Glossary of CD and DVD Terms

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Advanced SCSI Programmer's Interface. An expanded standard low-level interface used for accessing SCSI devices
ATA Packet Interface. Defines a set of commands supported through the ATA-2 interface for peripherals other than hard drives, such as CD-ROM, DVD-ROM, and tape drives.
The process of designing, creating, capturing, editing, and integrating information for a CD or DVD. Or, creating a database for a CD or DVD using tagging and indexing that generates a search and retrieval document.


Bad Block
A block (usually the size of a sector) that cannot reliably hold data because of a media flaw or damaged format markings.
One binary information element having the value ZERO or ONE
Bit Error Rate (BER)
Probability that a read bit does not match the written bit.
Also known as a sector or a logical block and is identified by a logical block number (LBN). A block is the smallest unit of information on a CD ROM that can be addressed.
Block Error Rate (BLER)
Number of blocks, each containing one or more erroneous bits, per unit of time (usually seconds).
A memory holding area used to temporarily store data.
Buffer Underrun
Occurs when the system cannot keep up a steady data stream to the CD recording software. The CD recorder itself has a buffer that is constantly filled with data in the event of a system slowdown or interruption. If the buffer is emptied before the system can recover, a buffer under-run occurs.
Contiguous set of eight data bits, represented by an equal or greater number of channel or recorded bits.


A memory buffering method used to obtain data faster than from a CD or other media
The tray or carrier where the CD is placed for reading or writing.
CD Text
Text information stored on an audio CD in either the lead-in or in audio tracks.  Sony has developed the lead-in format and uses that for storing information such as the track name, artist name and so on.  Philips has developed the format where the information is stored together with the audio which can be used for lyrics and other information.  At this time the Sony lead-in format is supported by most CD writers and is quite popular.
CD Writer
A CD device that can write on either CD-R or CD-RW discs.  There are no currently available devices which only write on CD-R discs any longer.  Other terms used for this are: CD burner, CD-RW drive, and so on.
Format adding graphics to CD-DA in reserved subcode bits R-W (6 bits per frame, 20 MB per disc). Primarily used for Karaoke discs.
Compact Disc-Digital Audio, developed by both the Philips and Sony corporations. These are playable on any audio CD player or computer CD-ROM drive.
Compact Disc-Interactive. A now obsolete format allowing storage of images, music, or video on a CD-ROM.
Compact Disc-Recordable. These are read-only on a standard CD-ROM drive. Images, text data, or sound can be recorded.
Compact Disc-Read Only Memory. Media which can contain data, audio, or video.
CD-ROM Drive
A hardware device which allows the CD media to be read, played, or recorded.
A rewritable CD. These can be erased and re-recorded.
A write-once CD.
A slang term for a ruined recordable CD.


Digital Audio Extraction - the process of copying audio information from a CD through the digital interface rather than simply playing the CD and capturing the audio signal.  Synonymous with "ripping".
Digital Audio Tape.
Disc at Once
A single process method of recording data on a CD. The Lead-in is written first, then the data sector, followed by the Lead-out.
Digital Versatile Disc.  This seems to be the settled upon definition, although it really does not mean much.  This refers to a format with approximately seven times the capacity of a CD using a slightly different laser frequency.  There are a number of different standards for DVD media, such as DVD Video, DVD Audio, DVD recordable, and so forth.  There are also a two conflicting standards for consumer DVD recordable media: DVD- and DVD+.  Both of these come in write-once and erasable forms.


Error Correction Code. A method used to scramble and record redundant data on a CD. This method can be used later to detect and correct errors on the CD
The ECMA standard is comprised of a-character sets and d-character sets.
Error Detection Code. A method used to detect errors in the sector data on the CD.


File Allocation Table (FAT)
The operating systems use FAT to keep track of which clusters are allocated to which files and which are available for use.
File System
A data structure that converts the physical image of a disc into a logical structure of files and directories.
The final step in creating a CD that makes it readable on other devices.
The programming instructions contained on a ROM in the CD recorder directing the recorder to respond to software commands.
Frames per second
Alternate term for a sector, used mostly for audio discs. A frame is 1/75th of a second of audio playback. This corresponds to the addressing of audio discs as MSF or Minute-Second-Frame.


A space (pause) dividing tracks on a CD.
Gigabyte (GB)
A unit of measure consisting of one billion bytes.  Most manufacturers use this form rather than a "memory size" gigabyte which is 1024 times 1024 times 1024.  For example, DVD media is commonly said to hold 4.7GB which is 4,700,000,000 bytes.  This works out to be around 4300 times 1024 time 1024.  This becomes important as you can only put 4.3GB of files the way they are counted when measuring file size.


Hierarchal File System. The file system used by the Macintosh operating system to arrange data on hard disks and floppy disks. This system can also be used for CD-ROMs.
High Sierra Format
The standard logical format preceding ISO-9660, which was developed by the High Sierra Group. The original High Sierra format is no longer used, but is nearly identical to ISO-9660.
Disc containing both an ISO 9660 (MS-DOS) partition and an HFS partition. Or, a disc containing both ISO 9660 and UDF volume and file structures. Or, may indicate that the first session of a multi- session CD-R or CD-RW disc is a mastered session followed by recorded sessions.
Hybrid CD
A CD containing both a PC format filesystem and a Macintosh format filesystem.


A single file containing all edited data on a CD. Image files are used in premastering.
Creation of a data index to speed up search and retrieval
An index marks a starting point in a single audio track. Indexes can be used to mark additional starting points in the track. Not all audio CD players support indexes. Index markers are written in the Q-subchannel and sequentially incremented by 1. An international logical file format for CD-ROMs originally developed by the High Sierra Group. All data on a CD is addressed using logical block numbers.
International Standard Recording Code. This contains the country code (two ASCII characters), owner code (three ASCII characters), year of recording (two digits), and serial number (five digits).


A logical file format created by Microsoft Corporation which conforms with ISO-9660 format. This format allows long file names (up to 64 characters) and uses the Unicode international character set.


Kilobyte (kB)
A unit of measure consisting of 1,024 bytes.


An imprint on the CD describing the contents. Professionally labeled CDs are usually imprinted using silk screening.
The starting area for each session where the TOC and additional session information are stored on the CD. The lead-in is written when the session is closed.
The ending area for each session where the index to the next session is stored. Writing the lead-out closes the session.
Logical Format
A format of directories and files used to locate data in a logical manner (e.g., ISO-9660, UDF, etc.). It provides a sector-by-sector view of a CD using a directory and file structure representation.


Once an image file is created, the first CD produced is known as the master CD. This is used to mass produce CDs
Media Catalog Number (UPC)
The media catalog number was formerly know as the UPC code.  It is not a bar code and generally is not used as a UPC code by retailers.
This term is used by manufacturers to mean 1,000,000 bytes.  When measuring files most operating systems call a megabyte 1024 * 1024 bytes.  This is how 80 minute CD-R discs are said to hold 720MB when only around 700MB of files will really fit on them.
Multisession CD
A CD that has been written to multiple times with each use creating a new session on the disc.
Mixed-Mode CD
A CD containing both music and data. Data usually resides on track 1, with audio data on following tracks.
Mode 1
Mode 1 - the original "ordering" of control information in the sector header. Most basic form read by all CD devices.
Mode 2
Mode 2 - (XA) "extended architecture" that allows definitions of sub-types within the data by using an additional 8 bytes in the sector header. This was moved from the back end of the sector (where it was unused in mode 1) to the front to allow for this. This is further subdivided into: Mode 2, Form 1: 2048 bytes of data per sector with full error correction. This simply allows for additional coding on each sector. Mode 2, Form 2: 2324 bytes without error correction. This can be used for streaming video and/or audio where minor errors can be ignored. Video CD (VCD) uses Mode 2 form 2. Everyone else is using mode 1 or mode 2 form 1.
Motion Pictures Expert Group compression methods for video, graphics, or audio information.
An acronym for Minute-Second-Frame addressing, used with both data and audio discs. This refers to the 1x playing time of an audio disc. The Sector Display tool allows the use of either logical block numbering or MSF addresses to access data.
Integration of more than one form of information, such as text, graphics, audio, video, animation, and computer data.
Multiple recording sessions, to which additional sessions are appended to the CD. When data is linked between sessions, all data is seen as part of a single logical structure.
A CD containing multiple sessions not linked together. Each volume on the disc is read as a separate disc.


Operating System (OS)
A program which acts as an interface between the user of a computer and the computer hardware. The purpose of the operating system is to provide an environment in which a user may run software applications. The goal of the operating system is to enable the user to conveniently use the computer's resources such as the CPU, memory, storage devices and printers.


Packet Writing
A technique of writing to a CD-R or CD-RW disc which allows small increments of data to be added to the disc. This is used by nearly all “drag-and-drop” type CD burning software. See also UDF.
Physical Format
The low-level format used to write information to a CD.
Post Gap
Two second area at the end of a CD program area or Mode change, encoded as null data or audio silence.
Power Calibration Area
A reserved area at the inside of the disc which is used to calibrate the laser power for writing.  This use has largely been superceded by "running optimum power calibration" or "running OPC" where the laser power is continuously checked as the disc is written.
Pre Gap
Two second first part of a CD program area or track, normally encoded as null data or audio silence, but should contain track descriptor blocks if session-at-once or incremental track-at-once recording is used.
Creating an image file (a snapshot of the data and directory structure) to be recorded on a CD.


A file naming option available in EasyCD 95 and Easy-CD Pro 95, allowing up to 128 character filenames. This does not support the Unicode character set or DOS filenames, and is not compatible with Joliet format. Romeo is not supported by InfinaDyne software.
Rock Ridge
A technique for adding long file names to CDs that is supported primarily by Unix and Unix-like systems, such as Linux.  These names are separate from Joliet names and it is possible to have both forms on a single disc.  Rock Ridge also allows for more file attributes, permissions and symbolic links between files.


Small Computer System Interface. An interface allowing you to connect media devices to your computer.
The smallest unit of information on a CD that can be addressed. Also referred to as a block. A sector may contain a header, synchronization bits, and user data. Different types of CDs contain different sector sizes. A data CD-ROM contains a sector size of 2048 bytes of data.
A single recording operation, consisting of lead-in, data, and lead-out areas. Several sessions may reside on a CD, which is known as a multisession CD. A single session CD contains only one session.
Sub-q Data
A hex dump containing current position data for the track, UPC code for the track, current minutes and seconds time into the track, and ISRC.


The Table Of Contents on the CD, which shows the contents of every recorded session. The contents consist of the number of tracks, the starting location for each track, and the total size of the data area. The lead-in contains the TOC.
On a data CD-ROM, one track may contain data, files, and folders. On an audio CD, a single track contains one piece of music. Each track is separated by a gap.


Universal Disc Format. Nearly all “drag-and-drop” CD burning software uses this format.
A unique bar code format (Universal Product Code) for a CD.


Process of matching information on a copy to that on the original.
Mountable sector address space consisting of a single set of sector addresses, usually as a continuous sequence of sectors.
Volume Descriptor
This resides at the beginning of the CD where the structure of the file system is located. A volume descriptor may contain: 
System Name (Optional) The name of the operating system running the application. Maximum: 32 a-characters. 
Volume Name (Recommended) The name of the CD displayed when it is mounted. Maximum: 32 a-characters. 
Volume Set Name (Optional) The name of a set of volumes. Maximum: 32 d-characters. 
Publisher's Name (Optional) Identifies the name of the CD's publisher. Maximum: 128 a-characters. 
Data Preparer's Name (Optional) The name of the author of the CD's contents. Maximum: 128 a-characters. 
Application Name (Optional) The name of the application necessary for accessing data from the CD. Maximum: 128 a-characters. 
Copyright Filename (Optional) The name of a file located in the root directory containing a copyright notice. Maximum: 8+3 d-characters. 
Abstract Filename (Optional) The name of a file located in the root directory describing the contents of the CD. Maximum: 8+3 d-characters. 
Bibliographic Filename (Optional) The name of a file containing bibliographic information (e.g., ISBN number). Maximum: 8+3 d-characters. 
Date Fields (Optional) Fields can be recorded for creation, modification, expiration, and effective dates. The format is: year/month/day hour:minute:second.
Volume Set
A collection of one or more volumes with identical volume set identification, on which a set of files is recorded.


See Mode 2.


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