Video cables carry electronic signals from a video
source, like a DVD player or cable box, to your TV. Selecting the right
cable is an essential step in getting the most out of home theater equipment.
Even with a top-of-the-line TV and Blu-ray player, you won’t get optimal
picture quality if the signal is travelling through the wrong type of cable.
This buying guide explains the available video cable options, so you can feel
confident you’re selecting the cable that meets your needs.
Factors to Consider
The video jacks on TVs have evolved from a single cable/antenna jack to seven standard connection types, designed to transmit varying qualities of video signals. For each type of connection, there is a corresponding type of interconnect video cable—a cable that carries the signal from your video source or A/V receiver to your TV. For optimal video quality, select an interconnect cable that fits the best quality connection available on both your video source and your TV.
The chief measure of video quality is screen resolution, represented as the number of vertical scan lines displayed on the screen. A scan line is made up of thousands of individual dots of light, called pixels. A higher resolution, or greater number of scan lines stacked from the bottom of the screen to the top, includes more pixels of visual information, which provides a clearer picture.
Video quality also depends on whether the picture is interlaced or progressive:
There are seven standard signal resolutions. An “i” indicates an interlaced signal and a “p” indicates a progressive-scan picture:
240i – The low-resolution signal used in standard VCRs
480i – The standard resolution for analog TV signals and non-progressive DVD players
480p –The resolution of digital, non-HD TV signals and progressive-scan DVD players
720i – An HDTV signal resolution option
720p – An HDTV signal resolution option
1080i – An HDTV signal resolution option
1080p – The highest HDTV resolution
A video source that generates a signal with that resolution
A TV capable of displaying that resolution
A video cable that can transmit that resolution between the video source and the TV
If you use a type of video cable with a lower maximum resolution, it will
degrade the signal from the video source down to the cable’s maximum
Video interconnect cables fall into two basic categories: Analog cables and digital cables.
Analog Video Cables
The older of the two cable options, analog video cables transmit video as a continually fluctuating electronic signal, similar to an undulating wave. An analog signal is susceptible to interference in the form of electromagnetic and radio frequency waves. This interference can introduce static into a video signal on its way from the video source to the TV. The level of potential interference depends on the shielding materials used in the cable. If there are digital connections on your equipment, it’s best to use a digital cable. For equipment with only analog connections, you will need to use analog cables.
There are four basic types of analog interconnect cables:
|Coaxial RF cable – Also called coax or F-type, coaxial cable is the most basic interconnect option. When used as an interconnect cable, coax can carry video signals up to 350i, which is lower than an analog TV signal. In other words, unless you’re connecting a VCR to a TV, coaxial cable will degrade the signal coming from your video source. Coax is also used as long-run cable, transmitting satellite or cable TV signals from your satellite box or connection to the cable company to your cable receiver, satellite receiver or built-in TV tuner. In this capacity, coax cable works very well. For optimal performance, use coax stamped “RG-6,” rather than “RG-59.” RG-6 coax cable includes better shielding, which reduces interference and signal loss.|
Composite – The next step up from coax, composite cable, can carry a 480i signal. This is adequate for analog TV, but will degrade high-definition signals. Composite cables typically have a yellow connector, and are often combined with a pair of analog audio cables, with red and white connectors.
|S-Video – Like composite cable, S-Video can carry video signals up to 480i. However, S-Video transmits brightness information and color information separately, which delivers richer colors than composite cable. S-Video is a good option for digital TV and DVD players when higher-quality connections aren’t available, but it will degrade high-definition signals. S-Video doesn’t carry audio, so must be used in conjunction with separate audio cables.|
Component – The most advanced type of analog interconnect, component cables can carry up to 1080p, which makes them a good choice for HDTV and other high-definition signals. Like composite cable, component cables are typically combined with red and white analog audio cables.
Digital Video Cables
For the best possible picture, use digital cables, which transmit video as a series of 1s and 0s. This binary signal, the language of computers, is much less susceptible to interference and degradation than an analog signal. Digital cables can also carry far more data than analog cables, making them the most advanced cable option available.
There are three types of digital cables in common use:
HDMI (High-Definition Multimedia Interface) – Now the standard for digital cable, HDMI is the best connection option available today. The newest version of HDMI cables (HDMI 1.3) can carry a 1080p video signal and eight channels of audio, with bandwidth to spare. You’ll find HDMI connections on most new HDTV sets, HDTV cable and satellite boxes, and Blu-ray players. Some DVD players also include HDMI jacks.
|DVI (Digital Visual Interface) – Originally developed for computers, DVI was the leading HDTV connection technology before the introduction of HDMI. Unlike HDMI, DVI cables don’t transmit audio signals. HDMI is replacing DVI, but some TVs still include DVI inputs. If your computer and TV both have DVI ports, you can use your TV as a second computer display. With a DVI-to-HDMI adapter, you can run a DVI signal from your computer to an HDMI jack on your TV.|
FireWire – Also known as i.Link and IEEE 1394, FireWire is a connection technology designed to carry high volumes of data. FireWire is rarely used to transmit HDTV signals, but some TVs have FireWire jacks, which allow you to play video directly from some digital camcorders.
Refer to the table below for a quick comparison of the available types of cable. The following sections explain the capabilities of each cable design in greater detail.
The chief distinction between different cable models is the materials used in their construction. High-quality materials typically do a better job conducting a video signal and filtering out interference than cables made from basic materials.
For composite cable, S-Video cable, component cable, and HDMI cable, consider the materials used in these four cable parts:
If you plan to run a cable behind your walls, be sure to select a cable rated for that purpose. Look for an Underwriters Laboratories® (UL) label with a CL2 or CL3 certification.
When making your purchase, keep in mind that cable length can also affect signal quality, particularly with analog cables. Signal degradation increases with cable length, so shorter cables are less susceptible to interference. For optimal results, use a cable that is just long enough to reach from your video source to your TV.