I used to buy albums on vinyl, then on CD and still think about my music in terms of albums. Before mp3 players, most portable music was on cassette in cars or on Walkman devices. Most people shunned pre-recorded cassettes and bought albums and then recorded them onto cassettes to listen to when not at home. Once people were taking their music out an about, it became a much less immersive experience, instead of listening to an album, (all of it, in the order the artist had carefully arranged), people would assemble tapes of their favourite songs rather as a DJ would, to suit a specific purpose. People had mix tapes for car journeys, for exercising to, for giving to friends. As mp3 players became prevalent you could access your music by artist, album, song, or a playlist (A replica mix tape). Space being at a premium early on, many people loaded only the songs they liked best from an album and used playlists to access them. As digital download stores appeared, the focus was less on albums than on songs. You could replicate your favourite mix tape by just buying the songs you liked from each album and using a playlist to assemble them.
When iTunes came along, the pattern was established and so the key item of data in iTunes is the song. Each song is stored with some meta data (Data about data) such as its name, the performer, the composer, the album it “belongs” to, its track number on that album, the album cover and so on).
Two interesting things arise from this :-
Albums don’t exist in their own right, they are called into existence by being mentioned in a song’s metadata.
Although songs know which album they belong to, they know nothing about which playlists they are referenced in.
Understanding these two things is a prerequisite to understanding iTunes match. It is a source of puzzlement to many that most of an album you have ripped from CD will match, but one or two songs may not. “Can’t it see ?”, we ask ourselves, “They’re on the same album, of course they should match” but it doesn’t see because it doesn’t look, because it doesn’t care.
Downloading all your favourite tracks from iCloud will not make your playlist appear, and similarly just copying a playlist to your iPhone or iPod does not ensure (Or didn’t when last I tried it) that all the tracks on it are transferred.
Album art in iTunes exists in many places, but the most important place is in the song, more specifically the copy of the song held on the PC/Mac holding the library. This may not be the same digital entity on your iPhone if your old mp3 file was matched in the iTunes store. You may hold an mp3 file with embedded art, but your iPhone/iPod has an m4a file from the store but not the album art from the store. Your preference for album art is given preference, so your old artwork is uploaded and attached to the new m4a download, in my case this is often not what I want.
Then begins the descent into the murky world of trying to outsmart the iTunes art mechanism and the near madness it engenders when it lets you change the artwork, and before you have had time to get it updated on your iPhone/iPod, changes it back to the crappy stuff you just spent ages updating.
I think I’ve got to the bottom of most of this mechanism, mostly by following guidance from those much cleverer and more persistent than I, but only via glimpses rather than a comprehensive understanding. Part of this is due to my failing to understand everything that’s going on and where, but much also is because the iTunes match / iCloud process is a complex one, which isn’t all necessarily working properly at the time you are using it, and things can only be detected from fragments of knowledge and inference.
For instance, I use iTunes match on my iPhone and as I’m writing new pieces of music I make changes, delete the old version from my iTunes library, insert the new one and update iTunes match. Usually the new file uploads and within seconds the phone updates the status of that song as needing download. Once in a while though, nothing happens after the upload and nothing I have tried can provoke the iPhone to check and update. This last happened to me about two weeks ago, so I went to the message boards to see what was up.
I read through a huge number of posts from people having trouble with iTunes match not making files available for download, interleaved with others asserting that they were having no problems so it must be something the original poster was doing wrong. This went nowhere for several pages until a grown-up entered the discussion and suggested that maybe Apple used different servers for iTunes matched content and user uploaded (Non-Matched) content and that maybe there was just a problem with this second group of servers. This seemed to fit all the facts and indeed fixed itself, (Apple fixed it) fairly soon. Nothing to do with the users or what they were doing, but a formerly hidden level of complexity revealed.
I shall write Part 2 “A definitive guide to sometimes fixing some of your iTunes artwork” presently.