Encyclopedia

VGA, DVI, HDMI, Definition

There are once again many terms in this sermon so grab the post for this episode so you can get more detail.

VGA

Introduced in 1987, the Video Graphics Array connector (or VGA) is the standard blue 15-pin connector we have all dealt with. It has also been called RGB, D-sub or “that blue cable”. The VGA cable supports resolutions from 640×400 to 2048×1536. With the right equipment, you might be able to pinch a little more res out but that is infrequent. A VGA connection is ANALOG and cable lengths are good up to 25-30 ft.

You may have heard terms like VGA, SVGA, SXGA, HDTV and WUXGA but these all just define the vector (resolution) of the signal. For PCs, we do not typically use this rating but this comes in to play when looking at projectors given that there native resolution is frequently considered important.

VGA is to be phased out by 2013 but I am sure support will be around for years after.

DVI

Introduced in 1999, the Digital Visual Interface (or DVI) is the 29-pin connector that came after VGA. It has been called DVI-DVI-D, the “white one” connector or I. This connector is digital, which means that data is transmitted and is not affected by noise or distortion. Something else to consider is that when your display is on its native resolution the DVI the source is based on each pixel on the monitor. When you use a VGA connector, the pixels are not individually lit and the lit pixels are affected by other pixels. For those of you with two monitors, one on VGA and one on DVI, you will notice the DVI looks slight more crisp. This signal is reason behind that. If you have a card that has VGA, DVI and HDMI try to not to use the VGA and get an adapter for the HDMI. You will get better results.

Now as far as the resolutions for DVI you need to understand single and dual DVI links. Look at your DVI connector and if there are missing pins in the middle then it is a single link DVI cable.

Just as an FYI, the DVI connector includes pins for analog signal, which is how you can use one of those adapters to go to VGA.

The highest resolution for a single DVI link is 2098×1311 so when a higher resolution is need the dual DVI link kicks in and you can get that higher resolution. Your video card must support dual link of course and single link is most common.

There is also Display Data Channel (or DDC or DDC2) on pins six and seven that have information that tells your PC the type of monitor it is. Modern VGA cables also have DDC/DDC2. This ID data is how your PC knows the type and resolution and what drivers to get for your monitors. As a recap, six pins are for data, six pins for analog signal, six pins for data two, five pins for monitor data and six for shield.

Cable lengths are good to 15 ft at 1080 while you can go longer with lower resolutions or by using a booster.

DVI is a great connector but since it does not include audio, it is losing out to HDMI.

BELOW DATA COPIED FROM WIKI at http://en.wikipedia.org/wiki/Digital_Visual_Interface

  • Example display modes (single link):
    • HDTV (1,920 × 1,080) @ 60 Hz with CVT-RB blanking (139 MHz)
    • UXGA (1,600 × 1,200) @ 60 Hz with GTF blanking (161 MHz)
    • WUXGA (1,920 × 1,200) @ 60 Hz with CVT-RB blanking (154 MHz)
    • SXGA (1,280 × 1,024) @ 85 Hz with GTF blanking (159 MHz)
    • WXGA+ (1440 × 900) @ 60 Hz (107 MHz)
    • WQUXGA (3,840 × 2,400) @ 17 Hz (164 MHz)
  • Example display modes (dual link):
    • QXGA (2,048 × 1,536) @ 75 Hz with GTF blanking (2 × 170 MHz)
    • HDTV (1,920 × 1,080) @ 85 Hz with GTF blanking (2 × 126 MHz)
    • WUXGA (1,920 × 1,200) @ 120 Hz with CVT-RB blanking (2 x 154 MHz)
    • WQXGA (2,560 × 1,600) @ 60 Hz with GTF blanking (2 × 174 MHz) (30-inch / 762 mm Apple, Dell, Gateway, HP, NEC, Quinux, and Samsung LCDs)
    • WQXGA (2,560 × 1,600) @ 60 Hz with CVT-RB blanking (2 × 135 MHz) (30-inch / 762 mm Apple, Dell, Gateway, HP, NEC, Quinux, and Samsung LCDs)
    • WQUXGA (3,840 × 2,400) @ 33 Hz with GTF blanking (2 × 159 MHz)

HDMI

Introduced in 2003, High-Definition Multimedia Interface (HDMI) is the 19-pin digital connector standard most people tend to favor now. This connector and cable supports any uncompressed video format and carries eight channels of audio. It also can carry Ethernet and a CEC connection which is how your Samsung TV can remote control your Samsung Blu-ray through the HDMI cable. Magic eh? Other names are Aquos Link, Viera Link, Easylink and Bravia Sync.

Most of us have the Type A Category 1 connector that we use for our home theater equipment.

HDMI cables made currently under the 1.3 and 1.4 spec fall under Category 1, which is Standard Speed and Category 2 which is High-Speed. Category 1 cable is fine for most uses but if you are going 3D, cinema 4K, 2160 or 1080p then you want the Category 2.

Cable length is generally limited to 16 feet (Category 1) but with a higher quality cable (Category 2) you can go to almost 50 feet.

Also there were specs released with versions 1.2, 1.3 and 1.4 the cables are only different in bit rate. With version 1.4, 3D support was added. It gets hard to weed through the advertised specs (which they are not supposed to advertise anyway) so just get cables that are 1.3 or 1.4 when you buy.

HDMI also uses the same signal as DVI so no signal conversion is necessary. You just need a simple DVI-HDMI adapter but you lose the audio. This works well, however not all device support HDCP so you may have issues. Check with your manuals for further information on your source device.