Abstract: A method and apparatus for reproducing MIDI (music instrument digital interface) music based on synchronization information are provided. MIDI performance information is detected from a musical score and/or MIDI data. Synchronization information, which contains real performance onset time information on an onset time at which each of all notes included in the MIDI performance information is estimated to be performed, is generated from the MIDI performance information or a predetermined synchronization information file. MIDI music is reproduced based on a real MIDI performance table, which is generated by matching the MIDI performance information and the synchronization information. Accordingly, even if musicla trainees do not have real performance sound played by a desired player, they can reproduce and listen to the player's performing music with only a small amount of score information and synchronization information.

Abstract: A method for extracting information in a data signal stored on an optical disc. The information is stored in a plurality of channel bits. The method includes initializing a recovery period of a recovery clock to a predetermined value expressed in cycles of a first clock; sampling the data signal with the first clock; obtaining a leading edge time period expressed in cycles of the first clock of a pattern of bits from the sampled data in which at least a first bit has a first binary value, followed by a plurality of bits having a second binary value, and ending with a last bit having the first binary value, wherein the first and second binary values are not equal; updating the recovery period of the recovery clock to be equal to a new maximum period that is the leading edge time period divided by a division factor; extracting the information in the data signal based on the newest recovery period of the recovery clock; and detecting a predetermined code in the data signal.

Abstract: A digital versatile disc (DVD) drive has a first memory for storing a region code and a source code, and a second memory for storing data temporarily. The method for changing the region code of the digital versatile disc drive comprises storing the source code in the second memory, and changing the region code in the first memory according to the source code stored in the second memory. The method and apparatus is capable of changing the region code of the digital versatile disc drive.

Abstract: An encoding efficiency higher than 1 is achieved by accomplishing ternary recording on a recording medium. For this purpose, an 8-bit binary data word is converted to a 5-symbol ternary code word. A look-up table stores a modulation/demodulation table defining the correspondence between the binary data word (8B) and the ternary code word (5T). A table generating circuit generates the modulation/demodulation table to be stored in the look-up table such that each of constraints specified by a plurality of parameters is satisfied. If a PRML (Partial Response Maximum Likelihood) scheme is combined with an 8B5T code thus obtained, a signal-to-noise ratio is improved.

Abstract: Method of registering a running time on an information carrier, the information carrier comprising main data and subcode data, the running time being indicated in a subcode channel by a subcode time expressed in accordance with a predetermined format. A pseudo-running time is described by incrementing the subcode time in accordance with a pseudo-tempo, which is different from an actual tempo, the actual tempo representing a tempo in accordance with the actual running time. The invention further relates to an information carrier and an apparatus.

Abstract: An EFM/EFM+ encoding system is adapted to modulate a source symbol sequence into a modulated bit sequence that is further converted to a channel bit sequence, which is to be recorded on a recording medium and which has a cumulative Digital Sum Value (DSV), through NRZI conversion. An apparatus for performing DSV protection in the EFM/EFM+ encoding system includes a DSV calculation unit for calculating the DSV associated with the EFM/EFM+ modulated bit sequence, and a decision unit for adjusting at least a bit in the modulated bit sequence according to the result calculated by the DSV calculation unit such that the channel bit sequence from the NRZI conversion of the adjusted modulated bit sequence accumulates a relatively small DSV. A method of using the EFM/EFM+ encoding system to inhibit disc copying is also disclosed.

Abstract: An optical disk apparatus for driving an optical disk having formed therein sawtooth wobbles of +STW and −STW. A pickup receives a laser beam reflected from the optical disk and supplies a reproduced signal to a wobble signal processing section. The wobble signal processing section differentiates the reproduced signal and binarizes the differential signal with reference to a zero level. A pulse length of the binary signal achieved during a positive period is compared with that of the binary signal achieved during a negative period. When the pulse length achieved during the positive period is longer than that achieved during the negative period, the binary signal is determined to be a +STW. In contrast, when the pulse length achieved during the negative period is longer than that achieved during the positive period, the binary signal is determined to be a −STW, whereby a wobble signal is demodulated.

Abstract: A data recording device comprises a block division unit dividing a sequence of user data blocks into first blocks and second blocks, a plurality of multi-level data generating units generating multi-level data blocks from the first blocks and the second block, a group data storage unit storing first and second groups of code data corresponding to one user data block, a plurality of averaging units each calculating an average of DC levels based on the multi-level data of one of the blocks, a level comparison unit comparing each of the DC level averages with a predetermined value; a revision data generating unit generating a revision data using a result of the comparison, a data selection unit selecting one of the first and second groups of code data, and an output storage unit storing the first blocks, the second blocks generated using the selected code data, and the revision data.

Abstract: There is provided a recording medium reproducing apparatus in which a digital signal immediately before being inputted to a D/A converting LSI is prevented from being taken out and unfairly copied. A digital signal processing LSI and the D/A converting LSI are connected to each other through an external bus. A scrambling processing circuit for scrambling a digital signal outputted from a digital signal processing circuit is provided inside the digital signal processing LSI. A descrambling processing circuit for descrambling the scrambled digital signal transmitted through the external bus is provided inside the D/A converting LSI.

Abstract: For each sync frame, an AND circuit detects whether a pre-pit synchronization signal can be obtained within a window set by a timing generator. Detection result of the AND circuit is held by a shift register, where it is shifted in response to each sync frame. On the basis of a parallel output from the shift register, a decoder determines whether the detection of the pre-pit synchronization signal is accurate or erroneous. Count value of a counter is incremented by one each time the decoder determines that the detection of the pre-pit synchronization signal is accurate, but is decremented by one each time the decoder determines that the detection of the pre-pit synchronization signal is erroneous. Identification section identifies stability/instability of the pre-pit synchronization signal detection.

Abstract: An ADIP demodulation method and apparatus, which are used in an optical disk driver to generate the ADIP information according to a wobble signal. The apparatus includes a slicing unit for receiving the wobble signal and generating a wobble pulse, a phase locked loop for generating a reference wobble signal with the same frequency and phase as the wobble pulse and a reference clock with frequency higher than the wobble pulse, a channel bit generator for generating a channel bit signal according to the reference wobble signal and the wobble pulse, and a decoder for decoding to ADIP information according to the channel bit signal. The channel bit generator generates a difference signal between the wobble pulse and the reference wobble signal, and outputs the channel bit signal according to the difference signal.

Abstract: A multi-level data processing method converts a binary data into a multi-level data having n bits per symbol, where n is an integer satisfying n≧2. A {(n−1)×m}-bit binary data is arranged in upper (n−1) bits of multi-level data of m symbols, where m is an integer satisfying m≧2, and a (m−k)-bit binary data is converted into m bits according to a predetermined conversion rule and arranged in a lower 1 bit of the multi-level data of m symbols, where k is an integer satisfying m>k≧1, so as to convert a (n×m−k)-bit binary data into 1 set of multi-level data made up of m symbols.

Abstract: Hold registers receive a hold register enable signal. When reading one kind signal of header field data, the hold register enable signal is High and the registers store newly renewed values of filter coefficients, and when reading a different kind signal of recording field data, the hold register enable signal is Low and the hold registers hold the last stored header field contents of the registers. Then, when a header field of a next sector is detected, the contents held in the hold registers are taken and preset to the registers. Thus, even in a case where an intermittent reproduction signal having different kinds of formats is processed in playback, the continuous adaptive equalization can be realized over the different kinds of reproduction signals in quality.

Abstract: An optical disc having a plurality of user data written to the disc from a lead-in zone to a lead-out zone, the disc comprising a plurality of control display data composed of a plurality of subcode registers, each having a value, where the control display data are written to the disc interposed with the user data and written to the lead-out zone and hidden data encoded within one of the subcode registers in the lead-out zone. The p-bit register in the lead-out zone of the optical disc required to toggle at a rate of 2 Hz. In one second, the optical disc reader reads 75 p-bit registers, therefore a perfect 2 Hz toggling cannot be achieved. The location of a p-bit state composed of a fewer number of p-bit sector is used to represent a bit value of hidden data.

Abstract: A modulation/demodulation method of a run length limited method and a modulation/demodulation apparatus relate to converting a bit stream of a recording data into a bit stream proper to a recording phase when recording a data onto an optical recording medium. In the present data modulation and demodulation method, modulation data consist of partly consecutive 0s or 1s which are quantized in length, satisfying the given minimum and maximum run lengths of RLL at the same time. Therefore, a reproducing error is checked and corrected based on whether the quantizing condition is violated or not during the demodulation. This error recovery capability makes it possible to enhance a recording density of a recording medium and to reduce a judgement error possibility due to a jitter component of a reproducing signal, so that provides a high reliability for high density recording medium compared to a conventional modulation method.

Abstract: The present invention relates to a disk recording medium such as a CD or a DVD in which data is recorded in high-density, and method and apparatus for reproducing data recorded in the high-density disk recording medium. The data reproducing method and apparatus according to the present invention converts a high-frequency signal reproduced from the disk into a plurality of binary signals through comparing the reproduced signal with two or more slicing levels which are different each other, selects one of the plurality of binary signals or a periodic pulse signal based on the difference magnitude between the plurality of binary signals, synchronizes a reference clock with the selected signal, and restores the selected signal into bit stream using the synchronized reference clock.

Abstract: A method is designed for forming a visual image having a specified shape on a surface of an optical disk by using an optical writing process of irradiating a laser beam onto the surface of the optical disk to form pits. The optical disk is normally capable of recording information on the surface thereof by the optical writing process. The method is carried out by the steps of acquiring image formation information associated to a visual image to be formed, forming the visual image on the surface of the optical disk based on the acquired image formation information by using the optical writing process, and recording the image formation information together with the formed visual image on the surface of the same optical disk.

Abstract: This invention relates to a reproduced signal evaluation method of evaluating a reproduced signal reproduced from an information recording medium in which information composed of a plurality of codes differing in length is recorded and evaluates the reproduced signal on the basis of the reproduced signal of the next shortest code after the shortest code reproduced from the information recording medium.

Abstract: A device according to the invention for writing information to an information carrier (1) includes conversion means (7) for converting symbols in an information signal (SINFO) into pulse sequences in a control signal (STR). The device further includes a transducer (10) for generating a physically detectable pattern on the information carrier (1) in response to the control signal (STR). The conversion means (7) include assignment means (702) for assigning properties of the pulse sequences to symbols in the information signal (SINFO). These properties include the duration and the magnitude of pulses in the pulse sequence. The conversion means (7) further include at least one counter (711) for supplying a count signal (TC1) after a time interval, which counter is coupled to the assignment means (702). The conversion means (7) further include a controllable delay line (761) coupled to the at least one counter (711), for delaying the count signal (TC1), and to the assignment means (702).

Abstract: Described herewith is an optical disk manufacturing apparatus for reading recorded digital data from an optical disk, comprising an encryption unit (22, 23) for encrypting entered digital data according to a plurality of key information; an optical disk substrate manufacturing unit 2 for manufacturing an optical disk substrate 4 on which the encrypted digital data and key information are recorded in the form of physical form changes; a reflection film forming unit 41 for forming a reflection film on the optical disk substrate 4; and a key information recording unit 7 for recording key information on the optical disk substrate on which the reflection film is formed. The reflection factor of the optical disk is changed locally, thereby giving a jitter to the position information of each pit edge, and desired data is recorded additionally according to this jitter. Pits, etc.

Abstract: In recording dots corresponding to the data to be recorded in the record transmission path, the dots are recorded optically readably so that the recorded data may be reproduced by using two-dimensional interference from the adjacent dots. In reproducing data, after the code image has been processed by equalization in the PR-equalization portion, and simultaneously based upon the reading point position information detected in the reading point calculation portion, the values in the reading points are judged, and in the decoding portion, these read data are judged and decoded based upon the predetermined decoding rules, and they are converted into the original data.

Abstract: A disk drive apparatus reads information with high accuracy from an information read/write medium. Information recorded on the information read/write medium is optically read with a pickup, and in accordance with the read signal Sin, an RF signal generated by an RF signal generation circuit is supplied to a frequency characteristic compensation circuit to generate an RF signal having a compensated frequency characteristic. Here, the frequency characteristic compensation circuit 10 is an equalizer comprising a differential amplifier, fixed resistors, variable resistors, and variable capacitance element. Values of the variable resistors and the variable capacitance element are adjusted to variably adjust the frequency characteristic of the frequency characteristic compensation circuit.

Abstract: EFM signals including margin bits read from a CD are passed to an EFM copy circuit. After cutting one bit from the margin bits, the EFM copy circuit stores the EFM signals with the margin bits into a buffer. The EFM copy circuit reads the EFM signals including the margin bits from the buffer, decompresses the margin bits, and supplies the EFM signals with the decompressed margin bits to a write strategy circuit. Then, the EFM signals are written onto a CDR from the recording start position on the CDR, which is detected by the information from a WBL detection circuit. The start address of the EFM data to be read from the buffer is located from subcode transferred from a subcode detaching circuit to the EFM copy circuit. In this manner, the content of a CD with copy guard protection can be copied to another disk.

Abstract: An optical disc having a data area in which information signals are recorded, a lead-in area and a lead-out area provided before and after the data area, and a program memory area for temporarily storing address information necessary for additionally writing information signals. A subcode Q of the lead-in area or a subcode Q of the program memory area is provided with identification information for identifying these subcodes Q. For example, the identification information is provided at least in one of address (ADR), track number (TNO), and zero (ZERO) constituting the subcode Q of the program memory area or the lead-in area. Thus, it is possible to discriminate the subcode Q of the program memory area and the subcode Q of the lead-in area securely and instantaneously.

Abstract: In an information recording medium including a plurality of sector fields and having various pieces of information recorded in the sector fields, the header field in each sector field includes a first field in which a continuously repeated pattern complying with the run length limitation in the predetermined range is recorded, a second field in which an address mark including a violation pattern different from a reproduced pattern obtained by reproducing the repeated pattern when a defective pit which cannot be recognized as a pit is included in pits representing the repeated pattern is recorded, the violation pattern exceeding the run length limitation in the predetermined range, and a third field in which address data is recorded.

Abstract: A disc-shaped information recording medium in which the recording density can be increase to secure a large storage capacity and in which there is no risk of an address section being mistakenly detected by cross-talk from a neighboring track, is disclosed. Specifically, an optical disc of a continuous servo system in which tracking is controlled using a pre-groove and in which information is recorded and/or reproduced with constant angular velocity using clocks of a sole frequency, is disclosed. On the disc is formed a spiral track made up of a data portion for recording data and an address section for recording management information for recording/reproducing data. Both a groove and a land are used as a recording/reproducing track. Odd tracks are formed on the land, while even tracks are formed on the groove.

Abstract: An address decoder includes a PLL circuit generating a PLL clock signal synchronized with an external clock signal, a frequency divider dividing the PLL clock signal, a selector selecting a binary wobble signal or an inverted signal thereof, a timing generator generating each of sync window signals, a biphase enable signal, CRC enable signals, a CRC polarity signal, and an output enable signal, a biphase decoder decoding a wobble signal selected by the selector, a Gray code decoder decoding a biphase decode data, and an output control circuit outputting a decoded address signal. Therefore, this address decoder can reproduce an address signal by decoding the wobble signal.

Abstract: Running time is registered on an information carrier that includes main data and subcode data. The running time is indicated in a subcode channel by a subcode time expressed in accordance with a predetermined format. A pseudo-running time is described by incrementing the subcode time in accordance with a pseudo-tempo, which is different from an actual tempo, the actual tempo representing a tempo in accordance with the actual running time.

Abstract: An optical recording medium having an information recorded at a high density, and an optical reproducing method and apparatus for reproducing the optical recording medium. The optical recording medium is provided with an information recording face having an information recorded as pit trains and including a track having any one of concentric circle and spiral shape, wherein at least two pit trains are arranged adjacently to be reproduced by a single light beam. An information is stored in a dual or triple pit train shape, so that a recording density can be increased at least more than twice. When a total length of the dual pit is recorded as a single pit length, it has a changeability with the existent optical recording medium such as CD and DVD, etc.

Abstract: A bi-phase mark reproduction apparatus which reduces an error rate of demodulated data by half and improves demodulation ability of ATIP and an optical disk drive device are provided. The bi-phase mark reproduction apparatus includes a data conversion unit which takes out a synchronous code portion, a data portion and an error detection code portion from a bi-phase mark input signal by means of a data separating signal and demodulates data of the data portion and the error detection code portion. The data conversion unit includes a pattern retrieval unit which detects a predetermined error pattern contained in the data portion and a conversion table which decodes the error pattern in accordance with a replacement rule based on bi-phase mark modulation.

Abstract: An information recording apparatus for recording data by applying energy to a recording medium to form thereon local physical changes of the medium includes a space length discriminating unit for discriminating a space length of a space in a channel data sequence when data is recorded, and a recording energy irradiating unit for generating at least two recording waveforms when successive spaces having a same length in the channel data sequence are recorded, in accordance with results discriminated by the space length discriminating unit. The at least two recording waveforms may be at least two mutually different recording waveforms.

Abstract: In an optical disk, address information, including an address information start mark, is recorded in a header region primarily based on variable-length codes such that, between each pair of nearest bits having a first logic value, at least two and at most seven bits having a second logic value are disposed. The address information start mark is detected based on a first criterion that a combination of pulse widths each defined in association with a nearest pair of bits having the first logic value is present in a pulse sequence, and also based on a second criterion that, when the logic level of the pulse sequence alternates between a first logic level and a second logic level in association with occurrence of bits having the first logic value intermittently disposed among bits having the second logic value, the logic levels of pulses in the pulse sequence coincide with their respective counterparts in the combination of pulse widths.

Abstract: In playing back data in an optical disk device, to perform high-speed data playback with a low number of playback retries even if an error occur when data is being read. In reading data composed of ECC blocks, if a data error occurs during a read operation, the data from sectors for which PI error correction can be performed is left alone. Playback retries using different playback conditions are performed just on the sectors for which PI error correction can be performed. Thus, the playback retry count can be reduced.

Abstract: The present invention relates to method for recording program specific information (PSI) for a recorded data stream in an optical disk such as a high-density digital versatile disk (HD-DVD) and providing the recorded PSI to a presenting device such as a digital television. This method writes program or stream specific information in a management data recording area of a high-density disk, and when the recorded data stream is reproduced, determines whether it is time to send the stream specific information, obtains stream specific information corresponding to a stream object being reproduced, or to be reproduced based on the determination result, and transmits the obtained stream specific information.

Abstract: There is provided a DVD-audio reproducing apparatus in which a digital signal immediately before being inputted to a D/A converting LSI is prevented from being taken out and unfairly copied. A digital signal processing LSI and the D/A converting LSI are connected to each other through an external bus. A scrambling processing circuit for scrambling a digital signal outputted from a digital signal processing circuit is provided inside the digital signal processing LSI. A descrambling processing circuit for descrambling the scrambled digital signal transmitted through the external bus is provided inside the D/A converting LSI.

Abstract: In an information recording medium including a plurality of sector fields and having various pieces of information recorded in the sector fields, the header field in each sector field includes a first field in which a continuously repeated pattern complying with the run length limitation in the predetermined range is recorded, a second field in which an address mark including a violation pattern different from a reproduced pattern obtained by reproducing the repeated pattern when a defective pit which cannot be recognized as a pit is included in pits representing the repeated pattern is recorded, the violation pattern exceeding the run length limitation in the predetermined range, and a third field in which address data is recorded.

Abstract: This invention provides a method of acquisition of binary information that has been stored physically in a periodic storage medium. The method, referred to as matrix-method deconvolution (MMD), is useful for use with optical storage media using an optical addressing system that reads and writes binary information in a periodic array of nano-particles. With this MMD method, the density of existing memory systems can be boosted to between 10 and 100 Terabytes of data per cubic centimeter. This matrix-method deconvolution method compensates for the effects of the optical addressing system's point spread function. Prior knowledge of a system's point spread function and inter memory-center spacing is used.

Abstract: Before original information is recorded in areas such as a recording medium management area where the same pattern of information is recorded many times, a dummy pattern that minimizes a recording film flow is recorded. Because the direction of the recording film flow depends on the length of a mark length, the dummy pattern is a pattern including marks with a unique length. Randomly or sequentially selecting and recording a plurality of dummy patterns, each with a recording film flow direction different from others, prevents jitters, which will be caused by the recording film flow, from increasing.

Abstract: This invention resolves the limitations of the binary data encoding and storage system by encoding multi-valued meaning to data elements prior to the recording and storing of these multi-valued data elements based on a plurality of quantities in a memory point. In order to make a single memory point suitable to record multi-valued data elements, where each value has a special meaning in a particular recording, quantities of magnetism or light, like its intensity, shape, etc., are digitized or analogized so that each of the quantities can be recorded and extracted. The invention additionally includes systems and methods for using multi-valued data elements, including wireless transmission.

Abstract: Disclosed is a method for detecting synchronous information adapted to decode information recorded on a burst cutting area (BCA) on the surface of a recording medium, which method is capable of decoding the recorded information, based on only the detection of resync bytes recorded on the BCA and adapted to provide a synchronization for information recorded on the BCA following them, even when no sync byte recorded on the BCA to indicate the start point of the burst cutting area is detected.

Abstract: An audio compact disc title with a high density format adapted to be used in a compact disc player is disclosed. The audio compact disc title includes a plurality of tracks, each of the tracks has a plurality of audio sectors for storing audio data, wherein the audio data are divided into a plurality of audio signals alternately stored in the audio sectors, and a compact disc identifying code for representing the relatively high density format of the audio compact disc title for the compact disc player. A method for recording audio data in an audio compact disc title with a high density format is also disclosed. The method includes steps of dividing the audio data into a plurality of audio signals, rearranging the plurality of audio signals to space any two continuous audio signals by other audio signals, and recording the rearranged audio signals in the audio compact disc title.

Abstract: In a run-length limited encoding method used in an optical data storage system for encoding input data of two bits into corresponding output data of five bits, a minimum run-length of zeroes (0's) in a stream of the output data is 3; a maximum run-length of zeroes (0's) in the stream of the output data is 11; and the number of 1 included in binary numbers of five bits expressing the corresponding output data is 1 or 0. In the encoding method, the input data of two bits is one of “00”, “01”, “10” and “11”; and the corresponding output data is one of “10000”, “01000”, “00100” and “00010”.

Abstract: An information recording apparatus for recording data by applying energy to a recording medium to form thereon local physical changes of the medium includes a space length discriminating unit for discriminating a space length of a space in a channel data sequence when data is recorded, and a recording energy irradiating unit for generating at least two recording waveforms when successive spaces having a same length in the channel data sequence are recorded, in accordance with results discriminated by the space length discriminating unit. The at least two recording waveforms may be at least two mutually different recording waveforms.

Abstract: A method and apparatus are described which demodulate channel bits modulated by an arbitrary one of two modulation schemes, by making use of a consolidated reference table with a small address space. The method of the invention comprises the steps of: generating first output bits for representing patterns that correspond to patterns represented by first channel bits other than those patterns being unable to exist under first RLL constraints, the first output bits having a lesser number of bits than the first channel bits; and generating second output bits for representing patterns that correspond to patterns represented by second channel bits other than those patterns being unable to exist under second RLL constraints, the patterns represented by the second output bits being located at discontinuous areas of the patterns represented by the first output bits, the second output bits having a lesser number of bits than the second channel bits.

Abstract: To correct a bit shift of binary data read from a medium and further enable correction of a bit error caused by mis-correction of the bit shift, a data recovery apparatus according to the present invention comprises: circuits for respectively correcting time at an intersection of a read signal and a slice signal; and a circuit for generating gray bits representing a time cell including an intersection, the time of the intersection being uncorrected and a time cell adjacent to the time cell, positioned in the direction of the intersection being shifted for correction.

Abstract: A data recording method for calculating a digital sum value (DSV) corresponding to a proportion of positive data and negative data included in predetermined data ranges, selecting a resync pattern to be inserted between the data ranges according to the DSV, and inserting the selected resync pattern between the data ranges, has a step of selecting a resync pattern that minimizes differences in DSV between the data ranges.

Abstract: A recording/reproducing method and apparatus for processing m-value (m is an integer at least equal to two) digital information data to produce recording data, for recording the recording data on an optical recording medium, for reading recording data from the optical recording medium, and for processing the read recording data to reproduce the information data as reproduced data. A predetermined relationship is established between information data x and n (n is an integer at least equal to two) of recording data y1-yn, and another predetermined relationship is established between reproduced data z and the recording data y1-yn.

Abstract: The invention provides an information recording medium, an information playback apparatus, an information playback method, an information recording apparatus and an information recording method which may be applied typically to an optical disk system and by which multi-value recording in a high density can be achieved while preventing an increase of the error rate effectively and tracks can be formed in a comparatively small track pitch in multi-value recording while minimizing crosstalk. The dc component and high frequency components of a multi-value signal are suppressed within a range within which intersymbol interference does not occur between adjacent data to produce a modulation signal, and the modulation signal is recorded as a displacement of a groove wall face or the like. Further, tracks are formed such that the track pitch normalized with a resolving power may fall within a range from 0.44 to 0.60.

Abstract: A method and apparatus are described which demodulate channel bits modulated by an arbitrary one of two modulation schemes, by making use of a consolidated reference table with a small address space. The method of the invention comprises the steps of: generating first output bits for representing patterns that correspond to patterns represented by first channel bits other than those patterns being unable to exist under first RLL constraints, the first output bits having a lesser number of bits than the first channel bits; and generating second output bits for representing patterns that correspond to patterns represented by second channel bits other than those patterns being unable to exist under second RLL constraints, the patterns represented by the second output bits being located at discontinuous areas of the patterns represented by the first output bits, the second output bits having a lesser number of bits than the second channel bits.

Abstract: A method and apparatus are described which demodulate channel bits modulated by an arbitrary one of two modulation schemes, by making use of a consolidated reference table with a small address space. The method of the invention comprises the steps of: generating first output bits for representing patterns that correspond to patterns represented by first channel bits other than those patterns being unable to exist under first RLL constraints, the first output bits having a lesser number of bits than the first channel bits; and generating second output bits for representing patterns that correspond to patterns represented by second channel bits other than those patterns being unable to exist under second RLL constraints, the patterns represented by the second output bits being located at discontinuous areas of the patterns represented by the first output bits, the second output bits having a lesser number of bits than the second channel bits.