--- Pat Farrell <[EMAIL PROTECTED]> wrote: > On Thu, 2005-05-26 at 16:47 -0400, ron thigpen wrote: > > Pat Farrell wrote: > > > The "standard" way most software on the 'net identifies a CD is > > > using the CDDB hash, which is not unique, neither is any rational > > > combination of artist/album names. > > > > this is just a hash of the CD title track data isn't it? it might > not > > do the trick all by itself, but if it exists it would be a very > strong > > hint. hash/ID collisions should be reasonably rare. but not > everyone's > > tracks will have this tag. > > It is not about the name or title. And it is not associated with the > specific track/song > > It is a hash calculated from the number of tracks and the length of > each > track. Since lots of pop/rock/country CDs have around 10 songs and > the > songs are about 3 minutes long each, there are a lot of collisions > in those types of songs. In other areas, like Classical Symphonies, > there are usually only 6 movements per Album, and there is a fair > amount > of variance, so you don't see that many conflicts. > I don't know what the actual statistics are, but when you use > any of the rippers that talk to CDDB (or freedb) to get track info, > you see it 'frequently' pop up a selection dialog box to let > the user resolve the collisions.
yes. CDDB has many collisions because it's a very bad hash. it doesn't use enough bits from the CD TOC and the hashing formula is naive. but there are better ones, like CDindex, which uses most of the TOC bits and SHA-1 for the hash. I use a similar hash for my own collection (which uses even more TOC bits and a slightly better message formulation). practically speaking collisions with these hashes only occur for CDs with identical TOCs. http://wiki.musicbrainz.org/wiki.pl?DiscIDCalculation Josh __________________________________ Discover Yahoo! Have fun online with music videos, cool games, IM and more. Check it out! http://discover.yahoo.com/online.html _______________________________________________ Discuss mailing list Discuss@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/discuss
