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.
Some people have mentioned that it can be easy to fool the system and gain free songs, but paying $9/month for Apple Music gives you access to every song either online or offline and you can add them to your library.
iTunes Match however is a different thing and they likely have to be almost sure the song you have is the song you should get access to from the iTunes Store.
> it can be easy to fool the system and gain free songs
I'm not sure what you mean by this. If you have Apple Music, you already have access to the entire catalog, so there's no trickery to gain "free songs", because they're already available. And if you don't have Apple Music, you can't do this either, because iTunes Match exclusively uses acoustic fingerprinting to ensure you can never download a song you didn't already have.
 For non-purchased content. For purchased content they obviously already know you own it.
It definitely does do acoustic fingerprinting since I've never had or continue to have issues with my music being swapped out for something else.
Absolutely. I have a number of mix CDs (above and beyond, mainly) where apple music has apparently looked up the songs by title and artist only and replaced all the tracks in a mix CD with single versions of those songs, needless to say not mixed. I also have other songs which simply refuse to sync.
The article says: If you subscribe to both iTunes Match and Apple Music, then iTunes matches your songs using digital fingerprinting - but I thought Apple Music included iTunes match. Do I seriously have to sign up for another product as well to get this working? Not very impressed.
Overall, it's actually working pretty amazingly.
I don't know if this is true, but it does make sense. Although I wonder who actually has music on their iOS device that isn't also in iTunes on their desktop, because the only way you'd hit this is by adding an iOS device to Apple Music that contains music that iTunes did not have.
Shazam does have acoustic fingerprinting, but it's much cheaper fingerprinting. And it's cheaper because Shazam is allowed to get it wrong. It doesn't have to get 100% of songs, and when it does get songs, it's perfectly ok for it to not recognize which particular performance a song is from if the artist has multiple versions.
But iTunes Match has to be as close to 100% accurate as it can (and better to avoid recognizing a song entirely, thus requiring it to be uploaded, than to mis-identify it as something else). Shazam is only listening to part of the song, but iTunes Match has to fingerprint the entire song, and the amount of processing it does per second of music may very well be higher as well.
 Where "use" means "upload music to"
I haven't been thrilled by the experience.
By the way, I agree that the same song can be sung by the same artist in multiple versions, especially if it is a "signature song" for the artist. Just Acoustic vs. Rock beat can totally be different, and they are both worthy of having in your music library and not wantonly purged because the metadata is the same.
My iPhone 5 was trying to process photos in the background last night and my Twitter app stopped responding to touches. The keyboard was lagging by 30-60 seconds.
Are you sure acoustic signatures will not be particularly onerous?
Pretty sure, yeah.
On the bright side, Apple does usually eventually fix or replace the hacky solutions. The other side of that is that it sometimes takes years.
If they checked acoustic signature wouldn't it still work with illegally downloaded music?
I imagine maybe this behavior is intended to replace uploading the song if the song doesn't match? It'd explain the situation in the quoted tweet where a live Phish show got replaced by a live recording, assuming that it failed to acoustically match and iTunes resorted to a metadata-based search instead.
If you want a bunch of songs or albums you don't have it's just a matter of search for it and listening to it, and to hit the 'make songs available offline' button.
 Note: I do not in any way condone music piracy. I'm just pointing out that it's more practical than stripping DRM. But really the best thing to do here is to just pay for your music.
I don't much care either way. People want digital content for free, publishers continue to rape the idea of works entering the public domain in a reasonable amount of time. Its hard to feel bad about either party.