Optical disc and method of identifying recording layer

An optical disc comprising:

• first and second recording layers on which data are recordable and/or reproducible, the first and second recording layers having the same track spiral direction, wherein, on the first recording layer, an address of smallest recording units recorded while recording the disc decreases as a physical address of the smallest recording units increases and increases as the physical address decreases, from an inner radius of the first recording layer to an outer radius of the first recording layer.

An optical disc comprising:

• first and second recording layers on which data are recordable and/or reproducible, the first and second recording layers having opposite track spiral directions, wherein a physical address of smallest recording units increases or decreases together with an address of the smallest recording units recorded during recording on the disc.

An optical disc comprising:

• first and second recording layers on which data are recordable and/or reproducible, the first and second recording layers having opposite track spiral directions, wherein:
• on the first recording layer, an address of smallest recording units recorded while recording data on the disc decreases as a physical address of the smallest recording units increases and increases as the physical address decreases.

A method of identifying a recording layer on an optical disc comprising first and second recording layers on which data are recordable and/or reproducible, the first and second recording layers having a same track spiral direction, the method comprising:

• assigning first smallest recording units on the first recording layer a physical address which is different from a physical address of second smallest recording units on the second recording layer.

An optical disc comprising two or more recording layers on which data are recordable and/or reproducible, wherein a physical address of smallest recording units and an address of the smallest recording units recorded during recording data on the disc increase or decrease on the two or more recording layers.

A method of recording data on an optical disc having first and second recording layers on which data are recordable and/or reproducible by a recording head, the method comprising:

• recording addresses in respective front portions of smallest recording units of the first and second recording layers wherein:
• the recorded addresses and the physical addresses of one of the first and second recording layers vary according to a direction of travel along the disc, and
• the recorded addresses and the physical addresses of the other of the first and second recording layers vary oppositely according to the direction of travel.

A method of recording data on an optical disc having first and second recording layers on which data are recordable and/or reproducible, the method comprising:

• recording addresses in respective front portions of smallest recording units of the first and second recording layers wherein:
• the recorded addresses and the physical addresses of one of the first and second recording layers vary oppositely according to a direction of travel along the disc, and
• the recorded addresses and the physical addresses of the other of the first and second recording layers vary oppositely according to the direction of travel along the disc.