Q: I recently edited the details of a large number of tracks and I want to restore the original data (ie, Artists Name instead of Various Artists). I thought if I deleted the tracks from iTunes and re-imported them this would restore the original track data but it doesn’t seem to work. I also tried changing the location of the folder I was importing from to see if this would make any difference but it seems wherever I import these tracks from they retain the changed information and not the original. Any suggestions?
A: When you update or modify track information via iTunes, this information is not only written to the iTunes database, but is also written directly into the AAC or MP3 file headers (or “tags”). As a result, when you reimport these files, or import them into a different library, iTunes reads this tag information to populate its database. There are a few pieces of information that are stored only in the iTunes library, but these are usually due to the lack of any corresponding standard tag to store them in (this includes information like rating, play count, last played date, etc).
The upside of this feature is that you don’t have to rely on a single point of failure (the iTunes database) for your critical track information. Unfortunately, this also means that if you want to revert to earlier information, there is really no easy way back unless you have a pre-import set of your media files backed up somewhere that you can revert to. Tag changes made by iTunes (or any other program) overwrite any information that was previously in the file headers, so there is really no way to get this information back without restoring to older versions of those files.
If you have a backup of your iTunes library database, you might be able to get away with reverting to that, although this can be tricky. iTunes will by default use the information contained in its database, but it will update this information from the ID3 tags whenever an MP3/AAC file is accessed (whether for editing or playback). Restoring the old iTunes database and using the “Convert ID3 Tags” under the menu will work to overwrite the MP3 file ID3 tags with the iTunes database information in some cases, but this is dependent on a number of factors that are likely outside of your control (such as existing ID3 tag versions within the MP3 files themselves).
Note also that marking your MP3/AAC files read-only will not solve this problem for future edits. Since iTunes insists on writing updated metadata into your file tags, it will not allow metadata to be updated for a read-only file, even in the iTunes database. Read-only tracks are shown with their properties greyed out when you try to edit them in iTunes.