How Many Matches Does iTunes Match Match, When iTunes Match Does Match Matches?

Apple introduced iTunes Match earlier this week, and I haven’t written anything about it, given that my colleagues at Macworld have done such a good job. I’m also busy working on an update to my Take Control of iTunes 10: The FAQ, which I hope to have finished very soon. (I also have some criticism of iTunes Match, which I wrote about for Macworld: iTunes Match shouldn’t shun those with big libraries.)

In the meantime, what has perplexed me in my experiments with iTunes Match is the number of tracks that aren’t matched. In some cases, a single song may not be matched, even though the rest of an album is matched – Lex Friedman, writing at Macworld, pointed out that in many cases, one song on The Beatles’ Abbey Road (She Came In Through the Bathroom Window) wasn’t matched, even though all the others were. (It turns out that in Lex’s survey of people who tried to match that album, I was the only person who did see that song matched.)

But it’s very odd that some things match and others don’t. I don’t think it has to do with Apple’s recognition algorithm, and suspect that it’s more of a bug. I’ve seen a number of cases where one or more tracks won’t match, even among items that I had purchased from the iTunes Store.

This morning I did an experiment for the people at Hyperion Records (who are one of my sponsors). They asked me to check two albums: one that is sold on the iTunes Store, and has sold quite well, and another, a compilation, that is not on the iTunes Store, but whose individual tracks are all available from the iTunes Store on different discs. The results were surprising: in both cases, some, but not all tracks were matched. In the first example, two of 14 tracks were not matched and had to be uploaded; in the second example, only 8 of 20 tracks were matched. The screen shot below shows the results (click to see a larger screen shot).

I’m perplexed by this, and I wonder how exactly Apple matches tracks. The album above that is sold on the iTunes Store uses exactly the same tags as in the files I tried to match, so if Apple were only matching by tags (which they are not), it would be a perfect match. I know they use some sort of acoustic fingerprinting, and I wonder what causes certain tracks to not be matched.

I have no answers here, simply evidence of the oddity of iTunes Match. If you have other interesting examples to share, feel free to mention them in the comments.

Addendum: it’s worth noting that if you have iTunes match files with poor or non-existent tags, you won’t get tagged versions of those tracks when you redownload them. iTunes stores your tags, and doesn’t supply tags based on their matches.

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18 replies
  1. Leopold Green says:

    Hi Kirk,

    Strange behaviour indeed. As I’m in the UK can’t try out ITunes Match yet… as someone else who has a large quantity of live GD music in iTunes [as well as much other live music never commercially released] I imagine iTunes Match will be of limited value. Do you know how it handles such material? Will it allow uploads or does it just match song titles back to their studio versions [assuming they exist] meaning, for instance, that one would end up with 150 Friends of the Devil all of which are the American Beauty version.

    I hope this some sense…

    • kirk says:

      It uploads your versions; it doesn’t match them with a different version of a song. So in my test library, it uploaded all the new Europe 72 release.

  2. bspachman says:

    I’ve seen the same behavior you describe.

    I’ve also had versions of purchased songs matched as DIFFERENT songs. I’ve also had MULTIPLE VERSIONS download. Notably, several of my DRM-encumbered tracks from the Complete U2 set were matched, but in the process of working through my library, I had occasion to use the “Update iTunes Match” command as well as toggle Match off and back on.

    Somewhere in that process, I ended up with at least a half-dozen cases of 2 downloaded m4a 256kbps versions of the original songs, where one of the new versions had the same duration as the original and the other new version had a substantially different duration.

    I have yet to actually listen to all of these tracks and see what the differences are–but it sure is odd!


  3. Dave Scocca says:

    Looking at all those tracks… is it possible that there are minor inconsistencies — capitalization, hyphen/en-dash/em-dash, curly v. straight quotes, spaces around punctuation — preventing an exact match?

    • kirk says:

      No, the matching isn’t based on tags, but rather on acoustic fingerprinting. You can see that if you try and match files (which I’ve done) where the tags have nothing to do with the names of the tracks.

  4. David Greene says:

    Most of my iTunes tracks are lossless versions of CDs. You say iTunes Match will upload these tracks? At the same “sound quality” level? I find that hard to believe. Their published materials say that one’s music in the Cloud will be at 256 kbps. Has your research informed this question?

  5. Joe says:

    Now that iTunes Match has crossed the pond to the UK, I’d like to add a little something to the conversation… Firstly I’m glad we have it, earlier than I expected! Secondly though, out of my library of approx 13,000 items (deducting for ineligible ones), only about 2,500 have been matched, less than 20%. Most of my music is 256kbps but at least 128kbps AAC, some are even lossless. I do have about 1,000 items I’ve personally ripped from vinyl so I get that those wouldn’t be matched… But even accounting for that, the match rate seems incredibly low.

    Is this a common phenomenon, or is it possibly due to glitches in the UK release?

  6. Steve says:

    I’m also in the UK and have set up iTunes Match. For comparison out of 16,889 songs, I have 13,312 matched = 78% matched. a bit better than your experience Joe.

    I also have 2,661 uploaded, 817 purchased, , 55 duplicates and 20 ineligible –

    There are strange discrepancies, some tunes on an album not matched while the rest are.

    I’m looking forward to getting better quality files downloaded over time but it is a bit hit and miss so far with trying to match better quality uploaded tracks which are in the iTunes store. I’ve ended up with two copies of the same song on my imac, one “uploaded” 128kbps and one “duplicate” at 256 kbps. Both play but I can’t delete one without deleting the other.

    Still it’s early days and overall I’m extremely pleased with iTunes Match. The time spent synchronising two computers and an ipod classic with exactly the same tracks seem to be over for me.

  7. Joe says:

    I’ve finally done all my uploads, thanks to our fat pipe at work. But two other oddities I’ve noticed are:

    1. I have about five albums that I bought from the iTunes Store which are AAC Protected 128kbps. iTunes no longer sells those albums and so I don’t seem to be able to upgrade them. iTunes Plus has also disappeared from the Store (probably because I’m now on Match) so I can’t even upgrade them if I wanted to.

    2. Dance music mix files I have created with AudioBinder/Chaptertool get stuck “Waiting” and never upload, even after forcing an update. Perhaps because it’s confused as to whether they are audiobooks or not?

    • kirk says:

      For 1, that’s the way it works. For 2, that’s odd; are the files more than 200 MB? If so, they should be “ineligible.” If not, perhaps the chapter breaks are freaking iTunes out. But it’s not seeing them as audiobooks, I don’t think.

      • Joe says:

        1 is fine, however I would’ve upgraded my songs to iTunes Plus had I known they were being discontinued… Ah well.

        2 does seem weird. Only one or two of the files are over 200MB, and yes they are just labelled as “Ineligible”. The rest just hang on “Waiting”. Have you used any Chaptertool-based apps to create audio files with chapters? It’ll be a shame if they don’t allow these, because I’ve invested quite a bit of time in creating them.

        • kirk says:

          1 – there’s no guarantee that you would have been able to. If they’re not in the iTunes Store any more, then you can’t. I noticed that for a number of my purchases, even before iTunes Match.

          2 – No, I’ve never tried that. Maybe I’ll try one and see what happens…

  8. Iain Boyd says:

    Another UK user here, and I found it all very slow to begin with. My library is just shy of 10,000 songs, most of which are pretty ordinary fare. Only achieved about a 37% match; I was surprised that it wanted to upload nearly 3500 tracks , suggesting it knew nothing about the CDs of such artists as Led Zeppelin, Massive Attack etc. (though there was some odd stuff, compilations etc in there too.)

    Well, it’s done all that, and now, using Jason Snell’s smart playlist approach, I have another 3600 downloading at higher quality. The unexplained step is how to delete all those items in a smart playlist. In the end I ‘rated’ them all with 2 stars, found them that way in the Music list and deleted them from there.

    Even now, in some cases, it seems to be replacing Purchased AAC 256 files with new copies of the same – which seems unnecessary.

    Once it’s finished, I will run Match again and see if it improves its results.

  9. tboy says:

    is it possible to check how many tracks you will match before itunes starts uploading them (and I have to pay for it). Also maybe i am missing something, but what happens with files already at 320, do they stay at 320? Finally – if you download a higher bit rate version, am I right assuming that my taggign and artwork will be replaced by the generic ones for that file, and my comments not appear? thanks

    • kirk says:

      No, you can’t check.

      320 kbps files, if matched, will be available as 256 versions. If not, they’ll be uploaded.

      Your tagging and artwork are maintained for matched tracks.


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