Glossary of terms

Please use the index in the left-hand collum to navigate through this extensive glossary.


The character set used in the file naming convention for ISO 9660 (Standard CD-ROM and CD-Digital Audio format). It consists of capital A to Z, digits 0 to 9, and various symbols.
American National Standards Institute. Publishes industry standards for a wide range of technologies.
Asynchronous Data Transfer

A method of SCSI data transfer. This is the type of transfer rate originally introduced with SCSI 1. With this type of transfer method, transfer rates of 2 Mbytes/sec are common. Asynchronous is faster on short cables, while synchronous is faster on long cables.
What you do to create an application that may eventually be stored on CD. For example, if you wish to create a multimedia game or CD presentation, you will need CD-Rom Authoring software that allows you to combine sound, graphics, and text, and provides some user interactivity. When you have finished creating your application with authoring software, you can use CD recording software such as Easy CD Creator or Adaptec Toast to write it to CD.
Auto-Insert Notification
A feature of Windows 95 and Windows NT that causes an audio CD to be played or an application disc to launch an application (for some discs) as soon as the disc is mounted in a CD drive. With earlier CD-R software it was recommended that this feature be turned off, but with Easy CD Creator and Direct CD it is preferable to leave it on. This setting must be made for each CD unit separately; in Windows 95 it can be made in Control Panel – System – Device Manager – CD-ROM (your CD-ROM drive) Settings.


A unique code for any manufactured unit. With recordable CDs, this number is often printed in the clear inner ring of the disc. Some CD recorders can also read this information digitally.
Bit Depth
In color images, the number of colors used to represent the image. Typical values are 8-, 16-, and 24-bit color, allowing 256, 65,536 and 16,777,216 colors to be represented. The latter is known as true color, because 16.8 million different colors is about as many as the human eye can distinguish.
An acronym for Basic Input/Output System. This is usually an EPROM (Erasable Programmable Read Only Memory) chip with computer program instructions in it. A motherboard BIOS (usually by companies such as Phoenix, Award and AMI) controls the basic functions of the computer (such as controlling the keyboard, monitor, on board controllers etc.).


  • Blue Book

The Blue Book defines the Enhanced Music CD (also known as CD EXTRA – the term CD Plus is not now recommended to avoid confusion with similar formats) specification for multisession pressed disc (ie not recordable) comprising audio and data sessions. Enhanced Music CD discs are intended to be played on any CD audio player, on PCs and on future custom designed players. The current version 1.0 was released in Jan 1996.

The Blue Book comprises of:

Disc specification and data format including the two sessions (audio and data). The second, data session must be a CD-ROM XA session. Directory structure (to ISO 9660) including the directories for CD Plus information, pictures and data. It also defines the format of the CD Plus information files, picture file formats and other codes and file formats. MPEG still picture data format.

  • Green Book

The Green Book, written originally in 1987, describes the CD-interactive (CD-i) disc, player and operating system and contains the following information:

    • CD-I disc format (track layout, sector structure). Data retrieval structure which is based on ISO 9660 with some additions. Audio data using ADPCM levels A, B and C (cf CD-ROM XA) Real-time video data which describes the disc coding of different types of still images, the video decoder and visual effects available.. Compact Disc Real Time Operating System, which is the operating system used in every CD-i player. The Green Book specifies the OS kernel, file managers, drivers and all the system calls available. Base case system which is a specification of the minimum CD-i hardware configuration. Full motion extension which defines the functions provided by the MPEG cartridge and the software calls available for MPEG decoding.
    • The Green Book is the most comprehensive specification of all the colored books, specifying in detail not just the disc but the coding of data and the architecture of the player hardware and software.
  • Orange Book

The Orange Book defines CD-Recordable discs with multisession capability. It is in three parts:

1.       Part I defines CD-MO (Magneto Optical) re-writable discs, last updated in November 1990.

2.      Part II defines CD-WO (Write Once) discs, last updated in January 1994.

3.      Part III defines the CD-E (Erasable) disc format. The tentative version 0.8 was released in September 1995.

All three parts contain the following sections:

Disc specification for the unrecorded disc and the recorded disc. Pre-groove modulation which is necessary for motor control information needed during writing. Data organization including linking to allow writing at different times. Multisession and hybrid discs

Recommendations for measurement of reflectivity, optimum power control, environment, light fastness, push pull magnitude, measurement of groove wobble amplitude, wavelength dependency, jitter, use of pre-gap, serial copy management and others.

  • Red Book

The Red Book describes the physical properties of the compact disc and the encoding of the digital audio data. It comprises the following information:

Audio specification for 16-bit PCM Disc specification, including physical parameters Optical stylus and parameters including laser wavelength, numerical aperture, pit sizes and track pitch. Deviations and block error rate. Modulation system and error correction. Control and display system (ie subcode channels)

A more recent addition to the Red Book describes the CD graphics option using the subcode channels R to W. This describes the various applications of these subcode channels including graphics and MIDI, both of which can be used for Karaoke applications.

  • White Book

The White Book defines the Video CD specification. First published in 1993, there have been several versions:

    • version 1.0: Karaoke CD specification, MPEG-1 data in tracks
    • version 1.1: Video CD: as 1.0 but chapter marks and multi-volume album facilities added
    • version 2.0: Video CD: addition of stills, generic menus, playlists, closed caption text.
    • The White Book (version 2.0) comprises:
      • Disc format including use of tracks, Video CD information area, segment play item area, audio/video tracks and CD-DA tracks. Data Retrieval Structure, compatible with ISO 9660. MPEG audio/video track encoding including image sizes allowed, video/audio bit rate, sector interleaving and examples of MPEG packets. Segment play item encoding for video sequences, video stills and CD-DA tracks. Play sequence descriptor to allow the playback of preprogrammed sequences. User data fields for scan data (enabling fast forward/reverse) and closed captions. Examples of play sequences and playback control.
  • Yellow Book

The Yellow Book was written in 1984 to describe the extension of CD to store computer data, ie CD-ROM. This specification comprises the following content:

Disc specification which is a copy of part of the Red Book. Optical stylus parameters (from Red Book) Modulation and error correction (from Red Book) Control & display system (from Red Book) Digital data structure, which describes the sector structure and the ECC and EDC for a CD-ROM disc.

As a separate extension to the Yellow Book, the CD-ROM XA specification comprises the following:

    • Disc format including Q channel and sector structure using Mode 2 sectors. Data retrieval structure based on ISO 9660 including file interleaving which is not available for Mode 1 data. Audio encoding using ADPCM levels B and C. Video image encoding (ie stills)

A CD (or floppy, hard disk, or other storage media) from which a computer can be started up, because it contains all the operating system software the computer needs to run. A bootable CD contains a bootable image, a file that is an exact representation of a floppy or hard drive. Bootable CDs are usually made according to the El Torito standard.
A pathway for data in a computer system. All PCs have an expansion bus, which is designed to host add-on (expansion) devices, such as modems, adapter boards and video adapters. Expansion devices use the bus to send data to and receive data from the PC’s CPU or memory. ISA (Industry Standard Architecture), EISA (Enhanced ISA) and PCI (Peripheral Component Interconnect) are the major bus standards used in PC’s.
BUS Mastering
A high performance method of data transfer in which the host adapter’s on-board processor handles the transfer of data directly to and from a computer’s memory without intervention from the computer’s microprocessor. This is the fastest method of data transfer available for multitasking operating systems.


A portion of RAM used for temporary storage of data that must be accessed very quickly. In applications that run from CD-ROMs, the cache is typically used to store directory files.
This is a process by which data requested by the operating system of a computer is retrieved from RAM instead of from a hard disk (or some other mass storage media). Caching algorithms will check if the requested data is in its ‘cache’ (or RAM). RAM access is an order of magnitude faster than today’s mass storage devices, so the more accesses to the cache, the faster overall system performance will be. Cache can be on a host adapter, on the motherboard (controlled by the operating system), and on any number of devices.
The plastic and metal carrier into which a CD must be inserted before it is loaded into some CD-ROM drives or CD recorders (others have trays that slide in and out to receive the disc and do not need caddies).
CD Bridge or CD-I Bridge
A set of specifications defining a way of recording CD-I information on a CD-ROM XA disc. Used for Photo CD and Video CD.
CD-R discs written that can be read in either a CD-DA player or in a CD-ROM reader.
CD Extra or CD Plus
A multi-session disc containing a number of audio tracks in the first session, and one CD-ROM XA data track in the second session. Additional characteristics are defined in the Blue Book standard. This is an alternative to mixed-mode for combining standard CD-DA audio (which can be played in a normal audio player), and a computer application, on a single disc.
(AKA karaoke) A special disc format in which simple graphics and text are stored in the subchannels of an audio disc, but you need a special player to read and display this information. The data in the subchannels cannot be copied with most current systems or software.
Compact Disc-Digital Audio. Jointly developed by Philips and Sony and launched in the U.S. in October, 1982, CD-DA was the first incarnation of the compact disc, used to digitally record and play back music at unprecedented quality. The standard under which CD-DA discs are recorded is known as the Red Book Standard.
A compact disc format developed by Philips, 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
Compact disc-recordable. Same as CD-WO when referring to recordable discs (media), often used to refer to write-once discs, in contrast to CD-RW, or Compact Disc Re-Writable.
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.
"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 could more easily be used for multimedia applications. CD-ROM XA was abandoned as an independent multimedia format. CD-ROM XA is also the physical format for Photo CD discs.
CD recordable media that can be erased and re-recorded up to 1000 times. CD-RW media can only be written in a CD-RW recorder, not in a normal CD recorder, though a CD-RW recorder can also record standard CD-R discs.
An audio CD format in which up to 5000 characters of disc information (title, artist, song titles, etc.) is written into the disc Table of Contents. This information is displayed when the disc is played back on CD Text-enabled audio players.
Cross-Interleaved Reed-Solomon Code. The first level of error correction used in every compact disc, and the only one used for audio CDs.
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 on the disc 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. Note: It is NOT necessary to close a disc in order to read it in a normal CD-ROM drive. Easy CD Audio because it is single session, Red Book, it automatically closes the disc, there is the option to close the session and leave the disc open for adding more session. Note only mutilsession CD Devices can read the add-on sessions. Almost all standard audio players cannot.
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 any subsequent sessions.
Compilation list
A list of audio files which are to be recorded to a CD in Red Book format. This is the same as a cue sheet.


The character set used in ISO 9660 Level 1 filenames, if the standard is strictly adhered to (which is not always necessary). Consists of capital A to Z, digits 0 to 9, and the underscore symbol ( _ ).
Digital Audio Tape.
Digital Audio Extraction

The process of copying CD-DA audio tracks digitally, from your CD recorder or another CD-ROM drive, to hard disk or to recordable CD. Not all CD-ROM drives support this!
A method of writing CDs in which one or more tracks are written in a single operation, and the disc is closed, without ever turning off the writing laser. Contrast with Track-at-Once. Not all CD recorders support Disc-at-Once.
This writing mode is especially useful for creating a master disc that you will send off to a replicator for mass production. In Disc-at-Once mode, the whole disc – Lead-in, Data, and Lead-out areas are written starting from the beginning of the disc to the end of the disc without ever turning off the recording laser. With Track-at-Once and Track Multi-session, the data area is written first, then the Lead-out area, then the Lead-in area; each time turning off the recording laser to jump to the next area. Each time the recording laser is turned off and on, link blocks are created on the disc. These link blocks "link" tracks with the Lead-in and Lead-out areas. However, these link blocks are interpreted as "uncorrectable errors" on most mastering systems at the replication plant. Writing in Disc-at-Once mode eliminates the link blocks because the recording laser never turns off. Disc-at-Once requires the pre-mastering software to send a "cue sheet" to the CD-R drive that describes the disc layout. From there, the CD-R drive accepts the data and begins writing the Lead-in with the Table of Contents (TOC), the actual data, and the Lead-out in that order, without interruption. Disc-at-Once creates a single session disc only.
Disc Image
A single large file that 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. This may be an ISO 9660 image (adhering strictly to the ISO 9660 standard), or some proprietary format such as the .cif format used by Easy CD Creator.


Error Correction Code. A system of scrambling data and recording redundant data onto disc as it is recorded. During playback, this redundant information helps to detect and correct errors that may arise during data transmission.

A graphic file format specifically used to transfer PostScript based data within compatible applications. Usually created by drawing tools such as Adobe Illustrator, an artist can transport curves, paths, spot colors and graphics into PageMaker or QuarkXpress.
In Illustrator you would use File > Save As > EPS.


File System
A data structure that translates the physical (sector) view of a disc into a logical (files, directories) structure, which helps both computers and users locate files. In other words, it records where files and directories are located on the disc. Reference Logical Format.
A single, complete picture in a video or film. A video frame is made up of two interlaced fields of either 525 lines (NTSC) or 625 lines (PAL). Full-motion video for NTSC runs at 30 frames per second (fps); for PAL, 25 fps. Film runs at 24 fps.
Free space
The amount of unused space available on a hard disk or other device. It is important to have enough free space when doing CD recording.


The gap (more correctly called a pause) is a space dividing tracks. In some situations a gap is required by the standards (Red Book and other "color" books). For example, if you have data and audio tracks within the same session, they must be separated by a gap. Also, there must be a gap of 2 to 3 seconds preceding the first track on a disc.
The gap which "belongs" to a track is actually the gap before it, not the one after it. This is why on some audio CD players you will see a countdown (-02, -01, etc.) before a track begins. It is counting down to the next track, not counting up from the end of the last one.
Green Book
The Philips/Sony specification for CD-I.
Gold Disc (CD-R Media not Gold ROM’s)
The recordable disc used in recordable CD systems. The blank disc is made of a bottom layer of polycarbonate, with a preformed track spiral that 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.


The file system used by the Macintosh operating system to organize data on hard and floppy disks. Can also be used for CD-ROMs.

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.


Image Pac
In Photo CD, a set of five versions of the same image, at varying resolutions
Incremental (packet) Writing
This is also referred to a just "Incremental Writing". This is a writing mode that is just a little ahead of its time. The concept behind Incremental Writing is simple: make the CD-R drive act like a hard disk or other storage device; able to write as little as a file at a time to the CD-R disc. While simple in concept, implementation has been more difficult. ISO9660, the current file system for CD-ROM, is not really appropriate for a disc written incrementally, because the indexing system (path tables) for ISO9660 depend on knowing about all the files that are to be recorded on the disc. Without this knowledge, the ISO9660 file system will have a very difficult time retrieving a file. With current multi-session writing, each time a session is written, the whole file system (or Table of Contents) must be re-written. A new file system has emerged called ECMA 168. ECMA 168 builds on the ISO9660 file systems and adds the flexibility to add data to a disc "a file at a time", without having to re-write the file system each time. The key drawback is that an incremental disc cannot be read back on today’s CD-ROM drives without a special driver. Direct CD uses a variation on this
Indexes provide additional starting points within a single audio track. Not all audio CD players support indexes. Index markers are written into the Q subchannel and are incremented by 1 sequentially during the track.
ISO 9660 Format
An international standard specifying the logical format for files and directories on a CD-ROM or CD-ROM image. format. Some other common logical formats such as Joliet (for Windows) and Rock Ridge are extensions of ISO 9660.
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 lowest common denominator, developed with DOS file naming limitations in mind):

    • 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, but there are no restrictions on filenames.
In Level 3 there are no restrictions. This allows for writing files in multiple extents, so it is used for packet writing (i.e.- using Direct CD to write the disc).
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).


Jewel Case
The hinged plastic case in which most CDs are often stored.
Jewel Case Sleeve (commonly known as "booklet")
The pieces of paper which can be inserted into the jewel case to help identify the contents of the CD stored in the case. The sleeve on the front is called the booklet, the sleeve in the back is the bottomcard
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.


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 points). 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 contains the next writeable address on the disc, (indicates whether the disc is MultiSession) so that future sessions can be added (unless the disc is closed).
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).
 Linked Multisession
A disc containing more than one session, in which all (or selected) data from the various sessions can be seen as if it had all been recorded in a single session.


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 pre-mastering by the desktop CD recorder, and the term is generally used to mean "recording."
Mixed-Mode Disc
A compact disc including both computer data and CD-DA tracks. The data is all contained in Track 1, and the audio in one or more following tracks.
MMC (Multi Media Command)
A standard command set used by some CD recorders. Many newer recorders follow this standard, though many of them also interpret it differently (so there are still differences in how software must address these recorders, despite the standard).
There are two recording modes for compact discs. In Mode 1, used with CD-ROM applications, 288 bytes of each sector are used for storing error correction code, and the remaining 2048 bytes per sector are available for user data. Mode 2, used in CD-I and CD-ROM XA, has two forms: Form 1 is similar to Mode 1, as it is also used to record data that requires error correction; Form 2 is used for recording information such as sound or images which do not require such extreme precision. Since less error correction is needed, more bytes in the sector can be freed for information storage, resulting in a data area of 2336 bytes per sector.
Mode 1
A somewhat inaccurate way of referring to the CD-ROM physical format.
Mode 2
A not-quite-accurate but common way of referring to the CD-ROM XA physical format.
To install a compact disc so that the computer recognizes its presence and can read data from it.
MP3 is a scheme for compressing audio. MP3 files do not maintain the quality of audio CD tracks, and cannot be recorded directly to CD as standard audio tracks. They can be recorded as data tracks and played back via your computer using appropriate player software.
Motion Picture Experts Group, whose name has been applied to the standards (MPEG 1 and MPEG 2) promulgated by the group for compression of full-motion video.
Microsoft DOS extensions for CD-ROM. Allows the DOS and Windows 3.x operating systems to recognize a CD-ROM disc. Version 2.23 or higher is required.
An OSTA standard for CD-ROM and DVD-ROM drives. Drives which follow the MultiRead standard can read commercial CDs (audio and data), CD-R discs, and CD-RW discs. They can also read discs written in fixed- or variable-length packets. For more information, see MultiRead Specification from OSTA. Note: Drives containing the MultiRead logo that have been issued by Hewlett-Packard have been tested for compliance with the MultiRead specification. Drives labeled as "multi-read" (without the logo) probably have not been tested for compliance with the specification, and may not be able to read CD-RW or packet-written discs.
The Orange Book specification which allows more than a single session to be recorded or read on a CD-ROM or CD-ROM XA disc. A method of adding data incrementally to a CD 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. Multisession is very different from packet writing.
The ability to record more than a single track on a disc. Track numbers are from 1 to 99. They continue to increment across session boundaries. For example, if session 1 used tracks 1 to 4, session 2 would start at track 5. Track numbers may start at any value, but must be incremented sequentially on the disc.
A disc containing multiple sessions which are not linked together, so that each "volume" on the disc must be read as if it were a separate disc. You can read different sessions on a disc using the Session Selector in Easy CD Creator Deluxe.


On the Fly
To write on the fly means to write directly from source data to CD data without first writing a disc image Same as Write Direct.
Optimum Power Calibration Area
(OPC Area) 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 to an optimum level for each individual 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. It includes the specification for the Hybrid Disc technology on which Photo CD is based. In other words, the standard by which recordable CDs are recorded.


Packet Writing
A method of writing data on a CD in small increments (contrast with Track-at-Once and Disc-at-Once). Packets can be of fixed or variable length. Adaptec’s Direct CD software supports packet writing on CD recorders which also support it — not all CD recorders do; check the manufacturer’s specs and the Direct CD recorders support list.
Power Calibration Area. A space reserved at the beginning of the disc for calibrating the laser to record to that disc. Reference OPC
 Photo CD
A compact disc format based on the CD-ROM XA, Orange Book and CD-I Bridge specification.
Physical Format
The physical format of a compact disc determines how data is recorded in each sector. The various physical formats are defined by the color book standards (Red Book, Yellow Book, etc.)
(Program Memory Area) On a recordable disc, an area which "temporarily" contains the Table of Contents information when tracks are written in a session which is not yet closed. When the session is closed, this same information is written in the session lead-in.
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, Adaptec software recording in Track-at-Once mode (default) records a post-gap after every track.

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.
The technical process of preparing data to be recorded (mastered) onto a compact disc. This includes dividing the data into sectors (logical blocks) 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.


Random Erase
(Available with CD-RW discs and Direct CD 2.0). The ability to erase a single file at a time from a CD-ReWritable disc, freeing up disc space for immediate re-use, just as you would do on a hard or floppy disk.
Recordable Disc
The media 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. A translucent layer of recordable material is laid on top of the polycarbonate, then a reflective layer (gold or silver colored). On top there is a thin layer of lacquer and sometimes a printed label. The standard recordable disc is "write-once" — it cannot be erased or re-used. For erasable discs, see CD-RW.
Red Book
The Philips/Sony specification for audio (CD-DA) compact discs.
Making multiple copies of a compact disc.
Fineness of detail. In computer monitors it is measured in pixels horizontal x vertical (usually) or in pixels per inch.
Rock Ridge
An extension of the ISO 9660 file system designed to support UNIX file system information (such as longer filenames and deeper directory structures).
 Run-In/Run-Out Blocks
Blocks of data written before and after a packet or a track, to allow the recorder to synchronize with the data on disc, and to finish up interleaved data. Four run-in blocks and two run-out blocks are written for each packet.


Small Computer System Interface. An interface that allows up to seven peripheral devices to be linked (daisy-chained) to a single controller. By contrast, IDE allows two devices.
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 it is recorded in; for "regular" CD-ROM (Mode 1) data, you can fit 2048 bytes (2 kilobytes) of data into a sector.
Sequential Erase
(Available with CD-RW discs.) Erasing the entire disc so that it can be re-used.
As defined in the Orange Book, a recorded segment of a compact disc that may contain one or more tracks of any type (data or audio). In data recording, there is usually only one track per session. In audio recording, all audio tracks are contained in a single session. A lead-in and lead-out are recorded for every session on a disc.
Session-at-Once is a subset of Disc-at-Once, used for CD Extra. In Session-at-Once recording, a first session containing multiple audio tracks is recorded in a single pass, then the laser is turned off, but the disc is not closed. Then a second (data) session is written and closed.
 SIF (Standard Input Format)
A format for compressed video specified by the MPEG committee, with resolutions of 352 (horizontal) x 240 (vertical) x 29.97 (fps) for NTSC and 352 (horizontal) x 288 (vertical) x 25.00 (fps) for PAL. SIF-resolution video provides an image quality similar to VHS tape.
Silver Disc (Stamped)
A disc that is mastered by a stamping process. It is read-only and cannot be modified.
Single Session
The smallest collection of information that can be read by a CD-ROM compatible device. It contains the ISO 9960 file structure and files. A single session can contain a single track or multiple tracks. Contrast MultiSession and MultiTrack.
Many new CD-ROM drives save power by spinning down (stopping the drive’s spin) when the drive is not in use. This may cause buffer underruns when recording a CD by copying tracks or files from another CD-ROM drive, if the drive "goes to sleep" and cannot be woken up quickly enough to keep up with the CD recorder’s demand for a constant stream of data.
Subchannels (or subcodes)
Audio CDs have 8 subchannels of non-audio data interleaved with the audio data, called the P, Q, R, S, T, U, V, and W channels. You can think of them as small, separate streams of data running alongside the audio, which can be read by a player at the same time as the audio, if the player is "smart" enough to interpret them. For example, CD+ Graphics discs (karaoke) store rudimentary graphics and text in the subchannels, but you need a special player to read and display this information.
The P and Q channels are used to tell an audio player how to play back an audio disc. The Q channel contains the index markers. In the pause (gap) before a track begins, the index marker is set to 0 (zero). When a track begins, the index marker changes to 1. (If a track contains subindexes, these are incremented by 1 sequentially during the track. In this case the Q channel might contain 1, 2, 3, 4, etc.) When the track ends, the Q channel index marker goes back to 0, then re-starts at 1 when the next track begins.
Synchronous Transfer
A method of SCSI data transfer. With this type of data transfer, the SCSI host adapter and the SCSI device agree to a transfer rate that both support (this is known as synchronous negotiation). With this type of data transfer method, transfer rates of 5 Mbytes/sec or 10 Mbytes/sec (for FAST SCSI) are common.


A physical requirement of the SCSI bus. The first and last devices on the SCSI bus must have terminating resistors installed, and the devices in the middle of the bus must have terminating resistors removed.
The Single Ended electrical class depends on very tight termination tolerances, but the passive 132-ohm termination defined in 1986 is mismatched with the cable impedance (typically below 100 ohms). Although not a problem at low speeds when only a few devices are connected, signal reflections can cause errors when transfer rates increase and/or more devices are added. In SCSI-2, an active terminator has been defined which lowers termination to 110 ohms and is a major boost to system integrity.
TOC (Table of Contents )
For a whole disc or any session within a disc, shows the number of tracks, their starting locations, and the total length of the data area. The TOC does NOT show the length of each track, only it’s starting point.
Every time you write to CD, you will create at least one track, which is preceded by a 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). Using the Cue Sheet you can record more than one track in a single writing. Packet Recording is the only smaller unit recording.
A method of writing data to disc. Each time a track (data or audio) is completed, the recording laser is stopped, even if another track will be written immediately afterwards. Link and run blocks are written when the laser is turned on and off.
Track Multi-Session
This write mode is very similar to Track at Once. In the Multi-session environment, each "session" must contain at least one track. Again, the size of the track must be at least 300 blocks. Track Multi-session, as you have probably guessed, allows you to incrementally add tracks to a disc. (Not to be confused with Incremental Writing) Each session will take up about 13.5Mb of disc space in overhead; what is called Lead-in and Lead-out areas. So it does not make sense to record small amounts of data (less than 50Mb), because each time a write is performed, 13.5Mb of capacity on the disc is lost. Since the disc can only be written to 99 times, this is important to factor).


Universal Disc Format. A file system endorsed by OSTA (the Optical Storage Technology Association) for use with packet writing and other recordable optical disc technologies, such as DVD.
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 standard for displaying full motion pictures with associated audio on CD. 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 Image
A database of files to be written to CD, created by dragging & dropping files into the main window. Can be used to write directly to CD on the fly, or to master a real ISO 9660 image to hard disk.
Under the ISO 9660 standard, "volume" refers to a single CD-ROM disc. However, "volume" is often used to mean a session on a multisession disc, which is not linked to other sessions.
Volume Descriptors
For an ISO 9660 disc, the Volume Descriptors are a set of optional information fields recorded at the beginning of the data area on the disc. They were originally designed for the needs of CD-ROM publishers. The full set of Volume Descriptors is as follows:


Write Direct
Also called on the fly. Files are written directly to the CD disc, however the ISO 9660 structures are temporarily written to the hard disk.
Write First to HD
Also called ISO image. Everything is written to the hard disk first. Contrast it to Write Direct.


Yellow Book
The book that sets out the standard developed by Philips and Sony for the physical format of compact discs to be used for information storage (CD-ROM).

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