If you’ve used iTunes Match in the past, you may know that it matches music using acoustic fingerprinting, which means that iTunes scans the music, and matches it to the same music. It doesn’t matter what tags files have: you could have, say, a Grateful Dead song labeled as a song by 50 Cent, and iTunes Match will match the Grateful Dead song correctly. (Here’s how Wikipedia defines acoustic fingerprinting.)

Apple Music, however, works differently. It does not use the more onerous (in time and processing power) acoustic fingerprinting technique, but simply uses the tags your files contain. And it can lead to errors. Here’s an example of how this can be a bit surprising.

Note: I have an iTunes Match subscription, which is active on the computer I used for these tests, so, theoretically, my tracks should be matched using digital fingerprinting. So I’m all the more confused about what’s happened here.

I started with a random piece of music from a disc of Bach chorales.

I changed its tags to Can’t Feel My Face, by The Weekend. (I picked this track because it’s one of the best selling tracks on the iTunes Store; I could have picked any track in the Apple Music catalog.)

I waited for Apple Music to match the file, deleted my local copy, and then downloaded it from the cloud.

Note that, so far, each version of the tracks shows a time of 1:57.

When the track downloaded, here’s what it looked like.

When I played it, it was not Bach.

Since Apple Music matches only using tags, it can’t tell the difference between, say, a studio recording and a live version of a song. Or an explicit version and a clean version. This explains why, for example, Macworld editor Susie Ochs found that a live Phish album was replaced by studio versions of the same tracks.

Note that, in my example above, even the duration was ignored: a 1:57 track was “matched” to a song that’s 3:36. You’d think that Apple Music would at least use durations (within a few seconds) to try and figure out which version of a song is being matched, when there are more than one, but it’s not even doing that.

Here’s another example. I took a short speech from a Royal Shakespeare Company CD of excerpts from their current production of The Merchant of Venice. I labeled it “The Other One” by the Grateful Dead. It matched, I deleted the local file, and downloaded this live track from April 1971, which was released on the Skull & Roses album.

Granted, the track that Apple Music gave me is a great version of the song, but at 18:04, it’s far from the 1:25 original track.

This is a very big problem with Apple Music. Since Apple already has the technology to match tracks using acoustic fingerprinting, they should be using this with Apple Music. Instead, it’s using scattershot matching, which results in lots of tracks showing up as being from different albums, from compilations, or totally different versions of songs.

Update: I’ve been unable to reproduce this issue, and my guess is that there was a glitch with Apple’s servers that has since been corrected. If you only subscribe to Apple Music, or are using it on a free trial, then your songs are matched using metadata only. If you subscribe to both iTunes Match and Apple Music, then iTunes matches your songs using digital fingerprinting.



Update 2: Monday morning. After someone on Twitter said that the above problem is happening to them, I tried again, and was able to reproduce it. As in my original experiment, I took a track, changed its name, and it got matched with the tracks whose name I entered in the tags. I downloaded it, and it was, indeed, that second track. I’ll keep looking into this.