M

master clock

Controls the rate of reference time within a graph and is used by filters within the graph to synchronize presentation times. Provides a standard mechanism to query the reference time, to query the physical clock time and rate (compared to the system clock) of the owner of the master clock, and to establish event notifications based on position changes in the master clock's reference time.

MB

Megabyte.

MCD

Miniclient Driver. An OpenGL driver model in which the driver is responsible only for handling those features that can be accelerated in hardware, leveraging software implementation to handle the rest of the pipeline.

MDL

Memory descriptor list. In Windows NT/Windows 2000, an opaque structure, defined by Memory Manager, that uses an array of physical page frame numbers to describe the pages that back a virtual memory range.

method set

Used in Windows NT/Windows 2000 and WDM drivers to perform an action, such as allocating memory, and to provide a way to access related actions. Each method set has a unique identifier used to retrieve that method set and can be fulfilled either synchronously or asynchronously. A resource method set contains resource-specific methods for manipulating a type of resource by a kernel-mode client, and is used in resource allocation by enumerated devices on a bus.

Microsoft ActiveMovie

A cross-platform API for developers of multimedia applications that provides a User-mode connection and Stream architecture to support high-quality digital video, high-fidelity audio, and special effects.

Microsoft DirectX

A low-level API that provides User-mode media interfaces for games and other high-performance multimedia applications. DirectX is a thin layer, providing direct access to hardware services, and takes advantage of available hardware accelerators and emulates accelerator services when accelerators are not present.

MIDI

Musical Instrument Digital Interface. An industry-standard connection for computer control of musical instruments and devices. A hardware and data standard for communicating between hardware. Most references involve only the data standard, which is a byte stream used for controlling musical instruments and storing the output of such instruments.

minidriver

A hardware-specific DLL that uses a Microsoft-provided class driver to accomplish most actions through functions call and provides only device-specific controls. Under WDM, the minidriver registers each adapter with the class driver, which creates the device object. The minidriver uses the class driver's device object to make system calls.

miniport driver

A device-specific kernel-mode driver linked to a Windows NT/Windows 2000 or WDM port driver, usually implemented as a DLL that provides an interface between the port driver and the system.

MIPS

Millions of instructions per second. A common measure of processor speed.

MIS

Management information system.

mixer class

The class of filters that deal with manipulating controls such as volume, treble, and so on.

monolithic driver

A driver that has many different classes of functionality contained in the same driver.

motherboard

See system board.

MPEG

Motion Picture Experts Group. Used when referring to one of several standard video-compression schemes. A codec for squeezing full-screen, VHS-quality digital video into a small data stream so it can be played from a CD-ROM drive.

MSDN

Microsoft Developer Network.

MTD

Memory technology driver. A protected-mode driver that works with Windows 95 protected-mode PC Card software to enable form-factor cards, such as flash memory cards. Such memory cards and their related drivers do not provide full Plug and Play capabilities.

multifunction device

A piece of hardware that supports multiple, discrete functions, such as audio, mixer, and music, on a single adapter.

multimedia

Refers to the delivery of information that combines different content formats (motion video, audio, still images, graphics, animation, text, and so forth).

multimedia processing driver

See filters.

music class

The class of filters that deal with music data, such as ZIPI or MIDI.