Video Wiring for your Home Theater
In our last article we discussed how to set up the audio cables for your DVD player. Now, unless you plan to only collect music DVD-Audio Only discs you will most likely want a picture to go with the sound. Guess what, as with the audio there are several options you can use with DVD video. Each has different performance and prices.
At the very low end of the spectrum there is RF video. This is the worse case scenario and should only be considered if you are unable to use any of the other options. What will force you to select this method is a TV that is an older model that does not have the jacks for external speakers or a receiver output. This is the type of TV that is usually mono. A few DVD players have RF video output for televisions with only an antenna connection. Connect a coax cable from the player to the TV. A 300 ohm to 75 ohm adapter may be needed. Tune the TV to channel 3 or 4 and set the switch on the back of the player to match. Audio is supplied with the RF signal, but its only mono, even on stereo TVs. If you have a player without RF output, you can buy an RF modulator (about $30) to hook up to an old TV that only has RF input. If you try to hook up your DVD through your VCR you can run into problems on discs protected with copy protection such as Macrovision in place.
The next level up is the composite video connector. You will most likely be very familiar with this type of connector if you have ever set up a VCR. There are three cables associated with this type of connection. They are color coded, red for right audio, white for left audio and yellow for video. They are the common RCA type connectors that fit into the little round jacks with a hole in the middle.
Next up in the food chain is the S-Video connector. Almost all players have s-video output. Hook an s-video cable from the player to the display (or to an A/V receiver that can switch s-video). The round, 4-pin connectors may be labeled Y/C, s-video, or S-VHS.This four pin connector provides superior video than the RCA connectors for two reasons, greater bandwidth and segregation of the signals. S-video, Super VHS, SVHS, Hi-8 and other "Y/C" formats use two separate video signals. The luminance (Y) is the black and white portion providing brightness information. The chrominance (C) is the color portion providing hue and saturation. The remaining two pins are grounds. With the typical RCA cable all video information is contained in one cable. This increases cross talk or overlap of information from one signal to the other. With all that techno babble out of the way lets talk about the practical side of this format. Because the signals are held apart they are cleaner, less interference and it provides a much sharper picture. You can try your own test by watching an extreme close up with the RCA connectors and then switch to S-Video. You will literally see the pores on the face with amazing clarity. Sounds disgusting but it is a dramatic demonstration.
Now we get to the real professional types of connectors. These methods will give superior video but they often need more expensive equipment including receiver and television. We now consider the Component video. Some U.S. and Japanese players have interlaced component YUV video output in the form of 3 RCA or BNC connectors. Connectors may be labeled YUV, color difference, YPbPr, or Y/B-Y/R-Y, and may be colored green/blue/red. Some players have RGB component video output via a 20-pin SCART connector or 3 RCA or BNC connectors labeled R/G/B. Hook cables from the three video outputs of the player to the three video inputs of the display, or a SCART cable from the player to the display. Note: For equipment with RGB inputs, the YUV signal won't work; a transcoder is required. It may be possible to obtain a converter to obtain component video from another format such as S-video. Be cautious since this is outside most design specifications and the quality may be compromised.
The latest in high definition cabling is the HDMI, High Defintion Media Interface. It is a single cable that combines high def video and surround sound audio. It not only provides the best possible reproduction but it is the simplest to install. One connection and you have it all done. Most modern home theater equipment have this as standard. It provides both progressive and interlaced forms of 1080, 720 and 480.
Here we have to consider the difference between interlaced and progressive scan video. For most TVs the picture is painted in two passes. The first electronically paints the odd lines while the second goes back and fills in the even. Its done so fast that the eye sees one picture but the reality is there is a lot of flicker. This method really only works with a smaller number of lines to paint. The 480 lines of standard TVs is about the maximum. Now that higher definition TV and digital TVs are becoming more commonplace, and more importantly, more affordable. The number of lines has increased. 1080 lines is now longer uncommon. With progressive scan the picture is sent to the TV in a faster, more efficient manner. There is almost no flicker and the definition of the image is like looking like a photograph.
That gets us ready to understand the last and best possible (for now) video connector, the Progressive connector. Players have been produced with progressive-scan YUV component video output in the form of 3 BNC or RCA connectors. Hook decent-quality cables from the three video outputs of the player to the three video inputs of a progressive-scan line multiplier or a progressive-scan TV. Toshiba's version is called ColorStream PRO. This format preserves the progressive nature of most 24-frame movie discs, providing a film-like, flicker-free image with higher vertical resolution and smoother motion. Until recently, this was restricted to computers since there are numerous copy protection problems. Now, many new televisions and DVD players are supporting this mode. Rather than painting the image with alternate lines, odd lines of the picture first followed by the even lines, the progressive scan pushes the entire picture to the screen. This greatly reduces the flicker.
Now that you have a better idea of the type of connections possible we get to consider the actual set ups. Many home theater receivers permit you to not only plug in the audio jacks but they have connectors for the video connections as well. This means that the selection of what video signal is sent to the TV is decided at the receiver. These receivers usually hook the audio and video together. So, for example, if you select the DVD player the receiver sends the proper sound to the speakers and the picture to the TV. Select the VCR and and the video is routed from the VCR to the TV and the sound goes through the prologic channels of the receiver. This method will make connecting several devices through a central piece of equipment and makes the job of changing sources a breeze. For this to work you may need a couple of different video connectors between the TV and receiver. The DVD player may connect through Progressive while the cable and VCR may use the S-Video. In most modern receivers there are enough inputs and outputs to meet the demands of most home systems.
The other method is directly connecting the DVD player, cable, VCR and other devices to the TV. Most TVs now have at least three audio/video inputs and typically one or two outputs. The third input is often on the front panel to permit a video camera to be connected. For the two outputs to the receiver there is usually one that sends a steady signal to the receiver, where you adjust volume with the receiver, and one that varies the signal through the TV. Well leave these final connections between the TV and receiver for the next time. Until then enjoy your new equipment.