diff --git a/MediaBrowser.Api/Playback/BaseStreamingService.cs b/MediaBrowser.Api/Playback/BaseStreamingService.cs
index 252eadbe8d..418ec7fcbc 100644
--- a/MediaBrowser.Api/Playback/BaseStreamingService.cs
+++ b/MediaBrowser.Api/Playback/BaseStreamingService.cs
@@ -1068,7 +1068,19 @@ namespace MediaBrowser.Api.Playback
 
                         arg += string.Format(" -canvas_size {0}:{1}", state.VideoStream.Width.Value.ToString(CultureInfo.InvariantCulture), Convert.ToInt32(height).ToString(CultureInfo.InvariantCulture));
                     }
-                    arg += " -i \"" + state.SubtitleStream.Path + "\"";
+
+                    var subtitlePath = state.SubtitleStream.Path;
+
+                    if (string.Equals(Path.GetExtension(subtitlePath), ".sub", StringComparison.OrdinalIgnoreCase))
+                    {
+                        var idxFile = Path.ChangeExtension(subtitlePath, ".idx");
+                        if (FileSystem.FileExists(idxFile))
+                        {
+                            subtitlePath = idxFile;
+                        }
+                    }
+
+                    arg += " -i \"" + subtitlePath + "\"";
                 }
             }
 
diff --git a/MediaBrowser.MediaEncoding/Encoder/BaseEncoder.cs b/MediaBrowser.MediaEncoding/Encoder/BaseEncoder.cs
index d7789a5fd2..80bbc87e38 100644
--- a/MediaBrowser.MediaEncoding/Encoder/BaseEncoder.cs
+++ b/MediaBrowser.MediaEncoding/Encoder/BaseEncoder.cs
@@ -474,7 +474,19 @@ namespace MediaBrowser.MediaEncoding.Encoder
 
                         arg += string.Format(" -canvas_size {0}:{1}", state.VideoStream.Width.Value.ToString(CultureInfo.InvariantCulture), Convert.ToInt32(height).ToString(CultureInfo.InvariantCulture));
                     }
-                    arg += " -i \"" + state.SubtitleStream.Path + "\"";
+
+                    var subtitlePath = state.SubtitleStream.Path;
+
+                    if (string.Equals(Path.GetExtension(subtitlePath), ".sub", StringComparison.OrdinalIgnoreCase))
+                    {
+                        var idxFile = Path.ChangeExtension(subtitlePath, ".idx");
+                        if (FileSystem.FileExists(idxFile))
+                        {
+                            subtitlePath = idxFile;
+                        }
+                    }
+
+                    arg += " -i \"" + subtitlePath + "\"";
                 }
             }