A lot of us rip our own cds and use sources like the CDDB to get our initial meta tag info, like artist, title, album, etc. Then more data is added to the songs, such as rating. Or we might change the title to remove the artist name.
That meta data is stored in the music file itself. What happens when a new codec like AAC comes out? We have to re-rip our music, and thus lose all of our tag customizations.
Apple tried to make this library management easier in iTunes 4, but if any of the tags don’t match the current CDDB tags, you get new songs. This is horrible because even the CDDB corrects it’s databases over time.
I suggest the following proposal. When a tune is ripped, that a tag be stored in MP3 or MP4 files, the MTST tag. This tag would initially hold three items of data:
Source: example is ‘CDDB’ ID: the cddb id for the album Track: the track number initially ripped Checksum: A checksum of ID against track, to allow even more uniqueness
This would let an application uniquely identify a song regardless of its current tags, allowing a user to replace the music but keeping their current meta tag information.