Glossary
720p - High-Definition Display/Projector specification meaning 720 lines of resolution and progressive scan (vs. interlaced). With the typical aspect ratio of 16:9, the screen resolution is 1280x720.
1080i - High-Definition Display/Projector specification meaning 1080 lines of resolution and interlaced (vs. progressive scan). Interlaced draws every other line on one frame then the other 540 lines on the next frame. With the typical aspect ratio of 16:9, the screen resolution is 1920x1080.
1080p - High-Definition Display/Projector specification meaning 1080 lines of resolution and progressive scan (vs. interlaced). With the typical aspect ratio of 16:9, the screen resolution is 1920x1080.
Adapter – Adapters are used when you need to convert from one type of connector to another, e.g. HDMI<->DVI, RCA<->1/8"mini_plug, etc.
Analog – A variable continuous signal.
Aspect Ratio - The width divided by the height of a display or screen. Most common HDTV aspect ratio is 16:9, or 1.78. Commonly movies are filmed in 1.85 or even 2.39 aspect ratios, thus the black bars sometimes seen on top and bottom of the display/screen.
Analog Audio - An audio connection/cable that carries a single channel of audio via analog signal, over a cable with RCA type connectors.
ANSI – American National Standards Institute.
Blu-Ray – High Definition DVD standard.
Brightness – HDTV/Projector light output specification. The higher the number the better for brightly lit rooms.
COAX – COAX connector outlets are typically found throughout your home to distribute video and audio to rooms. All of the rooms meet at a central point in the home (normally master BR closet), and is called a “wire closet” or “home run” where the audio/video source is found. Examples of A/V sources are; Cable TV, Satellite TV, and Antenna.
Coax Digital Audio - An audio connection/cable that carries digital audio signals over a single cable and uses RCA type connector.
Component Video – Component video cables carry analog video signals called Y, U, V. Cable has three RGB (Red, Green, Blue) RCA connectors on each end.
Contrast Ratio – TV/Display/Projector specification. Difference between the brightest white and the darkest black, the higher the number the better.
D-ILA – Direct Drive Image Light Amplifier. JVC's LCOS projector technology/branding.
Digital – A discrete discontinuous signal. Transmits binary values of 1s and 0s.
DLP – Digital Light Processing. System which uses millions of tiny mirrors in a chip to reflect light and create images in projection HDTVs and projectors.
DVR – Digital Video Recorder. TiVO is example of a DVR, also found in cable/satellite STBs.
Ethernet Cable – Used to create wired LAN (Local Area Network) in your home. Connects computers, media extenders, game consoles, Blu-Ray players, etc.
DVI – Digital Video Interface. Video interface cable for connecting video sources to HDTVs, Monitors, and Projectors. DVI-D – DVI Digital. DVI-I – DVI Integrated (digital + analog)
HDMI – High-Definition Multimedia Interface. Digital interface cable for connecting video sources to HDTVs, Monitors, and Projectors. The cable can pass video as well audio signals.
HDTV – High Definition Television (LCD, Plasma, LED, Rear Projection, etc.).
HTIB – Home Theater In a Box. A complete Surround Sound system that you purchase in one big box. The system includes all the surround sound speakers, and surr sound receiver that typically supports CD/DVD/Blu-Ray playback.
HTPC – Home Theater Personal Computer. A PC which has a media center graphical user interface which allows viewing/listening of media (music, photos, videos, TV, etc.) on your media room screen/TV.
Hz - Abbreviation for "hertz", which is unit of frequency (cycles/second). In an HDTV; 120Hz means that the image is updated 120 times per second, in a 240Hz HDTV the image is updated 240 times per second. Therefore the bigger the number the better (important if you watch a lot of high-speed movies or sporting events, where blurring can occur at lower refresh rates).
Keystone Correction – If forced to mount a projector on an angle to the vertical plane of the screen, which produces a trapezoidal shaped image, a projector with keystone correction can digitally correct image back to a rectangular shape. Note however that this can cause undesired visual artifacts, and a lens shift (or variable lens shift) feature is preferred.
LAN – Local Area Network
LCD – Liquid Crystal Display
LCOS – Liquid Crystal on Silicon. Technology used in high end HD projectors. LCOS is a reflective projection technology (vs. transmissive technology of LCD projectors), and utilizes liquid crystals applied directly to the surface of a chip. Three chips are used one each for red, green, and blue. The chips have a reflective surface for each red/green/blue pixel, and for each image the red/green/blue images are combined through a prism to create a single image. LCOS projector system is similar to DLP, where LCOS uses liquid crystal and DLP uses micromirrors. (D-ILA is JVC, and SXRD is Sony market name for LCOS projectors)
Lens Shift – If forced to mount a projector on an angle to the vertical plane of the screen, which produces a trapezoidal shaped image, a projector with lens shift can correct image back to a rectangular shape. Note some projectors have keystone correction, however that this can cause undesired visual artifacts, and a lens shift (or variable lens shift) feature is preferred.
Lumens – Unit of measurement for light output.
Media Center PC – A computer that has media center applications for organizing and playing music, videos, photos, etc.
Optical Digital Audio - A audio connection/cable that carries digital audio signals over a single glass fiber (via light)
Pixel – Picture element. The smallest dots on a display which together make up the image.
Pixilation – See Screen Door effect.
Projector – Projects video images onto screen in a Front Projection system.
Rainbow Effect – In a DLP HDTV or Projector, if only a single DLP chip is used then a color wheel spins to create red, green, and blue colors for each pixel. At any given time the screen is all red, all green, or all blue. Most human eyes cannot detect this, however some people can, and for those persons a "rainbow effect" is created, which can cause eye strain / distraction. Higher refresh rates (higher RPM color wheels) are improving this condition.
RCA Connector – Or RCA Jack, is the basic connector/cable that carries analog audio and video (e.g. Composite Video cables, Component Video cables, Analog Audio cables)
Resolution - How much detail a picture contains, the higher the number the better. For HDTV and Projectors the specification is provided in "pixel" resolution, e.g. 1920x1080 (for 1080p) or 1280x720 (for 720p). "Native Resolution" is the pixel resolution an HDTV/Projector can display. Specifications will typically also be provided which describe what "input" or "maximum" resolutions are supported, but this does not mean that the display/projector will display at that high of a resolution (refer to native resolution for the true resolution the HDTV/Projector will display).
RJ-45 – Connector type for Ethernet network (LAN – Local Area Network) cable.
Screen – Surface on which video images are projected in a Front Projection system.
Screen Door effect – Occurs in an LCD front projection system, when projected onto a large screen each pixel can be seen, as if being viewed through a "screen door". This is a distraction at lower resolutions, however at today's hi-def resolutions, this negative effect is minimal. Also referred to as "pixilation"
STB – Set Top Box. The box that is typically provided by the cable/satellite company, which tunes the incoming signals from cable/satellite feed and outputs audio and video to surround sound and HDTV. STBs can also contain DVR feature.
S-Video – Super Video cable carries analog video signals via a 4-pin mini-DIN connector. Supports standard definition video, does not support high-definition.
S/PDIF – Sony / Philips Digital Interconnect Format. A digital audio connector typically found as audio output on PCs. Connector type is usually RCA connector or 1/8” mini phono plug.
SXRD – Sony SXRD (Silicon X-tal Reflective Display), is Sony's proprietary LCOS technology/branding for projection television.
Throw Ratio – Projector specification, defined as D/W, where D = the distance from the projector lens to the screen, and W = the width of the screen. Throw Ratios are typically specified as a range, because projectors have zoom lenses. When laying out your home theater you must ensure that the screen width is no wider than the depth of the room divided by the projector's throw ratio. Or conversely, ensure that you can mount the projector at a distance equal to the throw ratio multiplied times the width of the screen.
VGA – Video Graphics Adapter (or Array), is an analog video connector commonly found on computers and monitors, and some TVs. Video Graphics Array refers to a display resolution of 640x480 pixels. Video Graphics Adapter commonly refers to the graphics card in a computer that provides the video output (independent of resolution).
Viewing Angle - Angle from the center of display of which you can still view the picture reasonably well.
Viewing Distance - The optimal viewing distance from the screen in a front projection home theater. For today's HD projectors, a rule-of-thumb is to keep V/W (V = viewing distance, W = width of screen) in the range of 1.4-3:1.
