Abstract: According to one embodiment, an electronic apparatus includes a receiving module, a receiving module and a sound output module. The receiving module is configured to receive data of a motion picture and data of sound associated with a given timing in the motion picture, the data of the sound generated separately from the motion picture. The receiving module is configured to play back the motion picture. The sound output module is configured to output the sound at the given timing when the motion picture playing back module plays back the motion picture.

Abstract: An original optical disk which is suitable for mass production and facilitates the densification of the optical disks by improving the transferability and the releaseability of an optical disk substrate with respect to a stamper, comprises concavities which constitute pits or grooves along tracks and which include side walls, along the track direction of the concavity, having inclinations such that a width of an opening between sidewalls decrease closer to the base of the concavity in the track width direction of the concavity becomes and such that the inclination has at least one inflection point so that the closer to the bottom side, the sharper the inclination becomes and the closer the opening edge side, the milder it becomes.

Abstract: An optical disk comprises a mark train, which has at least one shortest mark and at least one other mark, recording readable information by applying a light beam, wherein the shortest mark of the mark train have a width larger than that of the other mark.

Abstract: An optical disk including a substrate and a recording film formed on the surface of the substrate, wherein the recording film includes an information recording domain. A servo information for a tracking control and a format condition information for formatting the information recording domain are provided on the substrate, and the information recording domain is formatted in accordance with the format condition information.

Abstract: An optical disk has first and second substrates, at least one of which is provided with optically readable pits corresponding to record data, and a reflection film coated on the pits. In the optical disk, the first and second substrates are laminated on each other such that the surface on which the pits are formed, is located inside. Label information, indicative of the record data, is formed on at least one of the surfaces of the first and second substrates, which contact each other.

Abstract: A rotation detector includes a rotary disk in which slits are recorded, and a photodetector for reading the slits with a laser beam. The slits is constituted by concave and convex parts having different widths radially formed on one surface of the rotary disk at different intervals. The width of one of the concave and convex parts constituting the slits which has a smaller width or slit interval is set to be smaller than the spot size of the laser beam.