An optical disc drive device includes a spindle motor that rotates an optical disc, an OPU, a first controller that causes the spindle motor and the OPU to read recorded data from the rotating optical disc, and an transmitter that transmits the read recorded data to a signal processing device disposed external to the optical disc drive device. The recorded data transmitted by transmitter is stored in a buffer provided in the signal processing device. The first controller decreases the rotational speed of the optical disc based on free space information indicating the free space of the buffer.

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.

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.

In an optical disc apparatus that records and reproduces data onto and from an optical disc in units of predetermined block, an information divider divides the data so as to reduce an amount of the data included in each of blocks when a recording state of the optical disc does not satisfy a predetermined criterion, and reproduces recording data in units of the block by adding sub-information including a value indicating the amount of the data included in each of the blocks. An error-correction encoder circuit encodes the recording data in a first error-correction code format, and a recorder converts encoded recording data into a recording signal, and records the recording signal onto the optical disc. A quality evaluator circuit produces an evaluation value indicating a recording quality based on a result of reproducing the recording signal recorded on the optical disc.

In an optical disc apparatus that records and reproduces data onto and from an optical disc in units of predetermined block, an information divider divides the data so as to reduce an amount of the data included in each of blocks when a recording state of the optical disc does not satisfy a predetermined criterion, and reproduces recording data in units of the block by adding sub-information including a value indicating the amount of the data included in each of the blocks. An error-correction encoder circuit encodes the recording data in a first error-correction code format, and a recorder converts encoded recording data into a recording signal, and records the recording signal onto the optical disc. A quality evaluator circuit produces an evaluation value indicating a recording quality based on a result of reproducing the recording signal recorded on the optical disc.

A nonlinear light absorption material includes a compound having a nonlinear light absorption property at a wavelength of 390 nm or more and 420 nm or less and represented by the formula (1) as a main component:

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in the formula (1), X is an oxygen atom.

A nonlinear light absorption material includes a compound having a nonlinear light absorption property at a wavelength of 390 nm or more and 420 nm or less and represented by the formula (1) as a main component:

##STR00001##

in the formula (1), X is an oxygen atom.

A nonlinear light absorption material includes a compound represented by the following formula (1) as a main component:

##STR00001##

in the formula (1), R.sup.1 to R.sup.6 are each independently a hydrocarbon group.

An optical information storage medium includes a substrate and a multilayer polymeric film. The multilayer polymeric film has a first surface and an opposite second surface that extend the length of the multilayer polymeric film. The second surface is adhered to a surface of the substrate. The multilayer polymeric film includes a plurality of coextruded alternating polymeric active data storage layers and polymeric buffer layers.

A recording medium includes a recording layer. The recording layer includes an aliphatic polymer, and a multiphoton absorption compound containing at least one bond selected from the group consisting of a carbon-carbon double bond, a carbon-nitrogen double bond, and a carbon-carbon triple bond, and having a multiphoton absorption characteristic. When the thickness of the recording layer is 100 ?m, the transmittance of the recording layer in the thickness direction with respect to light having a wavelength of 405 nm is greater than or equal to 80%.