Understanding Video Connector Types
When selecting a monitor or projector for use with a particular video card or integrated video port, it's helpful to understand the physical and feature differences between different video connector types, such as VGA, DVI, HDMI, Component/RGB, S-video, and composite.
VGA is an analog display standard. By varying the levels of red, green, or blue per dot (pixel) onscreen, a VGA port and monitor can display an unlimited number of colors. Practical color limits (if you call more than 16 million colors limiting) are based on the video card's memory and the desired screen resolution.
All VGA cards made for use with standard analog monitors use a DB-15F 15-pin female connector, which plugs into the DB-15M connector used by the VGA cable from the monitor. Figure 3-20 compares these connectors.
Figure 3-20 DB15M (cable) and DB15F (port) connectors used for VGA video signals.
The DVI port is the current standard for digital LCD monitors. The DVI port comes in two forms: DVI-D supports only digital signals, and is found on digital LCD displays. Most of these displays also support analog video signals through separate VGA ports. However, video cards with DVI ports use the DVI-I version, which provides both digital and analog output and supports the use of a VGA/DVI-I adapter for use with analog displays. Figure 3-21 illustrates a DVI-D cable and DVI-I port.
Figure 3-21 DVI-I video port and DVI-D video cable.
Video cards and systems with integrated video that are designed for home theater use support a unique type of digital video standard known as High-Definition Multimedia Interface (HDMI). HDMI is unique in its ability to support digital audio as well as video through a single cable. HDMI ports are found on most late-model HDTVs as well as home theater hardware such as amplifiers and DVD players.
The most recent HDMI standard, version 1.3b, supports up to 1080p HDTV, 24-bit or greater color depths, and various types of uncompressed and compressed digital audio. However, all versions of HDMI use the cable shown in Figure 3-22 and the port shown in Figure 3-23.
Figure 3-22 HDMI cable (right) compared to DVI-D cable (left).
Figure 3-23 HDMI, DVI-D, and VGA ports on the rear of a typical PC built for use with Windows Media Center and home theater integration.
Systems and video cards with integrated HDMI ports might also feature DVI-I or VGA ports, as in Figure 3-23.
A converter cable with a DVI connector on one end and an HDMI connector on the other end can be used to interface a PC with an HDTV if the PC doesn't have an HDMI port.
Some data projectors and virtually all HDTVs support a high-resolution type of analog video known as component video. Component video uses separate RCA cables and ports to carry red, green, and blue signals, and can support up to 720p HDTV resolutions.
S-video divides a video signal into separate luma and chroma signals, providing a better signal for use with standard TVs, projectors, DVD players, and VCRs than a composite signal. The so-called "TV-out" port on the back of many video cards is actually an S-video port.
The lowest-quality video signal supported by PCs is composite video, which uses a single RCA cable and port to transmit a video signal. Video cards sold in Europe usually use a composite signal for their TV-out signal.
Composite video can be used by standard definition TVs (SDTVs) and VCRs. If you need to connect a PC with an S-video port to a TV or VCR that has a composite port, you can use an S-video to composite video adapter.
Figure 3-24 compares component, S-video, and composite video cables and ports to each other. Note that composite video cables are often bundled with stereo audio cables, but can also be purchased separately.
Figure 3-24 Composite video and stereo audio, S-video, and component video cables and ports compared.