It's really tricky & quite frustrating. I recently started using iTunes Match about two months ago & it's been stressing me out! I have tons of albums that don't completely match up. Some tracks will show a match from the iCloud & then some won't. The ones that aren't exactly matched get a "waiting" status until they are uploaded to the iCloud.
A reason for this is a lot of tracks from albums on iTunes (especially remasters & re-releases) have slightly different beginning & ending points than the old CDs or vinyl releases of the past. You can see this when you compare your tracks' time lengths to the lengths of the "same" tracks in the iTunes store. If the track length is the same as the one on iTunes, you will get a "matched" status. If you delete your old track & download or stream the newer iTunes track you may notice that the song ends or starts at a slightly different point. It really pisses me off. I ripped 'Joe's Garage'
directly from the CDs & only 10 of the 19 tracks match up. This means if I allow the un-matched tracks to upload to the iCloud & THEN delete all of the tracks in the album ....whenever I go to stream the entire album, my "uploaded" tracks will end either a few moments before or after the next "matched" track starts. It really ruins the whole experience of one track seamlessly bleeding into the next track like most Zappa albums do. Especially since the sound quality will change from track to track (assuming your ripped tracks have a lower bit-rate than the 256kbps AACs from the iTunes store).
A bunch of discussion boards suggest that you can take your unmatched tracks & drop them into an audio editor to attempt to trim the beginnings or ends to try to trick iTunes Match into thinking it's the same exact track. Sometimes this works, but many times it doesn't. You have to trim it at the same exact micro-second as the iTunes version. Since you can't sample the entire track in the iTunes store, you have no idea how or where the song is supposed to be trimmed. All you have to work with is a track length time & it turns out to be a blind process.
Also, because some of the Zappa remasters are remastered from different variations or mixes than the CD versions, they may not match up. I found this forum post that lists variations of some of the different Zappa releases over the years. http://www.stevehoffman.tv/forums/showpost.php?p=7945195&postcount=644
The new remaster of 'Hot Rats'
, for example, is actually taken from the original vinyl version. The CD version was a completely different mix & some of the tracks were extended in that version. I personally prefer my CD version's mix over the remaster. I listened to the remastered version samples on iTunes & I cannot even hear the guitars & half of the other cool ambient sounds in "Willie the Pimp"
. Even if iTunes Match was to match my tracks from the CD, I would not want to delete them to rely on the matched ones in the iCloud. The remastered version of "The Gumbo Variations"
is about 4 minutes SHORTER than the version I grew up with from the CD!
Soooooo, long story short (too late!), iTunes Match is a complete mess! ...especially if you own several different variations or mixes of music that differ from the iTunes store versions. Enter at your own risk.