Noodlings

Things have settled down with my 4.1 release so I thought I’d tend to my neglected blog.

Today, I’m going to talk about getting info about your iTunes library, playlists and albums.

Now, the obvious way to do this would be through AppleScript/AppleEvents. The problem with this approach is that it requires iTunes to be running for it to work. To actually change stuff in your iTunes library, you will have to use AppleScript but for the purposes of this article, we are just looking at ways to get information about it.

The old way to do this was to parse the iTunes Library.xml file (located in ~/Music/iTunes). This file contains a dump of everything you need. Unfortunately, recent versions of iTunes do not generate this automatically; you have to enable it in its preferences (it’s in the “Advanced” tab).

Now, the notion of having to parse an XML file does sound painful but luckily it’s actually a property list so you can load it that way and access everything as NSArrays, NSDictionaries, NSStrings, etc.

With OS X 10.9 (yes, I know it’s macOS now but back then it was still OS X), Apple introduced the MediaLibrary API (ML). This provided a way of not just accessing the iTunes library, but the libraries of all of Apple’s other media apps (Photos, GarageBand, even Final Cut). No parsing involved but it is a fully asynchronous API so expect to deal with a lot of callbacks.

The last one (I don’t know exactly when it was released but it was the last one I discovered) is iTunesLibrary (ITLib) and it’s a bit easy to miss because, from what I can tell, it is not a part of the OS, but iTunes itself. You can find the framework under /Library/Frameworks (not /System/Library/Frameworks). It provides similar functionality to the MediaLibrary framework, but specific to iTunes.

With so many options, which do you use? For the most part, they return the same information though it depends on the version of iTunes. With some versions, one API may return some special playlist that the others don’t. Also, ML is asynchronous while the others are synchronous. I don’t see that as a big deal either way as you can convert one into the other with a tiny bit of work.

The big differentiating factor is performance. Here are the results for getting a list of playlists for my library:

XML: 1.664939s
ML: 18.792855s
ITLib: 0.844415

I don’t think my library is the biggest in the world but it is significant (about 2000 albums). As you can see, ML is pretty damn slow with ITLib being much, much, much faster. What is surprising to me is how much faster parsing the XML file is than ML. It is possible, though, that I’m holding it wrong.

So, ITLib is my recommended API for this. It’s what Hazel uses starting with 4.1 (previously, it was parsing the XML when it was available and falling back to ML). That said, there is one wrinkle.

The persistent IDs of entities in iTunes are hex strings. In the XML file, they are zero padded. In ML, though it returns strings, they are not zero padded (rdar://26624642 for you Apple folks watching from home). To add even more confusion to the mix, they are NSNumbers in ITLib.

If you are using any of these APIs in isolation then it’s probably not a big deal, but if you want to later manipulate that entity using AppleScript (like importing files into a playlist), you will need to provide the zero-padded hex string. Something to keep in mind.