What are errors?
Errors, for the purposes of this discussion, refers to “read errors”. They occur as a result of a problem in the process of reading those pits and lands. In one sense, the errors do not exist on the disc, but occur in the reading process. How a drive responds to those errors can vary a bit, and the result is that some drives are better at reading than others. Thus, a disc that causes read errors on one drive may not on another. Or the amount of errors may vary from one drive to another with the same disc. There are different types of errors, the most common of which are referred to as C1 and C2. A discussion of what these really are, how they are measured, etc. is not relevant here. In very general terms, C1 errors are the most common, and all discs cause them. They are corrected by the drive and do not generally cause any trouble. One measurement of a disc’s quality can be the level of C1 errors that are occurring, less is better. However, even relatively high C1 rates are not usually
Block errors on a disc are not a physical thing. They are a manifestation of how a disc interacts with a player. So different players can produce different error-rates from the same disc. Although there are rigid specifications that define what a CD should be, there are no such specifications for players. Therfore, to ensure wide compatibility, discs should have low errors. Additionally, a disc that is unreadable on one player, may seem to perform well on another.
