DATA ENCODING METHOD AND DATA DECODING METHOD

摘要

A data encoding method by which a data word train constituted in units of (m x i) bits is converted into a code word train in units of (n x i) bits. In the method, a shift register (1) receives a data word train in units of (m x i) bits and an encoder (2) discrimates the constraint length indicating the length of the data word to be converted at present and, at the same time, discriminates which of the m bits is corresponding to the first bit of the data word to be converted at present. A selector (3) selects one conversion table out of a plurality of conversion tables which satisfy at least the minimum run length (d) and constitute variable-length tables in accordance with the constraint length and position of the first bit of the data word. Therefore, the product of the minimum inverting clearance and a detected window width can be made larger and, for example, data can be recorded on an information recording medium at a high density by generating the code word corresponding to the data word to be converted at present in accordance with the selected conversion table.