[Doc Sarvis]

When one inserts a CD for uploading to iTunes or other computer music coversion/storage software, the PC accesses an internet database of CD and track titles. My questions is, how exactly does this work? Does the CD contain a code that tells the database what it is looking for?

I just had a strange occurrence, that I'll explain once someone enlightens us on the process at work here.

 

[Davey]

No codes on CD. But the # of tracks and the individual track times make each CD pretty unique. Of course, the more that get entered and uploaded, the more chance there is for duplicates to show up. I think the local software on your computer that is CDDB compliant generates a number based on the above stats and uses that to index the database to find the CD. Or something similar.

 

[periurban]

But isn't that information held in a table of contents? If the TOC gets messed up (by being scratched or dirty) the CD can't be read.

Or am I thinking of minidisc?

 

[EyeAmEye]

Quote:

Originally Posted by Davey No codes on CD. But the # of tracks and the individual track times make each CD pretty unique. Of course, the more that get entered and uploaded, the more chance there is for duplicates to show up. I think the local software on your computer that is CDDB compliant generates a number based on the above stats and uses that to index the database to find the CD. Or something similar.

That can't be true. On a few cd's I've tried to encode through Itunes, a different cd of the same album title showed up instead of the actual one. If it goes by track number and track time, I can't see how that would be possible.

 

[Davey]

Quote:

Originally Posted by EyeAmEye That can't be true. On a few cd's I've tried to encode through Itunes, a different cd of the same album title showed up instead of the actual one. If it goes by track number and track time, I can't see how that would be possible.

Well, like I said in my post, the more popular CDDB gets, the more that will happen. The track times don't make a CD 100% unique, probably more like 99.9% or something.

 

[Davey]

Quote:

Originally Posted by periurban But isn't that information held in a table of contents? If the TOC gets messed up (by being scratched or dirty) the CD can't be read. Or am I thinking of minidisc?

Well yeah! That's what I was saying. The track numbers and track times are in a table of contents on the disc and that's the info used to compute the index number. But there aren't any track names or artist info or genre info or anything like that on the CD. It has to get it from the remote user database.

 

[EyeAmEye]

Quote:

Originally Posted by Davey Well yeah! That's what I was saying. The track numbers and track times are in a table of contents on the disc and that's the info used to compute the index number. But there aren't any track names or artist info or genre info or anything like that on the CD. It has to get it from the remote user database.

Still something missing here. What I meant was I would try to encode a cd, and the gracenote info would come up with a cd of the same album title, but with different track times and more/less tracks than the actual cd. If it was reading track info (track no. and time) off the cd, how would this be possible?

 

[grawk]

It generates a checksum based on # and length of tracks. It's possible to have different combinations result in the same final number. It's rare, but possible.

 

[Aman]

Quote:

Originally Posted by grawk It generates a checksum based on # and length of tracks. It's possible to have different combinations result in the same final number. It's rare, but possible.

Actually, I thought that iTunes used a simple Title search, and then if more than one of the same Title appears, it goes to an Artist search, and then once it has one CD the track number information is generated to see if they match, similar to an md5 file.

 

[Doc Sarvis]

Quote:

Originally Posted by Aman Actually, I thought that iTunes used a simple Title search, and then if more than one of the same Title appears, it goes to an Artist search, and then once it has one CD the track number information is generated to see if they match, similar to an md5 file.

That's what I thought, too. But here's the VERY strange thing that just happened to me. This will sound unbelievable, but I'm tellin' ya, it happened.

I have an extremely obscure vinyl LP (never released on CD) from the 1950s that I transferred to CD using an analog connection from my turntable to a home audio CD recording deck. I never entered anything by way of track names, titles, or anything else.

Then, I threw the CDR onto my PC to transfer the tracks into iTunes. I expected to see a list of track 1, track 2, track 3 and so on. However, I was completely amazed to see every track identified by name, along with the album, performer, and everything else.

You tell me, how the heck could this happen? It's almost mystical - I'm not making it up!

 

[Davey]

Quote:

Originally Posted by Doc Sarvis You tell me, how the heck could this happen? It's almost mystical - I'm not making it up!

It's a big world, Doc. Over 6 billion people and lots of them have internet connections. And probably quite a few have that very obscure album. And one of them did the same thing as you, transferred it to CDR and then uploaded the data to CDDB. I've heard of others that has happpened to so it's not too uncommon

 

[Doc Sarvis]

It truly boggles the mind. So you're saying that, when someone types in their data on a CDR and uploads it to iTunes for example, that data is shared with the Gracenote database? That I didn't realize.

 

[Doc Sarvis]

Follow Up: I did an experiement - I burned my vinyl copy of Jethro Tull's Songs from the Wood (excellent UK pressing, BTW) to CD using my stereo CD recorder. I then uploaded the disk to iTunes, and sure enough, the CDDB recognized it! Truly amazing.

 

[Davey]

Quote:

Originally Posted by Doc Sarvis It truly boggles the mind. So you're saying that, when someone types in their data on a CDR and uploads it to iTunes for example, that data is shared with the Gracenote database? That I didn't realize.

http://en.wikipedia.org/wiki/Gracenote

 

[Bunnyears]

Doc,

In the Itunes Advanced tab, there is the option "submit track names." A lot of people use that option, not understanding exactly what it does which is to send their track listings to gracenote. That is why you will find more than one set of track names for certain cds. It is also why you might find some of your vinyl albums on their database. If you find an album that doesn't have the track names and rip it to cd and don't send in the track names to gracenote, then if you put the cd into a different computer, it will again come up with blank tracknames. If you do "submit track names" then you will get your tracknames everytime you put the cd into any software program that accesses the gracenote cddb, even it it's just a compilation that you have made from a personal playlist.