CDDB

The Compact Disc Database ( CDDB abbreviation ) is a database containing information on available on the market Audio CDs ( artist, title, track lengths, music genre) that can be accessed over the Internet. Currently, around 7.6 million CDs 97.2 million titles (as of December 21, 2008 ) is detected. The detection is done using a so-called hash value. Conversely, it is the users also possible to enter unrecognized CD data in the database. This information can be accessed by many computer Musikkodier and playback programs or viewed directly via the CDDB site.

CDDB was developed in 1995 by Ti Kan and Steve Scherf, 1998, she founded the eponymous company. This was taken over by Escient and renamed Gracenote. Gracenote has since held the rights to the database. In April 2008 she was bought for 260 million U.S. dollars of the Sony Corporation of America. Since the relaunch of the websites of Gracenote in September 2010, the music search in the CDDB is no longer accessible publicly on the website.

A change to the license terms in 2001 and the introduction of a revised protocol made ​​the free database access for commercial software and shareware impossible ( the license terms of Gracenote, however, allow free access for non-commercial software, Release 18 August 2007). Then the freedb and MusicBrainz the project have been established as an alternative. Gracenote is now being used in different music playing programs ( iTunes, for example ), but in part this is possible only after registration.

Example hash value after CDDB1

To generate the hash value, the table of contents ( TOC "Table of Contents" ) will read the CD. Relevant are the number and the order of the tracks on the CD as well as the respective title length. example:

# Track frame offsets: # 150 # 15095 # 28530 # 40556 # 60479 # 81952 # 100762 # 112675 # 128656 # 145954 # # Disc length: 2258 From the values ​​read a 4 -byte hash value is generated in the format XXYYYYZZ. For the above example: 6808d20a

  • The last byte (ZZ, in the example: 0a ) is the number of tracks on the album.
  • The two middle bytes ( YYYY, in the example: 08D2 ) resulting from the sum of the lengths of titles in seconds.
  • The first byte is a checksum of all the values ​​of the TOC. The sum is formed from all points of the initial positions of all tracks ( Tracks ) ( in seconds), modulo 255

There are several programs on the Web can compute the sample IDs for CDDB1.

ID collisions

If two CDs the same number of tracks and the same overall length, then there is a chance of 1:255 or more, that they have the same ID

Such a collision has been mentioned as a possible reason for the incorrect title information at the SOS Children's Village CD

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