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

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

Mac OS
The operating system used by Apple Macintosh computers.

macroblock
In MPEGMP@ML, the four 8x8 blocks of luma information and two 8x8 blocks of chroma information form a 16x16 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 data
User data portion of each sector. 2048 bytes.

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 (720x576 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.

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

megabyte
1,048,576 (220) bytes.

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).

Menu
In DVD-Video there are two kinds of menus, System Menus and Interactive Menus. There are six types of System Menus: Title Menu, Root Menu, Audio Menu, Sub-picture Menu, Angle Menu and PTT or Chapter Menu.

Meridian Lossless Packing (MLP)
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.

MHz
One million (106) Hz.

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

middle area
Unused physical area that marks the transition from layer 0 to layer 1. Middle Area only exists in dual layer discs where the tracks of each layer are in opposite directions.

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

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

MKB
See Media Key Block.

MLP
See Meridian Lossless Packing.

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 bits is replaced by 16 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 disc 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).

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.

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

MPEG-1 video
Video encoded in accordance with the ISO/IEC 11172 specification.

MPEG-2 video
Video encoded in accordance with the ISO/IEC 13818 specification.

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.

Multi_PGC Title
In DVD-Video, a Title within a Video Title Set (VTS) that contains more than one Program Chain (PGC). Contrast with One_Sequential_PGC Title and One_Random_PGC Title.

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.