Preset Playlists
Right now, Preset Playlists are NOT dynamically updated, to technically they're not "Smart" playlists. That is, after you create them, they are not automatically updated based on the criteria they filter for. If you have made changes to your library that may affect what a Preset Playlist would show, you will need to re-generate it.
Preset playlists are generated from the playlist that is currently selected. So if you want to operate on your Library, please select it first. Searching does not affect what is generated into the new playlist.
Here's an example: Say I want to view duplicate files in my library, then remove any extras beyond the originals.
- Go to Library
- New Smart Playlist->Duplicate Files (if you have > 2000 songs, don't do it. you can't cancel and it'll take forever)
- go to newly created "Duplicates" playlist
- notice this holds EVERY copy of each duplicate song. What you want is a list that holds duplicates beyond the first one you imported, so you can delete them, leaving the first one you imported still in your library.
- Go New Smart Playlist->Cull Most Recent Duplicates (actually you could have jumped here from step 1)
- Go to newly created "Culled - Recent" playlist
- This list contains duplicates other than the first one you added to your library
- Select All (the next command operates on selection)
- Go Edit->Trash Original Files. This will not only remove them from your library, and all play lists, it will also move the original files on your hard drive into the trash, so you won't have them in your library ever again.
For an example of pulling all Audio out of iTunes, check out Consolidating.