A/V (Audio/Video)

A/V, or Audio/Video, is a generic term used to describe products and services associated with audio and video. A/V is used to describe speakers, amplifiers, receivers, televisions, CDs, and computer sound and graphics cards.

Analog

Analog refers to a non-digital, continuous waveform signal. An analog signal is a continuous line with peaks and troughs rising above and sinking below a baseline, just like the waves on a lake. The smooth wave differs from a digital signal, which is composed of discrete bits, or chunks, of information. A digital signal can approximate a waveform, but does not create the same smooth, continuous flow representative of analog signals.

All sound waves are continuous analog waveforms. Digital audio signals are converted into an analog form in order for the amplifier and speaker to recreate sound. Sound waves cannot be created from digital data; to create a sound wave from a digital data, the data must be converted into analog. This is done with a digital-to-analog converter, or DAC.

Analog-to-Digital Converter

An analog-to-digital converter is a device used to convert an analog (waveform) signal into a digital signal. Analog signals are constant, continuous waveforms.

Digital signals are made up of discrete (independent) ones and zeroes. The ones stand for an “on” state, and the zeroes for an “off” state. They do not form continuous waves like an analog signal; however, they are much easier to manipulate and they do not degrade with manipulation. For instance, a digital signal can be split it up, inverted and sent to multiple locations very easily. When an analog signal is manipulated in such a manner, the waveform is altered and noise is added, resulting in an impure signal.

The job of the analog-to-digital converter is to take the waveform (the analog signal) and split it up into the thousands of tiny “stairs” which simulate the sound wave. Once the signal is in the digital domain, it can be easily copied and manipulated with no degradation and with enhanced capabilities.

Anamorphic Process

Movies are filmed in a widescreen format; when a movie is shown on TV, in order to fit the image in a TV’s 4-by-3 format, the sides of the movie are cut off and not shown. The anamorphic process compresses a “wide” video image horizontally (squeezes the sides in) to fit the traditional 4-by-3 TV standard, but the picture expands to full size when played over a wide video display (e.g., 16-by-9 format).

This is known as the “Letterbox” format. Letterboxing an image lets the viewer see the entire widescreen presentation of a movie as it was intended to be shown in a theater. In order to fit a “wide” image in a “narrow” television, the image is shown with black bars above and below it.

A movie can be distributed in a squeezed anamorphic format without black bars. On a 4-by-3 format television, this results in an image, which seems tall and pinched with actors looking too narrow and objects distorted. However, when played on a widescreen display, the picture is stretched out to its proper width with no bars.

Antenna

An antenna is a metal rod or length of wire that sends or receives electromagnetic waves. Antennas are commonly used in audio/video to receive television signals and FM and AM radio signals.

Artifact

An artifact is a visual anomaly or error in a video image. Artifacts are created when a compression system (particularly MPEG-2 compression) can’t keep up with fast action or complex scenes in a video image. Most artifacts take place in a single frame or a few frames and result in errors lasting a fraction of a second. Artifacts tend to appear as clumps of colored blocks or pixels that obscure part of an image (pixelization).

Aspect Ratio

Aspect ratio is the relationship between the width and height of a video image. The aspect ratio for most televisions and computer monitors is 4:3 (four-by-three). The standard aspect ratio for digital HDTV is 16:9 (sixteen-by-nine), resulting in screens that are more rectangular. When a 4:3 image is displayed on a 16:9 screenblank areas appear on the left and right sides; sometimes these are referred to as black bars, pillars or side panels. Most widescreen TVs have a feature that can zoom or stretch a 4:3 image so that it fills up the 16:9.

ATSC

The ATSC (Advanced Television Systems Committee) is an international, non-profit organization developing voluntary standards for digital television. The ATSC has approximately 140 member organizations representing the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries.

ATSC Formats

ATSC formats are a series of 18 digital television formats, approved by the FCC for use by the television industry. The formats defined by the ATSC include both HDTV and SDTV formats to be used by off-air broadcasters.

Audio Input

The audio input is a connection jack (or plug) on an electronic component that receives electronic signals (with audio information) from a wire, or cable, sent by another component.