https://support.spotify.com/is/using_spotify/features/listen...
You have to install the Spotify App on your PC. Adding new songs has been incredibly flaky for me (not recognizing that I've put new songs in the folder, Windows 10). The artists and albums don't show up in the "Artists" or "Albums" part of my Spotify library.
To be fair, this is a pretty niche problem - tends to only be a problem when dealing with live music. So for example, if I have a concert recording, and make a playlist of those files for use in Spotify, Spotify will almost certainly replace at least one of those files with an album cut from the service. Now I'm left with a playlist of a live show that has had several tracks replaced with the _wrong_ version by Spotify.
The thing that initially drew me to Spotify was the fact that it made it pretty easy to integrate the music offered by the service with my personal library. I've always been disappointed that this feature was broken and left broken because the vast majority of people don't care about managing their own music libraries.
I'm a little salty about them closing off third-party development, but it's cool, they can do what they want with their stuff. I saw the writing on the wall a while ago when they were pushing Facebook integration like crazy -- as they become more and more anti-consumer, I'll simply avail myself of their services less and less until they offer me no value.
It's not an optimal solution, but iTunes can import songs from CDs, and you can add other mp3s to your library, but it doesn't cloud sync across devices.
Another solution is Google Play Music, which can import your iTunes library (and CDs indirectly from iTunes) and does do cloud sync.
The second way is if the file's fingerprint doesn't match any song in the iTunes Store catalog, then with iTunes Match, iTunes will actually upload the whole file and your other devices will then stream or download that exact file. There are some limits here; I think there's a limit on the song duration (not sure what it is but I'm pretty sure songs over 1 hour are past the limit), and there's a limit on total number of songs (at launch this was 25k; I think they've raised it higher but I don't know what the current limit is). Whatever the limits are, I do know my father's music collection (all manually ripped from a massive CD collection) is too large for iTunes Match, so he's stuck managing music the way we all used to do before Apple Music and iTunes Match came along.
As far as I'm aware, the Apple Music subscription supports the first mechanism but not the second, and the iTunes Match subscription is needed for the second option. That said, I'm not 100% positive.
Family sub for $14 month and $25 year for match to keep all my music even dodgy mp3s safe from bitrot is well worth it.
I move dozens of times a year, I no longer have to haul books and cds, I for one welcome my digital overlord.
There doesn’t seem to be a way for me to upload my own MP3s to the service like you can on Google Play Music.
It’s a separate service