles with encoded recordings

Emby.Server.Implementations/LiveTv/EmbyTV/EncodedRecorder.cs

@@ -154,7 +154,8 @@ namespace Emby.Server.Implementations.LiveTv.EmbyTV
 
             var durationParam = " -t " + _mediaEncoder.GetTimeParameter(duration.Ticks);
             var inputModifiers = "-fflags +genpts -async 1 -vsync -1";
-            var commandLineArgs = "-i \"{0}\"{4} -sn {2} -map_metadata -1 -threads 0 {3} -y \"{1}\"";
+            var mapArgs = string.Equals(OutputFormat, "mkv", StringComparison.OrdinalIgnoreCase) ? "-map 0" : "-sn";
+            var commandLineArgs = "-i \"{0}\"{4} " + mapArgs + " {2} -map_metadata -1 -threads 0 {3} -y \"{1}\"";
 
             long startTimeTicks = 0;
             //if (mediaSource.DateLiveStreamOpened.HasValue)