Eight-to-fourteen modulation (EFM) is a data encoding technique – formally, a line code – used by compact discs (CD), laserdiscs (LD) and pre-Hi-MD MiniDiscs.
According to European Patent Office former President Benoît Battistelli, "Immink's invention of EFM made a decisive contribution to the digital revolution.
Everyday handling damage, such as dust, fingerprints, and tiny scratches, not only affects retrieved data, but also disrupts the servo functions.
The use of EFM produces a disc that is highly resilient to handling and solves the engineering challenge in a very efficient manner.
The EFMPlus encoder is based on a deterministic finite automaton having four states, which translates eight-bit input words into sixteen-bit codewords.
The binary sequence generated by the finite state machine encoder has at least two and at most ten zeros between consecutive ones, which is the same as in classic EFM.