Optical recording and reproducing apparatus wherein data is recorded by stepwise shifting the edge position of each pit

An information reproducing apparatus for reproducing an information recording medium on which digital information is recorded while the edge position of an information pit is stepwise shifted from a predetermined reference position in accordance with a code being recorded within a predetermined shift period shorter than a transient period of a reproduced signal, which is determined in accordance with a transfer characteristic of an optical detection system for scanning a recording medium with a light beam along an information pit array, including:

• clock generating means for generating a clock which is synchronized with a reference position in phase on the basis of a reproduced signal obtained from said optical detection system;
• level detection means for detecting the reproduction level within the transient period of the reproduced signal at a timing defined by the clock;
• first decoding means for decoding recording data corresponding to the shift amount of the edge position of an information pit;
• correction value generating means for storing predetermined correction values to correct errors in a decoding operation, and outputting a correction value in correspondence with the data decoded by said first decoding means;
• adding means for adding the correction value with the reproduction level of a target code to be decoded;
• and
• second decoding means for decoding the recording data corresponding to the shift amount of the edge position of the information pit on the basis of the output of said adding means.