Consolidating albums on itunes
Apps and media you purchase, along with any files imported to i Tunes and all your interactions are kept in a special folder on your computer.
To locate the i Tunes folder on your Mac, choose Go → Home → Music → i Tunes in the Finder menu.
This usually affects embedded artwork, or anything with ID3 frames bigger than 32k B. This means you will get the same result as using Picard's "Renaming/Moving Files" capability but without making i Tunes lose track of where all your songs are.
To "fix" this problem, or play safe, always use Picard's default setting of ID3v2.3 tags in the options (and i Tunes also). If you really really want to use Picard to rename/move your files.
Know that this will cause i Tunes to lose track of where all of these files are; meaning you will have to re-add them to the library (manually), which will take you hours and which may mean you will lose play counts and any other information that i Tunes keeps in its own library. Click "Next" (or Cmd N/Ctrl N on the keyboard) repeatedly, until you've passed the last track.
It does a fantastic job with organisation, however it can be a little bit complex when it comes to actually finding the files on your computer if it hasn’t been set up correctly.
If you choose to prevent i Tunes from copying files to the i Tunes Media folder when adding items to your library, copying the entire i Tunes folder to an external drive won’t copy the referenced media files that live outside of the i Tunes folder.