How repeatable should the test results be?
Repeatability is excellent on good disc. Repeatability depends mostly on the disc, rather than the drive. If some parameter is outside Red Book limits (or even if one or more parameters are marginal), the results may be unpredictable. Once a disc is outside Red Book limits, you cannot predict how the player will react. Also, many errors are known as soft errors. They are not always repeatable because they are caused by disturbances to the players servo systems, rather than a loss of data. The disturbance can be slightly different each time you play the disc, with different results each time. Also, different players will react differently to these disturbances. Remember, the goal is not for every disc to test good; the goal is to detect problems! If you cannot get repeatable results on a disc, that is a sure sign that something is wrong with the disc. Almost certainly it has to do with pit geometry, because that is what determines how well the player’s servos will work.
