Basics of Disc Quality

What is CD & DVD Quality?

A high quality CD or DVD disc is one that will play in every drive, every time, with performance and lifetime appropriate to the application.

How can I measure disc quality?

Because the Compact Disc and DVD formats are standardized, you can ensure the quality of a disc by making sure that all parameters are well within the specification.  The specification for all CD's is the so-called "Red Book" (also public standard IEC 908).  The specification for DVD discs is the DVD Forum Books (also public standard ECMA-267).  Any disc made to these specs should play in every drive every time, and have a long lifetime.

Unfortunately, the specifications specify more than 50 different parameters.  To measure each of these would require a million dollars worth of test equipment and a PhD to run it!  The good news is that there are things you can do at a modest cost that will greatly increase the probability of making high quality discs.

There are two elements to measuring disc quality: Error rates and pit geometry.

Error measurements 

The easiest way to get a picture of disc quality is to measure error rates.  Most serious defects will cause an increase in error rates.  By looking at both the quantity and severity of errors, you can get a pretty good picture of disc quality.  Playback errors can be caused by two things: Localized defects, and poor pit geometry.

In order for a disc to play, the reflected laser beam must generate track-following and focus servo signals so that the player can follow the track and stay focused.  Generation of the proper servo signals is completely dependent on the size and shape of the pits on the disc.  Without the proper "pit geometry", the disc will not play reliably.