MAR
7, 2005 Nick
Stone
Technically inclined manufacturers of consumer electronics have entrusted marketing to advertising professionals who prefer a non-technical carnival atmosphere in which they can spin the buyer until facts are centrifugally expelled and only Controlled Idea Association remains (the other CIA). The spin-doctors are powerless if you always check the SPECIFICATIONS of any product before buying and (AND!) use the following definitions to decipher the technical jargon. Here terms are defined. The definition may contain other terms that also need to be looked up. But be patient and methodical and by doing so you can select the equipment that best suits you.
Pixel: the smallest dot that makes up a video image. Short for Picture Element.
Scan Lines: Pixels are controlled one at a time, sequentially, row after row, or in some cases, odd rows then even rows. If the pixels are on a tube screen (CRT), pixels are phosphorus that glow briefly when hit with a scanning electron beam. Transistors in plasma and LCD screens are also turned on or off sequentially. All the pixels on a screen are scanned 30 times per second. The pixel is composed of three light emitting dots in such close proximity as to look like one. The three dots are varying degrees of red, green and blue.
Interlaced and Progressive: Describes the order in which the rows of pixels are scanned. If odd rows then even rows the image is interlaced. If each adjacent row is scanned one after the other, then the image is progressive. Old standard TV and some new HDTV use interlaced images.
PROGRESSIVELY scanned images create the complete
image in one scan
without as much
flicker.
Two INTERLACED frames look like one.
This is the old standard TV. It receives 525 “lines” in the incoming video signal, but 45 are used for control info leaving 480 that can be viewed using the interlaced “i” method; this means 240 odd numbered lines are displayed followed by an equal number of even numbered lines producing an interlaced image. Each line has about 640 pixels so the resulting image is 640x480 pixels.
Resolution: Resolution (rez) is the pixel density. It is best measured with two numbers. The first number is the number of pixels in one horizontal line. The second number is the number of lines. An “x” separates the two numbers because multiplying the two numbers yields the total number of pixels. A shorthand method only references the second number or lines followed by “i” or “p” to signify interlaced or progressive ordering.
480i = 600 pixels per lines x 480 interlaced lines (Digital name for old NTSC TV screen)
480p = 853 pixels per line x 480 progressive lines (Enhanced Definition TV)
720p = 1280 pixels per line x 720 progressive lines (High-Definition Television)
1080i = 1920 pixels per line x 1080 interlaced lines (High-Definition Television)
1080p = 1920 pixels per line x 1080 progressive lines (Future consumer-ware)
It is important to be aware that DTV manufacturers sometimes avoid revealing the physical or “native” resolution but will tout the type of resolution that it is able to input. Many Enhanced Definition sets (480p native rez) cannot downsize a High-Definition signal. Most HDTVs (720p or 1080i native rez) can digitally scale any incoming video signal to fit its physical display by combining pixels to show a lower rez input or cleverly omitting pixel data if the signal contains more info it can display. Some of the native resolutions on products, especially projectors are:
WSVGA= 960 X 544 ( Close to 16:9 Ratio)
QHD = 964 X 544 ( 16:9 Ratio)
No Abbreviation 1024x576 (True native 16:9 Ratio)
XGA = 1024 X 768 (4:3 ratio)
Aspect Ratios (4:3 vs. 16:9): Old NTSC TVs and PC monitors are 4:3. that is, for every 4 units wide, it’s 3 units high; example: if it’s 32in. wide its 24in. high; (32/4 x 3 = 24).
HDTV is 16:9, that is, divide its width by 16 and multiply the result by 9 to get the height. Conversely, divide the height by 9 and multiply the result by 16 to get the width.
Some DVD discs only have wide screen display output, other dual layer discs, also allow 3:5.
(If a movie DVD label refers to the Widescreen as having an “aspect ratio 2:35:1”, only the Geek God knows what that means).
SDTV (Standard Definition TV): Digital version of basic NTSC. Although limited to 480i scan lines its 150- to 300-thousand pixels can display in either the traditional 4:3 or wide-screen 16:9 format. Equally matched with a low end or interlace only DVD player.
EDTV (Enhanced Definition TV): A Better digital television transmission than SDTV with at least 480p, in a 16:9 or 4:3 display and Dolby digital surround sound. 480p is the quality used by most DVD players (i.e. DVD players with progressive scan output). EDTV provides 300-400,000 pixels.
Most ED sets can’t down-convert HD signals.
HDTV (High-Definition Television): The best quality digital picture, widescreen (16 x 9) display with at least 720 progressively scanned lines (720p) or 1080 interlaced lines (1080i) and Dolby digital surround sound. HDTV provides 900 thousand to 2.1 million pixels.
HDTV Monitor (sometimes called HDTV Ready): A set that can display HDTV programming if you have a separate HDTV tuner, HD Cable Set-Top Box or HD Satellite Set-Top-Box Receiver.
Resolution of DVD Players & Recorders: The most any standard “movie” DVD can do is 720 pixels across x 480 pixels down (lines): To date, Movie DVDs are not “HighDef” and achieve 9:16 ratio by using different shaped pixels. DVD movie discs that are recorded in 9:16 are said to be “Enhanced for Widescreen” or “Anamorphic”. Dual layer discs contain both ratios.
DVD Players: Newer players can output 480p images but the “p” feature (progressive or all at once) can only be received by a DTV. The “p” image is not HD quality but it looks better due to less blurring of motion (it updates the entire image every 1/60 sec.; compare old NTSC that also has only 480 lines but takes twice as long or 1/30sec. to display the info.)
DVD Recorders: There are several types of discs to record on and they may not play back on any player. Old DVD players only read the dash (-) formats. Some newer players and recorders do multiple formats, some all formats.
The formats are...
DVD-RW: The recording standard began as DVD-RW (dash re-writeable). You can write new data over old data 1000 times before the disc is warn out.
DVD-R: Write once, no re-writing, same as a standard movie DVD, and it can be read by all DVD players.
DVD+RW: (DVD plus re-writeable) is a newer standard that enables a partially filled disk to have data files added later, an improvement of the dash’s “can’t add later” formant. This format is popular with both video and PC enthusiasts.
DVD+R: Write once, no re-writing, but add stuff later and do it faster than with other formats.
DVD-RAM: Allows not only re-writing, as with RW, but allows erasure of unwanted files, so it is more like a conventional data storage device and won’t wear out even after 100,000 re-writes.
DVD-A: Audio format developed by Digital Theater Systems.
The Technical Details of DVD: A single layer disc has a shiny aluminum foil imbedded in clear plastic. A dual layer disc has a translucent gold layer in the plastic between the aluminum and the surface. The laser shines through an angled two-way mirror then through a lens that can focus on either the translucent layer or through that onto the aluminum surface. The light is reflected back at a high or low intensity due to thermal sensitive dyes in the plastic. The light then exits the disc surface, hits the angled one-way mirror and is reflected at 90o to an optical sensor. If it is a recordable disc, the thermal sensitive dyes are changed from smoothed to dented when the intensity of the laser is increased to record mode. Light reflected off the disc at hi or low intensities is translated into data bits. The size of one recorded bit is almost as small as the wavelength of the laser light. Since the wavelength of light rays vary slightly depending on its color, the color of the laser determines how small the data bits can be. The standard CD uses a lazing LED that emits light in the infrared part of the spectrum. The ray has a wavelength of 780 to 850 nano-meters. A nano is one billionth (10-9). This allowed 650 to 800MB of storage on a disc. The first DVDs used red (650nm) and thus an increase to 4.37 giga-bytes (GB) of data or video could be stored. A giga is one billion. A byte is eight bits. A bit is either a ‘1’ or a ‘0’. Still not enough room for an HD movie. New “blue ray” LEDs can produce a color with a 405nm wavelength (actually a blue-violet color) enabling 25GB on a single layer one-sided disc. With double layered two sided discs HD on a DVD is in the future. Additionally ultraviolet lazing LEDs are in the works so there should be room for even 1080p HD.
HD Ready: HD Ready only means it can accept the HD signal from a Digital Tuner or Digital Cable Box. Note it is not necessarily a true HD set but can scale down the signal to its native resolution, which may be only ED.
Resolution of HDTVs: High Definition (HD) signals from TV Stations, satellite, cable, Blue-Ray DVD players, etc. can provide various picture clarity depending on which coding system is used. The HD coding systems are designated as 480p, 720p, 1080i and 1080p. High Definition’s low end is 480p, and the high end, 1080p. The latter is a more picture perfect system for future development. Meanwhile, the electronics that consumers are now buying should be able to decode anything it receives: 480p, 720p and even 1080i as well as the old NTSC “480i”.
Component Analog Video: same as Y,Pb,Pr and Y,Cr,Cb (see below)
Y,Pb,Pr or (also known as 770.3 and HDTV Component Cables): Three coax cables terminated with regular RCA type connectors (one luminance and two phase-opposite chrominance pair). Most new HDTV monitors offer YPbPr connections. Comcast HD Cable Service provides the Motorola’s DCT5100 cable box with Y Pb Pr connectors (not a DVI connector). RCA & Toshiba DVD Players also provide Y Pb Pr connectors as do newer Sanyo models (Sanyo once used “Y Cr Cb” instead; see below).
Y,Cr,Cb (also Component Cables):: “The digital luminance and color difference signals in ITU-R BT.601 coding”; some articles say its sort of like the digitized version of Y Pb Pr but it is still referred to as component video. Likewise it uses three coax cables terminated with RCA type connectors. Sanyo once had DVD with Y,Cr,Cb component but now also uses the more standard y,Pb,Pr. [The web is full of very conflicting statements as to the nature Y,Cr,Cb vs. Y,Pb,Pr and weather they are interchangeable. If you find out lets revise this entry. -N]
RGB or Red Green Blue: : the primary colors when painting with light; combining red, green and blue pixels can create any color. (Fun side note: Light is considered “positive” whereas a painter or a printer uses negative primary colors: yellow, cyan & magenta.). Here the color info is on separate cables with sync (horizontal and vertical sync) on either an additional cable or superimposed on one of the color channels. The cables are usually terminated with BNC connectors. This interface is becoming rare.
DVI (Digital Video Interface) Hollywood may allow analog (Y/Pb/Pr or RGB) high-definition connections to continue for a while, but lawyers will push for the potential copyright protection that's available through digital signals via DVI and especially HDMI because both emloy HDCP® (High-bandwidth Digital Content Protection). Consumers may also like the ability to pass digital signals directly to the display without conversion back to an analog signal. Physically the connector is (apx) a 45 pin DB connector. See also HDMI.
HDMI (High-Definition Multimedia Interface):
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It’s backwards compatable with DVI and transmits all ATSC HDTV standards and supports 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements. Employs HDCP® (High-bandwidth Digital Content Protection) for enforcing copyright protection. The HDMI connector will become the standard on most HD equipment. The consumer electronics industry began transitioning from DVI to HDMI connections in 2003.
HDMI is backwards
compatable with DVI but has higher bandwith. HDMI is based on
Silicon Image's TMDS® technology and is fully
backward compatible with PCs and displays incorporating the DVI
(Digital Visual Interface) standard, which was also pioneered by
Silicon Image. Because it was designed specifically for consumer
electronics applications, HDMI offers additional consumer
enhancements. Content comes in a variety of sizes, resolutions and
formats, and HDMI systems will automatically configure to display
content in the most effective format.
8VSB: TV Stations broadcast a digital standard referred to as 8VSB.
To receive signals off the air you need an 8VSB Tuner/Box
www.antennaweb.org: For help with selecting an antenna for local HDTV broadcasts.
COFDM (Coded Orthogonal Frequency Division Multiplexing): The new and belated contender to 8VSB is COFDM. In summary: with 8VSB it’s difficult to get a signal indoors; with COFDM it’s difficult not to get a signal. The early entry and inertia of 8VSB may, however, win out.
FireWire = IEEE-1394
Video Editing via PC is enhanced with this feature. Invented by & standard on Apple PCs and available on a Windows PC on FireWire cards (get the cheapest). Consumer Digital-VHS recorders are available and may only provide a Fire Wire interface for their input.
Some A/V Tuners, DVD players can output to TV monitors or PC monitors and many Digital TVs can interface to your PCs vidio output. All PC monitor formats are better than NTSC and employ progressive scan to eliminate eye-straining flicker:
VGA (Video Graphics Array): PC monitor with a resolution of 640 pixels across x 480 pixels down.
SVGA (Super Video Graphics Array): PC Monitor with a resolution of 800 pixels across x 600 pixels down.
XGA (Extended Graphics Array): PC Monitor with 1024 pixels across x 768 pixels (lines) down.
MPEG-4 or MP4 or DivX: Compresses Audio and Video into 10% of original size. Can squeeze a two-hour movie onto a single disc at HDTV resolution with Dolby surround at a CD-quality.
DivX is the pirated version. Development for commercial markets is being hindered by pirate problems.
DeCSS: Pirated software that enables PCs to crack the superficial encryption on most DVDs and by using DivX (MPEG-4) can easily store it to a hard-drive and then record it to a single disc. It is contained in illegal but readily available free programs, such as CladDVD.
HDCP® (High-bandwidth Digital Content Protection): Feature of DVI (Digital Video Interface)
and HDMI (High-Definition Multimedia Interface) that enforces copyright protection. The HDMI connector with HDCP protection will become the industry standard on HD equipment.
The Human Eye: Equivalent to about 20-million pixels in a 9: 16 ratio with 7.2meg high x 12.8meg wid. There are screens that can display an image with this rez.
DLP (Digital Light Processing™ ): A projector technology that uses an optical semiconductor that is an array of micro-miniature moveable mirrors. High speed control of each eliment yealds varing amounts of light. The technology is available for the home theater and is the current state of the art in commercial movie theaters. (Check out the flash educational demo at www.dlp.com).
DLP vs LCD Color Eliments
At any given moment, an LCD projector delivers all three color channels, red, green, and blue, to the screen simultaneously. On the other hand, a DLP projector can only deliver one color at a time due to its spinning color wheel. The result is that color on a DLP projector may looks dull when placed next to a LCD unit that delivers a comparable number of pixels.
Selecting an A/V Tuner or Amp: If you have multiple sources going into your TV, an A/V receiver with switching capabilities can really ease the hassle. The most-convenient option is to leave your TV set to one input and have the receiver switch all other sources into that input. Unfortunately, most receivers can't convert from, say, composite to component video. Many receivers have regular component-video switching, though, which is a great feature if you have both a DVD player and an HDTV receiver. (See also Nick’s Audio Standards re. the A/V Tuner or Amp).
DTS: (see Nick Notes: AUDIO Standards For the Surround Sound Theater)
Projection Screen Calculations:
If you are installing an HDTV projector (9:16 ratio), the wall is the limit! The following formula tells you how high the image will be if the wall’s width is the only consideration ~or~ if the space between the celing and furniture limits you to a particular screen height, what the resulting width will be.
H = 0.5625 x W
W = 1.777 x H
Where ‘H’ and ‘W’ are the Hight and Width of an HDTV 9:16 ratio screen.