Patent ID: 7835245

Claim:
An evaluation value calculating apparatus comprising: a difference metric selecting unit that selects a difference metric for a specific recorded sequence in recorded sequences obtained in a maximum likelihood decoding process when information expressed with marks and spaces on a recording medium is played back, the difference metric being obtained in the maximum likelihood decoding process; a difference metric error value calculating unit that determines a difference metric error value for the difference metric selected by the difference metric selecting unit using a calculation method that is selected according to an edge shift direction of each of the marks on a time axis, the difference metric error value representing an error from an ideal difference metric and the edge shift direction on the time axis; and a statistical processing unit that performs statistical processing on the difference metric error value determined by the difference metric error value calculating unit on the basis of each of states of path meeting points to generate an evaluation value, wherein each of a plurality of difference metric error values are classified into groups based on the states of the path meeting points and statistically collected on a group-by-group basis to generate the evaluation value.