Media Longitevity/Care

Guy wrote: Basically by the time the data has been through three layers of ECC with interleave, the scrambler, and the EFM modulation, there's no way to guarantee that your pathological pattern will actually be pathological, because you don't know the initial phase relationship of any of the stages. In a carefully controlled lab environment with support from the design engineers you could do it, but as an end user of a black box (commercial CD/DVD writer) you can't, even armed with copies of the revelant standards, because you don't have enough visibility into the black box. By comparison, coming up with the pathological test cases for FM, MFM, M2FM, RLL (1,7) and (2,7), etc. is a piece of cake. For instance, one of the worst-case test patterns for MFM is the repeating byte sequence 6D, B6, DB (hexadecimal), which generates alternating short and long intervals between flux transitions with no medium length intervals. Though most test programs just repeated the first two bytes. Eric