iTunes library tagging
A long while ago I looked into solutions to help me clean up and complete the mp3 tags of my iTunes music library. The problem is that many of my CDs were ripped on Linux, with a Ruby script I had written which used FreeDB (an alternative to CDDB) to fetch tags.
(Actually I've just dug out the sources of that script and it was more sophisticated than I remember - thanks to Ruby's DRb (Distributed Ruby) module, it had a ripper client feeding the wavs to an encoder server using lame and freeDB - not bad)
Anyway, FreeDB didn't really have the quality of CDDB, so many of my tags are lacking data such as genre or year. Having migrated now to OS X, I started searching for a convenient way of fixing this.
About the only solution I could find is Song Genie by Equinux (which name awfully sounds like a Linux shop :) ). It looked like a good solution but I quickly ran into serious limitations. One is that, in the case of tags with multiple choices, it's very tedious to undo the choice you've picked. But the main one is precisely that many songs will yield several possible tags. Song Genie treats your library as a list of tracks, not a list of albums. Therefore each track is seen independently of any other, and if a given song has been featured on an album and a compilation for instance, SongGenie will show both possibilities and ask you to you decide. It gets worse for jazz or classical music tracks, where the "packaging" scheme of songs into albums is much looser than in rock/pop. So, forget about using this for an automatic solution : you have to make sure you pick the right choice for each track, and it also occasionally gives only one choice which is still wrong. One particularly annoying detail : this applies to album titles, and also to track numbering.
To sum up, I'd often start with an album lacking genre and year, but otherwise properly named and numbered, and Song Genie would turn it to a bunch of tracks apparently coming from several different albums, each with their own numbering order. So much for a hassle-free solution.
When iTunes Match was introduced, I hoped it could provide a solution since the iTunes Store obviously has properly tagged files. I thought there would be a "update tags" feature in iTunes but no. I also tried matchtag which does pretty much that, fetching tags from iTunes Store (only on tracks which have been redownloaded via iTunes Match), but the problem of track vs. album dichotomy remains. Also, matchTag often fails to find info (I just tried with Pink Floyd's Dark Side of the Moon).
I also tried MusicBrain's Picard but the UI is very cumbersome, and while it does seem to be build around the concept of albums rather than tracks, I couldn't get it to work reliably and simply.
Finally I found iTunes Script, in particular this one which copies track info to CD tracks (for when you need to re-rip a CD). I simply reversed the source and destination, and now I can insert a CD, and copy its CDDB info on the tracks. The main problem is that it's so very tedious (I have to manually select the corresponding tracks in iTunes), but it's simple and does the job.
A remaining lead would be to use GraceNote's SDK to try and see if I can do without inserting a CD, or having to manually select the tracks in iTunes.