AniDB is built around files, and the basic structure of anidb assumes that each file will contain one episode. This is often not true, in two variations: split-episode files, and multi-episode files. Also there is the case of separate subtitle files.
Basically, what shadow-files would do is create an extra layer over the files - the episodes would point to shadow-files, and the shadow-files would then point to the actual files, be it just one single file, or more than one. Also, the shadow-file can belong to more than one single episode.
Because it would change the underlying structure of AniDB this would require a total rewrite of the database. Therefore, it will not be done in the current version. When (and if) AniDB gets a complete rewrite, it will most likely be included from the start.
The most common occurence of this are movies: almost every movie added the anidb will have several different versions released by different groups, some will only be one single file released, but some will be released as part 1 and 2 of 2, or even part 1, 2 and 3 of 3. With shadow-files all the files would be under the same "Complete Movie" entry, and when you select to get a version that is split into multiple files, you would see that it has more than one file, and be able to get each of the files you needed.
This happens alot when series air 2 episodes at the same time; there is normally not a separate opening/ending, and the episodes flow seamlessly into eachother. If you add one of these files, when shadow-files are implemented, all episodes that are contained in the file will get added to your mylist even though you only have 1 actual file. Also, for animes that end in these kind of special episodes, the groups' status will change to completed instead of stalled as they are now.
Very often movies will first be released as RAWs without subtitles, then afterwards, subtitles may be provided; but you can't be sure which RAW the subtitles are made for. The wrong raw for the wrong subtitles will most likely make the subtitles out of sync. With shadow-files you would be able to add the raws and the subtitle files to the correct shadow-file(s) in order to group them together in a logical way.
Here I have made some (crap) illustrations to further illuminate how it works, and what the differences are:
|Current (without shadow-files)||With shadow-files|
|Currently it works like this for normal files and episodes.||With shadow-files, the episode would link to the shadow-file and the shadow-file would link to the real file. Note that the shadow-files are transparent here - you will not notice a difference.|
|Currently if the file you have has multiple episodes in it, you need to add a generic file for the other episodes if you want to keep your mylist correct.||With shadow-files, you would only add the file you have, and both episodes would be added to your mylist.|
|Currently if an episode or movie is released in many files, you would haveto add each of those files to your mylist, and if they are not part of the regular episodes (i.e., listed as "O1 Episode 1 (Part 1 of 2)" and "O2 Episode 1 (Part 2 of 2)"), you would also need to add a generic file separately if you want your mylist to look like it should.||With shadow-files all files would be associated with the correct episode.|
|Separate subtitles for one episode|
|Right now, subs and RAWs are added separately to each episode, and you need to specify in a comment in the subfile which RAW it belongs to.||With shadow-files you would add the subs and the RAWs to the same shadow-file, and they would be grouped together that way.|
|Separate subtitles for many episodes|
|Currently, if you have a file with many subtitles in it, say a rar archive with subs for more than one episode, you need to add that to a Special "Other" episode "O1 Subtitles for episodes 1-2".||With shadow-files, you would add those subs to each shadow-file associated with the correct RAW for each episode.|
- Split episodes
- Currently for things like movies, when split files are released, they will get added to episode 2 and 3 (or 4, 5 and 6 in case of 3-file-splits).
However, if it is an OVA, this is sometimes not feasible, and it may get added to a special "Other" episode instead.
- Multiple episodes
- The current workaround for split episodes is to add the file to the first episode that it contains, and add generic files to your mylist for the remaining episodes in the file instead.
For some OVAs though, there will be special "Other" episodes added named something like "O1 Episode 1-3" or something like that.
- Separate subtitles
- There are a few different cases of these:
1. One subtitle file for one episode: the file will most likely be added to the episode with a comment telling which RAW(s) it belongs to.
2. Several subtitlefiles in an archive of some sort: The file will be added to a special "Other" listed as something like "O1 Subtitles for episodes 1-5".