An optical disk (100) of the present invention includes (i) a medium information region (101) (a) in which type identification information is recorded by recesses and/or protrusions which are formed by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device and (b) in which first address information is recorded in a first address data format and (ii) a data region (102) (a) in which content data is recorded by recesses and/or protrusions which are formed by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit and (b) in which second address information is recorded in a second address data format.

An information recording medium (10) including a first region (11) in which medium identification information has been recorded, a data region (13), and a second region (12) which is positioned between the first region (11) and the data region (13) and in which control information has been recorded, in which an area of the first region (11) is greater than an area of the second region (12) in size.

An information processing device includes: a data processing unit which executes a reproduction process of recorded data of a disc, in which the data processing unit reads disc type information that is recorded on the disc, and ascertains a recorded data configuration of the disc based on the disc type information that is read, and executes data reading-out and reproduction processes according to a reading-out rate corresponding to the ascertained recorded data configuration.

Data reproduction is performed in a mode decided on the basis of disc type information which is record data of a disc. A reading rate compatible with a physical format of a disc is compared with a reading rate compatible with a disc type, and in a case where the reading rates do not coincide with each other, data read from the disc at the physical format compatible rate is stored in the buffer, and the reproduction process is performed using the data output from the buffer at the disc type compatible rate. In a case where the physical format is BD-R or BD-RE, and the logical format is a logical format compatible with BDMV-UHD, the emulation mode reproduction accompanied with the rate conversion using the buffer is performed.

A virtual file system (VFS) is constructed by reliably acquiring subsequent data corresponding to an information recording medium from a local storage unit, and thus, data reproduction is executed. A data processing unit configured to read out and reproduce data recorded in the information recording medium, and data stored in the local storage unit which is different from the information recording medium, is provided. The data processing unit executes processing of selecting data associated with the information recording medium from the local storage unit, as reproduction target data, executes directory name calculation processing in which a conversion function corresponding to a version of the information recording medium is applied to configuration data of a root certificate recorded in the information recording medium, at the time of performing the processing of selecting the reproduction target data, and selects data which is recorded in a directory having a calculated directory name from the local storage unit, as the reproduction target data.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P2max) or a longest space (S2max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P2max) or a longest space (S2max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.

An optical disk (100) of the present invention includes (i) a medium information region (101) (a) in which type identification information is recorded by recesses and/or protrusions which are formed by a given modulation method and whose lengths are longer than a length of an optical system resolution limit of a playback device and (b) in which first address information is recorded in a first address data format and (ii) a data region (102) (a) in which content data is recorded by recesses and/or protrusions which are formed by the given modulation method and which include a recess and/or a protrusion whose length is shorter than the length of the optical system resolution limit and (b) in which second address information is recorded in a second address data format.

An information recording medium (10) including a first region (11) in which medium identification information has been recorded, a data region (13), and a second region (12) which is positioned between the first region (11) and the data region (13) and in which control information has been recorded, in which an area of the first region (11) is greater than an area of the second region (12) in size.