update video probing

MediaBrowser.Providers/Manager/ProviderManager.cs

@@ -495,8 +495,6 @@ namespace MediaBrowser.Providers.Manager
                 ParentId = Guid.NewGuid()
             };
 
-            dummy.SetParent(new Folder());
-
             var options = GetMetadataOptions(dummy);
 
             var summary = new MetadataPluginSummary

MediaBrowser.Providers/MediaInfo/FFProbeVideoInfo.cs

@@ -488,7 +488,8 @@ namespace MediaBrowser.Providers.MediaInfo
         {
             var subtitleResolver = new SubtitleResolver(_localization, _fileSystem);
 
-            var externalSubtitleStreams = subtitleResolver.GetExternalSubtitleStreams(video, currentStreams.Count, options.DirectoryService, false).ToList();
+            var startIndex = currentStreams.Count == 0 ? 0 : (currentStreams.Select(i => i.Index).Max() + 1);
+            var externalSubtitleStreams = subtitleResolver.GetExternalSubtitleStreams(video, startIndex, options.DirectoryService, false).ToList();
 
             var enableSubtitleDownloading = options.MetadataRefreshMode == MetadataRefreshMode.Default ||
                                             options.MetadataRefreshMode == MetadataRefreshMode.FullRefresh;
@@ -512,7 +513,7 @@ namespace MediaBrowser.Providers.MediaInfo
                 // Rescan
                 if (downloadedLanguages.Count > 0)
                 {
-                    externalSubtitleStreams = subtitleResolver.GetExternalSubtitleStreams(video, currentStreams.Count, options.DirectoryService, true).ToList();
+                    externalSubtitleStreams = subtitleResolver.GetExternalSubtitleStreams(video, startIndex, options.DirectoryService, true).ToList();
                 }
             }