HDTV is usually defined as video resolutions of 720p, 1080i or 1080p, however you will see that WXGA at 768p is also HDTV. The "i" and "p" represent the method in which your video screen is filled with video frames. Although they are filled from top to bottom and left to right, "i" and "p" represent two methods of frame filling. Put simply, the "i" stands for interlaced where your video screen displays all the odd-numbered lines first and then all the even-numbered lines next. The "p" stands for progressive scan or de-interlaced where all the lines are filled from top to bottom in order repeatedly. This line filling occurs very rapidly to give viewers a smooth moving picture. Generally, "p" (progressive scan) is preferred over "i" (interlaced) as far as video quality is concerned. At the same resolution, say 1080p versus 1080i, progressive scan video offers better video quality than interlaced video for two primary reasons: First, in interlaced video something called the "persistence of vision" (the human eye's tendancy to retain an image in memory for a brief moment) causes the human eye to see "artifacts" which are perceived as flickering on the video screen. The second reason progressive scan is preferred over interlaced is that it has double the number of verticle lines of resolution, since each video frame is filled alternately (odd-numbered lines and then even-numbered lines), so you only see half of the current frame and half of the next frame repeatedly. Confusing perhaps but this is why 1080i offers half the resolution of 1080p, UNLESS the 1080i signal is de-interlaced to 1080p. Newer video displays, such as LCDs, micromirror (DLP) or plasma displays are inherently progressive scan only and will automatically up-convert 1080i to 1080p.
The numbers "720" or "1080" in 720p or 1080i represent the number of verticle lines of resolution on your video display. The "720" stands for 1280x720 (displaying 921,600 pixels/dots), and "1080" stands for 1920x1080 (displaying 2,073,600 pixels/dots). Generally, more pixels lead to higher resolutions, so 1920x1080 would offer better video quality than 1280x720 if both video screens fill frames the same way ("i" or "p" above).
1080p represents the final frontier of high-definition television offers the highest quality video available for the home theater environment. However, it is also important to note that the advantages of 1080p are usually not noticed in all video programs or on 40-inch and smaller screens. Also, tests have shown that you need to sit back from the screen 3 times the viewing height of your screen to notice the benefits of 1080p. For example, you would need to sit at least 11.5 feet away from a 46-inch screen to notice the benefits of 1080p. To achieve 1080p quality you will need a video source offering 1080i or 1080p and an HDTV that is 1080p capable. Video sources offering 1080p are Blu-ray disc players, HD-DVD players, Microsoft's XBox 360, SONY's PS3 as well as 1080i content that can be up-converted (de-interlaced) to 1080p. De-interlacing 1080i content to 1080p content is done using a process called "3:2 pulldown reversal" and will work as long as the original video signal was not overly filtered. The best cables used to connect these sources to your HDTV will depend on the product's features. For example, the Microsoft Xbox 360 requires a component video cable to view HDTV at 1080p, but SONY's PS3 requires an HDMI cable to view 1080p.
It is important to note that some HDTVs will only display certain HDTV resolutions (listed in its product manual) while others will display almost any video resolution provided to it by converting it to the best screen fit and resolution automatically. This also applies to whether an HDTV's input signal is interlaced or progressive scan. An HDTV may simply display the exact signal it receives (or a blank screen), or it may up-convert a signal by de-interlacing. Newer displays, such as LCDs, micromirror (DLP) or plasma displays are inherently progressive scan and will up-convert any interlaced video to progressive scan.
Ports In General: Ports that are HDTV-capable are component, DVI, HDMI and RGB/RGBHV. Due to space limitations on the back of video devices and/or computers many manufacturers are moving towards "switchable" ports. These ports allow two types of video signals to travel through the same connection. The following are examples of common switchable ports: 15-pin RGB & Component ports, DVI & RGB ports, DVI & Component ports. To activate port switchablility features you may need to change the settings of your video device or add a special adapter. Check your product manual to verify if any of your video ports are switchable. IMPORTANT NOTE: You can damage your HDTV if you do not properly match the vertical frequency (refresh rate) of your computer's video output with your HDTV's video input. Be sure to check your product documentation for optimal settings.
Computer to HDTV Connectivity: Computers often require special software that will allow you to match your computer's vertical frequency (refresh rate) with one your HDTV can accept. For PCs a popular program called PowerStrip can be used: http://www.entechtaiwan.com/util/ps.shtm. For Macs a popular program called DisplayConfigX can be used: http://www.3dexpress.de. IMPORTANT NOTE: You can damage your HDTV if you do not properly match the vertical frequency (refresh rate) of your computer's video output with your HDTV's video input. Be sure to check your product documentation for optimal settings. Again, check the documentation of both your computer's video graphics adapter and your HDTV to see which resolutions they support.
Component Video Ports: Component cables can carry all HDTV video resolutions (including 1080p) and have three RCA connections, three BNC connections, or a single 15-pin connection. A trend on many flat screen displays is to have a 15-pin port that is switchable between RGB signals and Component signals, however your hardware settings usually require changing to enable one or the other. Also, some computer graphics adapters feature component video outputs to plug directly into your HDTV. Although 15-pin "Component" or "Y-Pb-Pr" connections are physically the same as the 15-pin connections found on many computers and monitors, they are completely different signals. Be sure to check your product manual to verify if your 15-port is RGB/VGA or component/Y-Pb-Pr. To connect a computer's 15-pin RGB/VGA port to your HDTV's component-video port you will first need a VGA-to-Component video converter like this: http://store.a2zcable.com/rgbconv.html . You will then need a "component" video cable with the appropriate connectors. Also, some DVI ports are component-video-capable DVI ports. Although not very common, DVI-component ports are usually "switchable" and may require a change in your hardware settings or a special adapter to work. Again, check your product documentation. See also the Computer to HDTV section above.
DVI & HDMI Ports: Both DVI cables and HDMI cables can carry all HDTV resolutions (including 720p, 1080i, 1080p and WXGA) and use the same type of digital video signal to plug seamlessly into each other. Although HDMI can carry both video and audio in the same cable, DVI transmits only the video signal. However, DVI is more backwards compatible than HDMI in that it can also transmit analog RGB and/or component video signals IF your DVI port is RGB video and/or component video capable AND your DVI cable is analog video capable. Also, the rules for connecting DVI & HDMI digital video (not analog) also apply to M1, EVC, DFP and P&D connections, as these connections use the same digital signals as DVI/HDMI. For optimal video performance over DVI or HDMI cables the maximum recommended cable distance is limited to about 15 feet, although heavy duty cables featuring thicker conductors can carry signals accurately beyond 15 feet. Success beyond 25 feet will often depend on the quality of the circuitry inside your video transmitting device. Maximum HDTV resolution is 1080p and this requires 4.4Gbps transfer rates. HDMI cables and single-link DVI cables carry 4.95Gbps, and dual-link DVI cables carry about 9.9Gbps, so any of these cables can carry maximum HDTV resolutions. One important note about DVI is this: Some DVI ports are analog-capable DVI ports (known as DVI-A or DVI-I ports) and can be connected to 15-pin RGB/VGA ports, 3-RCA component video ports (if component video enabled DVI ports) or other DVI ports with the appropriate cable and/or adapter. DVI ports that are "component video" enabled (see section) may require a change in your hardware or menu settings or a special adapter to work. See also the Computer to HDTV section above.
RGB / RGBHV Ports: RGB (short for RGBHV) cables use the same signals used by most 15-pin computer video ports and can transmit all HDTV resolutions, including 1080p. Many HDTV tuners and especially computers feature RGB ports in the form of a single 15-pin connection, five BNCs or five RCAs. (Although 15-pin "RGB" connections are physically the same as 15-pin "Component" or "Y-Pb-Pr" connections, they are completely different signals.) Although HDTV tuners simply pass HDTV signals to your HDTV, computers may have other requirements. Depending on the resolutions supported by your computer's video display adapter and those supported by your HDTV, RGB cables can carry a variety of HD resolutions, including WXGA (at 1280x768, 1280x800 and/or 1366x768) and HDTV's 1280x720 or 1920x1080. To connect your computer's 15-pin RGB port to your HDTV's DVI port two things are required: an RGB-capable DVI port (known as DVI-A or DVI-I port, NOT DVI-D) and a 15-pin-to-DVI cable or adapter. The reverse of this scenario is also true (DVI to 15-pin RGB). To connect a computer's 15-pin RGB port to your HDTV's component-video port you will first need a VGA-to-Component video converter like this: http://store.a2zcable.com/rgbconv.html . You will then need a "component" video cable with the appropriate connectors. Also, computers usually need some additional software to match your computer's resolution output to your HDTV's resolution input.
CABLE & SATELLITE BOX TO HDTV CABLES - To take advantage of HD cable television or HD satellite television, two things are first required: an HD-ready cable or satellite box (featuring component video and/or HDMI video ports) and a subscription to your cable or satellite provider's HD programming. If your HDTV or cable/satellite box has DVI instead of HDMI you will need an HDMI to DVI cable.
SONY PS3 - If the Playstation3 game, DVD disc or Blu-Ray Disc program content and your video display support it, the PS3's HDMI connection can provide 480i, 480p, 720p, 1080i or 1080p resolutions, and the PS3's component video connections can provide 480i, 480p, 720p or 1080i resolutions (but not 1080p).
Microsoft XBox 360 - If the Xbox 360 game, DVD disc or HD-DVD Disc program content and your video display support it, the Xbox 360's component video connection can provide 480i, 480p, 720p, 1080i or 1080p.
Blu-Ray Disc Players - Blu-Ray discs are recorded in 1080p and all Blu-Ray disc players provide 1080p source video. If your HDTV does not support 1080p, the signals would be down-converted to a resolution your video display supports (480i, 480p, 720p or 1080i).
HD-DVD Players - HD-DVD discs are recorded in 1080p and all HD-DVD disc players provide 1080p source video. If your HDTV does not support 1080p, the signals would be down-converted to a resolution your video display supports (480i, 480p, 720p or 1080i).
Notes On Using Adapters: Using adapters or extension cables (such as DVI-to-HDMI adapters, 15-Pin-to-3-RCA adapters, 15-Pin female/female couplers, RCA/RCA gender changers, 15-pin extension cables and such) increase overall signal degradation, especially when running longer distances. Whenever possible it is best to use a single cable with the appropriate connectors between your video devices for maximum video quality.
Although component video, DVI/HDMI and RGB can carry a variety of HDTV resolutions, your video devices may "prefer" one over the other. So it is best to check your hardware manual for any port preferences.
As you can see, there are numerous ways to connect your video sources and displays to achieve HDTV quality video. With respect to cables, video quality may depend on which video ports are preferred by the manufacturer of your video devices, so always check your product documentation for cabling preferences. The quality of the cables used to connect your video devices may also effect video quality. Since most cable shoppers believe high prices and big brand names determine quality, several cable companies now focus on higher prices and flashy marketing to sell cables rather than on the electrical specifications of their cables. (See our Comparing Video Cable Quality article for details.) The quality of your picture may also be effected by your cabling distance (such as long DVI or HDMI cable runs) and/or the quality of the circuitry inside of your video components. For example, some HDTVs may use low grade HDMI circuitry while using high grade component-video circuitry. In this case component will likely appear better on your screen. However, the reverse could also happen. Once again, always check a video device's documentation to verify which HDTV capabilities your device may, or may not, have.
Enjoy the show!
I've had a lot of inquiries about the various signal types that exist (including newer digital HDMI/DVI signals) and the best way to hook everything up.
Here are the different signal types - from worst to best:
Composite Video (Analog, limited to 480i, High Definition not possible)
The lowest quality of video signal, but also one of the most common, found in everything from video games to VHS machines and DVD players. Composite is limited to 480i (standard definition) resolution. Once you’ve seen a higher end high definition signal (720p, 1080i, 1080p), chances are you’ll abandon all sources using composite video, but if you have a large collection of Beta tapes or an old video game, you’ll still need to send a composite video signal to your projector.
Most commercial grade projectors will have a BNC connector for the video connection on the input jack panel. This is a higher grade connector than the consumer RCA jack on the back of a DVD player, and Radio Shack sells a BNC to RCA adapter that will convert the connections. One trick is to use RG-6 cablevision cable as your video cable connection to the projector. That way you can run the video cable up to about 300 feet without loss of the video signal. Simply buy an RCA to F (cablevision connector) adapter at the video source end, and get a second adapter at the projector which is a BNC to F adapter. Then run your cablevision wire between the two.
S-Video (Analog, limited to 480i, High Definition not possible)
One step above a composite video signal but still limited to 480i (standard definition) signals. High definition (720p, 1080i, 1080p) is not possible. Relatively speaking, I’d say that an S-Video signal is about 25% better in picture detail than a composite video signal, so wherever possible, use an S-Video feed to send to the projector over a composite video signal.
Use the S-video connection will get about 20% more detail (my estimation) over a composite video connection.
Due to the black and white and chroma (color) signal being run separately within an S-video cable, the general recommended length of an S-video cable is limited to 30 feet or less. Longer runs will show that the black and white and color images will not overlap completely on the screen, and the color portion of the signal can lag the black and white one by ¼" on the screen. I’ve seen this happen in one of my own installations, and the only cure is to use a shorter S-video cable (or buy a very expensive S-video signal booster with adjustable phasing controls on it). It is very easy to bend one of the 4 pins on the S-video cable, take care not to bend a pin, or a loss of picture or color will result.
Component/YPbPr (Analog, 480i to 1080p resolutions supported)
Component (YPbPr) signals come in varying resolutions and can support from a basic 480i standard definition video signal all the way up to 1080p high definition. High definition signals usually come in 1080i or 720p outputs from a high definition cable/satellite box and 1080i, 720p, or 1080p from HD-DVD/Blu-Ray players.
Note: A component signal is NOT the same as an RGB signal even through the color coding is the same. The signals in component cables are broken up differently than those carried in an RGBHV cable so you cannot switch between the two using simple cables.
The introduction of the component signal format has caused more confusion and frustration than any other signal format. Sometime in 1994 (I’m guessing), some brilliant engineer decided that the decades old RGB industry standard for commercial and industrial video was not good enough for the consumer industry, and thus the component format was invented. Even though the three wires that are coloured red, green and blue for the component signal would indicate a plug and play connection to a display or projecto's RGB input, as component signal and RGB signal are NOT compatible. If you connect a component signal to an RGB input, you’ll only get a green image. The R and B output will be very low.
In order to make a component signal compatible with an RGB input found on some displays and most CRT projectors, you need to use a TRANSCODER to convert the component signal to RGB. Naturally, not all transcoders are created equally, so in general, the more you spend on a transcoder, the better quality the RGB output will be. However, some CRT projectors like the Sony D50, G70, G90, Barco 701s and 708, and NEC XG 852 and 1352 do have component inputs along with RGB connections.
RGBHV (Analog, 480i to 1080p and beyond resolutions supported)
RGBHV signals also come in varying resolutions and can support from a basic 480i video signal all the way up to 1080p and beyond. High definition signals usually come in 1080i or 720p outputs from a high definition cable/satellite box and 1080i, 720p, or 1080p from HD-DVD/Blu-Ray players.
The connectors are typically 5 wire BNC as seen on the above left picture or a D-sub 15-pin (VGA style) connector as seen on the above right picture.
Most CRT projectors will use 5 cable runs to pass the RGBHV signal from the source to the projector: One cable is used for each primary color (red/green/blue), and one for each of the horizontal and vertical sync signals. This is referred to as 'RGBHV'. BNCs are used in higher end equipment as the wires can be made thicker (more robust, longer runs possible). Most consumer display types use the VGA style D-sub 15 pin connector as it takes less space. It's harder to cram large wires into such a short area so most often the cables used won't be as high quality as separate BNC cables.
Some projectors such as certain Ampros and Barco 70x units use four cables: One for each color and one for both the H and V sync signals. This is referred to as 'RGBs' or RGB with composite sync.
An older format will sometimes only use 3 cables by running the sync signals along with the green video signal. This is referred to as RGsB or RGB with sync on green.
DVI and HDMI (Digital, 480i to 1080p and beyond resolutions supported)
DVI and HDMI are the highest quality signals available. The video signals of a DVI and an HDMI cable are very similar. The HDMI cable is a later version that also adds digital audio (a DVI connector only carries digital video). Adapters to convert the video signal between DVI and HDMI connectors can be found at any good audio video store or online for very cheap.
There are three different DVI connectors:
- DVI-A: Analog only. Content is found on the four pin group that's separate from the main pin group.
- DVI-D: Digital only. The four pin group is usually not even present. If it is present, there is no content being carried on it.
- DVI-I: Both analog and digital. Both groups are active.
DVI you can think of as basically digital RGB, it sends digital 8-bit RGB format signals and supports high resolutions.
HDMI is the newer, more capable version of DVI which adds audio capabilities, where DVI was just designed as a video interface. HDMI also makes high definition copy protection (HDCP) mandatory whereas in DVI it was optional (see below for more on HDCP). HDMI is backwards compatible, so you can use HDMI-to-DVI adapters or cables and the devices will just revert to basic DVI capabilities which is 8-bit RGB without audio.
If you use HDMI to HDMI, then you're not limited to standard DVI capabilities, and also have digital audio capabilities such as: Dolby Digital, DTS, high-resolution PCM, etc. For Video, HDMI builds on the basically 8-bit RGB capabilities of DVI, it also specs for 8, 10, and 12-bit digital component video (YCbCr) transmission.
The newest version of HDMI (HDMI 1.3 and higher) allows un-decoded high res and high res lossless versions of Dolby Digital (True HD) and DTS (DTS-HD Master Audio) for HD-DVD and Blu-ray disc. HDMI 1.3 and higher also adds support for 'deep colour' which greatly extends the number of colours that can be transmitted in the signal. Support for 'deep colour' in source content today is however non-existent as the Blu-ray and HD-DVD specifications (and DVD and broadcast TV specifications) do not include 'deep colour' and never will as the specifications are done and final. Adding deep colour support today to say, Blu-ray, would make the new discs incompatible with current Blu-ray players. You will therefore not see support for deep colour any time soon in movies. About the only place you may see it is in PC desktops and video games.
Many displays (including all CRT projectors) do not come with any digital input connectors on them, but they're easy to add! There are companies that makes DVI/HDMI to RGB converter boxes such as the HDfury line and the Moome EXT-FULLHD. Specialized HDMI 1.3 input cards by Moome for Marquee, Sony, and NEC XG projectors are also available (to name a few). HDMI can therefore be added to any display with either RGB (VGA) or component inputs without having to replace your TV.
Some notes on HDCP:
HDCP is not a type of connector. It is a copy protection scheme that when used can shut off the analog outputs on equipment and also, by talking to the display device, can even turn off the DVI output when a non-HDCP compliant display device is detected. Some of the DVI to RGBHV cards CAN handle an HDCP signal and some CAN'T. You should be sure to check with the manufacturer of the card to make sure it can handle HDCP if you need it. If you are buying one so you can feed a DVI output cable box to your CRT projector, you should make sure it is HDCP compliant.
HDCP didn't exist when the first DVI equipment came out, therefore older DVI displays and source devices are not HDCP compliant. Nobody makes, nor would anyone buy, a piece of DVI equipment today that didn't support HDCP. In fact, if you intend to use a monitor/projector with a DVI output cable box, it won't work unless your equipment is HDCP compliant, which is why all HDMI equipment includes HDCP today.
HDCP didn't exist when the first DVI equipment came out, therefore older DVI displays and source devices are not HDCP compliant. Nobody makes, nor would anyone buy, a piece of DVI equipment today that didn't support HDCP. In fact, if you intend to use a monitor/projector with a DVI output cable box, it won't work unless your equipment is HDCP compliant, which is why all HDMI equipment includes HDCP today.
If you have a DVI or HDMI output on a digital device and the signal is HDCP encoded, the display needs to give a ‘handshake’ to accept this HDCP code before the content can be viewed. If the handshake signal is not received by the signal source the signal source will be blanked out and you end up with a blank screen.
HDCP encoding has been brought about primarily by the movie studios that are concerned about the illegal copying of DVD’s and HD content that comes off of satellite.
HDCP encoding has been brought about primarily by the movie studios that are concerned about the illegal copying of DVD’s and HD content that comes off of satellite.
HDCP is not to be confused with the Image Constraint Token (ICT). ICT is a flag that movie studios can enable on a per-disc basis on Blu-ray and HD-DVD to cause downsampling of HD video content to slightly better than DVD quality. If the ICT flag is enabled, the content will reduced to 540p though the component outputs. To avoid this limitation HDMI must be used. Hollywood has reportedly agreed to not activate this flag for discs released in either of the two formats until 2012.
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