IANAL - I am not a lawyer - so please take any legal implications below to a real attorney before you act on them. Similarly, I am not a cop; I have no concern whether you are pushing on - or across - the limits of copyright. Finally, my interests are in the sort of music to which none of this applies so I am reporting inferences from what I've read far more than my own experience.
The Compact Disc Data Base (CDDB) is a database of information about Compact Discs. I trust that the rest of what you read here will not be quite as simplistic as that. The CDDB contains timing information about commercial audio CDs. It uses a well-defined format to store the length of each track and information about the track (title, artist, etc.) and about the disc on which it is published. It is used by having a program describe a disc to the database in terms of the duration of its tracks. The database then reports the disc and track information back to the program that asked. The duration of a track is measured in minutes, seconds and frames - seventy-fifths of a second. Looking only at the values for seconds and frames, there is pretty nearly uniform (random) distribution over 4500 possible values. If there are fifteen tracks, then there are 4500^15 patterns of values. As long as no one has set out to spoof the system, two discs with the same pattern can be relied on to have the same contents.
An obvious question is: where is that database we are referencing? As long as it has the right structure and contents, it can be anywhere - and in fact it is distributed at Internet sites and (in fragments) on personal computers. Until recently, there was a master copy referenced freely over the Internet. At this time (July 2001) there is dispute over who owns the database, who owns its information, who can access it, who can duplicate it and on and on. It seems inevitable that litigation and disputation will continue longer than this page will last, so I have to leave you to find the CDDB you want to use for your applications.
Now we get to the question of protecting audio discs. The first issue is: what is being protected? Essentially, the publishers are trying to prevent digital copies; whatever the legal situation, they tolerate analogue copies. Of course, an analogue copy goes through DAC (Digital Analogue Conversion) followed by ADC (Analogue Digital Conversion - in case you hadn't figured it out), losing quality in each step. Whatever way the publisher mungs up digital extraction to prevent piracy, he cannot keep you from making an analogue copy or the disc simply wouldn't play. You can therefore get a good - good enough? - copy of a protected disc by playing it and capturing its output with a full-duplex sound card or a program such as TotalRecorder (linked from this site).
Now let's put the pieces together. If you make an analogue copy, count on it - your disc will not be recognized confidently by the CDDB. Your capture of the duration of a track simply won't match that of the protected source. That will give you the job of entering track information, but the copy will be made and will play. Unless you're selling the result, the publishers won't call in the cops.
E-mail me at cdrecording@mrichter.com
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