DVD glossary

CAV

Constant Angular Velocity of the information track resulting in variable, radius-dependent bit rates.

CD-Bridge

Combined features of CD-ROM XA and CD-i, playable in CD-i player or CD-ROM XA drive.

C1 or C2

See CIRC

CD-DA

CD-Digital Audio using 16 bits of linear coding to represent each digital sample of an audio channel. First specified in the Red Book, later in IEC 908 (also see Digitize.)

CD Extra

See Enhanced Music CD.

CD-i

Compact Disc Interactive specified by Green Book, designed as a TV adjunct featuring simultaneous integration of various levels of sound, audio, animation, graphics, and limited video. Used for multimedia and interactive software.

CD-i Ready

CD-Audio disc with additional features such as graphics information that can be accessed in a CD-i player. CD-i information hidden in a long, 3 minute or more, track #1 index 0 pre-gap that is skipped by CD-DA players.

CD+G

Format adding graphics to CD-DA in reserved subcode bits R-W (6 bits per frame, 20 MB per disc). Primarily used for Karaoke.

CD-R

CD-Recordable, write once-read many disc specified by Orange Book Part II using a pre-stamped, wobbled groove to guide a write laser that irreversibly changes regions of a dye polymer layer to an optically absorbing state. A special drive is required for writing.

CD-ROM

CD-Read Only Memory, first specified in the Yellow Book, later in ISO/IEC 10149 (Second Edition 1995).

CD-ROM XA

CD-ROM eXtended Architecture standard of Philips/Sony that incorporates a subheader to support interleaving of audio, graphics, video and computer data using CD- ROM XA Mode 2/Form 1 and CD-ROM XA Mode 2/Form 2 sectors. CD-ROM XA EDC and ECC structures differ from those of CD-ROM Mode 2.

CD-RW

CD-ReWritable phase change media specified by Orange Book Part III that can be reversibly recorded, erased, or overwritten. Uses a pre-stamped groove to guide a write laser. Data is contained in an alloy layer that can be converted by a laser from a reflective crystalline state to a non-reflective amorphous state or erased back to the crystalline state, depending on laser power. A special drive is required for writing, but CD-RW recorded media can be read in modified CD-ROM drives capable of detecting the low light levels resulting from CD-RW reflectivity of 15-25%. (Formerly CD- Erasable or CD-E.)

Channel Bit

Binary elements by which ZERO and ONE data bits are represented by optical information on the disc after encoding and modulation. Multiple (usually 14 or 16) channel bits are commonly used to represent one eight bit data byte to achieve higher information density when combined with NRZ-I coding.

CIRC

Cross Interleave Reed-Solomon Code is a method of error detection and correction employing Reed-Solomon parity bytes together with different interleaving, or delay, patterns that assists in error correction by distributing concentrated read errors over multiple frames that then form the input to a CIRC decoder. After the first deinterleave, CD discs correct small read errors at the C1 level, followed by a second deinterleave and correction of large read errors at the C2 level.

Circular Polarization

Two linearly polarized, orthogonal (right angle) light beams that are 90 degrees out of phase. Produced from unpolarized light by a linear polarizer aligned 45 degrees from a major axis of a quarter wave plate.

Clamping Area

Region between the center hole and information area where the disc is physically connected to the drive spindle.

CLV

Constant Linear Velocity of the information track achieved by variable angular velocity using higher rotational drive speeds on the inner tracks and lower speeds on the outer tracks resulting in a constant scanning velocity and bit rate.

Closure

See finalization.

Coherent Light

Illumination in which phasor amplitudes at all object points vary in unison, such as light from a point source or a laser.

Color

Response of the eye to different wavelengths of light. Ultraviolet < 400 nm, violet 400-424 nm, blue 424-491 nm, green 491-575 nm, yellow 575-585 nm, orange 585-647 nm, red 647-700 nm, infrared > 700 nm. Maximum visibility occurs at 556 nm.

Compression

Decreasing the size of stored information by reducing the representation of the information without significantly diminishing the information itself, usually by removing redundancies. Requires decompression upon retrieval. Lossless compression allows the original data to be recreated exactly. Lossy compression sacrifices some accuracy to achieve greater compression.

Control Byte

See subcode.

Conversion

Data transfer from one type of media to anotherþ often using DLT or 8 mm tape or CD-R as input.

Crosstalk

Unwanted signal from adjacent tracks.

Cutting Master Format (CMF)

Specification for storing copyright protection and other information, such as Disc Description Protocol (DDP), that is required for full DVD mastering.

Cyclic Redundancy Check Code (CRCC or CRC)

Type of error detection code (see EDC).

Calibration
Within the context of home video, calibration means adjusting the video display to adhere to a standard, usually NTSC. Within the context of audio, calibration means adjusting the sound level of each individual channel to match the level of all other channels.

Camera Angles
Scenes can be shot from different angles and played back to give the viewer the ability to see the scenes from different perspectives. DVD can support up to nine different camera angles to be recorded on a disc.

CBR
Constant bit rate compression. This indicates that in the encoding process the bit rate does not change, despite the simplicity or complexity of the image being encoded.

CEDIA
Custom Electronic Design and Installation Association.

CEMA
Consumer Electronics Manufacturers Association.

Center Channel
The channel in a surround sound setup that is directly in front of the viewer. The center channel speaker "anchors" sound that should be coming from the front of the screen. Most dialogs in a DVD are played through the center channel.

Center Speaker
The speaker in a surround sound system that handles dialogue and centrally positioned music and sound effects.

CGMS
Content Guard Management System. A copy protection method instituted for DVD to oversee digital copying of data. This method can dictate the number of digital-to-digital copies allowed of a specific title.

Channel
An individual (discrete) audio track. In the case of 5.1 Dolby Digital, there are six discrete channels.

Chapters
A method of organizing different scenes of a movie for easy navigation and access. DVDs are indexed by chapter, similar to the way a CD has a track. DVD players allow you to skip to a particular chapter (scene).

Chrominance
The color component of a video signal that includes information about hue and saturation.

CinemaScope
The brandmark for the anamorphic film process developed by 20th Century Fox. The process was duplicated by Panavision, and is identified in film credits as "Filmed In Panavision."

Clamping Area
The innermost area of disc used by CD/DVD player to grip and spin the disc during playback.

Closed Captions
A signal embedded in a video waveform, which, when fed into a captioning decoder, can product subtitles for the hearing impaired on screen.

Coaxial A/V Connection
The traditional RF connection for a Video signal. All DVD Players will have a coaxial output for purposes of hooking up to televisions without separate audio/video inputs.

Coaxial Connection
A type of connection used for consumer digital audio, which uses an RCA jack. The coaxial cable is an impedance-constant, two-conductor cable with either a stranded or solid core. For DVD digital audio, use a coaxial cable that has an impedance of 75-ohms (with 75-ohm connectors).

Codec
A software driver that is used to compress and decompress video, originally digitized from an analog source.

ColorStream
The component video connections for Toshiba DVD and TVs.

Color Temperature
The measure of a light source color in degrees Kelvin (K). Lower temperatures are redder in color, while higher temperatures are bluer in color. A properly calibrated display device measures 6500 degrees Kelvin.

Component Video
Component video offers the highest video quality available on DVD. Component video is a 3-channel system that is either RGB or color-difference. DVD component video is color-difference. Signals using color-difference contain the color component of the picture minus the brightness component. Component video is often regarded as being the next step beyond S-video that can be found on the majority of DVD players, the benefits include improved color accuracy and less color bleeding.

Component Video Output
3 RCA or BNC connectors for the transfer of Component Video signal to TV or projector.

Composite Video
An analog signal that contains the combined signals for luminance (black and white) and chrominance (color) components. This is the standard for broadcast TV, VHS and Laserdisc.
All DVD players have this type of output. S-Video offers a better picture while Component video offers the best picture quality.

Composite Output
Traditional RF type signal. All DVD players have this type of output since not all TV's have S-video or Component Video inputs.

Compress
The process of converting video and audio data into a more compact form for storage or transmission.

Connector
The terminating end of a cable.

Contrast
The range between the darkest tone and the lightest tone in an image.

Copy Protection
A process, like Macrovision, used to prevent illegal duplication of video (including DVD).

Constant bit rate (CBR)
Attribute of bitstream where the number of bits delivered to the MPEG System buffer (STD) and/or Video Buffer Verifier (VBV) is constant when measured over each picture period.

CSS
Content Scrambling System, a type of Digital copy protection sanctioned by the DVD Forum.