A code sequence is encoded using a code conversion table in which the parity
of
the code sequence varies until the code states become equal to each other. The
code word assignment used in this code conversion table is such that the decoded
code word constraint length is 3 blocks and q0q1
for an arbitrary information sequence is satisfied even if a DC control bit is
inserted at any of the first and second bits of an information word. Code states
s0 and s1 when information sequences d0 and d1
resulted from insertion of provisional DC control bits 1 and 0 inserted at
the top of an information sequence "1, 1, 0, 0, 0, 1, 0" are encoded starting with
a state 3 according to a predetermined code conversion table are equal to each
other, namely, s0=s1=6, in a third block, and two's complement
q0 of a sum of code sequences c0 up to a time when the code
states are equal to each other is "0" while two's complement q1 of a
sum of code sequences c1 up to that time is "1". That is, the condition
that q0q1 is met. The code sequence can be applied
to a recorder/player or encoder.
