Audio-Video Basics, Part I

Most newer coaches now boast state of the art LCD and Plasma televisions, with a host of custom electronics. Progressive up-converting DVD players, new generation HD-DVD players, digital audio and video, and home theater remotes are but a few of the options available for audio-video systems. There are also video projectors, but we will not cover those in this article.

All in all, it can be difficult to understand the technical particulars. There are several different types of tv sets as well as a variety of video formats. Newer systems require the consumer to complete a setup procedure before all of the features are enabled. And complicated systems can require printed operating guides to walk you through even the basic system operations.

In this article, we will take a look at the specifications of newer audio-video and control electronics. I attempt to filter out some of the technobabble, and give you a user-friendly look at what is out there. We will take a look at what you get for your money, and how it affects your viewing and listening. So now, some quick definitions and I'll cut to the chase:

Interlaced Video What you have been viewing on tv's since their inception. Half of the horizontal lines (every other line) in the picture are displayed for 1/60th of a second. The other half of the lines display the next 1/60th of a second. The signal is known as 480i.

Progressive Video When all 480 horizontal lines in the picture are displayed simultaneously, every 1/60th of a second. This significantly improves picture quality. This it is not High Definition, but it was a major step forward.

Pixel Short for picture element. It is not necessarily a shape, but a single point in a graphic image. In newer model televisions, it is a square or rectangular element. They are supposed to blend into a seamless video picture, but can sometimes be seen. This is an undesired side effect of a digitally reproduced signal. For example, when your signal from a satellite receiver becomes weak the picture can "freeze" and you can see the rectangular pixels. This is known as "pixellation", but there are many other things that can influence picture quality.

Resolution The number of pixels on the television screen. Generally speaking, this is a good indicator of the quality of the television or input video.

HD High definition. Basically a higher resolution picture due to a greater number of pixels on the screen. Currently HD formats are as follows:

    720p 720 pixels high (vertical resolution) x 1280 pixels wide (horizontal resolution) in a progressive format.

    1080i 1080 pixels high (vertical resolution) x 1920 pixels wide (horizontal resolution) in an interlaced format.

    1080p 1080 pixels high (vertical resolution) x 1920 pixels wide (horizontal resolution) in a progressive format.

Native Resolution The number of pixels (height x width) that the television screen was designed with.

Scaling Conversion of incoming video signals to the native resolution of the television screen. For instance: if a screen with a native resolution of 720 x 1280 has an input signal of 1080 x 1920, the television will need to "compress" the picture to fit the screen. Conversely, if a screen with a native resolution of 1080 x 1920 has an input signal of 720 x 1280, the television will need to "expand" the picture to fit the screen.

Aspect Ratio The ratio of width to height on a television screen or video input signal. The two most common aspect ratios we will be dealing with are 4:3 and 16:9.

4:3 Older television sets, "full screen" VHS and DVD movies use this format. Some broadcast television and cable channels still utilize this. Also referred to as "pan and scan", as movies are "modified" to fit the aspect ratio of the television screen.

16:9 Newer televisions and "widescreen" movies are designed for this format for maximizing your viewing experience. You see the entire picture as you would in a movie theater, provided your video source is widescreen as well. On some movies you will get black bars above and below your picture, but we'll take a look at that later.

First, beware of electronics stores that are pushing certain models of equipment. Usually the store is trying to move certain models first, and they may not necessarily be what is best for your system. If a salesperson is not able to provide you with useable information about equipment specifications and comparisons, watch out.Keep in mind that you are building a system, and that you want the most bang for your buck. Saving money on equipment should be second to video and audio quality. Make sure all the components work well together. If you are looking at High-Definition equipment, perhaps HDMI would work for you. Then maybe a Plasma or LCD television with at least 1 HDMI input and upscaling. Sharp and Sony both make outstanding televisions with these built-in features. For both cost and operations, simpler is better. Any good system can easily consist of only the following:

    1. Plasma or LCD HDTV (1080p) with built-in digital and analog tuners for cable and antenna, HDMI inputs, and upscaling. Consider whether you want a widescreen set (HIGHLY recommended). A good place to start would be a 32" or 37" tv set.

    2. Home theater receiver for video switching and audio control, also functions as surround processor.

    3. Good matching speakers (2 front, 2 surround, 1 center, and 1 subwoofer). Certain systems may incorporate additional speakers (See "Surround Sound").

    *4. HD-compatible satellite dish and receiver(s)

    5. A good quality progressive DVD player with upconversion or perhaps an HD-DVD player.

    *6. An external rf switcher to route cable and antenna signals to the rf input of your television set(s).

    *7. A digital-ready roof-mount tv antenna with booster

    *8. Cabling to support High Definition video and audio to all other televisions in the coach (if desired)

    *9 (Optional) Home Theater remote for control of your system to avoid having to use multiple remotes.

    *items possibly built into the coach by the converter.

Here are video formats, from lowest to highest quality. 1 through 5 are analog, 6 and 7 are digital. When it comes to video quality, digital is second to none. The biggest difference between analog and digital is the reproduction of the signal. Digital is cleaner and can differentiate between noise and signal. Analog signals have a tendency to blend in with the noise, making it harder to separate from signal. The best digital tv picture is only as good as the signal input. To use an old computer phrase, "GIGO-Garbage In, Garbage Out".

1. RF:
Coaxial cable, what many older coaches have. Signals are switched by a push-button "video" selector, and you have to tune your tv to channel 3 or 4 to pick up VCR, Sat or DVD. Video and audio are sent together on the same cable, and your television has to separate them.

2. Composite video:
"Yellow" video cable, usually with attached "white" and "red" audio cables. Although the video and audio are separated, you are still dealing with video that has multiple signals mixed together. Switching is accomplished via stand-alone switcher or home theater receiver.

3. S-Video:
Very similar in many aspects to #4. Cables cost less. For years this was the ultimate quality video signal, and still is very cost-effective, works with some High-Definition signals.Switching is accomplished via stand-alone switcher or home theater receiver.

4. Component Video:
Red, Green and Blue. 3 cables molded together. Separate color signals, with the other signals piggybacked on the color feeds. Audio is sent through separate cabling. Switching is accomplished through stand-alone switcher or home theater receiver.

5. RGB:
Red, Green, Blue, Yellow and White. 5 cables molded together. Better yet, Less for the television to separate from the color information. Cleaner video. Switching is accomplished through stand-alone switcher or home theater receiver.

6. DVI:
Digital Video Interface. The only true competition for HDMI. Uses expensive cables, and the equipment needs to be DVI compatible. Audio is sent through separate cabling. Some adaptors for DVI to HDMI and vice-versa are available. Switchers and compatible home theater receivers are expensive.

7. HDMI:
High Definition Media Interface. Digital video AND digital audio in one cable. Cables are very expensive (good quality 10 foot cable can run upwards of $200). Switchers and compatible home theater receivers are expensive.

When it comes to input signals and displays, go with digital. Sharper pictures, brighter colors. In new tv's,there are three good indicators of improved video quality: backlighting, black level and contrast ratio.

Backlighting: The video will not lose significant clarity even in environments where ambient lighting is very bright: i.e., having sunlight on the television screen.

Black Level: An indicator of color intensity and clearly defined colors. The colors are bolder, with better definition. The overall effect is of a crisper, more realistic picture.

Contrast Ratio: When it comes to contrast ratio, the higher the number, the better. Good sets start at around 1700:1, and go up from there. While this is not the most important feature to look for, it is an excellent indicator.

With the direct digital video (and digital audio) feed offered by HDMI, you can view video the way it was intended, without the signal loss inherent in other analog (non-digital) signal inputs. As good as some other video inputs are (Component, RGB, S-Video), they don't hold a candle to HDMI.

The primary difference between Plasma and LCD televisions is that Plasma is better at displaying rapidly changing video (such as water) than LCD tv's. The picture quality is good even on lower-priced sets. The main drawbacks to plasma screens is the heat that they generate. If not well ventilated, they can overheat and suffer permanent damage. They are also heavy.

LCD televisions are lighter, draw less power and generate much less heat than Plasma sets. They are rapidly closing the gap in video quality, because of recent advances in video processors. Newer sets by Sony, Sharp and Toshiba have startling video quality, and the price gap between LCD and Plasma tv sets is closing rapidly.

As an aside, LCD televisions are more power-efficient than plasma sets of the same size, and this means dry camp time. Power management can only go so far if you do not have efficient electronics. To put this in perspective, you have approximately a 10 to 1 ratio of dc current expended to produce ac when dry camping (on inverters, no charging) This means that to produce 5 amps of ac you need to expend 50 amps of dc. Now you can see how just a couple of amps of ac draw can seriously impact battery usage.

Widescreen, Anamorphic widescreen, Letterbox, 4:3, Zoom, Full screen. What the blazes are they, and how do they affect me? In a nutshell, they are about something called "Aspect Ratio". As an example, 4:3 is the ratio of the width to the height of your old glass-tube tv set of years ago. 4:3 was THE ratio, and to see anything else you had to go to the movie theater.
 

With newer television sets and the advent of HDTV, the consumer now has the choice. Some newer tv sets have an "automatic" feature that when enabled can detect the aspect ratio and select it for you.

Here are some brief descriptions. While this is by no means all of the formats available, this covers some of the most commonly used ones:

4:3 Standard tv format for decades. Some broadcast, cable, VHS and even DVD discs come in this format. It is commonly referred to as "pan and scan", or "full screen". Beware of this when you are movie shopping. If you already have a widescreen tv, you may see black bars on both sides of your picture. If you choose you can fill the screen by using the "zoom" or "full" options, but the picture may be "stretched" to fit, and quality will be lost. With some antenna and cable inputs still broadcast in 4:3, you may not have a choice.

16:9 Widescreen in all it's glory. What most newer "widescreen" tv sets are designed for.

2.39:1 Anamorphic widescreen. Usually shows as black bars above and below the picture, and is a result of the way the movie was filmed originally. Not all movies are filmed this way.

Letterbox: This predates widescreen movies for home use, as it was originally intended for showing a movie in it's full width but on a standard 4:3 television set. Still useable and will display on newer widescreen tv sets, but may need to be adjusted to avoid "stretching" and distorting the picture. You could still have bars above and below the picture, as well.

Even in this enlightened age of home theater and widescreen tv, there are still signals reaching your television that are not in the widescreen format. With a little experimentation and some information, it should be a short learning curve to dial your new tv in. That about covers displays and video. Next time we'll explore audio and the wonderful world of surround sound. We'll also cover home theater remotes, and look at what complete systems can do to improve your viewing and listening experience.

By Nick Hessler

If you have any questions, I can be contacted at: omnitech_nick1@yahoo.com or (541) 321-2545. I would be more than willing to send you website links or other tutorials concerning this subject.Have a great day and happy hunting!