1) I'll use the following terminology in this reply:Cover Art = a cover art file is a physical image file that is linked to the video file. The link is visible in the Image File library field. If the link contains just the file name without a directory path then the image file is stored in the video file's folder.
Thumbnail = MC creates and maintains a fast thumbnail cache of the cover art source files. The cached thumbnails make possible to quickly display thumbnail views that contain thousands of cover art images. This would be impossible if MC would need to read thousands of disk files each time such a view is browsed.
2) "Use Screen Grab for Thumbnail"When a grabbed image is saved the Image File field is updated accordingly. The linked image files are used for creating the thumbnails.
The old MC17 builds and MC16 stored the grabbed images automatically in a specific folder in the application data location. (
%appdata%\J River\Media Center 17\Data\ScreenGrabs\ or
%appdata%\J River\Media Center 16\Data\ScreenGrabs\ ) The filename was generated solely from the Name field and if necessary the filenames included an additional number part to avoid overwriting an existing image file.
The storage location and naming system changed in the build 17.0.55. The grabbed image file is now automatically stored in the same folder as the video file and the filename is identical with the video filename (only the filename extension differs).
3) What happened?Probably the Image File links were lost for some reason. I don't know why it happened. Though, if auto-import actually removed the missing video files from the database and the files were re-imported, the behavior is logical.
4) How to fix the problem?I don't think there's any way to fully automatically fix the problem, but the following steps would probably provide a useful workaround.
-- Install the latest MC17 build, if you don't already have it installed.
-- Load a library backup file that precedes the incident (File > Library > Restore Library...). You may want to create a new backup file of the current library state before proceeding (it will be useful if you have made changes that you want to preserve.)
-- Create a list view that shows the video files. Add the Image File column to the view. Does it show values that point to "...\Data\ScreenGrabs\" ?
-- If the answer is yes
*, select all video files and do:
right-click > Cover Art > Save Cover Art to External Location Specified In Options. This will copy the linked cover art files to the video files' locations, rename the copied files, and update the links in the Image File field accordingly.
The advantages of having the cover art files in the new default location and having the new default filename include:
- MC can automatically find the files and recreate the links.
- Uninstalling an old MC version (e.g. MC16) cannot delete the files that are stored in the old version's "appdata" location.
- When video files are moved by using the internal tools MC will move cover art automatically.
- The cover art files can be easily backed up together with the video files.
If necessary you can still link differently named or placed cover art files manually and MC will preserve the links. It just can't relink them automatically. A typical example would be a single common cover art image for a complete TV series.
5) "But I have created 20 new playlists and tagged 1500 audio and video files since the unfortunate incidence."No problem, just restore the latest backup file that you created during the step 4).
The video files will lose the cover art links again, but now the "Cover Art > Quick Find in File / Cover Art Directory" tool can easily fix the problem.
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* if the answer is no, you may have lost the old cover art links even earlier. If restoring the links is not possible you may need to relink the grabbed cover art files manually (assuming they still exist in the "appadata" location.) I hope that at least this would save you from "re-grabbing".
If you need to resort to manual linking the following posts might be helpful:
- How to add cover art by dragging & dropping an image file from Windows Explorer:
http://yabb.jriver.com/interact/index.php?topic=59513.msg415474#msg415474- More screenshots and additional info:
http://yabb.jriver.com/interact/index.php?topic=65156.msg436968#msg436968
