Everything You Ever Wanted To Know About Gracenote, & Some You Didn't
I know this Forum is old but I found it looking for the Supported Genres of Gracenote so I figured I'd add info for any future searchers.
Gracenote is a registered CDDB, & is used by iTunes, WinAMP & QMP to upload, & by many car radio systems, cellphones, Stereos, DVD/CD/Blu-Ray players & Pandora.
The biggest benefit to Gracenote over FreeDB is that Gracenote gets a lot of it's Metadata from the 'Content Owners' or the Artist/Label. Making a lot of it very good.
The next biggest advantage over FreeDB is that Gracenote offers more tag information. FreeDB gives you: 1.) Title (Album), 2.) Artist, 3.) Year, 4.) Genre, 5.) A Yes/No for [Various Artists] (For 'Band' commonly shown as 'Album Artist'), 6.) Year, & 7.) Track Title. It gives the Various Artists option, but doesn't allow for individual track artists.
Gracenote has: 1.) CD Artist, 2.) CD Composer, 3.) Album, 4.) Disk (like 1/3 or one of three), 5.) Genre (With more options than FreeDB's 'Category' genres but not unlimited like FreeDB's 'Genre' which could be "My Elbow Noises"), 6.) CD Year, 7.) 'Yes/No's for [Compilation] & [Gapless Album], 8.) TRACK Artist, 9.) TRACK Album Artist, 10.) Track Name, 11.) TRACK Grouping, 12.) TRACK Composer, 13.) TRACK Comment, 14.) TRACK Genre, 15.) TRACK BPM (Beats Per Minute)
FreeDB entries can be submitted to one of 11 categories, each of which can only contain 1 CD with any given identifier (hash number created by the number of tracks & length of each track.
Gracenote however, can have an (I believe) unlimited number of entries in the same category.
FreeDB is better at letting you choose between any of the matching 11 possible entries as it always shows a list unless there's only 1 entry that matches. Gracenote will think it knows better & sometimes give you the one it 'Thinks' you're looking for, even when there's 5 submitted entries (although if you re-search over & over, it might randomly pop-up a choice list)
Gracenote is much slower at processing submissions, FreeDB will usually be there 1 hr -5 days after submitting, while Gracenote can take over a month.
FreeDB was created because many Free 3rd-party apps creators didn't like the terms required for Gracenote licensing (like "if your program uses Gracenote it can't allow use of any other CDDB service" (FreeDB, MusicBrainz, Discogs, etc) thus why you can't get tag data from FreeDB or Apple Music Store in iTunes without Apple loosing it's Gracenote approval & since Apple Music Store will drop stuff it doesn't deem popular enough for people to buy anymore, that would make those CDs not found when importing.
FreeDB & MusicBrainz are linked so you can get info on MusicBrainz (used by those apps that listen to the song & determine the info as well as the most used one for Radio SongIDs, as well as Last.fm) using FreeDB
FreeDB uses the older, more compatible CDDB1, which is why there is less info (like no 'Composer' field) making Gracenote (CDDB2) better for classical music.
Gracenote can include Lyrics (Though not through iTunes) & can identify downloaded MP3s (Although I don't know why you'd want to as it is part of the Metadata & if you loose the Metadata, you loose the identifier too)
Gracenote can also include the Album Art, though this is disabled in iTunes store as iTunes wants you to have a store account to get it from their store (for free) & not allow you to get foreign artwork without an account in that country's store.
Gracenote works with DVDs & Videos.