Glossary - A Practical Guide to Video and Audio Compression - page 722

Topic Description

ASF (Continued) streaming media solution from Microsoft. Biggest competitor is

Real Networks. While this 'wrapper' supports many standard
formats, ASF files are themselves proprietary. This file format is
sometimes called the Advanced Systems Format.

ASIC Application-Specific Integrated Circuits.

Aspect Ratio The relationship between the height and the width of a picture.

Standard aspect ratio is 4 × 3 and wide screen is 16 × 9.

Asymmetry We can allow encoding to take longer than playback unless we

are encoding live content. Even then it can be buffered unless
it's a video-conferencing application. Decoding must take place
in real time in order to maintain the playback speed.

Atom A small component object within a structured movie file. It is

called an atom because it is generally indivisible to a smaller
component without special tools and techniques.

ATSC Advanced Television Standards Committee.

AVC Advanced Video Coding describes a format for compressing

video that was jointly developed by ISO MPEG and the ITU. It
is also known as MPEG-4 Part 10 and H.264.

AVI Audio Video Interleaved. A Microsoft format for digital audio

and video playback from Windows 3.1. Somewhat cross-platform,
but mostly a Windows format. Has been replaced by the ASF
format but is still used by some multimedia developers.

Backward-motion A motion-compensation vector used when the video is

vector playing in reverse.

Bandwidth A term borrowed from radio and TV broadcasting to describe

the capacity required to transport information from one place to
another. Broadcasting engineers used the term to describe the
frequencies on either side of the carrier that were used as a
consequence of modulating an audio or video signal by that
carrier frequency. Computing specialists adopted the
terminology to loosely describe bit rate.

Baseband A means of transmitting using a single carrier frequency shared

by all nodes. All nodes must be aware of each other's traffic to
avoid collisions. Ethernet is such a network.

BCDF Broadband Content Developer Forum. Now called the

Broadband Services Forum.

Beating When two signals of similar frequency are mixed, they

alternately enhance and cancel one another at a cyclic
rate equivalent to the difference between them. For example,