MAM CD/DVD Glossary

Posted: 06/21/2005 4:14 pm

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Access Time
The time needed for the reader to cross the CD gathering information (between 120 and 600 milliseconds, depending on the reader).

A-TIME (Absolute-Time)
The CD coding system includes a clock which monitors recording time and predicts a total.

A/D (analogic/digital)
Conversion of an analogue signal to digital.

ABERL (Atip Burst Error Length)
Number of consecutive ATIP errors. The Orange Book specifies a maximum of 3 (see also, BERL).

ADPCM (Adaptive differential pulsation code modulation)
Audio file compression format used for CD-I or CD-ROM/XA to increase listening time or insert more data. By using this format, up to 16 hours of audio files can be recorded onto one disc (14400 Hertz radio quality).


Artwork
Any design for printing on a CD.

ASCII (American Standard Code for Information Interchange)
Coding for alphanumeric characters used in computing.

ATER (Atip Error Rate)
Number of CRC errors per second in the ATIP. The Orange Book specifies a maximum of 10% error, equivalent to a maximum of 7 errors detected every second.

ATIP (Absolute Time In Pregroove)
Marks the spiral length in time. The different areas have set lengths (The spiral starts at 96:15:00, lead-in area starts at 97:27:55, data starts at 00:00:00, lead out area starts at 74:05:10 end of spiral beyond 76:05:10).


DVD authoring
The conversion of a high quality digital or analogue video source to a MPEG-2 file for processing by a DVD reader.

BER (Bit Error Rate)
The number of errors divided by number of correct bits. The usual rate for a CD-ROM is 1 per 1012 bits.

BERL (Burst Error Length)
This is the measurement of the quantity of blocks containing type E21 et E31 errors, which generally indicates physical damage. E22 usually indicates the presence of dust, scratches or handling errors. This is an important parameter since it indicates the presence of physical damage with an impact on more than one block of data.

Birefringence
Double light refraction. Certain types of material have this double refraction. The substrate used for CD-Rs has this property, and it is caused by the way the molecules are organized and by the internal tensions created when the disc is molded. Excessive birefringence can cause interference and read errors.

BLER (Block Error Rate)
A measurement of the integrity of data contained on the CD. Error type E11, E21, E31 rate is measured over one second using analysis equipment. An average rate lower than or equal to 220 is considered acceptable in the Yellow Book and Red Book.


Bloc (Block)
The data is organized into blocks on the CD, containing a header, the data, error correction and information checks. This is the minimum logical addressable unit found on a CD, and each one has a logical block number to enable the data to be found.

Books
These summarise the DVD specifications and are marked from A to E depending on the applications they are intended for :
Book A : DVD-ROM, specifications for read only.
Book B : DVD-Video, contains video specifications and an Applications specification defining the software and functions built into video readers.
Book C : DVD-Audio, contains audio specifications and an Applications specification defining the software and functions built into audio readers.
Book D : DVD-R, specifications for one-time writing and rereading.
Book E : DVD-E (erasable or re-recordable) and DVD-RAM, contains re-recordable specifications.

Buffer
A temporary storage area to compensate for the difference in speed between the peripherals and ensure a smooth flow of data. A CD CD-Recorder uses from 512 kb to 2 Mb of buffer space.

Caddy
A plastic case in which the CD can be placed before being put into a reader or CD-Recorder.

Capacity
A CD usually has 650Mb organized into 335250 sectors of 2 kb each. This is equivalent to 74 minutes of high-quality sound. A CD can hold a minimum of 650 Mb but capacity depends on several factors such as rotation velocity or the pitch of the track. It is sometimes possible to record or copy more data that the nominal capacity (over writing) but some readers will have problems reading it.

CAV (Constant Linear Velocity)
This depends on the reading speed of the data track. Many magnetic storage media such as floppy-disks and hard-discs revolve at a constant angular velocity (a constant number of revolutions per minute) so the data on the outer edge is more widely distributed than in the center.

CD-DA (Compact Disc - Digital Audio)
Commonly known as a CD, this is an audio disc containing up to 74 minutes of high-fidelity stereo sound. Unlike a vinyl disc where the needle follows a groove with a variable depth and transmits vibrations, the laser beam detects the presence of hollows on the surface and transmits binary information (0 or 1). The sound is converted to a digital signal 44,1000 times a second, and its value is encoded into 16 bits (for example 1001 0101 1011 1101). Encoding one second of hi-fi sound takes 1.5 million bits. Other CD types exist: the CD-ROM, CD-ROM/XA, and the CD-I. Introduced in the US in 1983, CD sales overtook vinyl in 1986. The Red Book gives specifications for CD-DA.

CD-ROM (Compact Disc - Read Only Memory)
A CD format used to save computerized text, pictures or sound. CD-ROMs are similar to CD-DAs but use several tracks for data. A CD-DA reader cannot read a CD-ROM but a CD-ROM reader can read a CD-DA. A CD-ROM can hold the equivalent of 250.000 pages of text or 20.000 pictures at average resolution.

CD-ROM mode 1
Has three error detection and correction levels for computerized data.

CD-ROM mode 2
Has two error detection and correction levels for sound and videos.

CD-ROM/XA
(Compact Disc Read Only Memory eXtended Architecture)
A CD-ROM using mode 1 and mode 2 and enabling simultaneous reading of low-quality sound and data.

CD-Bridge Disc
A version of CD-ROM/XA readable by a CD-I or CD-ROM/XA reader.

CD-I (Compact Disc Interactive)
CD which can store data, sound, video, etc. The Green Book gives the specifications of the CD-I. It can only be read by one specific reader.

CDV (Compact Disc Video)
A version of the CD storing only video and sound.

CD-WO (Compact Disc Write Once)
A CD writable only once (also known as a CD-R). A CD-WO complies with ISO standard 9660 and can be read by a CD-ROM reader.

CIRC (Cross Interleaved Reed-Solomon Code)
Error-correction method specially developed for use with CDs meeting Red Book standards.

Close Session
Closing a recordable CD session consists of writing the TOC onto the disc and preparing a lead-in area for the next operation.

Close disc
Closing a CD prevents other write operations regardless of remaining free space. When the disc is closed, the lead-in area for the final session will not include the address for the next recording area.

CLV (Constant Linear Velocity)
Data speed in front of the pick-up head is constant. Disc rotation speed varies according to the position of the reading head.

CRC (Cyclic Redundancy Check)
Returns the number of blocks per second where CRC errors have been detected. This parameter varies between 0 and 75 blocks per second.

Cross Talk
See XT

DAT (Digital Audio Tape)
System for recording onto special magnetic tape. Used for saving computerized information.

Data Area
An area of data beginning with reference number 00:00:00 (ISO 9660).

Data transfer rate
A CD-DA reader can transfer data at a rate of 150 kb per second. A CD-ROM 12x reader transfers at 1.8 Mb per second.

Digital audio
Each sample is coded using 16 bits.

Digital data
All computer data is digitalized.

Digitalize
To convert an analogue signal (a sound, a picture, etc.) to digital.

Disc Description Protocol
Protocol for describing CD sectors.

Disc at Once
Method for writing in a single session and by making only one pass. The TOC and the lead-in area are written in succession and must be compiled beforehand by the recording software.

DRAW (Direct Read After Write)
Refers to optical discs.

DVI (Digital Video Interactive)
A data compression/decompression algorithm for video files.

DVD-R
Recordable DIGITAL VERSATILE DISC
E11
A type E11 error indicates the loss of only one recoverable data bit.

E12
A type E12 error indicates the loss of only one recoverable data bit by the second decoder.

E21
A type E21 error indicates the loss of two recoverable data bits.

E22
A type E22 error indicates the loss of two recoverable data bits by the second decoder.

E31
A type E31 error indicates the number of non-recoverable errors by the first decoding algorithm.

E32
A type E32 error indicates some irretrievable errors by the second decoder. A working disc cannot have this type of error.

ECC (Error Correction Code)
An algorithm through which data lost as a result of an error can be reconstituted.

ECC (Eccentricity)
The difference in the size of the center of the disc and the center of the spiral. In CDs it is 70 but should be 50 in CD-ROMs, as they are read in a much less methodical way than CD-Rs.

EDC (Error Detection Code)
Error detection algorithm.

Electroforming
Technical procedure for creating a metal or master mask for continuous production of CDs from a glass matrix.

Form1
Mode 2 CD-ROM sub-format used for Photo - CDs and electronic books.

Form2
Mode 2 CD-ROM sub-format used for applications where data will not suffer from low correction levels (video, sound).

Glass Master
The first recorded media and used for the CD duplication. A photosensitive film is applied to the glass master and data is written with a laser. The film applied to the exposed glass master gives the master information.

Green Book
The standards applying to CD-I

Header field
4 bits at the beginning of every CD-ROM sector. The header gives the sector address amd recording method.

High Sierra
A file organization format on which ISO 9660 is based.

IG (Intensity Groove)
Measure of the percentage of the reflectivity of the spiral. The figure is obtained by taking measurements at 10 points in the disc data area (measurements taken before and after recording: IGa and IGb ).

IL (Intensity Land)
Measure of the percentage of the reflectivity of the land. The figure is obtained by taking measurements at 10 points on the surface of the disc (measurements taken before and after recording: ILa and ILb).

Index
Easily-located points marked on a track.

Injection molding
Polycarbonate discs which form the basis of a CD, are created by injecting pressurized plastic into a mold.

ISO 9660
International norm describing computerized file organization on CDs.

ISRC (International Standard Recording Code)
An optional unique code assigned to a track. The ISRC value, situated in the Q channel, identifies a track by the region of origin (2 ASCII characters), the year of creation (2 numbers), the owner (3 ASCII characters) and a serial number (5 numbers).

Jewel Case
Plastic storage case for CDs.

Jitter (Standard Deviation)
Jitter is measured on single pits and lands from 3T to 11T. Each pit and land is measured and jitter is calculated statistically as a standard deviation.

Kb (kilobytes)
1024 bytes (1024*8 bits).

Label
A print on the upper surface of the CD, which may include the manufacturer's name, the disc contents, etc.

Lacquer coating
A protective layer on the surface of the CD, applied on top of the the layers of dye and gold (or silver).

Land
Also called a flat. The part of the spiral (groove) which is left unburnt by the laser.

Lead In Area
On a CD, the lead-in area is the area containing the Table of Contents at the beginning of the spiral. The TOC contains the track listing and location. It is left blank until the session is closed. This zone uses up to 4500 sectors (about one minute or 9 Mb). If the disc has not been closed, the lead-in area gives the address of the next writable zone.

Lead Out Area
Zone buffer at the end of the disc after the last track. It is left empty and and occupies 6750 sectors for the first session and 2250 sectors thereafter.

LECC (Layered Error Correction Code)
Error-correction code replacing the CIRC when the latter cannot correct errors. The LECC performs a fresh error-detection and tries to correct them by using EDCS values and ECCS.

Length Deviation
The length of every pit and every land is measured and average lengths are compared to the recommended lengths. The recommended values of pits and lands are defined by the equation nT = n x 231.4, where n=3 to 11. Deviation is the difference between measured average and recommended value.

Master
The glass original from which copies of CDs can be created.

Mastering
Recording the data from a CD onto a photosensitive surface on a glass disc (the master) used for continuous CD production.

Metalizing
A process which applies a thin metallic layer to the surface of the plastic disc after molding. The process takes place under a vacuum.

MID (Maximum Information Diameter)
Must be lower than 116mm. The MID parameter is an important measure because molding and processing result in very high probability of problems at the end of the track. The MID signal indicates the end of the disc. If the MID does not meet specifications, there is a danger that high frequencies in the track following signal will be weakened owing to birefringence, to scratches, or fingerprints left when handling.

Mixed Mode
A CD containing several tracks that are not the same type.

MO (Magneto-optical)
An optical disc recordable and erasable at will.

Mb
Approximately one million bytes.

NWA (Normalized Wobble Amplitude)
Relationship between the wobble signal and the Push Pull. The Orange Book specifies a NWA of between 0,035 and 0,05.

Orange Book
The standard for recordable CDs. It has two parts, one for CD-Rs and one for CD-RWs.

OS-9
Real-time operating system used by the CD-Is.

PCM (Pulse Code Modulation)
Standard method for coding audio.

Photo-CD
Recordable CD specially developed by Kodak to store photos and view them on CD-ROM/XA, Photo - CD or CDI readers. One CD can contain 100 photos.

Pit
Areas of the CD burnt by the laser beam in order to create a change in reflectivity.

Post-Gap
An area at the end of a track with a minimum length of two seconds.

Pre-Gap
Area at the beginning of a track.

Premastering
Preparing data to be recorded onto CD before continuous production.

Programm Area
Area of a disc where data is kept.

Proof Disc
Test CD.

Protective coating
Protective layer of lacquer or polymer applied with a nozzle and baked under UV rays to protect the layers of dye and gold (or silver).

Push Pull
The Push Pull (PP) parameter is a measure of how easily the reader is able to follow the spiral. The PPa is the PP value after recording, which is compared to the reflective value of the spiral after recording (IGa). The same applies to the PPb (before recording with IGb). Particularly significant is the normalised Push - Pull ratio (NPPR) given by the following formula :

The NPPR must fall between 0.5 and 1. The Push-Pull is measured at 10 points in the data area of the disc. In CD-Cats system, the PP is measured with a linear polarized light. A measurement system using polarized light can modify results in a linear direction.

RC (Radial Contrast)
The radial contrast is the difference in reflectivity of spirals and the areas parts between spirals. According to the Orange Book, RC must be over 20% on a recorded disc and over 5% on a blank disc. The RC is measured at 10 points across the disc's surface. It is calculated as follows :

Red Book
The CD - DA standards.

REF (Reflectivity)
Reflectivity is adjusted according to a reference disc and is used to detect and normalize variations in reflection.

RIFF (Resource Interchange File Format)
File format for storing diagrams, sounds, and animations.

RN (Radial Noise)
Radial noise may be present when tracks are damaged. It is found in a frequency range of between 500 and 2500 Hz.

SVY (Scanning Velocity)
This is between 1.2 m/sec and 1.4 m/sec. If it falls below 1.2 m/sec I3 length information is affected. The SVY parameter represents the speed at which the reading light passes. If the speed is too high, the I3 level will be too weak. SVY is measured as vertical information at 10 points across the data area on the disc. The result is returned as a minimum, maximum and average. SVY variations on the disc must be be lower than 0.01 m/sec (CD-CATS).

SLD (Start Lead In)
The beginning of the lead-in area must be to the radius 23,1 mms. The reader uses this surface to identify the table of contents (TOC). If the SLD is outside specification the reader will not be able to identify where the TOC is.

SPD (Start of Program Diameter)
This must be located between the radius 24.8 mms and 25.04 mms. The SPD parameter is used by the reader to find the beginning of a track. If the SPD parameter is outside specification, the reader will take more time to find the first track.

Stamper
A metal tool which creates the spiral (groove) and is held in the injection mold.

Substrate
The main polycarbonate body of a CD to which are applied several other layers.

TIFF (Tagged Image File Format)
When a picture is scanned, it is saved as a TIFF.

TOC (Table Of Contents)
Information located in the lead-in area. It specifies the location of the beginning of every track and the type of disc.
Track</td></tr><tr><td bgcolor="#beda15"><img height="1" src="http://mam-a.com/images/ghost.gif" width="1" alt=""></td></tr></tbody></table><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont">In audio, each song is represented by a track. Computerized data sees this only as one track. If the CD-ROM is mixed format, it holds both a data and sound track. A CD can hold up to 99 tracks.</td></tr></tbody></table><br><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont" nowrap><b><i>Track Pitch</i></b></td></tr><tr><td bgcolor="#beda15"><img height="1" src="http://mam-a.com/images/ghost.gif" width="1" alt=""></td></tr></tbody></table><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont">Physical distance between two curves of a spiral, equivalent to between 1,5 to 1,7. </td></tr></tbody></table><span class="cont"><div align="right"><font face="Arial, Helvetica, sans-serif" size="2"><a href="http://mam-a.com/technology/glossary/glossary_m_z.html#up"><img height="20" src="http://mam-a.com/images/up.gif" width="20" border="0" alt=""></a></font></div><br></span><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont" nowrap><b><i>Turnaround Time</i></b></td></tr><tr><td bgcolor="#beda15"><img height="1" src="http://mam-a.com/images/ghost.gif" width="1" alt=""></td></tr></tbody></table><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont">Time needed to manufacture a CD.</td></tr></tbody></table><br><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont" nowrap><b><i>Volume description</i></b></td></tr><tr><td bgcolor="#beda15"><img height="1" src="http://mam-a.com/images/ghost.gif" width="1" alt=""></td></tr></tbody></table><table cellspacing="0" cellpadding="0" width="500" border="0"><tbody><tr><td class="cont">The area at the beginning of the disc reserved for recording suc