Glossary Terms

Below is a list of terms (in alphabetical order) that appear in this guide and might be of help to our readers. Please ask us to add more terms by submitting the form here.

ECC

Error Correction Code

MSB

Most Significant Byte

LSB

Least Significant Byte

Channel bit (DVD)

The elements by which, after modulation, the binary values ZERO and ONE are represented on the disk by pits.

Physical sector number (DVD)

A serial number allocated to physical sectors on the disk.

Track

A 360° turn of a continuous spiral.

Track pitch

The distance between the centrelines of a pair of adjacent physical tracks, measured in radial direction.

DVD Disc Types

Type A

Consists of a substrate, a single recorded layer and a dummy substrate. The recorded layer can be accessed from one side only. The nominal capacity is 4,7 Gbytes.

Type B

Consist of two substrates, and two recorded layers. From one side of the disk, only one of these recorded layers can be accessed. The nominal capacity is 9,4 Gbytes.

Type C

Consists of a substrate, a dummy substrate and two recorded layers with a spacer between them. Both recorded layers can be accessed from one side only. The nominal capacity is 8,5 Gbytes.

Type D

Consists of two substrates, each having two recorded layers with a spacer between these two recorded layers. From one side of the disk, only one pair of recorded layers can be accessed. The nominal capacity is 17,0 Gbytes.

Track modes

Tracks can be recorded in two different modes called Parallel Track Path (PTP) and Opposite Track Path (OTP). In practice, the lengths of the Data Zones of both layers are independent from each other.

In PTP mode, tracks are read from the inside diameter of the Information Zone to its outside diameter, this applies to both Layer 0 and Layer 1 for Types C and D. On both layers, the track spiral is turning from the inside to the outside.

In OTP mode, tracks are read starting on Layer 0 at the inner diameter of the Information Zone, continuing on Layer 1 from the outer diameter to the inner diameter. Thus, there is a Middle Zone at the outer diameter on both layers, see figure 5b. The track spiral is turning from the inside to the outside on Layer 0 and in the reverse direction on Layer 1.

PO

Parity (of the) Outer (code)

PI

Parity (of the) Inner (code)

DVD ECC Blocks

ECC of DVD block is a self-contained block of data and error correction codes that grouped into a sequential series of 16 DVD sectors.

An ECC Block is formed by arranging 16 consecutive Scrambled Frames in an array of 192 rows of 172 bytes each. To each of the 172 columns, 16 bytes of Parity of Outer Code are added, then, to each of the resulting 208 rows, 10 byte of Parity of Inner Code are added. Thus a complete ECC Block comprises 208 rows of 182 bytes each.

PI/PO

Type of measured errors for DVD's. The I corresponds to "inner", the O to "outer". This is a distinction being made when each sector along with the error correction data is presented in a tabular form. The I's and O's then correspond to the 2 different directions of the 2-dimension Euclidean space (plane).

Recording Frames

Sixteen Recording Frames shall be obtained by interleaving one of the 16 PO rows at a time after every 12 rows of an ECC Block Thus the 37,856 bytes of an ECC Block are re-arranged into 16 Recording Frames of 2,366 bytes. Each Recording Frame consists of an array of 13 rows of 182 bytes.

Random errors (DVD)

A byte error occurs when one or more bits in a byte have a wrong value, as compared to their original recorded value. A row of an ECC Block that has at least 1 byte in error constitutes a PI error. If a row of an ECC Block contains more than 5 erroneous bytes, the row is said to be “PI-uncorrectable”. During playback after the initial recording, the errors as detected by the error correction system shall meet the following requirements:

- in any 8 consecutive ECC Blocks the total number of PI errors before correction shall not exceed 280,

- in any ECC Block the number of PI-uncorrectable rows should not exceed 4.

Jitter (DVD)

Jitter is the standard deviation s of the time variation of the digitized data passed through the equalizer. The jitter of the leading and trailing edges is measured to the PLL clock and normalized by the Channel bit clock period.

Sector

In case of CD media, “Sector” refers to the data contained in one frame. In the CD-ROM standard document the term block is used for this unit. In the case of DVD media, “Sector” is the smallest user addressable part of media. The user data contained within a sector is 2048 bytes.

Physical Sectors (DVD)

The structure of a Physical Sector shall consist of 13 rows, each comprising two Sync Frames. A Sync Frame shall consist of a SYNC Code from table 4 and 1,456 Channel bits representing the first,respectively the second 91 8-bit bytes of a row of a Recording Frame. The first row of the Recording Frame is represented by the first row of the Physical Sector, the second by the second, and so on. Recording shall start with the first Sync Frame of the first row, followed by the second Sync Frame of that row, and so on row-by-row.

Data Frames (DVD)

A Data Frame shall consist of 2 064 bytes arranged in an array of 12 rows each containing 172 bytes. The first row shall start with three fields, called Identification Data (ID), the check bytes of the ID Error Detection Code (IED), and Copyright Management Information (CPR_MAI), followed by 160 Main Data bytes. The next 10 rows shall each contain 172 Main Data bytes, and the last row shall contain 168 Main Data bytes followed by four bytes for recording the check bits of an Error Detection Code (EDC). The 2,048 Main Data bytes are identified as D0 to D2047.

Reed-Solomon code

An error detection and/or correction code for the correction of errors.

BLER

Block Error Rate. The total number of C1 errors per 10 consecutive sectors. It should be below 200, for perfectly readable disc.

C1/C2

Type of errors during reading a recordable or pressed disc. It is evaluated per sector and presented (usually) averaged or summed-up over a number of sectors. (This gives rise to the various BLER measurements.)

CD-R

A glorious recordable disc:)

DVD-R

The recordable DVD Forum defined format. The term might also refer to the media or a drive capable of handling (recording) these.

DVD-RW

Re-writable format/disc/..., according to the DVD Forum specifications.

KProbe

A program for detecting reading errors that works on drives (readers, recorders) based on the MediaTek chipset.

LBA

Logical Block Address. The disc is measured (addressed) according to 1/75 of the second intervals (sector, frame), in 1x speed.

MSF (CD)

MSF Address (Minute/Second/Frame) The physical address, expressed as a sector count relative to either the beginning of the medium (absolute) or to the beginning of the current track (relative). As defined by the CD standards, each F field unit is one sector, each S field unit is 75 F field units, each M field unit is 60 S field units. Valid contents of F fields are binary values from 0 through 74. Valid contents of S fields are binary values from 0 through 59. Valid contents of M fields are binary values from 0 through 74.

For example 63m:45s:70f. An alternative disc addressing scheme. It is essentially the same with the LBA method, in case you divide LBA by 75 (the number of frames per second) and then transform the seconds to minutes by dividing by 60. In the literature there is an arbitration of a 2 second track lead-in.

UmDoctor

A program by Sanyo for estimating and writing down disc reading errors (in the form of C1/C2 for CD's and PI/Unc-PI for DVD's). It works on drives based on Sanyo chipsets. In case of DVD, the software measures PI/Unc-PIU errors on each 8 ECC.

Groove

A trench-like feature of the disk, applied before the recording of any information, and used to define the track location. The groove is located nearer to the entrance surface than the land. The recording is made on the centre of the groove.

Land

The area between the grooves.

CIRC

Cross Interleaved Reed-Solomon Code (CIRC) is the error detection and correction technique used within small frames of CD audio or data. The CIRC bytes are present in all CD-ROM data modes. The error correction procedure which uses the CIRC bytes is referred to as the CIRC based algorithm. In most CD-ROM drives, this function is implemented in hardware.

Frame (CD)

A sector on CD media. Also the F field unit of a MSF CD address. The smallest addressable unit in the main channel.

DVD Control Area

The DVD Control area is comprised of 192 ECC blocks in the Lead-in Area of a DVD medium. The content of 16 sectors in each block is repeated 192 times. This area contains information concerning disc.

Lead-in Area

The CD Lead-in area is the area on a CD-ROM disk preceding track one. The area contains the TOC data and precedes each program area. The main channel in the lead-in area contains audio or data null information. This area is coded as track zero but is not directly addressable via the command set. The Q sub-channel in this area is coded with the table of contents information.

The DVD Lead-in area is the area comprising physical sectors 1.2 mm wide or more adjacent to the inside of the Data area. The area contains the Control data and precedes the Data area.

Lead-out Area

The CD Lead-in area is the area on a CD-ROM disk beyond the last information t rack. The main channel in the leadout area contains audio or data null information. This area is coded as track AAbcd but is not directly addressable via the command set. The READ CD-ROM CAPACITY data is the first logical block address of this area minus one.

The DVD Lead-out area is the area comprising physical sectors 1.0 mm wide or more adjacent to the outside of the data area in single layered disc for PTP (Parallel Track Path) disc, or area comprising physical sectors 1.2 mm wide or more adjacent to the inside of the data area in layer 1 of OTP (Opposite Track Path) disc.

DVD Reference Code

The DVD Reference code is comprised of 2 ECC blocks (32 sectors) in the Lead-in Area and used for the adjustment of equalizer system of the drive hardware.