Car Audio Blog

AMD (Active Matrix Display)
A type of flat-panel display in which the screen is refreshed frequently for superior resolution. The most common type of active matrix display is based on technology known as TFT (thin film transistor). TFT technology provides the best resolution of all flat-panel display techniques. The two terms are often used interchangeably.

Aspect ratio
The ratio between the width and height of an image or display screen. The NTSC television standard is 4:3 (1.33:1). However, most movies are made for the wide screen of a theater, and are originally displayed at the wider ratios of 1.85:1 or 2:35:1. DVD’s huge data storage capacity makes it possible to include multiple versions of a movie on a single disc. It’s not unusual for a DVD disc to feature a Standard (4:3) version on one side and a Widescreen version on the other.

Composite Video Output
A video signal in which the brightness and color portions of the signal are combined. Examples of composite video include standard VHS and regular broadcast TV. A standard RCA-type video jack provides a composite video signal.

Digital Output
All DVD players include at least one digital audio output for sending the Dolby Digital or DTS bitstream to a compatible decoder. Digital data transfer offers extremely wide bandwidth, immunity to radio frequency (RF) interference, and an easy one-cable connection. The two most common types of digital output are coaxial and optical. Both types require a special cable to connect to the digital input of your Dolby Digital/DTS-equipped in-dash receiver or surround processor.

DolbyВ® Digital
A discrete, multichannel digital audio standard offering enhanced sonic realism. Dolby Digital is normally associated with 5.1-channel surround sound. A 5.1-channel system offers five full-bandwidth channels (including true stereo surrounds), plus a “low frequency effects” subwoofer channel.

DolbyВ® ProLogicв„ў
If you don’t have a Dolby Digital system, you can still enjoy excellent Pro Logicв„ў or stereo sound. All DVD players have the ability to take a 5.1-channel Dolby Digital soundtrack and “downmix” it to two channels, which can then be sent to a surround processor or an in-dash receiver with Dolby Pro Logic decoding. The decoder converts the matrixed two-channel signal back into three channels of full-range sound (left front, center, right front), and a fourth mono channel of limited bandwidth that is shared by two surround speakers.

Digital Theater Systems (DTSВ®)
DTS is an established multichannel audio format in movie theaters, but a relative newcomer to car video. Like Dolby Digital, DTS is primarily a 5.1-channel format. The compression scheme used in DTS “throws away” significantly less audio data than Dolby Digital, so it should sound better, but so far, side-by-side comparisons have been inconclusive.

DVD-Audio (DVD-A)
A music-oriented DVD format that can carry up to 6 channels of 96kHz/24-bit audio (music for 5.1-channel mobile theater systems), or 2 channels of ultra high-resolution 192kHz/24-bit audio. Most DVD-Audio discs also carry Dolby Digital or stereo soundtracks for playback on DVD players that lack DVD-Audio decoders. A DVD-Audio disc may also contain liner notes, lyrics, menus, and still pictures that can display on your video monitor.

DVD/CD Player
The DVD/CD player plays DVD movies (and may play DVD audio discs), but does not include a built-in AM/FM tuner. Some models send the video signal to an outboard backseat monitor for on-the-go viewing, while other models include a built-in screen for stationary viewing. Its audio signal is sent to an in-dash receiver or to external amplifiers.

DVD/CD Receiver
Versatile DVD/CD receivers have built-in AM/FM tuners, can play DVD movies, and may play DVD audio discs. Some models send the video signal to an outboard, backseat monitor for on-the-go viewing, while other models include a built-in screen for viewing while parked.

Monitor
A screen that translates a video signal into a picture. In car systems, a monitor can be mounted in a seatback, floor console, or the roof. A TV is a monitor with a built-in VHF/UHF tuner.

S-video Inputs/Outputs
Special four-pin connectors that carry the chrominance (color) and luminance (brightness) portions of the video signal separately, for improved color accuracy and reduced distortion

Signal-to-Noise Ratio (Video)
This ratio is a measure of the content portion of the video signal in relation to the noise in the signal. As with audio, video signal-to-noise is measured in decibels (dB). Here’s how the decibel scale works — if component A has a signal-to-noise (S/N) ratio of 20 dB and component B has a S/N ratio of 30 dB, component B will have ten times less noise in the signal than component A.

Basically, a S/N ratio tells you how “clean” a video signal is. Because of the way they process signals, digital video formats like DVD are extremely clean. A standard VHS VCR may have a S/N spec in the low 40s, while DVD is rated to deliver a S/N ratio of 65 dB!

Surround Processor
A device which can decode (or simulate the effect of) multi-channel soundtracks found on DVDs and videocassettes. These processors usually send separate audio information to right front, center, left front, right rear, and left rear speakers, with a separate signal for a subwoofer. In a car’s confined listening environment, the effect of a fully-realized multi-channel audio/video system can be stunning.

TFT Screen
A type of LCD screen that uses thin film transistor (TFT) technology. Each pixel is controlled from 1 to 4 transistors, giving TFT screens the best resolution of all flat-panel displays.

Toslink
A Toslink connector is a specialized plug found on many optical cables. Optical cables permit distortion-free connections from a digital source to a digital recorder or digital receiver/processor. Since the signal is carried optically rather than electronically, an optical cable is virtually impervious to magnetic or electrical interference.

TV Tuner
A TV tuner receives UHF and VHF television broadcasts (from channels 2 to 69), providing local programming for a mobile video system.

Video Cassette Player (VCP)
A video cassette player (VCP) is designed strictly for playback — it does not have the ability to record.

Virtual Surround Sound (VSS)
This feature makes a two speaker system sound as though it includes rear speakers; the “virtual” rear speakers allow you to enjoy a surround-like effect. It is for use with Dolby Digital DVDs only.