You may occasionally want to re-rip one or more CDs that you own. One of the most common reasons for this is to rip CDs at a higher bit rate than you did back when disk space was more limited.
Wen you do this, you may want to ensure that you don’t lose metadata for the existing files. Not just the names of the tracks, albums and artists, but also information like play counts, artwork and ratings. If you do this carefully, you can ensure that when you re-rip CDs, you keep all the metadata.
The first thing you should know is that, if you rip a CD, and you already have the tracks in your iTunes library, iTunes will alert you to this, asking if you want to replace the existing tracks:
This is, in fact, what you want to do when re-ripping CDs. When iTunes replaces existing tracks, it only replaces the music. It retains all the other metadata, and it keeps the tracks in any playlists you’ve created. (If you re-rip and add the tracks to your iTunes library anew, then delete the old ones, these tracks will no longer be in playlists, though they will be in smart playlists.) But iTunes can only replace existing tracks if all the metadata matches.
So if you want to re-rip a CD, and have iTunes replace the music, you need to ensure that all the tags – the ones you can change – are the same. These are Name, Album, Artist, Genre, Year, Disc Number, Composer, Grouping, Album Artist and Comments. If any of these are different – if there’s even a comma or different capitalization – iTunes will think the track is different.
When you insert the CD, and examine it in iTunes, you can check the tags, comparing them to the existing files. You can correct any differences manually, or you can use Doug Adams’ Copy Tag Info Tracks to Tracks AppleScript. Read the information on Doug’s site to find out how to use this script.
I find it best to rip CDs by dragging their tracks to a “Temp” playlist; this lets me examine the tracks without having to find them in my iTunes library. If you want to re-rip CDs, I recommend making another playlist with their tracks, then checking that playlist after you rip each CD. You should see the tracks have been replaced. So, if you had tracks at 128 kbps, and you’re re-ripping them at 256 kbps, you’ll see the new bit rate in the playlist.
If you follow this procedure when re-ripping CDs, you’ll find that you save a lot of time: not only do you not have to manually update tags, but you also retain all the metadata that you can’t edit.