fixes #2365 - External bitmap subtitles are loaded incorrectly

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 + "\"";
                 }
             }
 

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 + "\"";
                 }
             }