Glossary of DVD Terminology "M to N"

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 anti-taping 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.

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.

mosquitos - 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 analysing 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.

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.

NAB - National Association of Broadcasters.

NCTA - National Cable Television Association.

nighttime mode - Name for Dolby Digital dynamic range compression feature to allow low-volume nighttime listening without losing legibility of dialog.

Noise - Irrelevant, meaningless, or erroneous information added to a signal by the recording or transmission medium or by an encoding/decoding process. An advantage of digital formats over analog formats is that noise can be completely eliminated (although new noise may be introduced by compression).

Noise floor - The level of background noise in a signal or the level of noise introduced by equipment or storage media below which the signal can’t be isolated from the noise.

NRZI - Non-return to zero, inverted. A method of coding binary data as waveform pulses. Each transition represents a one, while lack of a transition represents a run of zeros.

NTSC - National Television Systems Committee. A committee organized by the Electronic Industries Association (EIA) that developed commercial television broadcast standards for the United States. The group first established black-and-white TV standards in 1941, using a scanning system of 525 lines at 60 fields per second. The second committee standardized colour enhancements using 525 lines at 59.94 fields per second. NTSC refers to the composite colour-encoding system. The 525/59.94 scanning system (with a 3.58-MHz colour subcarrier) is identified by the letter M, and is often incorrectly referred to as NTSC. The NTSC standard is also used in Canada, Japan, and other parts of the world. NTSC is facetiously referred to as meaning never the same colour because of the system’s difficulty in maintaining colour consistency.

NTSC-4.43 - A variation of NTSC where a 525/59.94 signal is encoded using the PAL subcarrier frequency and chroma modulation. Also called 60-Hz PAL.

Numerical Aperture (NA) - A unitless measure of the ability of a lens to gather and focus light. NA = n sin θ, where θ is the angle of the light as it narrows to the focal point. A numerical aperture of 1 implies no change in parallel light beams. The higher the number, the greater the focusing power and the smaller the spot.