DVD Glossary Part 4 (I

I picture (or I frame) - In MPEG video, an intra picture that is encoded independent from other pictures (see intraframe). Transform coding (DCT, quantization, and VLC) is used with no motion compensation, resulting in only moderate compression. I pictures provide a reference point for dependent P pictures and B pictures and allow random access into the compressed video stream.

i.Link - Trademarked Sony name for IEEE 1394.

IDE - Integrated Drive Electronics. An internal bus, or standard electronic interface between a computer and internal block storage devices. IDE was adopted as a standard by ANSI in November 1990. ANSI calls it Advanced Technology Attachment (ATA). Also see E-IDE and ATAPI.

IDTV - Improved-definition television. A television receiver that improves the apparent quality of the picture from a standard video signal by using techniques such as frame doubling, line doubling, and digital signal processing.

IEC - International Electrotechnical Commission. (See Appendix C.)

IED - ID error correction. An error-detection code applied to each sector ID on a DVD disc.

IEEE 1394 - A standard for transmission of digital data between external peripherals, including consumer audio and video devices. Also known as FireWire.

IEEE - Institute of Electrical and Electronics Engineers. An electronics standards body.

IFE - In-flight entertainment.

I-MPEG - Intraframe MPEG. An unofficial variation of MPEG video encoding that uses only intraframe compression. I-MPEG is used by DV equipment.

interframe - Something that occurs between multiple frames of video. Interframe compression takes temporal redundancy into account. Contrast with intraframe.

interlace - A video scanning system in which alternating lines are transmitted, so that half a picture is displayed each time the scanning beam moves down the screen. An interlaced frame is made of two fields. (See Chapter 3.)

interleave - To arrange data in alternating chunks so that selected parts can be extracted while other parts are skipped over, or so that each chunk carries a piece of a different data stream.

interpolate - To increase the pixels, scan lines, or pictures when scaling an image or a video stream by averaging together adjacent pixels, lines, or frames to create additional inserted pixels or frames. This generally causes a softening of still images and a blurriness of motion images because no new information is created. Compare to filter.

intraframe - Something that occurs within a single frame of video. Intraframe compression does not reduce temporal redundancy, but allows each frame to be independently manipulated or accessed. (See I picture.) Compare to interframe.

inverse telecine - The reverse of 3:2 pulldown, where the frames which were duplicated to create 60-fields/second video from 24-frames/second film source are removed. MPEG-2 video encoders usually apply an inverse telecine process to convert 60-fields/second video into 24-frames/second encoded video. The encoder adds information enabling the decoder to recreate the 60-fields/second display rate.

ISO 9660 - The international standard for the file system used by CD-ROM. Allows filenames of only 8 characters plus a 3-character extension.

ISO - International Organization for Standardization. (See Appendix C.)

ISRC - International Standard Recording Code.

ITU - International Telecommunication Union. (See Appendix C.)

ITU-R BT.601 - The international standard specifying the format of digital component video. Currently at version 5 (identified as 601-5).

Java - A programming language with specific features designed for use with the Internet and HTML.

JCIC - Joint Committee on Intersociety Coordination.

JEC - Joint Engineering Committee of EIA and NCTA.

jewel box - The plastic clamshell case that holds a CD or DVD.

jitter - Temporal variation in a signal from an ideal reference clock. There are many kinds of jitter, including sample jitter, channel jitter, and interface jitter. See Chapter 3.

JPEG - Joint Photographic Experts Group. The international committee which created its namesake standard for compressing still images.

k byte - One thousand (10³) bytes. Not to be confused with KB or kilobyte (2¹⁰ bytes). Note the small “k.”

k - Kilo. An SI prefix for denominations of one thousand (10³). Also used, in capital form, for 1024 bytes of computer data (see kilobyte).

karaoke - Literally empty orchestra. The social sensation from Japan where sufficiently inebriated people embarrass themselves in public by singing along to a music track. Karaoke was largely responsible for the success of laserdisc in Japan, thus supporting it elsewhere.

KB - Kilobyte.

kbps - Kilobits/second. Thousands (10³) of bits per second.

key picture (or key frame)- A video picture containing the entire content of the image (intraframe encoding), rather than the difference between it and another image (interframe encoding). MPEG I pictures are key pictures. Contrast with delta picture.

kHz - Kilohertz. A unit of frequency measurement. One thousand cycles (repetitions) per second or 1000 hertz.

kilobyte - 1024 (2¹⁰) bytes. See p. 12 for more information.

land - The raised area of an optical disc.

laserdisc - A 12-inch (or 8-inch) optical disc that holds analog video (using an FM signal) and both analog and digital (PCM) audio. A precursor to DVD.

layer - The plane of a DVD disc on which information is recorded in a pattern of microscopic pits. Each substrate of a disc can contain one or two layers. The first layer, closest to the readout surface, is layer 0; the second is layer 1.

lead in - The physical area 1.2 mm or wider preceding the data area on a disc. The lead in contains sync sectors and control data including disc keys and other information.

lead out - On a single-layer disc or PTP dual-layer disc, the physical area 1.0 mm or wider toward the outside of the disc following the data area. On an OTP dual-layer disc, the physical area 1.2 mm or wider at the inside of the disc following the recorded data area (which is read from the outside toward the inside on the second layer).

legacy - A term used to describe a hybrid disc that can be played in both a DVD player and a CD player.

letterbox filter - Circuitry in a DVD player that reduces the vertical size of anamorphic widescreen video (combining every 4 lines into 3) and adds black mattes at the top and bottom. Also see filter.

letterbox - The process or form of video where black horizontal mattes are added to the top and bottom of the display area in order to create a frame in which to display video using an aspect ratio different than that of the display. The letterbox method preserves the entire video picture, as opposed to pan & scan. DVD-Video players can automatically letterbox a widescreen picture for display on a standard 4:3 TV.

level - In MPEG-2, levels specify parameters such as resolution, bit rate, and frame rate. Compare to profile.

line doubler - A video processor that doubles the number of lines in the scanning system in order to create a display with scan lines that are less visible. Some line doublers convert from interlaced to progressive scan.

linear PCM - A coded representation of digital data that is not compressed. Linear PCM spreads values evenly across the range from highest to lowest, as opposed to nonlinear (companded) PCM which allocates more values to more important frequency ranges.

lines of horizontal resolution - Sometimes abbreviated as TVL (TV lines) or LoHR. A common but subjective measurement of the visually resolvable horizontal detail of an analog video system, measured in half-cycles per picture height. Each cycle is a pair of vertical lines, one black and one white. The measurement is usually made by viewing a test pattern to determine where the black and white lines blur into gray. The resolution of VHS video is commonly gauged at 240 lines of horizontal resolution, broadcast video at 330, laserdisc at 425, and DVD at 500 to 540. Because the measurement is relative to picture height, the aspect ratio must be taken into account when determining the number of vertical units (roughly equivalent to pixels) that can be displayed across the width of the display. For example, an aspect ratio of 1.33 multiplied by 540 gives 720 pixels.

Lo/Ro - Left only/right only. Stereo signal (no matrixed surround information). Optional downmixing output in Dolby Digital decoders. Does not change phase, simply folds surround channels forward into Lf and Rf.

locale - See regional code.

logical unit - A physical or virtual peripheral device, such as a DVD-ROM drive.

logical - An artificial structure or organization of information created for convenience of access or reference, usually different from the physical structure or organization. For example, the application specifications of DVD (the way information is organized and stored) are logical formats.

lossless compression - Compression techniques that allow the original data to be recreated without loss. Contrast with lossy compression.

lossy compression - Compression techniques that achieve very high compression ratios by permanently removing data while preserving as much significant information as possible. Lossy compression includes perceptual coding techniques that attempt to limit the data loss to that which is least likely to be noticed by human perception.

LP - Long-playing record. An audio recording on a plastic platter turning at 33 1/3 rpm and read by a stylus.

LPCM - See linear PCM.

Lt/Rt - Left total/right total. Four surround channels matrixed into two channels. Mandatory downmixing output in Dolby Digital decoders.

luma (Y´) - The brightness component of a color video image (also called the grayscale, monochrome, or black-and-white component). Nonlinear luminance. The standard luma signal is computed from nonlinear RGB as Y´ = 0.299 R´ + 0.587 G´ + 0.114 B´.

luminance (Y) - Loosely, the sum of RGB tristimulus values corresponding to brightness. May refer to a linear signal or (incorrectly) a nonlinear signal.

M byte - One million (10⁶) bytes. Not to be confused with megabyte (2²⁰ bytes).

M - Mega. An SI prefix for denominations of one million (10⁶).

Mac OS - The operating system used by Apple Macintosh computers.

macroblock - In MPEG MP@ML, the four 8 x 8 blocks of luma information and two 8 x 8 blocks of chroma information form a 16 x 16 area of a video frame.

macroblocking - An MPEG artifact. See blocking.

Macrovision - An antitaping process that modifies a signal so that it appears unchanged on most televisions but is distorted and unwatchable when played back from a videotape recording. Macrovision takes advantage of characteristics of AGC circuits and burst decoder circuits in VCRs to interfere with the recording process.

magneto-optical - Recordable disc technology using a laser to heat spots that are altered by a magnetic field. Other formats include dye-sublimation and phase-change.

main level (ML) - A range of proscribed picture parameters defined by the MPEG-2 video standard, with maximum resolution equivalent to ITU-R BT.601 (720 x 576 x 30). (Also see level.)

main profile (MP) - A subset of the syntax of the MPEG-2 video standard designed to be supported over a large range of mainstream applications such as digital cable TV, DVD, and digital satellite transmission. (Also see profile.)

mark - The non-reflective area of a writable optical disc. Equivalent to a pit.

master - The metal disc used to stamp replicas of optical discs. The tape used to make additional recordings.

mastering - The process of replicating optical discs by injecting liquid plastic into a mold containing a master. Often used inaccurately to refer to premastering.

matrix encoding - The technique of combining additional surround-sound channels into a conventional stereo signal. Also see Dolby Surround.

matte - An area of a video display or motion picture that is covered (usually in black) or omitted in order to create a differently shaped area within the picture frame.

MB - Megabyte.

Mbps - Megabits/second. Millions (10⁶) of bits per second.

megabyte - 1,048,576 (2²⁰) bytes. See p. 12 for more information.

megapixel - A term referring to an image or display format with a resolution of approximately 1 million pixels.

memory - Data storage used by computers or other digital electronics systems. Read-only memory (ROM) permanently stores data or software program instructions. New data cannot be written to ROM. Random-access memory (RAM) temporarily stores data—including digital audio and video—while it is being manipulated, and holds software application programs while they are being executed. Data can be read from and written to RAM. Other long-term memory includes hard disks, floppy disks, digital CD formats (CD-ROM, CD-R, and CD-RW), and DVD formats (DVD-ROM, DVD-R, and DVD-RAM).

MHz - One million (10⁶) Hz.

Microsoft Windows - The leading operating system for Intel CPU-based computers. Developed by Microsoft.

middle area - On a dual-layer OTP disc, the physical area 1.0 mm or wider on both layers, adjacent to the outside of the data area.

Millennium Group - The group of companies proposing the Galaxy watermarking format. (Macrovision, Philips, Digimarc)

mini DVD - 1) Small size (8-cm) DVD. 2) DVD-Video content stored on a CD (or CD-R/RW). Less ambiguously called cDVD.

mixed mode - A type of CD containing both Red Book audio and Yellow Book computer data tracks.

MKB (Media Key Block) - Set of keys used in CPPM and CPRM for authenticating players.

MLP (Meridian Lossless Packing) - A lossless compression technique (used by DVD-Audio) that removes redundancy from PCM audio signals to achieve a compression ratio of about 2:1 while allowing the signal to be perfectly recreated by the MLP decoder.

MO - Magneto-optical rewritable discs.

modulation - Replacing patterns of bits with different (usually larger) patterns designed to control the characteristics of the data signal. DVD uses 8/16 modulation, where each set of 8 data bits is replaced by 16 channel bits before being written onto the disc.

mosquitoes - A term referring to the fuzzy dots that can appear around sharp edges (high spatial frequencies) after video compression. Also known as the Gibbs Effect.

mother - The metal discs produced from mirror images of the father disc in the replication process. Mothers are used to make stampers, often called sons

motion compensation - In video decoding, the application of motion vectors to already-decoded blocks to construct a new picture.

motion estimation - In video encoding, the process of analyzing previous or future frames to identify blocks that have not changed or have only changed location. Motion vectors are then stored in place of the blocks. This is very computation-intensive and can cause visual artifacts when subject to errors.

motion vector - A two-dimensional spatial displacement vector used for MPEG motion compensation to provide an offset from the encoded position of a block in a reference (I or P) picture to the predicted position (in a P or B picture).

MP@ML - Main profile at main level. The common MPEG-2 format used by DVD (along with SP@SL).

MP3 - MPEG-1 Layer III audio. A perceptual audio coding algorithm. Not supported in DVD-Video or DVD-Audio formats.

MPEG audio - Audio compressed according to the MPEG perceptual encoding system. MPEG-1 audio provides two channels, which can be in Dolby Surround format. MPEG-2 audio adds data to provide discrete multichannel audio. Stereo MPEG audio is the mandatory audio compression system for 625/50 (PAL/SECAM) DVD-Video.

MPEG video - Video compressed according to the MPEG encoding system. MPEG-1 is typically used for low data rate video such as on a Video CD. MPEG-2 is used for higher-quality video, especially interlaced video, such as on DVD or HDTV. (See Table 3.5 for a comparison of MPEG-1 and MPEG-2.)

MPEG - Moving Pictures Expert Group. An international committee that developed the MPEG family of audio and video compression systems.

Mt. Fuji - See SFF 8090.

MTBF - Mean time between failure. A measure of reliability for electronic equipment, usually determined in benchmark testing. The higher the MTBF, the more reliable the hardware.

multiangle - A DVD-Video program containing multiple angles allowing different views of a scene to be selected during playback.

multichannel - Multiple channels of audio, usually containing different signals for different speakers in order to create a surround-sound effect.

multilanguage - A DVD-Video program containing sound tracks and subtitle tracks for more than one language.

multimedia - Information in more than one form, such as text, still images, sound, animation, and video. Usually implies that the information is presented by a computer.

multiplexing - Combining multiple signals or data streams into a single signal or stream. Usually achieved by interleaving at a low level.

MultiRead - A standard developed by the Yokohama group, a consortium of companies attempting to ensure that new CD and DVD hardware can read all CD formats (see “Innovations of CD” in Chapter 2 for a discussion of CD variations).

multisession - A technique in write-once recording technology that allows additional data to be appended after data written in an earlier session.

mux - Short for multiplex.

mux_rate - In MPEG, the combined rate of all packetized elementary streams (PES) of one program. The mux_rate of DVD is 10.08 Mbps.