Direct Drive Image Light Amplifier. Proprietary JVC version of LCoS light valve technology.

Digital tape standard with backward compatibility to SVHS and VHS. First device offering HDTV recording and playback at up to 28Mbs data rates. D-Theater capable D-VHS VCRs are capable of playing back copy protected pre-recorded HD movies.

Digital to Analog Converter. Electronic component that converts a digital signal to an analog.

dB or decibel is a measure of relative loudness. 0 dB is the threshold of hearing. 60 dB is equivalent to normal conversation. 120 to 140 dB is the threshold of pain such as a jackhammer or gun shot. 10 db of change will double the loudness.

Direct Broadcast Satellite. Also called Direct To Home, a small dish digital broadcast system that gets sent via satellite between 12GHz and 18GHz frequencies. Subject to attenuation by rain.

Directional Correlation Deinterlacing (DCDi)was developed by Faroudja and is a video algorithm designed to eliminate jagged edges that are generated by interlaced video.

Electric coil used to deflect the electron beams in a CRT display.

Method to get rid of magnetic fields that build up in CRT monitors and distort the video signal causing discoloration.

Electronic component that converts an interlace video signal to progressive scan.

Act of converting an interlace video signal to progressive scan.

Commonly used in sound engineering where a sound is played back later at different speakers in order to maintain directionality of original sound. Uses the psychoacoustical phenomenon of precedence effect where a sound is first heard is where it is perceived to come from even when coming from multiple places.

An all-digital monitor connection using TDMS designed by the Digital Flat Panel Group. Limited to 1280x1024 resolution and a cable length of 10 meters. Uses an MDR20 connector.

The diagonal of a screen or flat panel can be computed by using the Pythagorean theorem: squaring the width, squaring the height, adding them together and taking the square root. A 100" diagonal 16:9 screen measures 49" high by 87" wide; a 100" diagonal 4:3 screen measures 60" high by 80" wide. Use the Projection Calculator to get screen dimensions on all common aspect ratios.

A mirror or lens that reflects or refracts selective wavelengths of light. Typically used in projector light engines to separate the lamps "white" light into red, green, and blue light.

Description of how a digital signal deteriorates with interference and attenuation. Either the signal is completely functional or not at all with no slight quality degradation that exists with analog.

Digital closed caption is available on digital TV programs at the election of the service provider. Unlike the Closed Caption sytem, Digital Closed Caption allows the setting of the size, color, style and opacity of captioned text. When Digital Closed Caption is in use, it will be indicated by the appearance of a 3-letter abbreviation that indentifies the language of the displayed text.

Display device where the imager is viewed directly as opposed to a projection surface.

As it relates to surround sound systems, discrete sound is a separate recorded track for each channel. Other systems may amalgamate tracks into one and then separate them out electronically.

A usually undesirable variation from an intended output caused by the characteristics of a particular device.

An amplifier used to maintain a clean noise free signal to a projector or flat panel device over significant distances. Even with good heavily shielded cables, range of video and computer signals is limited to a few dozen feet before noticeable degradation. In ceiling mount situations, where the wiring may pass along side or across electrical conduits, a distribution amp may be needed with shorter distances. Many distribution amps can also split the signal into 2 or more amplified signals for driving multiple projectors or flat panels.

Method of displaying intermediate colors that don’t exist in a limited palette by using a pattern of small dots out of that palette.

Video format based on the MPEG 4 standard. Commonly used for downloadable video files.

DLP (Digital Light Processing) is a commercial name for a display technology from Texas Instruments (TI). The technology inside is often referred to as DMD (Digital Micro-Mirrors). It consists of an array of mirrors where each mirror represents a pixel element. For example, a high-definition DLP projector or rear projector with 1920 x 1080 pixel resolution would have over 2 million tiny mirrors. Each mirror is attached to an electronically driven hinge that controls the amount of colored light that is reflected from the mirror into the projection lens and onto a screen. Projection systems using DLP technology use 1 to 3 DMD devices.

Digital Micromirror Device. Name of the actual imaging chip used in a Texas Instruments DLP projection systems.

Digital Noise Reduction. A system that reduces picture noise by comparing previous frames to the present and smoothing out what appears to be noise to the algorithm. Helps reduce flickering in still parts of a video image.

A lossy compression system to deliver sound on DVDs, ATSC and DBS broadcasts in up to 5.1 channels. Also called AC-3. See AC-3.

Backwards compatible system to add a sixth channel used for the middle rear playback to Dolby Digital (AC-3) making it 6.1 or 7.1 sound. 7.1 sound uses an additional center rear speaker playing back a duplicate track. Needs a Dolby EX decoder. See AC-3.

An analog 4 channel surround sound system with left, right, center channels and a mono rear channel, typically duplicated across 2 speakers. Rear channel is limited to 7KHz and system stores all channels in a matrix recording on 2 discrete analog channels. Has difficulty playing back non-encoded material at full fidelity.

Updated version of Pro Logic. Offers better performance with playing back non-encoded sources over a surround sound system with full spatial cues and fidelity.

Video artifact where little dots crawl along the borders of differing colors, particularly noticeable on graphics. Effect of composite encoding and easily removed by using s-video or component cabling. Will not disappear if the source was recorded using composite video and the artifact has been recorded.

The distance between side-by-side phosphor color groups (RGB) on a direct view display that uses phosphors. The smaller the better.

To convert a higher resolution signal to a lower resolution. For example, 720p to 480p.

Missing information from a broadcast or recorded media and typically show up as white specks in an analog environment. Dropout is more pronounced with interframe compression techniques such as MPEG because the error displays until the next complete frame is drawn, otherwise known as an I-frame. This can take up to ½ a second.

Digital Signal Processing. A digital method of manipulating incoming and outgoing signals on an ongoing basis. Often used in audio to create reverb among other effects.

Digital Satellite System and now called DBS. A system for sending and receiving digital satellite broadcast signals using small receiver dishes.

Digital Transport Copy Protection. A digital rights management technology standard issued by the DTLA (Digital Transmission Licensing Administrator) to prevent the unauthorized copying of copyright material.

Digital Transmission Licensing Administrator. Controls the licensing of the DTCP copy-protection technology.

Digital Theater Systems. An alternate method of encoding multitrack audio used on DVDs and other sources like D-VHS. Offers less compression compared to Dolby’s more common AC3 system and, arguably, better fidelity.

Digital Theater Systems. A version of DTS that plays back a 96kHz sampling rate, 24-bit resolution recording at full fidelity.

Digital Theater Systems Extended Surround. Backward compatible system to DTS with a center rear channel added.

Sound process that separates stereo audio into 5 or 6 channels. Also decodes Pro Logic encoded analog sources. It offers two modes, music and cinema. Music mode allows the left and right channels of a stereo signal to pass through without processing, retaining fidelity, but still adds signals for the remaining speakers. This gives up some imaging for fidelity.

Digital Television. A system that uses digital signals instead of analog including the ATSC standards, DBS and digital cable.

Digital Versatile Disc. Same physical size as a compact disc but has a capacity to hold a minimum of 4.7GB of data, 9.4GB if dual layer and/or dual sided. DVD-Video discs can hold about 4 hours of video on a dual layer disc depending upon the amount of compression applied. It uses MPEG-2 compression at a maximum rate of 9.2 Mbps with most video compressed at about 4Mbps at 720x480 pixels. All players support AC-3 (Dolby Digital), PCM, and MPEG-2 audio with up to 8 separate tracks. DTS is usually supported but isn’t mandatory to the format. DVD-Audio supports up to 6 channels of 24 bit, 192KHz sampled PCM audio.

Digital Versatile Disc + Recordable. A write-once recordable DVD format with 4.7GB capacity supported by the DVD+RW Alliance. More robust that DVD-R.

Digital Versatile Disc + Read Write. A rewriteable DVD format with 4.7GB capacity supported by the DVD+RW Alliance. Can be rewritten up to 1000 times.

Digital Versatile Disc-Audio. Allows for very high quality audio with up to 6 channels. Sample rates can be up to 192KHz at 24 bits of resolution. It allows for video as well as asynchronous slide shows of up to 99 still pictures per track. MLP (Meridian Lossless Packing) is supported as a lossless compression alternative to PCM.

Digital Versatile Disc - Recordable. A recordable write-once DVD format with 4.7GB capacity supported by the DVD Forum. Not as robust as DVD+R.

Digital Versatile Disc Random Access Memory. More robust as a rewritable format for computers than DVD±RW, it is housed in a cartridge and is incompatible with DVD-ROM drives and video players. Can be rewritten up to 100,000 times.

Digital Versatile Disc - Read Write. A rewriteable DVD format with 4.7GB capacity supported by the DVD Forum. Can be rewritten up to 1000 times.

Digital Visual Interface. DVI is a standard that defines the digital interface between digital devices such as projectors, flatscreens and personal computers. For devices that support DVI, a digital-to-digital connection can be made that eliminates the conversion to analog and thereby delivers an unblemished image. It can also carry an analog signal and comes as DVI-I (integrated - analog and digital), DVI-D (digital only) and DVI-A (analog only). Dual link DVI connections add additional resolution capabilities. Digital cable lengths should not exceed 15 feet. Specifications on DVI are available at http://www.ddwg.org. Click for more details on DVI.

Digital Video Recorder. Also known as a PVR or Personal Video Recorder. A hard disk based video recorder, which usually offers long recording times and the capability to pause incoming broadcasts. When the unit has access to electronic programming guides, it can record shows on an ongoing basis as well as do keyword and genre searches.

The ratio between the highest and lowest levels a device can perform. For a video device it is a measure of contrast ratio. For an audio device it is usually stated in dB.