RECORDING MEDIUM, METHOD AND APPARATUS FOR REPRODUCING, AND METHOD AND APPARATUS FOR RECORDING

摘要

A circular recording medium comprises first and second recording layers. The first and second recording layers each include first and second tracks extending in the shape of concentric circles or a spiral. The first and second track each include a plurality of first and second sectors. The first sector includes first and second areas, and the second sector includes third and fourth areas. The second and fourth areas include first and second concentric circular or spiral grooves oscillating sinuloidally. The oscillation of the first groove has a first oscillation characteristic in a first predetermined position in the second area, whereas the oscillation of the second groove has a second oscillation characteristic in a second predetermined position in the fourth area. The first oscillation characteristic differs from the second oscillation characteristic.