M

Mac (Macintosh)

A popular operating system developed in the 1980s by Apple Computers, noted for its graphic interface and ease of use. [Variable Media]

Machine code, Machine language

The 1s and 0s that a software program sends to a computer's processor to run the program. Whether compiled or not, all source code eventually becomes machine code when it is running. [Variable Media]

Magnetic media

Tape and discs that store information on a magnetized surface such as videotape, audiotape or computer floppy discs. [BAVC]

Magnetic particles

The materials incorporated in the binder to form the magnetic layer on a magnetic tape. Iron oxide, chromium dioxide, barium ferrite, and metal particulate are various examples of magnetic pigment used in commercial tapes. The term 'pigment' is a carry-over of terminology from paint and coating technology - the magnetic coating on a tape is analogous to a coat of paint in which the magnetic particle is the paint pigment. [AMIA]

Magnetic remanence

The ability of the pigment to retain a magnetic field [BAVC]

Magnetic tape

A plastic, paper, or metal tape that is coated or impregnated with magnetizable iron oxide particles on which information is stored as a pattern of polarized spots." (Screensound): "With few exceptions, magnetic tape consists of a base film coated with magnetic particles held in a binder. The magnetic particles are usually of a circular shape and approach single domain size. [UPF]

Main memory

Also known as RAM (Random Access Memory), information stored in the active virtual memory of a running computer. Information in RAM is lost when the computer is turned off, unless it has been saved to disk first. [Variable Media]

MARC (MAchine Readable Cataloging)

The standard system for computerizing cataloging records. In US, also called USMARC, and systems may vary internationally, e.g., DenMARC. [BAVC]

Master

The earliest generation of a finished tape that should also be of the best quality. Masters should not be used as exhibition tapes, i.e., not for repeated playback. See also dubmaster. [BAVC]

MB

A megabyte is a unit of information or computer storage equal to one million bytes. [EAI]

Metadata

Commonly defined as 'structured data about data,' or data captured in specific categories or elements. Metadata can include data associated with either an information system or a data object or set of objects for purposes of description, administration, preservation, the documentation of legal requirements, technical functionality, use and usage, and so forth. [Getty]

Metal Halide Lamp

The type of lamp used in most high-end portable projectors. These lamps output a very "hot" temperature light, similar to lamps used in streetlights. Metal Halide whites are super white (with a hint of blue) and make Halogen lamp white appear very yellowish by comparison. [Projector People]

Metal-evaporated tape

These tapes require no binder polymer, as the entire magnetic layer comprises a single, homogeneous metal alloy layer that is evaporated onto the substrate. Their chemical stabilities are similar to those of metal-particle tapes. However, because the magnetic coating on a metal-evaporated tape is much thinner than the corresponding layer on a metal-particle tape, they are also generally not as durable. Repeated play or freeze-frame video applications present problems with wear. [See Magnetic particles]. [Vidipax]

Metal-particle tape

Metal-particle and chromium-dioxide pigments provide a higher tape signal output and permit higher recording frequencies than do iron-oxide pigments. They are not, however, as stable as iron-oxide pigments. A decrease in signal output of two decibels may be observed over the lifetime of metal-particle and chromium dioxide-based tapes. Even with these losses, the output signal will still be better than a comparable iron oxide-based tape... Metal particulate is used in high-grade audio and low-to high-grade video tape. Metal particles are also used in most digital audio and video tape formulations. [See Magnetic particles]. [Vidipax]

Micron

A unit of measure for the thickness of magnetic tape. Symbol is ┬Ám.[AMIA]

Migrate

Digital preservation strategy that involves transferring data from a format or standard that is in danger of becoming obsolete to a current format or standard." Other interchangeable (if not precisely synonymous) terms include: converting, copying, refreshing, reformatting, transferring. [Getty]

MiniDV

See DV.

M-JPEG

Motion-JPEG is a format for digital images based upon a series of JPEG still images. It generally produces poorer quality for a given bit-rate than MPEG.[MIC]

Moire

1. A wavy or satiny effect produced by the convergence of lines. It usually appears as a curving of the lines in the horizontal wedges of a test pattern. It is a natural optical effect when converging lines in a television picture are nearly parallel to the scanning lines. 2. Optical disturbance caused by interference of similar frequencies. [BAVC]

MPEG (Motion Picture Experts Group)

A body within the ISO that has produced standards for the compression, storage,and documentation of multimedia and motion pictures, such as the MPEG-7 standard or the MPEG-21 Multimedia Framework. [Getty]

MPEG-1

Uses a data rate of 1.2 Mbps (Mega Bits per Second), the speed of CD-ROM transfer. [ScreenSound Australia]

MPEG-2

Uses a data rate (also called a bit rate) of from 2 to 10 Mbps. MPEG-2 is the format most favoured for video-on-demand and DVD. [ScreenSound Australia]

MPEG-4

First released in 1999 with a follow-up version in 2001, MPEG-4 is a standard for multimedia applications intended for use by an array of industries and employs advancements in compression coding. [MIC]

MPEG-7

A metadata standard that provides a set of standardized tools to describe multimedia content. Both human users and automatic systems that process audiovisual information are within its scope. [Getty]

Multiplexing

The condensing of many signals into a few or one signal that still represents all of them. An LCD panel performs the de-multiplex function. It takes video signals that contain whole frames of video data and displays them as individual signals on each pixel. [Projector People]

Multi-standard

A term that refers to machines that can play more than one video format. Different regions of the world use varying standards for video formatting. These are Phase-Alternating Line (PAL), National Television System(s) Committee (NTSC), and Compagnie Franaise de Television (SECAM). While North America uses NTSC, PAL and SECAM are used in Europe, with South America using PAL-M, PAL-N, PAL and NTSC. [EAI]