masking The blacked-out areas to the sides of a front-projection screen.

matrix A method of encoding multiple audio channels into two channels for transmission or storage.

Mbps (mega bits per second) Million bits per second. A unit of measure for expressing bit rates. For example, MPEG-2 video encoding has a variable bit rate that averages 3.5Mbps.

microdisplay A rear-projection video display based on a fixed-pixel technology such as DLP, LCoS, or LCD.

midrange Audio frequencies in the middle of the audible spectrum, such as the human voice. Generally the range of frequencies from about 200Hz to 2kHz. Also: a driver in a loudspeaker that reproduces the range of frequencies in the middle of the audible spectrum.

millisecond (ms) One one-thousandth (0.001) of a second.

modular A/V controller An A/V controller built with interchangeable modules for upgrading to future technologies.

monoblock A power amplifier with only one channel.

motorized masking A projection screen in which a motor-driven black drop moves into position over the screen to create different aspect ratios.

motorized screen A projection screen that retracts by motor drive into a housing when not in use.

motion artifacts Visible defects in a displayed image resulting from motion of objects within the image.

MP3 A perceptual coding format that reduces the number of bits required to represent a digital audio signal. Shorthand for MPEG-1 Audio Level 3.

MPEG (Motion Picture Experts Group) The body that develops data-compression standards for audio and video. Pronounced “em-peg.”

MPEG-1 video compression A video encoding method that reduces the bit rate needed to represent the video signal to 1.4Mbps. Provides poor picture quality.

MPEG-2 video compression A much-higher-quality encoding technique than MPEG-1. Used in DBS and DVD.

MPEG-4 video compression Also called Advanced Video Coding (AVC). A video compression algorithm that produces higher-quality pictures at standard MPEG-2 bit rates, and high-definition pictures at bit rates of 7–10Mbps. Adopted for use in HD DVD and Blu-ray Disc as well as in the next generation of satellite transmission.

MTS (Multichannel Television Sound) The method of broadcasting stereo audio over conventional television channels.

multichannel power amplifier A power amplifier with more than two channels, usually five or six.

multichannel sound Sound reproduction using more than two channels feeding more than two loudspeakers.

multipath In FM-radio or television transmission, interference caused by the signal traveling two or more paths to travel between transmitter and receiver. Multipath is caused by mountains or buildings that reflect the radio or TV signals; the receiving antenna picks up the directly broadcast signal along with the signal after it has been delayed by the reflections. Multipath introduces audible distortion in FM tuners, and in television transmission is seen as “ghosting” in the picture. Multipath can cause HDTV receivers to pick up no usable signal.

multiroom A feature on some A/V products that lets you listen to two different sources in two different rooms.