Device and method for recording information

ES 2 348 906 T3

DESCRIPTION

Device and procedure for recording information.

The invention relates to a device for recording information in at least one information volume on a track in a recordable area on a recording medium, the information volume comprising a start zone, a data zone and an end zone, device comprising recording means for recording marks representing the information and control means for recording and retrieving position data indicative of the position of the recorded volume of information.

This invention further relates to a method of recording information in at least one information volume on a track in a recordable area on a recording medium, an information volume comprising a start zone, a data zone and a recording zone. extreme, a method comprising recording marks representing the information and position data indicative of the position of the recorded volume of information.

The invention further relates to a recording medium having a track in a recordable area for recording at least one volume of information, which volume of information comprises a start area, a data area and an end area, the track comprising Marks representing information and position data indicative of the position of the recorded volume of information.

From US 5,341,356 (PSN13661) a device and a method for recording information signals on a recording medium are known. Information is encoded into information blocks comprising data words and error correction words to correct errors within the information block. The device comprises recording means for recording marks representing the information. The information in at least one information block is modulated to give a modulated signal and is recorded on the track at predefined locations indicated by the previously formed track position information. The device records the formatted information in successive volumes, also called sessions, in a multi-session scheme. Each volume has a start zone, also called the entry line, a data zone, and an end zone, also called the exit line. The device has control means for recording and retrieving position data indicative of the position of the recorded information volumes. In particular, a pointer is recorded on the output line to locate the starting area of ​​the session. In addition, the entry line contains information about the position of the exit line of that session and, therefore, of the starting area of ​​the next session (if there is one). To locate a specific session, the device can locate the last recorded session by detecting the boundary of the unrecorded area and reading the last output line, and follow the chain of sessions to the beginning of the recorded area. Alternatively the device can read the input line of the first session, and follow the chain of sessions by reading the input line of consecutive volumes. The time to access a specific session is determined by the amount of time required to jump through that chain of sessions. On a write-only type of recording medium such as CDR, the position data cannot be overwritten.

An object of the invention is to provide a more flexible system for recording position data.

To this end, the device as described in the opening paragraph is characterized according to claim 1. The method as described in the opening paragraph is characterized according to claim 7. The recording medium as described in the opening paragraph is characterized according to claim 8. This has the advantage that a map of the recorded session is available to the recording device. In particular this is advantageous for locating recorded data, for example files in a computer application, which have been deleted from the user's content management data, for example according to a UDF file system. When such a deleted file is to be recovered, the device can access previously recorded sessions to recover previous versions of the content management data, which still have the location data of the deleted data. In the device, the mapping means is arranged to record consecutive session map blocks, and the last recorded session map block contains session data units for each closed session. This has the advantage that the most up-to-date information about all recorded sessions is available in a single session map block. The response time of the device to access a session is reduced because only the last recorded session map block needs to be retrieved and processed.

The invention is based on the following recognition. The inventors have observed that a substantial amount of the response time of a recording device to a request to access a previously recorded session is due to the amount of time required to retrieve the position data of the session to be accessed. Subsequently, the inventors have observed that the response time can be reduced by recording the information about the sessions in the session map area.

It is noted that US 5,825,726 discloses a device for recording and reproducing a multi-session compact disc (CD) that allocates a total index information storage area (TTOC), which includes the position information of the respective sessions, to a specific area of ​​the CD, allowing high-speed access to the data recorded on the CD. The TTOC storage area is assigned to the outermost circumferential area of ​​the disk and the indices of the respective sessions are recorded in the TTOC storage area when recording is complete. Furthermore, EP 0712130 describes some elements of the multi-session CD system. On the multi-session CD the multi-session TOC information

ES 2 348 906 T3 is recorded within sessions. However, the documents do not describe recording a sequence of consecutive session map blocks in a separate session map area.

These and other aspects of the invention will become apparent and further clarified with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which Figure 1a shows a recording medium (top view ), figure 1b shows a recording medium (cross section), figure 2 shows a recording device, figure 3 shows the alignment of ADIP and information blocks, Figure 4 shows ADIP word structure, Figure 5 shows ADIP error correction structure, Figure 6 shows ADIP modulation rules, Figure 7 shows physical disk information table, Figure 8 shows leading edge correction times, figure 9 shows the recording medium sector numbering, figure 10 shows a schematic of a single session recorded disc, figure 11 shows the internal drive area, Figure 12 shows a session map block format, Figure 13 shows a session data unit, Figure 14 shows recorded area indicators, Figure 15 shows the input line area, Figure 16 shows the structure of a control data block, figure 17 shows the line-out area, figure 18 shows the external drive area, figure 19 shows the schematic of the information area of ​​a multi-session disk, Figure 20 shows details of the open session n, Figure 21 shows the general format of a disk control block (DCB), Figure 22 shows the format of the DCB session (SDCB), Figure 23 shows a unit of reserved area data, and

Figure 24 shows a previous session data unit.

Corresponding elements in different figures have identical reference numerals.

Figure 1a shows a disc-shaped record carrier 11 having a track 9 and a central hole 10. Track 9, being the position of the series of marks (to be) recorded representing information, is arranged in a spiral pattern of turns constituting substantially parallel tracks in an information layer. The recording medium may be optically readable, called an optical disk, and has a recordable-type information layer. Examples of a recordable disc are CD-R and CD-RW, and writable versions of DVD, such as DVD + RW. Other details about the DVD disc can be found in the reference: ECMA-267: 120mm DVD - Read-Only Disc - (1997). Information is represented in the information layer by optically etching detectable marks along the track, for example crystalline or amorphous marks in phase change material. Track 9 on the recordable type of recording medium is indicated by a pre-embossed track structure provided during manufacture of the blank recording medium. The track structure is constituted, for example, by a pre-groove 14

ES 2 348 906 T3 which allows a read / write head to keep track during scanning. The track structure comprises position information, eg addresses, for indicating the location of information units, commonly called information blocks. The position information includes specific timing marks to locate the start of such information blocks. Position information is encoded in modulated wobble frames as described later.

Fig. 1b is a cross section taken along line bb of the recording medium 11 of the recordable type, in which a transparent substrate 15 is provided with a recording layer 16 and a protective layer 17. The protective layer 17 may comprise an additional substrate layer, for example, as in DVD where the recording layer is on a 0.6mm substrate and an additional 0.6mm substrate is adhered to the back side of the same. The pre-groove 14 can be implemented as an indentation or elevation of the substrate material 15, or as a material property that deviates from its surroundings.

The recording medium 11 is provided to carry information represented by modulated signals comprising frames. A frame is a predefined amount of data preceded by a sync signal. Typically such frames also comprise error correcting codes, eg parity words. Several such frames constitute an information block, the information block comprising additional error correction words. The information block is the smallest writable unit, from which information can be reliably retrieved. An example of such a recording system is known from the DVD system, in which the frames carry 172 data words and 10 parity words, and 208 frames constitute an ECC block.

In one embodiment of the record carrier, the track comprises information from multiple sessions according to the format described below with reference to Figures 19 to 24.

Figure 2 shows a recording device for writing information to a recording medium 11 of a type that is writable or rewritable, for example CD-R or CD-RW. The device is provided with recording means for scanning the track on the recording medium, means including a drive unit 21 for rotating the recording medium 11, a head 22, a positioning unit 25 for roughly positioning the head 22 in the radial direction of the track and a control unit 20. The head 22 comprises an optical system of a known type for generating a beam 24 of radiation guided through optical elements focused to a point 23 of radiation in a track of the information layer of the record carrier. Radiation beam 24 is generated by a radiation source, for example a laser diode. The head further comprises (not shown) a focus actuator for moving the focus of radiation beam 24 along the optical axis of said beam and a tracking actuator for precision positioning of point 23 in a radial direction about the center. track. The tracking actuator may comprise coils for radially moving an optical element or it may alternatively be arranged to change the angle of a reflective element. To write information, radiation is controlled to create optically detectable marks on the recording layer. For reading, the radiation reflected by the information layer is detected by a conventional type detector, for example a four quadrant diode, in the head 22 to generate a read signal and additional detector signals including an error signal. tracking and a focus error signal to control said tracking and focus actuators. The read signal is processed by the usual type read processing unit 30 which includes a demodulator, a deformer and an output unit to retrieve the information. Therefore, the retrieval means for reading information includes the drive unit 21, the head 22, the positioning unit 25, and the read processing unit 30. The device comprises write processing means for processing the input information to generate a write signal to drive the head 22, means comprising an input unit 27 and modulator means comprising a formatter 28 and a modulator 29. The unit Control 20 controls the recording and retrieval of information and can be arranged to receive instructions from a user or a central computer. The control unit 20 is connected via control lines 26, for example a system bus, to said input unit 27, formatter 28 and modulator 29, to read processing unit 30 and to unit 21 drive and positioning unit 25. The control unit 20 comprises control circuitry, eg, a microprocessor, a program memory, and control gates, for performing procedures and functions according to the invention as described below with reference to Figures 3 to 24. The control unit 20 can also be implemented as a state machine in logic circuits. During the writing operation, the marks representing the information are formed on the recording medium. The marks can be in any optically readable form, for example, in the form of areas with a different coefficient of reflection from the surrounding ones, obtained when engraving on materials such as dye, alloy or phase change material, or in the form of areas with a direction of magnetization different from the surrounding ones, obtained when engraving on magneto-optical material. The writing and reading of information for writing to optical discs and the rules of usable formatting, error correction and channel coding are well known in the art, for example, from the CD system. The marks can be formed by means of the point 23 generated in the recording layer through the beam 24 of electromagnetic radiation, usually from a laser diode. User information is displayed on input unit 27, which may comprise compression means for input signals such as analog audio and / or video, or digital uncompressed audio / video. Suitable compression means are described for audio in WO 98/16014-A1 (PHN 16452), and for video in the MPEG2 standard. The input unit 27 processes the audio and / or video to the information unit, which is passed to the formatter 28 to add control data and format the data according to the recording format (as described later), for example, adding codes error correction (ECC) and / or interleaving. For computer applications, control units can be interconnected.

ES 2 348 906 T3 information to formatter 28 directly. The data formatted from the output of the formatter 28 is passed to the modulation unit 29, comprising, for example, a channel encoder, to generate a modulated signal that drives the head 22. In addition, the modulation unit 29 comprises synchronization means for including synchronization patterns in the modulated signal. Formatted units presented at the input of modulation unit 29 comprise address information and are written to corresponding addressable locations on the record carrier under the control of control unit 20. The control unit 20 is arranged to record and retrieve position data indicative of the position of the recorded information volumes. The device has mapping means comprising a mapping unit 31 coupled to the control unit 20 and detection means comprising a detection unit 32 coupled to the control unit 20 and the mapping unit 31. The mapping unit 31 has an output 33 coupled to the formatter 28 for writing session map blocks to a session map area as described later. The detection unit 32 has an input 34 coupled to the reading unit 30 for detecting the session map blocks from the session map area. The detection unit 32 is coupled to the mapping unit 31 to transfer data from the detected session map blocks to generate new session map blocks that include the existing data. The mapping unit 31 is arranged to determine the position of the recorded volume of information, also called a session, in particular the start and end address of each closed session. First, a session is opened by writing an input zone, then user data can be written using various write instructions, and finally the session is closed by filling in all the remaining blank areas and recording session control blocks and a part of close at the end zone of that volume, as described later.

In one embodiment of the device, the mapping unit is arranged to record consecutive session map blocks. When a session is completed, a next session map block is recorded, comprising a session data unit for each closed session as described below with reference to Figures 12 and 13.

A practical embodiment of the system for recording information according to the invention is as follows. The system specifies the mechanical, physical, and optical characteristics of 120mm writable optical discs with 4.7 Gbyte and 9.4 Gbyte capacities. Specifies the quality of the recorded and unrecorded signals, the data format, and the procedure. recording , thereby allowing the exchange of information via such discs. Data can be written once and read many times using a non-reversible procedure. These discs are identified as DVD + R. The conformation of the track is as follows. The recordable area, called the information zone, must contain tracks formed from a single spiral groove. Each track must form a 360 ° turn of a continuous spiral. Recordings must be made in the groove. Tracks in the information area contain a phase modulated sinusoidal deviation from nominal center lines, called wobble, which contains addressing information called Address-in-Pregroove or ADIP. The tracks must be continuous in the information area. Groove tracks must start with a maximum radius of 22.0mm and end with a minimum radius of 58.50mm. The track path must be a continuous spiral from the inside (start of the line-in area) to the outside (end of the line-out area) when the disk rotates counterclockwise as viewed from the optical head. Track pitch is the measured distance between the average track center lines of adjacent tracks, measured in the radial direction. The runway pitch will be 0.74 pm ± 0.03 pm. The averaged runway pitch over the information zone will be 0.74 ± 0.01 pm. The oscillation of the tracks is a sinusoidal deviation from the nominal center lines, with a wavelength of 4.265 6 pm ± 0.045 0 pm (equivalent to 32 channel bits). The total harmonic distortion (THD) of the oscillator to generate the sine wave of the oscillation will be <-40 dB. The oscillation is modulated in phase by reversing the oscillation cycles. The information contained in the oscillation modulation is called Address-in-Pregroove or ADIP.

Figure 3 shows the alignment of ADIP and information blocks. The information blocks 37 to be recorded on the disk must be aligned with the ADIP information 39 modulated in the oscillator 38. It is shown that 93 oscillations correspond to 2 sync frames that are the start of an information block. Out of every 93 oscillations, 8 oscillations are phase modulated with information from ADIP. Furthermore, 1 oscillation is equal to 32 channel bits (= 32T) and one unit of ADIP = 8 modulated oscillations for every 2 synchronization frames.

Figure 4 shows the ADIP word structure. 52 ADIP units are grouped into one ADIP word each. This means that one ADIP word corresponds to 4 x 13 x 2 sync frames ξ 4 physical sectors. Each ADIP word consists of: 1 ADIP sync unit + 51 ADIP data units. The ADIP sync unit = 4 inverted wobbles for word sync + 4 monotone wobbles. The ADIP data unit = 1 inverted wobble for bit synchronization + 3 monotonous wobbles + 4 wobbles representing one bit of data. (see 0).

The information contained in the data bits of an ADIP word is as follows:

bit 1: this bit is reserved and must be set to ZERO.

bit 2 to 23: these 22 bits contain a physical address. Data bit 2 is the most significant bit (MSB) and data bit 23 is the least significant bit (LSB). The addresses increase by one for each subsequent ADIP word. The first address in the information area must be such that the physical address (00C000) is located in the radius 24.0 / 0.0 mm.

ES 2 348 906 T3 bit 24 to 31: These 8 bits contain auxiliary information about the disc, eg recording control information. In the data area and the disk output line area the auxiliary bytes should be set to (00). In the input line area of ​​the disk the auxiliary bytes must be used as follows: Bits 24 to 31 from 256 consecutive ADIP words must form an ADIP auxiliary frame with 256 bytes of information. The first byte of each ADIP helper frame must be located in an ADIP word with a physical address that is a multiple of 256 (physical address = (xxxx00)). The content of the 256 bytes is defined in figure 7.

Bit 32 to 51: These 20 bits contain error correction parities for the ADIP information.

Figure 5 shows the ADIP error correction structure. For ADIP error correction the ADIP data bits are grouped into 4-bit nibbles. The mapping of the data bits in the nibble arrangement is defined in Figure 5. Bit 0 is a dummy bit, which should be considered as set to ZERO for the error corrector. A code (13,8,6) RS is constructed based on a quartet, of which the 5 parity quartets N₈ to Ni₂, are defined by the remaining polynomial R (x):

R (x) = ^ 2 N, x¹²'¹ = I (x) x⁵ mod G_PA (x) f = 8 where

I (x) = £ n, x⁷'= = 0 θΡΑ (^χ)⁼⁼Π (^ + α^λ)

A = 0 α is the primitive root 0010 of the primitive polynomial P (x) = x⁴ + x + 1

All bits of the 5 n parity nibbles₈ to N_í2 they must be reversed before recording.

Figure 6 shows the modulation rules of ADIP. The ADIP units are modulated by reversing some of the 8 oscillation cycles. Figure 6a shows the ADIP word sync modulation, Figure 6b shows the modulation of a bit of ADIP ZERO, and Figure 6c shows the modulation of a bit of ADIP ONE, where

- PW is a positive oscillation, which starts moving towards the interior of the disk.

- NW is a negative oscillation, which begins by moving towards the outside of the disk.

- all monotonic oscillations are indicated as PW.

Figure 7 shows a table of physical disk information. Physical disk information is encoded in ADIP as described above. This information will comprise the 256 bytes shown in Figure 7. It contains information and disk values ​​used for the Optimal Power Control (OPC) algorithm to determine optimal laser power levels for writing. The information is copied to a writable area called the control data during disk initialization. The content of the data is

Byte 0 - Disk category and version number

Bits b7 to b4 will specify the disc category, they will be set to 1010, indicating a DVD + R disc.

Bits b3 through b0 will specify the version number, they will be set to 0000, indicating the version.

ES 2 348 906 T3

<td>Byte 1</td><td>- Disk size and maximum transfer rate</td>

<td>Bits b7 to b4</td><td>will specify the disk size, will be set to 0000, indicating a 120mm disc</td>

<td>Bits b3 to b0</td><td>specify the maximum read transfer rate, will be set to 1111 indicating that no maximum read transfer rate is specified</td>

<td>Byte 2</td><td>- Disc structure</td>

<td>Bits b7 to b4</td><td>will be set to 0000</td>

<td>Bits b3 to b0</td><td>specify the type of recording layer (s): they will be set to 0010, indicating a write-only recording layer.</td>

<td>Byte 3</td><td>- Recording density</td>

<td>Bits b7 to b4</td><td>specify the average channel bit length in the info zone, set to 0000, which indicates 0.133 pm</td>

<td>Bits b3 to b0</td><td>will specify the average track pitch, will be set to 0000, indicating an average track pitch of 0.74pm</td>

<td>Bytes 4 to 15</td><td>- Data zone assignment</td>

<td>Byte 4</td><td>will be set to (00).</td>

<td>Bytes 5 to 7</td><td>will be set to (030000) to specify PSN 196.608 of the first physical sector of the data zone</td>

<td>Byte 8</td><td>will be set to (00).</td>

<td>Bytes 9 to 11</td><td>will be set to (26053F) to specify PSN 2,491,711 as the last possible physical sector in the data zone.</td>

<td>Bytes 12 to 15</td><td>will be set to (00)</td>

<td>Byte 16</td><td>- (00) will be set to (00).</td>

<td>Bytes 17 to 18</td><td>Reserved. These bytes are reserved and must be set to (00).</td>

<td>Bytes 19 to 26</td><td>Disk manufacturer ID. These 8 bytes will identify the manufacturer of the disk. Unused tail bytes will be set to (00).</td>

<td>Bytes 27 to 29</td><td>- Media type ID. Disc manufacturers may have different types of media, which will be specified by these 3 bytes. The specific type of disk is indicated in this field.</td>

<td>Byte 30</td><td>- Product revision number. This byte will identify the product revision number in binary notation. All discs with the same disc manufacturer ID and the same product ID, regardless of product revision numbers, must have the same recording properties (only minor differences are allowed: Product revision numbers will be irrelevant to recording devices). If not used, this byte will be set to (00)</td>

<td>Byte 31</td><td>number of bytes of physical format information in use. This byte forms an 8-bit binary number that indicates the number of bytes actually in use for physical format information. It will be set to (36) which indicates that only the first 54 bytes of the physical format information are used.</td>

ES 2 348 906 T3

Byte 32

Byte 33

Byte 34

Byte 35

Byte 36

Byte 37

Byte 38

Byte 39

Byte 40

Byte 41

Byte 42

Byte 43

- Reference recording speed. This byte indicates the lowest possible write speed of the disk, which is also called the reference speed, as a number n such that n = 10 xv_ref (n rounded to an integral value)

It will snap to (23), indicating a reference write speed of 3.49 m / s.

- Maximum recording speed. This byte indicates the highest possible write speed of the disk, as a number n such that n = 10 xv_ref (n rounded to an integral value)

It will be set to (54), indicating a maximum write speed of 8.44 m / s.

Wavelength .UNID This byte will specify the wavelength in nanometers of the laser with which the optimal writing parameters have been determined in the following bytes, as a number n so that n = Wavelength - 600

Reserved

Maximum reading power, Pr at reference speed. This byte will specify the maximum read power Pr in milliwatts at the reference speed as a number n so that n = 20 x (Pr - 0.7)

PIND at reference speed. PIND is the starting value for the determination of Ppo used in the OPC algorithm. This byte will specify the PIND indicative value of Ppo in milliwatts at the reference speed as a number n such that n = 20 x (Pi_ND - 5)

Aim at reference speed. This byte will specify the target value for β,_J6_obj_effective, at the reference speed used in the OPC algorithm as a number n so that ⁿ = ^{10 x β}target

Maximum reading power, Pr at maximum speed. This byte will specify the maximum read power Pr in milliwatts at maximum speed as a number n such that n = 20 x (Pr - 0.7)

P_IND at maximum speed. P_IND is the starting value for the determination of Ppo used in the OPC algorithm. This byte will specify the PIND indicative value of Ppo in milliwatts at maximum speed as a number n so that n = 20 x (PIND - 5)

A * j_effective at maximum speed. This byte will specify the target value for β, / Di_ljelr._or, at the maximum speed used in the OPC algorithm as a number n so that ⁿ = ^{10 x} ^ objective

Ttop (> 4) duration of first pulse for current mark> 4 at reference speed. This byte will specify the duration of the first pulse of the multi-pulse train when the current mark is a 4T mark or greater to record at the reference speed. The value is expressed in fractions of the channel bit clock period as a number n such that^Tt ° p / n-16x /^Tw V 4 <n <40

Ttop (= 3) duration of first pulse for current mark = 3 at reference speed. This byte will specify the duration of the first pulse of the multi-pulse train when the current mark is a 3T mark to record at the reference speed. The value is expressed in fractions of the channel bit clock period as a number n such that

ES 2 348 906 T3

Byte 44

Byte 45

Byte 46

Byte 47

Byte 48

Byte 49

Byte 50

Ttop / n = 16x /^Tw V 4 &lt;n &lt;40

Tmp duration of multiple pulses at the reference speed. This byte will specify the duration of the 2nd pulse from the 2nd to the last pulse of the multi-pulse train to record at the reference speed. The value is expressed in fractions of the channel bit clock period as a number n such that^Tmp / n = 16x '^Tw Y 4 &lt;n &lt;16

Tlp duration of the last pulse at the reference speed. This byte will specify the duration of the last pulse of the multi-pulse train to record at the reference speed. The value is expressed in fractions of the channel bit clock period as a number n such that

V n = 16x /^Tw and 4 &lt;n &lt;24 dTtop lead time of the first pulse at the reference speed. This byte will specify the lead time of the first pulse of the multi-pulse train with respect to the trailing edge of the second channel bit of the data pulse to record at the reference rate. The value is expressed in fractions of the channel bit clock period as a number n such that dT_lop/ n = 16x /^Tw y 0 &lt;n &lt;24 dTle leading edge correction of 1^er pulse for space before = 3 at reference speed. Bit 7 to bit 4 of this byte will specify the leading edge correction for the 1^erpulse of the multi-pulse train when the previous space was a 3T space to record at the reference speed. The value is expressed in fractions of the channel bit clock period according to Figure 8.

Ttop (> 4) duration of first pulse for current mark> 4 at maximum speed. This byte will specify the duration of the first pulse of the multi-pulse train when the current mark is a mark of 4T or greater to record at maximum speed. The value is expressed in fractions of the channel bit clock period as a number n such that n = 16x '^Iw and 4 <n <40

Ttop (3) duration of first pulse for current mark = 3 at maximum speed. This byte will specify the duration of the first pulse of the multi-pulse train when the current mark is a 3T mark to record at maximum speed. The value is expressed in fractions of the channel bit clock period as a number n such that^Ttop / n = 16x /^Tw and 4 &lt;n &lt;40

Tmp duration of multiple pulses at maximum speed. This byte will specify the duration of the 2nd pulse from the 2nd to the last pulse of the multi-pulse train to record at maximum speed. The value is expressed in fractions of the channel bit clock period as a number n such that^Tmp / n = 16x /^Tw Y

4 &lt;n &lt;16

ES 2 348 906 T3

Byte 51 Tlp duration of the last pulse at maximum speed. This byte will specify the duration of the last pulse of the multi-pulse train to record at maximum speed. The value is expressed in fractions of the channel bit clock period as a number n such that ν n = 16x^{/ Tw} and 4 &lt;n &lt;24

Byte 52 dTtop first pulse anticipation time at maximum speed. This byte will specify the lead time of the first pulse of the multi-pulse train with respect to the trailing edge of the second channel bit of the data pulse to record at the maximum rate. The value is expressed in fractions of the channel bit clock period as a number n such that © op / n = 16x /^Twy 0 &lt;n &lt;24

Byte 53 dTle 1st pulse leading edge correction for leading space = 3 at maximum speed. Bit 7 to bit 4 of this byte will specify the leading edge correction for the 1^erpulse of the multi-pulse train when the above gap was a 3T gap to record at full speed. The value is expressed in fractions of the channel bit clock period according to Figure 8.

Bytes 54 to 255 Reserved - All (00). These bytes will all be set to (00).

Figure 8 shows leading edge correction times. The parameter is named dT, „and was previously described with Figure 7 in byte 47. Bit 3 to bit 0 of this byte will be set to 0000. Unspecified bit combinations will not be used.

Figure 9 shows the record carrier sector numbering. The recordable area is called the information zone. The information area will contain all the information about the disk relevant to data exchange. The information zone can contain one or more sessions. Each session will be divided into three parts: an entry / entry line zone, a data zone, and a exit / close line zone. In double-sided discs there is an information area for each side. The data areas are intended for the recording of user data. The input line zone contains control information. The line-out zone allows for continuous smooth output and also contains control information. The internal and external drive areas are dedicated to testing the disk. A description is given for a single session disc. In such a disc, the line-in area, the data area and the line-out area constitute the recordable area in which the information is recorded using an irreversible effect. The schema for a multi-session disk is defined later.

Figure 10 shows a schematic of a single session recorded disc. The information area of ​​single-sided discs and each side of double-sided discs is subdivided into an internal drive area, an input line, a data area, an output line area, and an external drive area. Radii are indicated for zones by nominal values ​​of the center of the first (or last) runway in the zone. Physical Sector Numbers (PSN) for the first physical sector in each zone are displayed. The data zone must have a first PSN (030000). PSNs increase by 1 for each subsequent physical sector in the entire information zone.

Figure 11 shows the internal drive area. The internal drive area is the innermost area of ​​the disk that is used by the drive to perform disk tests and OPC algorithms. The physical sector number of the first and last physical sector in each part is indicated in hexadecimal and decimal notation, and the number of physical sectors in each part is indicated in decimal notation. The following subdivision is displayed:

- Initial zone: This zone must remain virgin.

- Internal disk test zone: 16384 physical sectors reserved for testing the drive and OPC.

- Internal disk count zone: 4096 physical sectors reserved to count the number of OPC algorithms performed in the internal disk test zone. Whenever an ECC block or part of it has been recorded in the internal disk test area, the ECC block must be labeled by writing 4 physical sectors in the internal disk count area.

- Internal disk management zone: 4096 physical sectors to be used for optional drive specific information. The first 16 physical sectors in this zone must be filled with all the main data set to (00). The internal disk management area contains drive information, for example a drive identification (drive ID) and data as defined by the drive manufacturer.

ES 2 348 906 T3

- Session map area: 4096 physical sectors to store information about the locations of sessions and recordings on the disk. The first 16 physical sectors in this zone must be filled with all the main data set to (00). This zone consists of 2 parts:

part 1: consists of 191 ECC blocks called session map blocks (SEM) that are going to be used to store the locations of all closed sessions, part 2: consists of 1024 physical sectors, grouped in units of 4 sectors, where each unit corresponds to one word of ADIP. These units will be used as recorded area indicators.

Figure 12 shows a session map block (SEM) format. Whenever a session is closed, the next ECC block in the session map zone, immediately following the last SEM, should be recorded with the locations of all closed sessions. The first ECC block in the session map area should be used as the start-up for the second ECC block. If all 191 blocks have been used, additional sessions can still be added, however the unit will have to perform a search procedure to find the additional sessions. The figure shows the following content for the SEM for each physical sector:

Physical sector 0 / bytes D0 to D3 - Content descriptor. These bytes identify the DCB session and will be set to (544F4300), representing the characters "SDC" and version number 0.

Physical sector 0 / bytes D4 to D7 - Reserved. Will be set to (00)

Physical sector 0 / bytes D8 to D39 - Drive ID. These bytes will contain the ID of the unit.

Physical sector 0 / bytes D40 to D63 - Reserved. Will be set to (00)

Physical sector 0 / bytes D64 to D2047 - Session data units. These bytes are grouped into units of 16 bytes each. Each 16-byte unit can contain one session data unit according to Figure 13. All unused bytes will be set to (00).

Figure 13 shows a session data unit. The session map block (SEM) must contain a unit of session data for each closed session on disk. Session data units should be ordered with increasing numbers and addresses, as follows:

Bytes B0 to B2: these 3 bytes identify the type of data unit and will be set to (53.53.4E), representing the “SSN” characters.

byte B3: this byte will specify the sequence number of the session specified in this data unit.

Bytes B4 to B7: These 4 bytes will specify the PSN of the first physical sector in the session data zone specified in this data unit.

Bytes B8 to B11: These 4 bytes will specify the PSN of the last physical sector in the session data zone specified in this data unit.

Bytes B12 to B15: These 4 bytes are reserved and will be set to (00).

Figure 14 shows recorded area indicators. The last part of the SEM area for recording SEM blocks 61 is shown schematically. A mapping area 60 is located at the edge of the SEM zone. The next zone, that is, security zone 62, is shown on the far right. The mapping area is recorded starting from the upper direction. A recorded part 64 indicates the recorded regions of the recordable area, and the unrecorded part 63 indicates the unrecorded regions. To speed up disk access, the recording apparatus needs to know in which region of the disk the last written ECC block can be found. For this, the mapping area is defined, based on areas recorded with the size of 4 physical sectors, each area corresponding to one ADIP word. These areas will be recorded with random EFM signals. No spaces are allowed between recorded ADIP words. 1024 physical sectors have been reserved for this purpose, allowing the disk to be divided into a maximum of 256 regions. Etched area indicators should be used from the outer side of the SEM zone to the inner side of the SEM zone. By "HF detection" the recording apparatus can find the location of the start of the recorded area indicators and determine the region in which the last recorded ECC block can be found. Each 640 block region of ECC between PSN = (030000) and PSN = (26053F) corresponds to a recorded area indicator. All regions up to and including the last recorded ECC block should be indicated by their recorded area indicator. In mathematical form: if the first recorded area indicator consists of the physical sectors with PSNRAI to PSNRAI + 3, then the ECC block recorded last can be found between:

PSN = {(02A47C) - (PSNRAI)} x (A0) + (030000) y

PSN = {(02A47C) - (PSNRAI)} x (A0) + (030280)

ES 2 348 906 T3 or in decimal notation:

PSN = {173180- (PSNRAI)} x160 + 196608 y

PSN = {173180- (PSNRAI)} x160 + 197248

Figure 15 shows the entry line area. The entry line zone is located on the inner side of the information zone. A blank disc does not have any data recorded in the line-in area. After finalizing the disc or closing the first session, the line-in area will be recorded as described below. Figure 15-10 shows the zones and directions, as follows (notation as in Figure 11):

- Security Zone 1: The Security Zone is used to create a minimum amount of entry line zone required for compatibility. This zone should contain 14,848 physical sectors, all populated with main data set to (00).

- Reserved Zone 1: 4096 physical sectors are reserved and will be set to (00).

- Reserved Zone 2: 64 physical sectors are reserved and will be set to (00).

- Internal disk identification zone: 256 physical sectors reserved for information stipulated by the data exchange parties. Each set of 16 physical sectors in an ECC block is either a disk control block (DCB) or is written with all main data at (00). Each ECC block in this zone that follows one recorded with all the main data at (00) will also be recorded with the main data at (00).

- Reserved Zone 3: 64 physical sectors are reserved and will be set to (00).

- Reference code area: The recorded reference code area must consist of the 32 physical sectors of two ECC blocks that generate a specific channel bit pattern on disk. This should be achieved by setting (AC) the main 2048 bytes of data of each corresponding data frame. Also, no scrambling should be applied to these data frames, except for the first 160 bytes of main data of the first data frame of each ECC block.

- Buffer zone 1: This zone must consist of 480 physical sectors of 30 ECC blocks. The main data of the data frames in this area will all be set to (00).

- Control data zone: This zone must consist of 3072 physical sectors of 192 ECC blocks. The content of the 16 physical sectors of each ECC block is repeated 192 times.

- Buffer zone 2: This recorded zone must consist of 512 physical sectors of 32 ECC blocks.

The main data of the data frames in this area will all be set to (00).

Figure 16 shows the structure of a control data block. The first 2048 bytes constitute physical format information, the content of which is given in Figure 7. The next 2048 bytes constitute disk manufacturing information. The last 14x 2048 bytes are available for content provider information. In one embodiment of the device, the 28,672 bytes of content provider information are set to zero (00). Data received from a central computer is locked and is not recorded in this field. This avoids recording data of a confidential nature here, for example decryption keys for decoding video from a DVD video disc. The physical format information contains disk and format information. The information in bytes 0 to 255 50 should be copied from the ADIP ancillary data during disk finalization or first session close, and should reflect the actual state of the disk or the first session (for example, the real end of the data area). The 256 bytes have the same definitions and content as the physical disk information defined in Figure 7, except for the following bytes:

Byte 0

Bits b7 to b4

Bits b3 to b0

Byte 1

Bits b7 to b4

- Disc category and version number will specify the disc category, indicating a DVD + R disc.

specify the version number of the system description

- Disc size and maximum transfer rate will specify the disc size, will be set to 0000, indicating a 120mm disc

<td></td><td>ES 2 348 906 T3</td>

<td>Bits b3 to b0</td><td>they will specify the maximum read transfer rate. These bits can be set to one of the following values, depending on the maximum read rate required by the application: 0000: a maximum transfer rate of 2.52 Mbits / s 0001: a maximum transfer rate of 5.04 Mbits / s 0010: a maximum transfer rate of 10.08 Mbits / s 1111: no maximum transfer rate specified. All other combinations are reserved and should not be used.</td>

<td>Byte 2</td><td>- Disc structure</td>

<td>Bits b7 to b4</td><td>will be set to 0000</td>

<td>Bits b3 to b0</td><td>specify the type of recording layer (s): they will be set to 0010, indicating a write-only recording layer.</td>

<td>Bytes 4 to 15</td><td>- Data zone assignment</td>

<td>Byte 4</td><td>will be set to (00).</td>

<td>Bytes 5 to 7</td><td>will be set to (030000) to specify PSN 196.608 of the first physical sector of the data zone</td>

<td>Byte 8</td><td>will be set to (00).</td>

<td>Bytes 9 to 11</td><td>they will specify the sector number of the last physical sector of the data zone of the first session.</td>

<td>Bytes 12 to 15</td><td>will be set to (00).</td>

<td>Bytes 256 to 2047</td><td>- Reserved. These remaining bytes have no relation to the ADIP information and will be set to zero (00).</td>

Figure 17 shows the starting line area. At the top, the data area 70 is shown for recording user data. The data zone has 2,295,104 physical sectors of user data area. The starting radius of the data zone is determined by the location of the ADIP physical address (00C000). After the data area, the start line area follows. The start line zone is located on the outside of the information zone. Figure 17 shows the following parts:

- Buffer zone 3: This recorded zone must consist of 768 physical sectors. The last possible starting location of buffer zone 3 is (260540). The main data of the data frames in this area will all be set to (00).

- External disk identification zone: 256 physical sectors reserved for information stipulated by the data exchange parties. Each set of 16 physical sectors in an ECC block is either a disk control block (DCB) or is written with all main data at (00). The content of this zone must be equivalent to the content of the last internal session identification zone (or the content of the internal disk identification zone in case of a single session disk).

- Security zone 2: This security zone is used as protection to separate test write zones from information zones containing user data. This area must be filled with main data set to (00). This zone must contain a minimum of 4096 physical sectors.

- External drive area: The external drive area is the outermost area of ​​the disk that is used by the unit to perform disk tests and OPC algorithms.

Figure 18 shows the outdoor drive area, starting from security zone 2. The following parts are shown below:

- External disk management zone: 4096 physical sectors to be used for optional drive specific information. The first 16 physical sectors of this zone must be filled in with all the main data

ES 2 348 906 T3 set to (00). This zone can be used in the same way as the internal disk management zone (see 0).

- External disk count zone: 4096 physical sectors reserved to count the number of OPC algorithms performed in the external disk test zone.

- External disk test zone: 16384 physical sectors reserved for testing the drive and OPC algorithms. Whenever an ECC block or part of it has been recorded in the external disk test area, the ECC block must be labeled by writing 4 physical sectors in the external disk count area.

- Security zone 3: This zone must remain virgin.

Figure 19 shows the diagram of the information area of ​​a multi-session disk. There can be more than one session on disk; Session 1, Session 2, and the last Session N are displayed. A session with an introduction and a close is called a closed session. The first session must be preceded by an entry line zone instead of an introduction zone, the final session must be followed by a exit line zone instead of a closing zone. Once a line-out zone has been recorded, the disc is said to be "finalized" and no further recordings will be allowed on the disc. A session without an introduction or closure is called an open session. All sessions must be closed sessions, except the last one, which is allowed to be an open session. User data can only be added to an open session. If all sessions are closed, a new open session can be added. The first closed session on disk must have an input line as described in Figure 15. Subsequent closed sessions must have an introduction as defined below. Each closed session must have a closure as defined below, except the final session, which must have an output line as described in reference to Figure 17.

Each new session that occurs after the first session starting at PSN 30000 must begin with an introductory zone. The input zone consists of a buffer zone A, an internal session identification zone, a session control data zone, and a buffer zone B. All physical sectors in the entry zone must have bits b27 through b26 of the data frame set to ZERO ZERO, identifying the entry zone as if it were a data zone as described in reference to Figure 9. The zone Buffer A consists of 64 physical sectors that should be set to (00). The internal session identification zone consists of 256 physical sectors reserved for information stipulated by the data exchange parties. Each set of 16 physical sectors of an ECC block is either a disk control block (DCB) (see Figure 21) or is written with all main data at (00). Each ECC block in this zone that follows one recorded with all the main data at (00) will also be recorded with the main data at (00). The session control data area consists of 640 physical sectors of 40 ECC blocks. The content of the 16 physical sectors of each ECC block is repeated 40 times. The structure of a control data block must be as shown in figure 16. Finally, buffer zone B consists of 64 physical sectors that must be set to (00).

Each session must end with a closing zone that consists of two parts; a buffer area C and an external session identification area. All physical sectors in the closing zone must have bits b27 to b26 of the data frame set to ZERO ZERO, identifying the closing zone as if it were a data zone. Buffer area C consists of 768 physical sectors that should be set to (00). The external session identification zone consists of 256 physical sectors reserved for information stipulated by the data exchange parties. Each set of 16 physical sectors in an ECC block is either a disk control block (DCB) (see Figure 21) or is written with all main data at (00). The content of this zone must be equivalent to the content of the last internal identification zone.

Write-only type recording media according to the invention, for example DVD + R discs, must be recorded sequentially from the inner side of the disc to the outer side of the disc. Read-only device support can only be achieved when the disk has a line-in zone, all sessions have been closed, and there are no blank areas between the start of the line-in zone and the end of the last line zone exit or closing.

Figure 20 shows details of open session n. New data can be added to disk by adding data to an open session. If all sessions have been closed, a new session must be opened. A new session is opened by writing a buffer area A and an SDCB (session disk control block, see FIG. 22) in the first ECC block of the internal session identification area. Additionally, the buffer zone B of the introduction must be recorded. The first session on a blank disc is opened by recording the reserved area 2 plus an SDCB in the first ECC block of the internal disc identification area, and additionally the buffer area 2 of the input line area must be recorded in case the first session needs to be recorded on a blank disc. User data added to the data area must be immediately linked to previously written user data in the data area or to previously written data in one of the reserved areas. If a recorded area is preceded by a reserved area, an additional ECC block is required as a start-up for the first ECC block of the recorded area. The additional ECC block must be considered as part of the recorded area and therefore does not belong to the previous reserved area.

ES 2 348 906 T3

When it is not necessary to record more user data, the session can be closed. When compatibility with DVD-RO devices is desired, all sessions on the disc should be closed. A session is closed by recording all the remaining parts in the entry / intro line zone and adding the closing zone. In the input line area or input area the control data area is to be recorded. At each input, the session control data area must be recorded with 40 ECC blocks according to the format described above with reference to figure 15 with the following settings for the physical format information:

<td>Byte 0</td><td>- Disc category and version number</td>

<td>Bits b7 to b4</td><td>will specify the disk category, they will be set to a preset value, indicating a DVD + R disc.</td>

<td>Bits b3 to b0</td><td>specify the version number, they will be set to a predefined value, which indicates the version of the standard.</td>

<td>Byte 1</td><td>- Disk size and maximum transfer rate</td>

<td>Bits b7 to b4</td><td>will specify the disk size, will be set to 0000, indicating a 120mm disc</td>

<td>Bits b3 to b0</td><td>they will specify the maximum read transfer rate. These bits can be set to one of the following values ​​(depending on the maximum read rate required by the application): 0000: specify a maximum transfer rate of 2.52 Mbits / s 0001: specify a maximum transfer rate of 5.04 Mbits / s 0010: specify a maximum transfer rate of 10.08 Mbits / s 1111: do not specify a maximum transfer rate.</td>

All other combinations are reserved and should not be used.

<td>Byte 2</td><td>- Disc structure</td>

<td>Bits b7 to b4</td><td>will be set to 0000</td>

<td>Bits b3 to b0</td><td>specify the type of recording layer (s): they will be set to 0010, indicating a write-only recording layer.</td>

<td>Byte 3</td><td>- Recording density</td>

<td>Bits b7 to b4</td><td>specify the average channel bit length in the info zone, set to 0000, which indicates 0.133 pm</td>

<td>Bits b3 to b0</td><td>will specify the average track pitch, will be set to 0000, indicating an average track pitch of 0.74pm</td>

<td>Bytes 4 to 15</td><td>- Data zone assignment</td>

<td>Byte 4</td><td>will be set to (00).</td>

<td>Bytes 5 to 7</td><td>they will specify the sector number of the first physical sector of the data zone of the current session.</td>

<td>Byte 8</td><td>will be set to (00).</td>

ES 2 348 906 T3

<td>Bytes 9 to 11</td><td>they will specify the sector number of the last physical sector in the data zone of the current session.</td>

<td>Bytes 12 to 15</td><td>will be set to (00).</td>

<td>Bytes 16 to 255</td><td>- Reserved - All (00) These bytes should not be copied from the ADIP information, but should be set to (00).</td>

Bytes 256 to 2047 - Reserved - All (00)

These remaining bytes have no relation to the ADIP information and will all be set to zero (00).

Disc manufacturing information and content provider information as described above.

The closing zone is defined as follows. When closing a session, the buffer area C must be written together with the external session identification area.

When no more sessions are to be recorded the user can decide to finalize the disc. When the disc is finalized, instead of a closing area a line-out area should be recorded as described above with reference to Fig. 17. After finalizing the disc, it is no longer possible to add data.

Figure 21 shows the general format of a disk control block. Disk Control ECC Blocks (DCBs) are provided as a structure on the disk to include additional information for exchange between the data exchange parties. DCBs are recorded in the internal and external identification areas of the disc or session. All DCBs must be in the same format for the first 40 bytes of data. A special DCB is defined to reflect the state of the session (s). If a disk control block must be updated, a substitute DCB must be written immediately following the last DCB written in the internal session identification zone. Once a session has been closed, DCBs can no longer be updated. The main data of each disk control block is defined as follows (see figure 21):

Bytes D0 to D3 - Content descriptor

- if it is set to (00000000) the DCB is unused. The content descriptor of all subsequent DCBs in this internal or external identification zone must be set to (00000000). All remaining bytes, D4 through D2 047 in physical sector 0 and D0 through D2 047 in physical sector 1 through 15 should be set to (00).

- if set to (53444300) this DCB is a session DCB (SDCB) as defined below.

- all other values ​​for the content descriptor are reserved.

Each new DCB added to the inner or outer identification block must be written to the first available unwritten DCB location.

Each DCB with a content descriptor not set to (00000000) in the internal identification zone of a session must have an identical DCB in the external identification zone in the respective session. The order of the DCBs in the internal identification zone must be the same as the order in the external identification zone.

Bytes D4 to D7 - Unknown content descriptor actions

- These bits are provided to specify required actions when the content and usage of the DCB is unknown (ie the content descriptor does not conform to a known assigned value). These bytes form a field consisting of individual 32 bits.

<td>Bits b31 to b4</td><td>Reserved These bytes must all be set to ZERO.</td>

<td>Bitb3</td><td>Rewrite DCB, if it is set to ONE, it should not be allowed to replace the current DCB, if not, it should be set to ZERO.</td>

<td>Bit b2</td><td>Formatting, if set to ONE, disk reformatting should not be allowed or not possible, if not, it should be set to ZERO.</td>

ES 2 348 906 T3

Bit b1 DCB read protection, if set to ONE, the information in this DCB is for unit use only and should not be transferred out of the drive, if not, it should be set to ZERO.

Bit b0 Data zone write, if set to ONE, no data zone write should be allowed, if not, it should be set to ZERO.

Bytes D8 to D39 Unit ID

- Bytes D8 to D39 must contain a single descriptor, which identifies the unit that has the DCB written. The format of this unique drive identifier should be as follows: Bytes D8 through D23 should identify the manufacturer of the drive. Bytes D24 through D35 should identify the model name / type number of the unit. Bytes D36 through D39 must contain a unique drive serial number. The 4 bytes must form a 32-bit binary number.

- Bytes D40 to D2047 Specific to the content descriptor. The bytes are specified by the description for the DCB with the actual content descriptor value.

Physical Sector 1 to 15: Bytes D0 to D2047 Content descriptor specific. The bytes are specified by the format description for the DCB with the actual content descriptor value.

Figure 22 shows the format of the session disk control block (SDCB). Both the entry / entry line area and the exit / exit line area of ​​a session must contain an SDCB that contains a session map of the session. The SDCB in the internal and external session identification zones must be identical and have the following content:

Physical sector 0 / bytes D₀ to D₃ - Content descriptor. These bytes identify the DCB session and must be set to (53444300), representing the characters "SDC" and version number 0.

Physical sector 0 / bytes D₄ to D₇ - Unknown content descriptor actions. Bytes should be set to (0000000D) indicating that if the system does not know this DCB, the DCB should not be replaced, the disk cannot be reformatted, it should not be allowed to write to the data zone, while it is allowed to transfer the DCB information from the unit to the central computer.

Physical sector 0 / bytes D₈ to D₃₉ - Unit ID. These bytes should contain the Drive ID as specified above with Figure 21, Bytes D₈ to D₃₉.

Physical sector 0 / bytes D₄₀ to D₄₁ - Session number. These bytes must specify the sequence number of the session to which the SDCB belongs. The first session must have sequence number 1 and each subsequent session number must be incremented by one.

Physical sector 0 / bytes D₄₂ to D₆₃ - Reserved. These bytes are reserved and must be set to (00)

Physical sector 0 / bytes l ')_(J to D₉₅ - Disk ID. In the SDCB in the internal disk identification zone in the input line zone of the first session, these 32 bytes must be written with a random, statistically unique, 256-bit binary number on disk initialization (opening of the first session). In the SDCB in the internal session identification zone at the introduction of each next session, the bytes l ')_(J to D₉₅ they should all be set to (00).

Physical sector 0 / bytes D₉₆ to D₁₂₇ - Field dependent on the application. The field must consist of 32 bytes and is reserved for use by the application to store information such as specific copy protection data. If this setting is not specified by the application, the bytes must be set to (00). In each session these bytes can be adjusted independently.

Physical sector 0 / bytes D₁₂₈ to D₂₀₄₇ - Session data units (SES). These bytes are grouped into units of 16 bytes each. Each 16-byte drive can contain one of two different types of SES data drives:

- a reserved area data unit that specifies reserved areas in the current session

- a previous session data unit specifying the starting and ending addresses of previous sessions.

All unused bytes must be set to (00).

Fig. 23 shows a reserved area data unit. An SDCB can contain more than 1 unit of reserved area data. If there are no reserved areas, there should be no reserved area data units. If a new reserved area is to be added to an existing open session, a new SDCB is written to the internal identification zone of the current session, immediately following the last SDCB. The last SDCB written to the internal identification zone is the valid SDCB. The areas reserved in a session must not overlap. Data units

ES 2 348 906 T3 reserved area must be ordered with increasing addresses. The figure shows the reserved area data drive schematic as follows:

bytes B₀ a B₂: these 3 bytes identify the type of data unit and must be set to (525356), representing the “RSV” characters.

byte B₃: this byte will specify the sequence number of the reserved area. The first reserved area in the session must have sequence number 1 and each subsequent reserved area number must be incremented by one.

bytes B₄ a B₇: these 4 bytes will specify the PSN of the first physical sector belonging to the reserved area specified in this data unit.

bytes B₈ a B₁₁: these 4 bytes will specify the PSN of the last physical sector belonging to the reserved area specified in this data unit.

bytes B12 to Bi₅: These 4 bytes are reserved and must be set to (00).

Figure 24 shows a previous session data unit. An SDCB must contain a previous session data unit for each session that precedes the current session. The first session SDCB must not contain a previous session data unit. Previous session data units should be ordered with increasing addresses. The figure shows the schematic of the previous session data unit as follows: bytes B₀ a B₂: these 3 bytes identify the type of data unit and must be set to (52534E), representing the “SSN” characters.

byte B₃: This byte will specify the sequence number of the previous session specified in this data unit.

bytes B₄ a B₇- These 4 bytes will specify the PSN of the first physical sector in the data zone of the previous session specified in this data unit.

bytes B₈ a B₁₁- These 4 bytes will specify the PSN of the last physical sector in the data zone of the previous session specified in this data unit.

bytes B₁₂ a B₁₅: These 4 bytes are reserved and must be set to (00).

Although the invention has been explained primarily by embodiments using DVD + R, similar embodiments are suitable for other optical recording systems. Furthermore, for the information carrier an optical disk has been described although other media, such as a magnetic tape or disk, can be used.