Patent ID: 7164644

Claim:
A reproduction apparatus for an optical disc that has a sector including a plurality of frames, said reproduction apparatus comprising: a reading unit operable to optically read, from the plurality of frames, a first channel bit value and a second channel bit value that constitute main information, and generate a channel signal, the channel signal being composed of High sections and Low sections, the High sections and Low sections each corresponding to run lengths of the first channel bit value in the main information, and each transition point between a High section and a Low section corresponding to the second channel bit in the main information; a first judgment unit operable to judge whether or not leading and lagging errors appearing at transition points in the channel signal are arranged according to a predetermined rule; and a bit setting unit operable to set a predetermined bit value of sub information when said first judgment unit judges that the leading and lagging errors are arranged according to the predetermined rule, wherein: the leading and lagging errors cause jitters; and a displacement amount Δt for the leading and lagging errors is determined from σ′≧√{square root over (σ 2 +Δt 2 )}, where σ denotes a standard deviation of base jitters that occur naturally, and σ denotes a permissible jitter amount for the optical disc.