Abstract: A record carrier on which information is recorded in the form of first variations caused by the presence or absence of information marks along a recording track, such variations representing an information signal. The record carrier also exhibits second variations in the form of changes in the position of the information marks in a direction transversed to the track direction. The second variations having a frequency spectrum substantially entirely outside the frequency spectrum of the first variations. The second variations are detectable by the same playback transducer which detects the first variations, and the presence of the second variations may be necessary to enable the transducer to detect the first variations.

Abstract: Audio-centered information is stored on a unitary medium by a Table-of-Contents (TOC) mechanism for specifying an actual configuration of various audio items on the medium. In addition to the TOC mechanism a file-based access mechanism to the information is assigned through a ROOT directory that contains a highest level TOC directory pointing at various audio items.

Abstract: Playback apparatus for a record carrier on which information is recorded in the form of variations of a first physical parameter. The playback apparatus scans the record carrier by means of a transducer which is responsive to the variations of the first physical parameter. An information recovery circuit recovers the information from a detection signal produced by the transducer. The record carrier also exhibits a variation of a second physical parameter, which differs from the first physical parameter but is of a type which is detectable by the same transducer. A detection circuit detects the presence of the second variation on the basis of a further detection signal produced by the transducer. A circuit controlled by the detection circuit enables the information recovery circuit in the event that the presence of the second variations is detected.

Abstract: A read device for reading a record carrier which has recorded thereon a data signal which represents data words, added codewords of a first type and added codewords of a second type. The added codewords of the first type have a predefined first relation to the data words, and the added codewords of the second type have a second predefined relation to the data words and the added codewords of the first type. The added codewords of both types enable error correction according to a given algorithm. The data signal is divided into blocks which each contain a control portion which includes control words and a data portion which includes user-supplied data words. The data words and added first and second type codewords are ordered and interrelated so that the order of the data words is not altered by error correction according to the given algorithm, and the second-type codewords are located closer to the related control data words than are the first-type codewords.

Abstract: An information system including a record carrier and a playback apparatus. Information has been recorded on the record carrier in the form of variations of a first physical parameter. The playback apparatus scans the record carrier by means of a transducer which is responsive to the variations of the first physical parameter. An information recovering circuit recovers the information from a detection signal received from the transducer. The record carrier exhibits second variations of a second physical parameter, which differs from the first physical parameter but which second variations are of a type that are detectable by the transducer. A detection circuit detects the presence of the second variations on the basis of a detection signal received from the transducer. A circuit responsive to the detection circuit enables the information recovering circuit when the presence of the second variations is detected causing it to recover the information.

Abstract: Information of a specific application, such as, CD-ROM or CD-DA is organized according to a specific information structure and also contains application data related thereto. There is disclosed a method of transferring information organized according to one or more information structures with an information signal subdivided into blocks. The header of each block contains an application code and application data, while the structure of the application data depends on the application code. According to a layered hierarchical structure the blocks are organized in groups having a group application code and the groups are organized in a volume having a volume application code. The invention makes it possible to know the information structure at any moment. Furthermore, an information carrier is described on which such an information signal is recorded. Also an arrangement for receiving and an arrangement for transmitting such information signals are described.

Abstract: A record carrier has recorded thereon a data signal which represents data words, added codewords of a first type and added codewords of a second type. The added codewords of the first type have a predefined first relation to the data words, and the added codewords of the second type have a second predefined relation to the data words and the added codewords of the first type. The added codewords of both types enable error correction according to a given algorithm. The data signal is divided into blocks which each contain a control portion (20) which includes control words and a data portion (21) which includes user-supplied data words. The data words and added first and second type codewords are ordered and interrelated so that the order of the data words is not altered by error correction according to the given algorithm, and the second type codewords are located closer to the related control data words than are the first-type codewords.

Abstract: An information system including a record carrier and a playback apparatus. Information has been recorded on the record carrier in the form of variations of a first physical parameter. The playback apparatus scans the record carrier by means of a transducer which is responsive to the variations of the first physical parameter. An information recovering circuit recovers the information from a detection signal received from the transducer. The record carrier also exhibits second variations of a second physical parameter, which differs from the first physical parameter, but which second variations are of a type that are detectable by the transducer. A detection circuit detects the presence of the second variations or a predetermined property thereof (e.g., that they exhibit a predetermined variation pattern) on the basis of the detection signal received from the transducer.

Abstract: A record carrier, a playback apparatus and a system including the record carrier and the playback apparatus. Information has been recorded on the record carrier in the form of variations of a first physical parameter. The playback apparatus scans the record carrier by means of a transducer which is responsive to the variations of the first physical parameter. An information recovering circuit recovers the information from a detection signal received from the transducer. The record carrier exhibits second variations of a second physical parameter, which differs from the first physical parameter, but which second variations are of a type that are detectable by the transducer. A detection circuit detects the presence of a predetermined property of the second variations (e.g., that the second variations exhibit a modulation pattern representing a code) on the basis of a detection signal received from the transducer.

Abstract: A method and apparatus for successively recording a first and a second information signal on a record carrier track which is pre-recorded with track position-code signals alternating with track position-synchronizing signals. Each information signal is converted into a respective modulated digital signal having successive subcode frames, each subcode frame including subcode synchronizing signals and successive information frames which include time code signals. Upon completion of recording of the information in the first modulated signal, recording of succeeding information frames thereof is continued for a predetermined time interval thereafter so that recording of such signal terminates at a boundary position located between successive subcode synchronizing signals on the track. Generation of the second modulated signal is initiated the aforesaid time interval prior to recording, so that recording thereof begins at the boundary position of the first modulated signal.

Abstract: An optical recording system wherein the record carrier is pre-recorded with adjustment information indicative of the waveform of the write signal (V.sub.s) to be employed for recording an information signal (V.sub.i) thereon. The recording apparatus includes a read/write head for reading the adjustment information before recording, and a control circuit for deriving the write signal (V.sub.s) from the information signal (V.sub.i). The control circuit includes an adjustment circuit which selects a write signal waveform in conformity with the adjustment information read from the record carrier.

Abstract: "Method of coding data bits on a recording medium, arrangement for putting the method into effect and recording medium having an information structure."The so-called Miller modulation has the disadvantage that a direct current is generated in the information channel. When this modulation method is used for magnetical or optical recording, the result is that the amplitude values and the zero crossings are deformed as these channels cannot transmit direct current.According to the invention, in order to obtain, a d.c. free modulation, the Miller modulation concept is modified such that sequences of data bits which, after coding, result in the introduction of a d.c. component are coded differently. It appears that, the frequency zero excepted, a good suppression of the response is obtained also in a fairly wide low-frequency portion of the spectrum.