Sorting out Connections & Cables for my Home Theater Projector  

RCA or Composite Cables / BNC Cables 

Composite cables are the most common cables used for video or audio equipment and are easily identified by their red, white, and yellow colour codes. Red is for right channel audio, white is for left channel audio and yellow is for video. Since the entire video signal is transmitted by just one yellow cable, the video quality is low. In fact, composite cables are the lowest quality cables for video source, but it is also the most common. RCA cables belong to this class of cables, classified by their pin plug design. 

BNC cables have the same quality as that of an RCA/composite cable. The difference is in the end of the cable connection. BNC cables connect by turning it clockwise to lock the connection in place. It is more secure then the pin plug design of common RCA cables. BNC cable can be changed to an RCA end with a simple adapter.  

S-Video or Y/C Cables 

This cable might also be referred to as a SVHS cable and can be found on most high-end audio/video equipment. S-video split video signals into two different components: luminance and chrominance, rather than a single signal in the composite cables. The S-video cable will offer marked improvement over a composite cable. 

Component Cables 

Component cables look just like composite cables. However, while composite cables transmitted the video signal via a single line, component cables split the signals into three. The three signals are referred to as either Y,Cr,Cb, or Y,Pb,Pr. In order to identify the cables easily, most manufacturers colour code them by red, green and blue. Unfortunately, this results in confusion with computer RGB connections which are colored in the same way.

One usually differentiates between computer RGB and component cables by its end connection head. If the connections are RCA type (pin plug), it is usually a component cable. Computer RGB cables are usually be BNC type (twist and lock). Component cables produce video connections of much better quality than common composite cables. 

Portable Projectors Cables (15-pin and/or 3-RCA connection) 

When it comes to portable projectors, they are very small and normally have very little space for connections. Because of this little space available, most of them simply have a 15-pin VGA connection that doubles as the component connection. The projector uses the three out of the fifteen-pins for component video that it uses for its RGB computer connections. These projectors are designed to automatically detect the type of signal it is receiving from the connection and process it accordingly. If you are using such a projector and want to connect it with a component cable, you will need a component cable that has a 15-pin connector on one side, and three RCA/BNC connectors on the other. 

RGBHV Cables 

These cables look like simple composite cables but are split into red, green and blue (RGB) instead of the red, white and yellow of composite cables. RGBHV cable splits the video signal into five. It splits the video signal for colour into red, green, and blue, and then further splits the sync for the signal (horizontal and vertical sync) into two more cables. Some RGBHV cables have only four cables, known as RGB H/V. The colour is split into three signals as normal, but has the horizontal and vertical sync signal is carried on the fourth cable. Another type of RGBHV cable with only three cables split the color signal in three and carries the additional sync signal on one of the color cables.

RGBHV signals are used in the connection between a computer and a projector. Typically, 5 pins out of the 15 pin VGA cables of the computer monitor cable carries these RGBHV signals. VGA cables are commonly used for computer monitors. You may be able to recognize it by its male-to-male connection with three rows, totaling 15 pins.  

DVI Cables 

Digital Video Interface (DVI) cables look like a larger version of the VGA cable and contain more pins. Ideally, DVI cables enable a 'digital to digital' connection between the data source and display device. However, the ideal situation is rare. Usually, the source signal requires some sort of translation or conversion into the digital format that your projector is able to receive before projecting into an image. 

HDMI Cables 

HDMI cables are a much smaller version of DVI cables. At the same time, they can also send and receive 24 bit, 8-channel, 192 kHz audio digital signals, a function that is not included in DVI cables. However home theater projectors normally do not provide high quality audio output, therefore users generally do not require audio input into their projectors. Instead, users generally rely on a separate audio system to provide them with their home theater experience.

HDMI connections are also backwards compatible with DVI devices for video sources. Since the conversion is a pin-to-pin connection, there is no detectable signal loss except for the lack of audio signal transmission.

 

In summary, for high quality home theater experience, you not only require a high quality data source and projector output, you need a high quality cable to transmit them. Old cables such as composite cables (RCA, BNC) are very commonly used and are useful connections to have if you are bringing your projector around often. However, newer cables like S-Video or component cables provide higher quality images. Finally, if you are looking to the future of HD technology, either DVI or HDMI cables should be your choice of cables.