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The signature that the CD block looks for is stored in the outer "ring", and embodies part of the graphical content of the ring; however, it is known that most of the ring data is ignored by the Saturn*. The graphical content of the ring is formed as patterns in the CD channel data and is read as such, by exploiting the fact that the Yellow Book / ECMA-130 "scrambling" algorithm is deterministic and constructing the input data to deliberately produce runs of long and short pits after EFM encoding.
*: Actually, it appears likely that the Saturn is not even looking for an exact match. It might accept "fuzzy" matches for reliability reasons; runs of long/short pits can be difficult for CD readers to track. |