Yes, iCloud Music Library has metadata-matching issues, but you don’t need to panic
- jul
- 31
Matching songs is hard, and Apple Music's not doing too well with it. But you can keep it from messing up your library pretty easily.
Earlier this week, Kirk McElhearn posted a rather-worrying article about iCloud Music Library's "matching" algorithms.
As you might know, Apple offers the iCloud Music Library service as part of Apple Music and iTunes Match. This scans your Mac's music library and attempts to do two things: "match" tracks in your library with songs in the Apple Music or iTunes Store catalog (which catalog depends on which service you're subscribed to), and upload songs it can't match directly to iCloud.
From McElhearn:
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...
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.
This means that by changing metadata on a track, you may be able to "fool" Apple Music into matching it with a different track in your iCloud Music Library.
Does this suck? Yep. It's also likely a bug, and I have no doubt that the folks at Apple are well aware of it and working hard to make sure it happens as infrequently as possible—preferably not at all.
But there's no reason to panic.
I can't reproduce it in my library
I have both an iTunes Match and Apple Music subscription, and decided to duplicate McElhearn's testing to see if I could get the same results. Answer: Not so much.
I used my auxiliary MacBook Pro which has a handful of local songs; most are stored in iCloud Music Library, matched with my desktop iMac.
I did this test three times for both a matched and uploaded track: First, I saved a copy of an AC/DC track that iTunes Match had matched to my desktop and reuploaded it to iTunes as The Weeknd's "Can't Feel My Face"; upon local deletion and redownload, the track remained AC/DC's music, though it kept the erroneous metadata I'd assigned it.
For the uploaded track, I added a 7-minute voice test I did for The Incomparable Radio Theatre on the Air, and labeled it as Foreigner's Juke Box Hero. Interestingly, when I first uploaded the track to iCloud, it very briefly matched as Apple Music; when I deleted it from my hard drive, however, the track reverted to showing as "Uploaded" in my iTunes library, and upon redownload, played the same 7-minute test as before. On redownload I did get pretty Foreigner album art, however.
What does this mean?
Likely what I've been saying about Apple Music, iCloud Music Library, and Match from the start: matching tracks is hard, and if you're trying to trick a complicated system, there's a chance you might do it.
From my tests, it looks as though Apple is still using acoustic fingerprinting, but may be augmenting this with metadata matching. I wouldn't be surprised if, due to the whole "having to connect to the Internet thing", the metadata matching occasionally happens before the fingerprinting; if you happen to immediately delete your track as it's processing, you may wind up accidentally with an Apple Music track.
I'm nervous now! Should I not use iCloud Music Library?
Well, first of all, do you have a local backup of your music? If so, none of this should really matter: iCloud Music Library is, ultimately, making a secondary copy with its matching and uploading. You'll get these matched and uploaded copies when you download tracks on secondary devices, but it shouldn't mess with tracks local to your hard drive.
Shouldn't and doesn't, however, are two different things, and as I said before—matching is hard. So if you have a history of problems with your Mac's iTunes library and you're concerned about iCloud Music Library messing up your tracks, it's simple: Just don't use it.
I made a really handy guide last week for people who want to use Apple Music without iCloud Music Library, which details a few different ways you can set up your devices to prevent your primary library from getting screwed up.
But seriously. Local backups are going to be your number one fix in this situation. Do not use iCloud Music Library as your backup. It was never designed as a backup service. Okay?
Still panicking?
Make a backup. Turn off iCloud Music Library. Check our our troubleshooting guide. Call Apple. Or ping us in the comments if you're confused about this whole thing and this didn't help straighten it out.
