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Glossary of terms relating to writeable CD's

3DO
A CD-ROM multimedia system owned by Matsushita. M2 as a replacement will be available soon.
a_characters
This is a character set used in the ISO 9660 Volume Descriptors consisting of capital A to Z, digits 0 to 9, and the following symbols: (space)! " % & '()=*+,-./:;<?>_
A-Time (Absolute time)
Is the time elapsed from the beginning of the an audio CD in minutes and seconds. A-Time access involves mapping the audio portions relative to the beginning of the disc in the CD-ROM (start and stop of each) using time addresses (Min-Sec-Sector). This allows random access of audio or video segments. Used for programming an application on a mixed-mode disc measuring from the very beginning of the data area (including the computer data in Track 1). The timecode is contained in the subcode Q-channel as minutes, sectors and frames measured from the beginning of the disc.
AC-3
Dolby's surround sound digital audio system, specified for NTSC DVD video discs.
Access Time
The time it takes to retrieve a piece of information. With hard disks or compact discs, maximum access time is measured as the time it takes to move from one end of the disc to the other, find a piece of information, and transfer that information to RAM.
Active Movie
Released by Microsoft in 1996, Active Movie, is the replacement for Video for Windows and Media Control Interface. The 32-bi architecture, enhanced video playback capabilities (higher frame rates) should enhance MPEG-2 video.
Adapter cards
Used in computers to attach peripheral devices to the PC. The cards installed into spare slots on the motherboard.
ADPCM
Adaptive Differential Pulse Code Modulation is a compression algorithm which take half the space of PCM. Works by recording the predicted value of the signal instead of the absolute value of original waveform.
Al
The chemical symbol for aluminum. Aluminum is is used for the reflective layer on CD and DVD discs.
Aliasing
Image distortion caused by a signal sampling at low resolutions. Diagonal lines appear stepped - like staircase.
Amaray Case
The plastic case for DVD disc.
Amiga CD32
The Commodore multimedia based CD-ROM console.
Analogue
Physical variable such as voltage and current represented by numerical values. These devices generally have dials and sliding mechanisms.
Analogue Video
A signal that represents video. There are infinite smooth gradations between given video levels. Digital video has a finite set of levels.
Analog Signal
A signal that is constant rather than discrete nature or pulsed. The analog signal is used to reflect the variation in a physical phenomena - light, heat, position, pressure or sound. Note: To be used in computers the analog signal must first be converted into a digital signal.
Analog to Digital Converter (A/D)
A device that samples an analog signal at regular intervals and quantizes each sample, that is, represents each sample's value with a binary number of some predetermined length. Analog-to-Digital conversion samples analog signals to produce a digital signal that describes the original analog signal.
Anamorphic
The method of fitting a wide-screen format into a traditional 4:3 aspect ratio (TV).
Angles
The ability to view a single screen from multiple camera angles. This is a DVD feature.
ANSI-Labeled
A tape recorded with a file structure and tape label system which defines the Volume name and file header for the information contained in the tape, according to ANSI (American National Standards Institute) specification X3.27-19778. Most disc manufacturers prefer ANSI-labeled tapes.
ANSI-Unlabeled
A tape recorded with a file structure, but without the ANSI tape labels.

Advanced SCSI Programmer's Interface. Set of software primitives and data structures which allow software using the ASPI interface to be SCSI host adapter-independent.

Anti-Aliasing
A method of providing smooth transition from pixels. A form of interpolation is used.
API
Application Program Interface: allows a program application to communicate with the operator.
Application
In terms of computers, application refers to software designed to perform a specific task on a computer.
APS
Analogue Protection System: A copy protection for DVD that distorts the output to video so that it can not be recorded and played back on VHS. Developed by Macrovision.
Artifact
A visual distortion in an video image that is unwanted.
ASCII
The American Standard Code for Interchange of Information is a character set consisting of 128 text characters (abc...) ASCII (askey) was implemented as the standard for communications, and mini and microcomputers.
ASPI
Advanced SCSI Programmer's Interface. It defines a set of software primitives (command) and data structures or an application to use when communicating with SCSI host adapters to be SCSI host adapter-independent. This is essentially a driver.
Aspect Ratio
An image's width to height ratio. Example would be 16:9 - wide screen format or 4:3 regular T.V. format. On computers this is a relationship between width and height of pixels in an image.
ATAPI
The IDE/ATAPI is a data interface that often is provided by PC manufacturers and, is generally included when you purchase a new computer. Usually, the computer motherboard comes with a primary and a secondary IDE bus. Up to two IDE/ATAPI devices, a master and a slave, can be connected to each bus. Because this interface is less sophisticated than the SCSI one, ATAPI devices are usually more affordable. Note, however, that often IDE/ATAPI devices are slower and, particularly in case of CD-Readers, less accurate. If you are considering using DiscJuggler with multiple recorders, SCSI is the preferred bus.
Audio
Audio signals were recorded and reproduced using analog signals - LP records, tape etc. Computers convert all analog signals into digital code. The quality of the sound is determined by the bit-rate (or the sampling rate.) The higher the rate the large digital code is needed.
Audio_TS
The directory name for audio files in a DVD volume using the Universal Disk Format.
Authoring
The creation of courseware (application) which combines graphics, audio, video, and/or text. When you have finished creating your application with an authoring software, you can use CD recording software such as Nero Burning ROM to write it to CD.
Auto Insert Notification
A file on a disk that tells Windows how to treat the CD. The AIN is most often used to auto launch a program on a CD.
CD Audio
Standard CD format for storing audio soundtracks. For example, music and songs.
Average Access Time
The amount of time it takes a CD-ROM/CR-R/CD-RW to find a random piece of information. This is generally used measure the performance of a CD Drive; however, many factors need to be considered when looking at the performance of CD Drive.
Bandwidth
In terms of computers this indicates the amount of information/traffic per unit of time. Generally expressed in megabytes per second.
Barcode
A set of bars in the inner ring of a CD used to identify the CD.
Bidirectional Prediction
The Codec (coder-decoder) tracks what has been processed while reading ahead to prepare appropriate actions. This enables efficient processing of burst in data transfer rates. Bidirectional prediction is implemented in compression and the decompression procedures.
Binary Code
A code where the elements can assume either one of two possible states. Computers use 0s and 1s to form the code into bytes. Storage devices mediums are coded with binary files. CDs, for example use pits to represent the binary code. The CD ROM will read the pits and convert them into 0s and 1s and eventually into music or data.
Birefringence

Double refraction of light in a crystal: the splitting of incident light into two rays with polarisations at right angles to each other and causing two images to appear, e.g. in calcite

For Optical devices, CDS/DVDs, it means double refractive ability. This is generally caused by improper cooling of the substrate material (glass). This is an unwanted effect as it will cause errors in reading of the CD.

Bit
A compressed form of 'binary digit.'
BLER
BLER stands for Block Error Rate - the "raw" digital error rate before any error correction, which in turn is a determining factor in the quality and readability of a given disc.
Block
A unit of 252 bytes as defined in the Yellow Book.
Blue Book
The CD Extra standards book.
Buffer
Memory that holds momentarily information/data which is directly available to the CPU. Buffers are a solution to speed differences, interface delays, and other variations between a device and CPU.
Buffer Underrun
An uninterrupted stream of data is required by the CD Recorder during a recording session. If the stream becomes insufficient or is interrupted during the session and the buffer is unable to provide the pick-up the shortfall the recording will stop and report a buffer underrun.. See also "About Buffer Underruns."
Burst Error
Errors detected in consecutive data bits on compact discs often caused by scratches, fingerprints, or other physical defects on a disc. Error correction codes are designed to compensate for the anticipated frequency and duration of burst errors.
Cache
A portion of RAM used for temporary storage of data which must be accessed very quickly. In applications which run from CD-ROMs, the cache is typically used to store directory files.
Caddy
The loading device for CD players/Recorders..
Calibration
PCA or Program Calibration Area. Space at the beginning of the CD for calibrating the laser to read or write to the CD.
Capacity
CDs - The capacity of a CD depends on many factors. Capacity is generally measured in Mbytes or minutes. CDs hold from 63 to 80 minutes of data (music) or 650 Mbytes.

DVD - Capacity of a DVD ranges from 4.76 GB (single side - single layer) to 17.0 GB (double-side - double layer)

CD Bridge
Specifying a way to record CD-I information on a CD-ROM XA. This is used for Photo CD and Video CD.
CD+G
CD+Graphics. Audio, text and graphics used in the same application. This type of disc is usually used for Karaoke machines.
CD-DA

Compact Disc-Digital Audio. A CD-DA disc contains tracks with Audio sectors only.

In 1982 Philips and Sony introduced the necessary technology for storing digital audio signals on a Compact-Disc, and introduced the CD-Digital Audio.

CD Extra/CD Plus
In track 1 data and/or graphics are included. This addresses problems of Mixed-mode disc. This is a format that uses the Red Book.
CD-I
A compact disc format designed to allow interactive multimedia applications to be played through a computer/disc player attached to a television. Especially good for real-time animation, video, and sound. The CD-I standard is called the Green Book.
CD-R [disc]
An acronym for compact disc-recordable which is a type of media that allows you to record information using a CD Recorder.
CD-ROM
Compact Disc-Read Only Memory. A standard for compact disc to be used as a digital memory medium for personal computers. The specifications for CD-ROM were first defined in the Yellow Book.
CD-ROM disc
A CD-ROM disc contains only data sectors as defined in the Yellow Book.
CD-ROM Drive
A peripheral device attached to a computer which allows it to read/play a CD-ROM disc. All CD-ROM players can also play back audio CDs, but you need external headphones or speakers to hear them.
CD-ROM XA (CD-XA)
"XA" stands for Extended Architecture. CD-ROM XA is an extension of the Yellow Book standard, generally consistent with the ISO 9660 logical format but designed to add better audio and video capabilities (taken from the CD-I standard) so that CD-ROM can more easily be used for multimedia applications. CD-ROM XA is also the physical format for Photo CD discs.
CD-RW
Compact disc-rewritable. The most recent addition to the compact disc family. It was originally called "CD-Erasable." The official name is CD-ReWritable, and it is a media and recording system that allows the user to erase previously recorded information and then record new information onto the same physical location on the disc. See "What is CD-ReWritable?" article.
CD-Text
CD-Text - Philips' standard for encoding disc and track data on audio CDs - adds text information to a conventional audio CD, enabling music CDs to be read as well as listened to. The text displayed could be the artist's name, album title and track title, for example. The disc is fully compatible with the 500 million audio CD players around the world, which will simply play the music and ignore the text
CD-WO
Compact Disc-Write Once. Recordable compact disc.
CD Bridge
A set of specifications defining a way of recording CD-Information on a CD-RO disc. Used for Photo CD and Video CD.
CD Duplication

The process of making one or more copies of a compact disc. CD Extra or CD Plus

Enhanced CD - includes two sessions, the first containing "n" (up to 98) audio tracks, and the second session containing a CD-ROM XA format data track. Additional characteristics are defined in the Blue Book standard.

CD Image File
A file containing an exact representation of the data that will be placed on the CD-ROM. CD Image files are often written as the first step in the pre-mastering process when the complexity of the disc makes "On-the-fly" recording impossible. In these cases the CD Image file is created from the source data on the hard disk then transferred to the CD Recorder.
CIRC
Cross-Interleaved Reed-Solomon Code. The basic level of error correction provided for Audio CD with one uncorrectable bit out of every 109. CD-ROM provides additional protection for data (ECC/EDC), reducing the error rate to one bit in 1013.
Close disc
To "close" a recordable disc so that no further data can be written to it. This is done when the last session's lead-in is written - the next writeable address is not recorded in that lead-in, so the CD recorder in subsequent attempts to write has no way of knowing where to begin writing. It is NOT necessary to close a disc in order to read it in a normal CD-ROM drive.
Close Session
When a session is closed, information about its contents is written into the disc's Table of Contents, and a lead-in and lead-out are written to prepare the disc for a subsequent session.
Compact Disc
CD stands for compact disc which is a general term for all formats of CD media. CD formats available on the market now include CD Audio, CD-ROM, CD-ROMXA, VideoCD, CD-I and others.
Compact Disc Formats

During the last two decades several Compact Disc formats were developed to serve different purposes and uses. Starting with the CD-DA format in 1980, as a way to distribute high quality music in a compact and convenient format, the first compact disc standard was formulated. Then, the idea of storing computer data on the same media, more than 10 years ago, lead to a new format: the CD-ROM (along with CD-DA the most important ever invented). In the last few years, the desire to store a whole new generation of multimedia contents (audio, video, games, pictures etc.) demanded new formats: CD-I, CD-XA, Photo-CD, Video-CD, CD+ etc. were invented. Compact Disc Recording & Data Throughput

Because a CD-Writer is a real-time device, it places special demands on a computer and its peripherals. For a CD Recorder to successfully create a compact disc, it must receive an uninterrupted flow of data that must be transferred at a speed equal to or greater than the recording speed of the CD Recorder. For CD Recorders operating in single-speed (1x) mode, data must be transferred at a continuous rate of 150 KB per second for data, and ~172 KB per second for audio. For CD Recorders operating in double-speed (2x) mode, data must be transferred at a continuous rate of 300 KB per second for data, and ~344 KB per second for audio. For CD Recorders operating in quadruple-speed (4x) mode, data must be transferred at a continuous rate of 600 KB per second for data, and ~689 KB per second for audio. Data transfer rates in the range of 150 to 600 KB per second are well below the data transfer rates claimed by hard disk manufacturers. However, slow CPU or SCSI bus performance and sub-optimal hard disk performance may combine to reduce the actual sustained data transfer rate below the transfer rate requirement of double-speed or quadruple-speed CD Recorders.

Cooking
A process that entails blocking user data and adding information identifying each block. Formatting information includes the data address and synchronization information and may include error correction check sums and data and data type specification.
Cue Sheet
In Easy-CD Pro for Windows 3.1, a list of tracks which will be written one after the other in the same session without user intervention. Generally used to create multi-track audio or mixed-mode discs.
d-characters
A character set used in ISO 9660 filenames, if the standard is strictly adhered to. Consists of capital A to Z, digits 0 to 9, and the underscore symbol ( _ ).
D/A
See Digital to Analog Converter.
DAO
See Disc-at-Once.
Data Area
In ISO 9660, the space on a CD-ROM where the user data is written. It begins at the address 00:02:16.
Data Formats
Three different types of data can be recorded on CD. They all share the same physical block size (2352 bytes). However, they have different user block sizes (bytes effectively available to the user) depending on the level of error correction adopted: the lower the read accuracy required, the smaller the error correction code required, the bigger the user data block is. The following is a list of CD compatible data formats:
  • Audio: No extra error correction is required to read and play back audio. The user block size matches the "physical" block size and is 2352 bytes.
  • Mode 1/Form 1: Mode 1 and Mode 2/Form 1 formats are used to store digital data therefore the highest read accuracy is required. The user block size is 2048 bytes (2KB). The remaining bytes are used to store sync patterns, block headers and error correction and detection codes (ECC/EDC).
  • Mode 2/Form 2: This format is used almost exclusively to store digital video data, thus requiring only moderate read accuracy. The user blocks size is 2324 bytes. The remaining bytes are used to store sync patterns, block headers and error detection codes (EDC).
Digital Audio Extraction (DAE)
The process of copying CD-DA audio tracks digitally from your CD-Writer or another CD-ROM drive, to hard disk or to recordable CD. Not all CD-ROM drives support this!
Digital to Analog Converter (D/A)
A device (DAC) that converts digital numbers to an analog signal. In a CD Audio player the DAC takes the stream of numbers read off of the disc and produces an analog audio signal.
Disc-at-Once (DAO)
A method of writing in which one or more tracks are written in a single operation. The laser will not stop until the whole disc recording is finished and the disc is closed -- hence no Run blocks and no clicks between audio tracks. (See also Track-at-Once.) Disc-at-Once has only been added/available with the recent generation of CD recorders and recent firmware upgrades. For more information, read "disc-at-Once, Track-at-Once and Packet Writing".
EAN
See UPC.
ECC
Error Correction Code. A system of scrambling data and recording redundant data onto disc as it is premastered. On playback, this redundant information helps to detect and correct errors that may arise during data transmission.
EDC
Error Detection Code. 32 bits in each sector which are used to detect errors in the sector data.
Extended Architecture
See CD-XA.
File System
A data structure that translates the physical (sector) view of a disc into a logical (files, directories) structure, which the application and user can more easily use to locate files. See also Logical Format.
Gold Disc
The recordable disc used in recordable CD systems. The blank disc is made of a bottom layer of polycarbonate with a preformed track spiral which the recording laser follows when inscribing information onto the disc. This type of disc is therefore also called pre-grooved. A translucent layer of recordable material is laid on top of the polycarbonate, then a reflective layer of gold. On top there are thin layers of lacquer and label.
Header Field
Four bytes recorded at the beginning of each sector which tell the address of the sector (expressed as a Logical Block Number) and the mode in which the sector is recorded.
HFS
The file system used by the Macintosh operating system to organize data on hard and floppy disks. Can also be used for CD-ROMs.
High Sierra Format
The standard logical format for CD-ROM originally proposed by the High Sierra Group, on which the ISO 9660 standard is based; essentially identical to ISO 9660. High Sierra is no longer used.
Hybrid
Under the Orange Book standard for recordable CD, hybrid means a recordable disc on which one or more sessions are already recorded, but the disc is not closed, leaving space open for future recording. However, in popular use, the term "hybrid" often refers to a disc containing both DOS/Windows and Macintosh software, which on a DOS/Windows platform is seen as a normal ISO 9660 disc, while on a Mac it appears as an HFS disc.
ISO 9660 Format
An internationally accepted standard specifying the logical format for files and directories on a CD-ROM. The standard allows different computers with different operating systems to access the same data format.
ISO 9660 Image
Or CD-ROM image, image, disc image. A single large file which is an exact representation of the whole set of data and programs as it will appear on a CD, in terms of both content and logical format.
ISO 9660 Interchange Levels

These are three methods of recording and naming files on disc under the ISO 9660 standard. There are three nested, downward-compatible Levels.

In Level 1 (the most restrictive):

  • Each file must be written on disc as a single, continuous stream of bytes -- files may not be fragmented or interleaved.
  • A filename may not contain more than eight d-characters.
  • A Filename Extension may not contain more than three d-characters.
  • A directory name may not contain more than eight d-characters.

In Level 2, again, each file must be written on disc as a single, continuous stream of bytes.

In Level 3 there are no restrictions.

ISRC
International Standard Recording Code. Some recorders allow the ISRC to be recorded for each audio track on a disc. The code is made up of: Country Code (2 ASCII characters), Owner Code (3 ASCII characters), Year of Recording (2 digits), Serial Number (5 digits).
Incremental Multisession
Incremental Multisession uses pointers in each session to link all the sessions together. These links enable you to access the latest information, starting from the last session on a disc.
Jitter
One of the possible causes of disc recording error, jitter is actually defined as a "timing problem." Simply, jitter is the result of pits on a disc being or appearing to be too short or too long, based on a certain clock cycle. For example, pits on a disc can range from what is called a "3T" pit to an "11T" pit. If a pit that was intended to be written as 3T varies or is perceived to vary from the length of a 3T pit beyond a certain time period, it can be interpreted incorrectly, resulting in a possible disc error. This deviation is known as "jitter." The same is true for lands.
Joliet
Joliet is an extension of the ISO 9660 standard, developed by Microsoft to allow CDs to be recorded using long filenames, and using the Unicode international character set. Joliet allows you to use filenames up to 64 characters in length, including spaces. Joliet also records the associated DOS-standard name for each file so that the disc may be read on DOS systems or earlier versions of Windows. The number of characters allowed in a long file name is up to 64, and the number of characters in the long file name plus its file path cannot exceed 128.
Land Jitter
See Jitter
Lead-In
An area at the beginning of each session on a recordable compact disc which is left blank for the session's Table of Contents (track numbers and start-and-stop points) and other miscellaneous information about the disc and about the recorded tracks. The lead-in is written when a session is closed, and takes up 4500 sectors on disc (1 minute, or roughly 9 megabytes). The lead-in also indicates whether the disc is multisession and, if the disc is not closed, which is the next recordable address on the disc.
Lead-Out
An area at the end of a session which indicates that the end of the data has been reached; there is no actual data written in the lead-out. The first lead-out on a disc is 6750 sectors (1.5 minutes, about 13 megabytes) long; any subsequent lead-outs are 2250 sectors (.5 minute, about 4 megabytes).
Link Area or Link Blocks
See Run-in/Run-out Blocks below.
Linked Multisession
A disc containing more than one session, in which all of the data in the various sessions on disc can be seen as if it had all been recorded in one single, large session. To link sessions in Easy-CD Pro 95, you must check a box in the Load Contents tab. In Easy-CD Pro for Windows 3.1, use Load Contents.
Logical Block
The smallest addressable space on a disc. Each logical block is identified by a unique Logical Block Number (LBN), assigned in order starting from 0 at the beginning of the disc. Under the ISO 9660 standard, all data on a CD is addressed in terms of Logical Block Numbers. At present, CD recording is supported at one Logical Block per logical sector.
Logical Format/Logical Structure
A logical file format such as ISO 9660 translates the sector-by-sector view of a compact disc into a virtual "tree" of directories and files, which makes it easier for both humans and computers to use the information on the disc.
Mastering
Technically, refers to the process of creating a glass master from which compact discs will be reproduced in quantity. In desktop recordable CD systems, mastering is done together with premastering by the desktop CD recorder, and the term is generally used to mean "recording."
MPEG
Motion Picture Experts Group, whose name has been applied to the standard promulgated by the group for compression of full-motion video.
MSCDEX
Microsoft DOS extensions for CD-ROM. Allows the DOS operating system to recognize a CD-ROM as a DOS volume.
Mixed-Mode disc
A compact disc including both computer data (CDROM tracks) and audio (CD-DA) tracks. The data is all contained in Track 1, and the audio in one or more of the following tracks.
Mount
To install a compact disc so that the computer recognizes its presence and can read data from it.
MultiRead
MultiRead is an OSTA specification that recognizes the importance of having future CD readers capable of reading a wide variety of CD-based media compared to older generations of CD readers. MultiRead CD-ROM drives, for instance, will be able to read newer CD-RW media as well as CD-R and CD-ROM.
Multisession disc
If a disc contains more than one session, then the disc is called a Multisession disc. It is a compact disc to which data is added incrementally in more than one recording session. If data is linked between sessions, all data on a multisession disc, when read on a multisession CD-ROM drive, may be seen as part of a single logical structure.
Multi-Volume
Multi-volume is used to organize multiple sessions as completely separate volumes, each with its own directory of information.
On the Fly
To write on-the-fly means to write to CD data referenced in a virtual CD image without first writing a real ISO 9660 image.
Optimum Power Calibration (OPC)
OPC is found in the newer 8X CD-R drives. 4X drives, for example, calibrate the laser at the beginning of the CD and then use the fixed laser power across the entire CD surface. The OPC circuit allows the laser outp8ut power to continuously adjust to the CD surface throughout burning. CD-Rs produced with OPC show the lowest BLER rates ever - less than 5 on most CDs.
Optimum Power Calibration Area
(OPC Area) The optimum calibration area is a special area near the center of the recordable disc. Before writing a track on a disc, the CD recorder must adjust the amount of power applied to the writing laser for the optimum level for the mounted disc. The optimum calibration area is reserved for this purpose.
Orange Book
The Philips/Sony specification for compact disc Magneto-Optical (CD-MO) and Write-Once (CD-WO) systems - in other words, the standard by which recordable CDs are recorded.
P-Q Editing
Subchannels that can be manipulated, when recording in disc-at-once mode, which give the user control over the P through Q subchannels for optimal glass mastering.
Packet Writing
A method of writing data on a CD in small increments, as opposed to writing large blocks of information as required by the Track-at-Once and disc-at-Once methods. Packet writing (also "packet resourcing") allows small packets or pieces of data to be written one packet at a time, lessening the chance of buffer underrun. Packet writing is good only for data tracks.
Path Table
The Path Table contains the addresses for the Directory Files so that they can be used to directly access the data files.
PCA
(Power Calibration Area). A space reserved at the beginning of the disc for calibrating the laser power needed to record to that disc.
Photo CD
A compact disc format based on the CD-ROM XA and Orange Book Hybrid disc specifications, used to store photographic images for display and printing.
Pit Jitter
See Jitter
PMA
(Program Memory Area) On a recordable disc, an area which "temporarily" contains the information about the recordings on the disc -- track numbers and their starting and stopping points when tracks are written in a session which is not yet closed. When you do not close the current session, to keep track of all data recorded, a kind of pre-TOC is written to the disc in an area that is only accessible by the CD recorder. When the session is closed, this same TOC information is written in the session lead-in.
Post-Gap
A space dividing tracks, recorded within the track data area at its end. The post-gap is 150 sectors (2 seconds) long and is required only where successive tracks are of different types. However, because many disc replicators expect a post-gap at the end of every track and may erroneously strip out data sectors if they do not find one, Easy-CD Pro Software records a post-gap after every track. See also "About Gaps Between Tracks".
Pre-Gap
A space dividing tracks, recorded before the track data area. The length of the pre-gap varies with the CD recorder and the types of tracks. Where successive tracks are both of data, one track is separated from another by a track pre-gap of 150 sectors (2 seconds). Where successive tracks are of different types, the pre-gap is usually of 225 sectors (or three seconds). If two successive tracks are audio, there may be no pre-gap at all. See also "About Gaps Between Tracks".
Premastering
The process of preparing data to be recorded onto a compact disc. This includes breaking the data into sectors and recording those sectors with the appropriate header (address) and error correction information. In the case of recordable CD systems, premastering and mastering are done in one operation, resulting in a ready-to-read compact disc.
Primary Volume Descriptor
The PVC or Primary Volume Descriptor, can always be found at the 16th sector of each data session. It is the hook of the file system to the medium. It refers to the Path Table and to the Root Directory.
Real CD Image
A Real CD Image can also be called a Physical ISO Image. This refers to a file that exactly duplicates how data will appear on the CD in ISO 9660 format. Since a Real CD Image contains the actual contents of the source, it requires the same amount of disc space as the CD-ROM disc to be created.
Red Book
The Philips/Sony specification for audio (CD-DA) compact discs.
Romeo
Windows-95 long file names only -- up to 128 characters. Also a file naming option in Easy-CD 95 Software and Easy-CD Pro 95 Software which allows you to write files to disc with names up to 128 characters long, including spaces. This is not part of the Joliet standard, the Unicode character set is not supported, and there is no provision for associated DOS filenames. Romeo filenames can be read on Windows 95 and NT systems. Romeo discs can be read on Macintosh systems if the filenames are not longer than 31 characters. Do not use Romeo if your disc must be read in other conditions.
Root Directory
The Root Directory is a special Directory File in that no other Directory File refers to it.
Run-In/Run-Out Blocks
When the recording laser is turned off after writing, two run-out blocks are written. When it is turned back on again, five run-in blocks are written. These seven blocks are also known as link blocks.
SCSI
Small Computer System Interface (pronounced "scuzzy"). A standard for high-speed data transfer between computers and their peripheral devices. A SCSI interface allows up to eight different peripheral devices to be connected to a single controller.
Sector
The smallest recordable unit on a CD. A disc can contain [(75 sectors per second) x (60 seconds per minute) x (number of minutes on disc)] sectors. The amount of data contained in the sector depends on what physical format and mode it is recorded in; for "regular" CD-ROM (Mode 1) data, you can fit 2048 bytes (2 kilobytes) of data into a sector.
Session
As defined in the Orange Book, a Session is an area on the disc consisting of a Lead-In Area, a Program Area and a Lead-Out Area; a recorded segment of a compact disc which may contain one or more tracks of any type (data or audio).
Table of Contents (disc)
Shows the number of tracks, their starting locations, and the total length of the data area of the disc.
Track

The Table of Contents (TOC) contains information about the disc and tracks. When you close the current session, the Table of Contents will be written in the Lead-In Area. With an unfinished (unclosed) recording of the disc, however, the TOC cannot be written to the disc.

Every time you write to CD, you will create at least one track, which is preceded by a pre-gap and followed by a post-gap. Any session may contain one or more tracks, and the tracks within a session may be of the same or of different types (for example, a mixed-mode disc contains data and audio tracks).

Track-at-Once

With Track-at-Once writing mode, a CD-Recorder will record one track at a time. In between every two tracks (unless you are only recording a single track). The CD-Recorder laser will stop while the hard disc prepared for the contents of the next track.

Each time the laser is stopped, it writes Run-Out blocks. When starting again, it writes Run-In blocks (a total of 7 blocks). These are ignored by CD-ROM readers and so do not disturb data transmission, but in some audio players you might hear a click between tracks. This is why disc-at-Once recording is preferable for audio discs.

UPC
Universal Product Code. With some CD recorders, you may define a thirteen-digit UPC catalog number for the entire disc, which will be written in the disc's Table of Contents. Also known as EAN.
Video CD

A VideoCD disc may include video clips converted from MPEG files and still images converted from BMP, GIF, JPEG, PCX, TIFF or TGA files. The video clips must conform to the MPEG for VideoCD specification defined in the White Book.

VideoCD is a reproduction system to present full motion pictures with associated audio by using the compact disc format. The video and sound are compressed together using the MPEG 1 standard and recorded onto a CD Bridge disc.

A Video CD disc contains one data track recorded in CD-ROM XA Mode 2 Form 2. It is always the first track on the disc (Track 1). The ISO 9660 file structure and a CD-I application program are recorded in this track, as well as the Video CD Information Area which gives general information about the Video CD disc.

After the data track, video is written in one or more subsequent tracks within the same session. These tracks are also recorded in Mode 2 Form 2. The session is closed after all tracks have been written.

Virtual CD Image
A Virtual CD Image is an ISO-formatted directory database that indicates how files will be arranged on your CD. The image contains pointers to where those to-be-recorded files actually reside on your drives, while the actual contents of the files or directories are still on the original storage media.

It also refers to a database of files to be written to CD with Easy-CD Pro for Windows 3.1, created by dragging & dropping files into the main window. It can be used to write directly to CD on-the-fly or to record a real ISO 9660 image to hard disk.

Volume
Under the ISO 9660 standard, a single CD-ROM disc.
Volume Descriptors
In ISO 9660, a set of information on the disc containing vital information about the CD and how the computer should read it.
Yellow Book
The book which sets out the standard developed by Philips and Sony for the physical format of compact discs to be used for information storage (CD-ROM).
Wave
A Wave file (.WAV) is a type of sound file which stores digitized analog signals.