US Patent 7483353 Optical disk device

In an optical disk of HD-DVD, data is recorded in both grooves and lands. A groove track includes its own data region called a groove (G) track address system formed therein and a land track includes its own data region called a land (L) track address system formed therein. One bit of address data is composed of four redundant wobble waves. When only three or two of the four wobble waves can be detected, an error is determined. When an error is determined in tracing of a groove track, bit data of the L track address system is used to correct the error. When an error is determined in tracing of a land track, bit data of the G track address system is used to correct the error.