iTunes’ sharing skills

One of the joys in life is sharing your tastes—and iTunes obliges that desire with built-in sharing features that let you open your library to other people, as well as take advantage of their reciprocal generosity. iTunes’ sharing features let you store your music in a central location and access it from any of your home computers—Mac or PC—that run iTunes.

Setting up sharing

While iTunes’ sharing functions may use complex network voodoo under the hood, setting them up is child’s play thanks to Apple’s zero-configuration networking technology, Bonjour. (iTunes sharing works only within the confines of a local network—a home or an office—and not over the Internet. iTunes did enable Internet sharing at one point, but Apple quickly shut it down due to copyright concerns).

Turn It On To get started, open iTunes’ preferences and click on the Sharing icon. Select the Look For Shared Music option to tell iTunes to search your network for other shared libraries, and select Share My Music to make your files available to others.

Sharing Options After you tell iTunes to look for other shared libraries, there isn’t much else to worry about. But when you share your music, you have a few more options (see “Open the Floodgates”). You can share your entire library or just selected playlists. You can give your library a unique name (in the Shared Name field). And you can set and require a password that users must enter to access your files (maybe you don’t want your kids getting into your stash of Richard Pryor routines just yet). When you’re done, click on OK. You’re now ready to share. Note that you can even share music from a copy of iTunes running in one user account with another account via OS X’s fast user switching feature—just leave iTunes running when you switch accounts and its library will be accessible. (If you want to create a centralized music repository, see “Set Up a Music Server,” below)

Firewall If other users on your network can’t see or connect to your library after you’ve enabled sharing, you may need to tell OS X’s built-in firewall to allow the traffic through. To set this up, open the Sharing preference pane (System Preferences: Sharing: Firewall, and then select iTunes Music Sharing). If one of the computers on your network is a PC, check out Apple’s instructions on how to work with Windows’ Internet Connection Firewall to share.

Playing shared music

Once you’re sharing files in iTunes, the other iTunes users on your network will see the shared name that you have set in iTunes’ preferences. You’ll see the name of their shared files in your Source list when iTunes discovers a shared library. If iTunes finds more than one shared library, it displays a blue icon labeled Shared Music; click on the triangle next to that icon to see all the available shared libraries.

Accessing Files To load a library, just click on its name once and wait for it to load; this can take a few seconds or a bit longer, depending on the size of the library you’re connecting to and the speed of your network. Once connected, you’ll see a list of all shared material in your main iTunes window. To find something, you can scroll through the selections in the main window, click on the Browse button at the top right of the iTunes window, or use the Search box next to it—just as you can with a local library. Unless you’re connected to someone who is sharing a single playlist, you’ll see a triangle next to that person’s shared icon, too—click on that triangle to see and access the playlists it contains (see “Let There Be Songs”).

Once you’ve found what you want, double-click on it to start playback. You can listen to individual songs, entire albums, or playlists. You can listen to nearly everything in a shared library, including MP3, AAC, Apple Lossless, AIFF, and WAV files; podcasts; videos; and Internet radio station links. If you try to play music or video that another user has purchased from the iTunes Music Store (iTMS), iTunes will require you to authorize your Mac for that user’s iTMS account (which counts against the total number of computers [five] that can play purchased content).

Limitations The only thing you can’t listen to from a shared library is Audible spoken-word content—it won’t even show up. But there are other limitations to consider with shared music. First, you can’t create your own playlists from shared files, or use shared files in iTunes’ Party Shuffle feature (if you want the songs in someone else’s library to play in random order, he or she will have to create a smart playlist with those files in random order). The other limitation, which affects only people on large networks, is that iTunes allows just five users to connect to any shared library in a given day (a 24-hour period). For most people, this won’t be an issue—but at work or on a campus, it may prevent you from listening to music in popular libraries.

Performance You’ll rarely come up against any performance or bandwidth limits when sharing music via iTunes. Even an original AirPort (802.11b) wireless network should be able to handle five streams of MP3 or AAC files at a time (but if you’re on an older Mac, send-ing out multiple streams may cause a drop in overall performance). For lossless or uncompressed audio (or video files), however, a faster network and computer can alleviate possible interruptions.

Keeping tabs on who’s listening

The Sharing pane in iTunes’ preferences will tell you how many users are connected to your shared library. But what it won’t tell you is what they’re actually listening to. To find out, open Activity Monitor (/Applications/Utilities), highlight the iTunes entry, and then click on the Inspect button in the toolbar. Now click on the Open Files And Ports tab and then scroll to the bottom of the list in the window below. If you’re listening to something in iTunes, your current song will show up first, but anything someone connected to you is viewing or listening to will show up like this:

	192.168.1.3:daap->192.168.1.8:56089	/Volumes/Backup/iTunes Music/Brian Eno/Another Day On Earth/01 This.m4a	

In this example, the person is connected from IP address 192.168.1.8 and is listening to Brian Eno’s “This.”

Set up a music server

Sharing music from individual computers is nice, but it requires that each Mac or PC be turned on for anyone to access files in the shared iTunes library (and you usually end up with a lot of duplicate songs, as many people on the network may have similar musical tastes). If you have a computer that is always available (a server, for example), you might want to consider consolidating all your iTunes files in one place. It doesn’t even need to be a fast Mac (you could get by with a 400MHz G3, Apple’s minimum for running iTunes), but it does need to be connected to your network.

Start by copying all your music and video files from the different computers around the house (either over the network or using DVDs or portable hard drives) to the iTunes library on the central Mac. With an entire household’s music, each person will want to create playlists to access his or her favorite files more easily. When you add new music from CDs, rip them on the server Mac. And when you purchase content from the iTunes Music Store, buy music from the server Mac so it gets added to your library.

The one downside to using a music server is that play counts and last-played dates don’t get updated on shared libraries, so any smart playlists you want to make that depend on these criteria won’t work. To get around these restrictions, check out Neil Evan’s free Shared Music Monitor 1.3.1. Once you install it on your server, this AppleScript monitors your iTunes Music folder, and keeps track of what songs the other copies of iTunes on your network play. Because of the way it works, Shared Music Monitor can also monitor songs played through hardware devices such as Roku’s SoundBridge or Slim Devices’ Squeezebox. Shared Music Monitor can be a CPU hog, and it does have several limitations, but it might be enough to make setting up a music server a good solution to your home media needs. And remember that by dedicating a spare Mac as a music server, you not only save disk space on your other Macs, but also give everyone in your house or office access to the same music.

[ Kirk McElhearn is the author of several books on the Mac and the iPod, including iPod and iTunes Garage (Prentice Hall, 2004). His blog, Kirkville, features articles about OS X, the iPod, iTunes, and more. ]