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Glossary:
Gamma - ITTS
Glossary of CD and DVD related
technical terms and abbreviations in alphabetical order. |
G
Gamma: Gamma is the transfer characteristic or relationship
eg between the input video signal and output display, needed to
compensate for non-linearities in the display's or eye's response.
GB: Gigabyte, which can either be 1,000,000,000 or 1,024 x 1,024 x
1,024. The first meaning is used when giving the capacity of a DVD disc,
eg 4.7 GB. The second meaning is more common for PC memory capacity,
which is usually a power of 2.
GIF: Graphics Interchange Format used by CompuServe and the World Wide
Web for 8-bit (256 colour) graphics images.
Glass Mastering: Part of the CD and DVD disc manufacturing process that
uses a laser (which is modulated by the data to be stored on the disc)
to expose areas of a photo-resist layer on a glass disc, where the final
pits are required. These areas are then developed and the photo resist
layer metallised so that stampers can be grown by electroforming using
this metal layer. The stampers are then used for moulding CD and DVD
discs.
GOP: Group of Pictures of frames in a MPEG video sequence,
usually starting with an I-frame.
Green Book: Specification from Philips & Sony defining the
CD-interactive (CD-i) standard.
Group: Every side of a DVD-Audio disc (also called an Album) can contain
up to 9 Groups, each of which can be subdivided into up to 99 Tracks.
GUI: Graphical User Interface. A software application that lies on top
of other applications and provides a user interface based on graphical
icons.
H
HC-R: High capacity versions of CD-R discs having a capacity of
98 minutes, 29 seconds and 74 frames on a single session 12 cm disc.
This extra capacity is achieved by reducing the track pitch to 1.28
microns and scanning velocity to 1.13 m/s.
HDCD: High Definition Compatible Digital, an enhanced version of PCM
encoding that improves the quality of audio on a CD when using a HDCD
player but does not impair the quality when playing on a normal CD
player. HDCD uses the least significant bit of each sample to provide
additional information to increase the number of bits per sample from 16
to 20.
HD-DVD: High Density DVD, being studied by the DVD Forum to store
HDTV content. Two options have been proposed, AOD and Blu-ray.
HDTV: High Definition Television, offering better pictures with more
lines.
Header: The bytes in a CD-ROM sector that contain the time-code and
mode.
HFS: Macintosh's Hierarchical Filing System, which is needed on Mac
CD-ROMs instead of (or in addition to) ISO 9660.
High Sierra Format: A standard format for placing files and directories
on CD-ROM, revised and adopted by the International Standards
Organisation as ISO 9660.
Hotspots: Areas (usually rectangle) within a graphic or other image
which when selected using a mouse or other user input device results in
an action being performed. Hotspots are used in computers, multimedia
applications, Video CDs and DVD-Videos for menus allowing interactivity.
HQ-VCD: Renamed Super Video CD (SVCD). A new higher quality version of
Video CD that incorporates MPEG-2 encoding and partly matches DVD-Video
except for playing time.
Huffman Coding: For a given character distribution, by assigning short
codes to frequently occurring characters and longer codes to
infrequently occurring characters, Huffman's minimum redundancy encoding
minimises the average number of bytes required to represent the
characters in a text.
Hybrid: The use of two file systems (usually ISO 9660 and HFS) on a
single CD-ROM. The file system data, ie Volume Descriptors etc, occupy
different areas on the disc. Hybrid discs are designed to be used on two
different computer systems eg PC and Macintosh. The disc will contain
common data, accessible by both file systems and data unique to only one
system. Hybrid: An Orange Book CD-R disc on which one or more
sessions are recorded, but the disc is not closed, leaving space open
for future recording.
Hybrid DVD-Audio: A version of the DVD-Audio format which
comprises a CD layer (at the top of the disc) and a DVD-Audio layer,
which is semi-reflective allowing a CD player to read the CD layer,
which contains CD audio data. This is currently being studied by the DVD
Forum.
Hybrid SACD: A version of the SACD format which comprises a CD
layer (at the top of the disc) and a SACD high density audio layer,
which is semi-reflective allowing a CD player to read the CD layer,
which contains CD audio data.
Hz: Abbreviation for Hertz; cycles per second.
I
I3: Signals used in QA measurements of a CD or DVD, representing the
signal from the shortest pit.
I11: Signals used in QA measurements of a CD, representing the signal
from the longest pit.
I14: Signals used in QA measurements of a DVD disc, representing the
signal from the longest pit.
I-Frame: Intra-coded frame of an MPEG sequence is a picture coded using
information only from itself and not from preceding frames.
ICDIA: Interactive Compact Disc Association, representing CD-I
developers.
ID: Inside Diameter, eg of a CD or the print area of a CD.
IDMA: The Interactive Digital Media Association, formed by the ICDIA to
represent developers in the interactive digital media industry (but now
called the DVD Association - DVDA).
IEEE: The Institute of Electrical and Electronics Engineers (IEEE) is
the world's largest technical professional society.
IFPI: International Federation of the Phonographic Industry, which
represents over 1,000 record producers worldwide and was founded over 60
years ago to protect the interests of the recording industry worldwide.
IFPI introduced the SID Code to identify where a CD has been mastered
and replicated.
Image Pacs: Group of encoded versions of the same photographic image at
different resolutions according to the Photo CD specification.
Image Resolution: The fineness or coarseness of an image measured in
pixels per line, for display, or Dots Per Inch (DPI), for print
applications.
Indexes: Sub-divisions of each track of a CD or DVD-Audio. Each track
may, if necessary, be divided into up to 99 indexes to provide more than
99 'tracks' per disc.
Injection Moulding: A manufacturing process in which molten plastic (eg
polycarbonate for CD and DVD discs) is 'injected' into a mould under
pressure. The plastic fills the cavity and, after cooling, a perfect
replica is created.
Interactive Video: The combination of video and computer technology
offering user interaction for training and other applications.
Interframe Coding: Compression techniques used for MPEG coding that code
the differences between frames of video.
Interlace: Scheme to display a video image by displaying alternate scan
lines in two discrete fields.
Interpolation: The process of averaging pixel information when scaling
an image.
Intra coding: Coding of a macroblock (see MPEG) or picture that uses
information only from that macroblock or picture.
IRMA: International Recording Media Association, previously known as the
International Tape Association (ITA), which represents the optical disc
and magnetic tape industries. Their website is www.recordingmedia.org.
ISC: International Steering Committee, comprising the six major
international music companies plus the RIAA, RIAJ and IFPI. The ISC has
set the requirements for DVD-Audio and is very involved in the
development of the standard.
ISO: International Standardisation Organisation. A worldwide group
responsible for establishing and managing various standards committees
and expert groups, including several image compression standards.
ISO-10149: ISO version of the Yellow Book CD-ROM specification.
ISO 10646: ISO standard for the encoding of characters from all
languages into a single 32-bit code space (Universal Character Set).
ISO 11172: ISO MPEG standard for encoding video. MPEG (Moving Picture
Experts Group) is the ISO committee that is responsible for defining the
various MPEG video specifications. MPEG-1, originally defined in 1992,
was aimed at full screen video stored on a CD-ROM. It has since been
incorporated into the Video CD specification.
ISO 13818: ISO MPEG-2 standard for digital television applications and
is used for DVD-Video. MPEG-2 is intended for interlaced video
applications and also supports high definition video.
ISO 9001: ISO standard for quality, including manufacturing. Deluxe Global Media Services Ltd received ISO 9002 accreditation in 1998 and Deluxe Global Media Services France Sarl in
2000.
ISO 9660: ISO standard for CD-ROM file system, particularly for PC
applications.
ISRC: International Standard Recording Code, for uniquely labelling
audio and audio/visual recordings. The appropriate unique ISRC should be
included on every track of an audio CD.
ITTS: Interactive Text Transmission System standard, used for CD Text.
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