Ask the iTunes Guy: Consolidating iTunes libraries and library track limits

In this week’s column, I answer just two questions, both of which require fairly long explanations. The first asks about consolidating iTunes libraries on two computers, and the second asks if a large iTunes library slows down the app. You may be surprised how easy it is to accomplish the first, and how quirky iTunes can be regarding the second.

Consolidating two iTunes libraries

Q: I have two laptops, and both have iTunes. About 95% of each library is the same songs; the rest are different. I want to consolidate the two libraries into one that includes all the songs in both libraries. Then, I want that one consolidated library to be shared by these same two computers. How can I do this?

You can do both of these tasks using Home Sharing. This iTunes feature is designed to let you share libraries to other computers running iTunes on the same network. You also use Home Sharing to allow an Apple TV to access an iTunes library.

To start with, on each laptop, turn on Home Sharing. In iTunes, choose File > Home Sharing > Turn on Home Sharing. Enter your Apple ID and password to set this up. Note that both computers need to be signed in with the same credentials.

The first thing you want to do is to consolidate the libraries. Choose which computer will hold the final, complete library. In iTunes on that computer, click the Media Picker, at the top left of the iTunes window, and select the other library. It displays at the bottom of the menu with a house icon next to its name.

When you select a shared library, iTunes spins its gears for a bit, then loads its media. Click the Show menu, and choose Items Not in My Library. This filters the music to show only those tracks that are in the remote library, but not in the local library.

Now you can easily copy this music. Just select all the items—press Command-A on a Mac, or Control-A on Windows—and then click Import. iTunes copies all the music that’s not on the first library.

Now that you have consolidated your music to a single library, you can access this library from the other computer. You’ll probably first want to delete all the music from the second computer, and, after that, just mount the library as you did above. You’ll be able to play all the music from the main library on that computer, or on any other computer on your local network that is running iTunes.

How big can it be?

Q: Is there any limit to the number of tracks I can have in my iTunes library? Will a large library slow the app down?

Over the years, I’ve heard from thousands of iTunes users, and one question that comes back fairly often is this one. Not that there are a lot of iTunes users who are worried about having too much music, but there are enough who are worried.

My iTunes library contains about 70,000 tracks (though I have a second library with as many tracks again), but I’ve corresponded with iTunes users who have more than 200,000, even 300,000 tracks. Many are classical music collectors, but some are DJs, or people who work in recording who have versions of their own music, sound effects, or music to use for sampling or loops.

One thing to note is that when discussing the size of an iTunes library, it’s not the aggregate size of the files that matters, but the number of files. You may have many terabytes of high-resolution files, which take up twenty times as much space as, say, iTunes Store downloads, but if the two libraries contain the same number of tracks, iTunes will more or less react the same. (It can be a bit slower when writing tags to very large files, especially if you store them on a network volume.)

There’s no hard and fast answer to this question, other than “it depends.” iTunes is a database. It simply records the locations of files and then, when you play them back, finds them on your computer or hard drive, and plays them. It’s really that simple. However, if you’re on an oldish computer without a sufficient amount of RAM, iTunes may struggle to search its database.

The only thing I’ve seen that can slow down iTunes is the presence of lots of smart playlists. Every time you make a change to a file, no matter how small the change, iTunes has to update all its smart playlists. These are like live searches, and iTunes has to constantly keep them up to date.

So if you are experiencing problems with iTunes’ responsiveness, and your computer is fairly recent, with a decent amount of RAM, check to see if you have a lot of smart playlists. Getting rid of some might speed things up.

Have questions of your own for the iTunes Guy? Send them along for his consideration.