This document paves the way for my upcoming series on the Micomsoft XRGB-2 Plus Upscan Converter. Since I tend to readily drift into jargon, I thought I'd write a primer of sorts to explain some jargon I use, which is unavoidable in the subject matter. I will also expound on the virtues of various video signal formats and give a certain corresponding cable manufacturer a plug — or, as G. Gordon Liddy would say, give time to some crass commercial messages. Mind you, I don't mention a manufacturer or supplier without good reason.
Most people who play video games on a console are generally happy to view these games on a television screen. The quality of the image varies enormously, depending on the quality of the screen itself and that of the video signal. For some gamers, however, nothing but the best image possible will do. One method to achieve a better image is to get a high quality television, one preferably equipped with component video inputs if you live in the United States, or SCART inputs in the UK, Europe, Australia or Japan. The cost of this approach can skyrocket quickly, but the results can be very satisfactory.
A second approach is to use a VGA monitor. Due to the requirements of modern computers, the quality of the cathode ray tube on a VGA monitor is generally far superior to that available on a television. Most, if not all, televisions tasked with displaying a resolution of 1600×1200 or greater would balk at the proposition, and prove incapable of the pixel definition required to clearly display even a page of text at such a resolution. These tasks are well within the capabilities of many VGA monitors.
While there were people happily playing video games on a VGA monitor long before the release of the Dreamcast, my personal epiphany occurred when I first saw the Dreamcast game Expendable on my wife's little 15" VGA monitor. The improvement over a TV screen was simply astounding, and the very next day I acquired a Nokia 445 xi 21" monitor from a second hand computer store so I could properly appreciate the advantages such a display had to offer. I have been using that monitor for several years now and it has given me sterling service. Indeed, as I type these words I am viewing them on that same monitor.
The Dreamcast is unique as it is the only console designed from the outset to be capable of producing a VGA signal, albeit via a simple adapter. The resolution of the image was 640×480 at 60Hz, and using the PlanetWeb browser, viewing sample images on the Internet revealed that the picture quality was close to a PC viewing the same pages at the same resolution and refresh rate. It wasn't identical, but it was very close indeed.
My next question was, could I achieve the same result with my PSX within a reasonable price? Inevitably that same question was redirected at my PlayStation 2 when I acquired one in January of 2001, and courtesy of much research on the Internet, and experimentation with various products the answer is a qualified "YES!" I'd best define what I mean by "a reasonable price". There is a maximum amount the average gamer is willing to pay for a peripheral. Don't forget, money spent on additional hardware is money that can't be spent on games, and unlike PC's with their multiple uses, games are what consoles are all about. The price ceiling for a peripheral appears to be around $300, or the same price as a new console.
I find the number of people wanting to use their VGA monitors with their video game consoles has increased since the advent (and subsequent demise) of the Dreamcast. I suspect many of us, having become accustomed to the image quality offered by the Dreamcast and its VGA adapter, wish to continue as before; a few manufacturers, almost exclusively in the Far East, have expanded their product lines to meet the needs of this niche, but demanding, market. These products have generally been targeted at the low end, resulting in cheap VGA adapters such as those from Redant in Taiwan costing around $50. Redant markets their VGA adapters for the PlayStation 2, GameCube and Xbox. Based on my personal experience of the PS2 version, I can confirm that it does provide a crisper image than that normally available on a TV screen, though at a cost in color quality.
These low-end products are simple line doublers. What is a line doubler, you may ask? I shall tell you. If you were to take a close look at the image being displayed on your TV screen by your video game console, you would see that it is only outputting half the lines on the screen at a time. The lines being displayed are separated by single black lines. This display technique is known as interlacing and was invented in the 1930's to address deficiencies in the display technology of the time. Which lines are displayed varies. Initially it is the odd numbered lines, and with the next frame it is the even numbered lines. Run this sequence thirty times a second, and the eye is fooled into thinking it is seeing a solid image. In actuality you are seeing sixty pictures a second for a total of thirty frames a second.
A line doubler fills those missing scan lines by accumulating information from the image, creating a signal that can be displayed on a VGA monitor. The quality of these peripherals is enormously variable; as a rule of thumb the more you pay, the more you get.
That's not the end of the story, however. You also need to pay attention to the video signal itself. Most people, I'm guessing, bring their new consoles home, plug in whatever audio/video cables came with the console, and rarely think beyond that. But when you are thinking about displaying your console's picture on a VGA monitor, the signal quality becomes extremely important. Not only that, the cable quality also becomes extremely important.
In the United States, there are four commonly encountered types of video signal and accompanying cable.
RF — This is the cable that plugs into your cable or antenna socket on the back of your TV. It is the worst possible signal you can get, carrying as it does not only the video but also the audio signals, and with it all kinds of possibilities for interference. The result is a noisy image, rife with crossover artifacts. Nowadays, only older televisions need the after market RF adapter that is always made available for whatever consoles are released. For our purposes, you should refuse to even consider that such a thing exists.
Composite — The default cable accompanying a new console. The video signal travels through one cable, and suffers from interference. Because the left and right audio signals are separated, the result is a cleaner image than RF, but due to crossover artifacts, the image is still noisy. Ideally, you should never even consider that this cable exists, at least not for our purposes.
S-Video — Also known as SVHS and Y/C, the jump in image quality from composite to S-Video is the biggest in the list. The luminance (brightness) and chrominance (color) signals are kept separate, and the interference problem is much reduced. For our purposes, this is the minimum signal quality we should be considering. At this point it is worth considering the cable itself, as worthwhile improvement can be gained simply by switching to a better cable. I once did a review of Monster Cable's GameLink 300 S-Video cable for the PlayStation 2 in which I compared it with Interact's S-Video cable, and there was a noticeable improvement. In the gaming world, Monster Cable's products are preferred.
Component Video — Also known as YPbPr or YCbCr or Y,R-Y,B-Y, component signals are matrixed to reduce bandwidth. That is, the signal components are derived from RGB by adding or subtracting them to get the new components. Adding Red, Green, and Blue together in a specific formula (30% Red, 59% Green, and 11% Blue) to make a black and white signal derives Y, the luminance component.
R-Y (or Pb or Cb if you prefer) is derived by taking the newly created luminance signal and subtracting it from the raw Red signal. Since there is already a luminance signal (Y), this information is redundant, so it is subtracted, leaving only the color difference component for red called R-Y. The same process is performed with the Blue signal, subtracting Y from it to leave only the color component of blue, B-Y. We do not need to make a G-Y component because the signals created already can be matrixed to get what's left, which is Green.
There are a few other formats, such as SCART, a form of RGB found primarily in Europe and Australia. The color image is split into three entirely separate signals, Red, Green and Blue, each with their own luminance. Synchronization is carried either on the Green video signal where it doesn't interfere with the color signal, or as a separate signal, either a composite signal, or separate horizontal and vertical synchronization signals. The PSX RGB cable terminates in a 21 pin SCART plug that also delivers the audio signals.
SCART is one variation on RGB; VGA is another.
Japan also has its own video formats. There is D-Terminal, which is component video by another name; the only console that outputs this format is the GameCube. Another Japanese format looks like a SCART connector, but is wired differently. Calling it Japanese SCART is sufficient to differentiate if from Euro SCART, but the term is technically incorrect. It would be more nearly correct I suppose, to call it Japanese RGB. In theory, SCART and Japanese RGB should provide the best image quality possible, though in practice I have yet to see much difference on the equipment available to me. Should you accidentally get a Euro SCART thinking it is the Japanese format, you should know that it is reported to be possible to rewire the cable, but that it is a serious pain to do.
With the GameCube and Xbox consoles, you may have read that they support a video signal called 480p. What is this, you ask? Essentially it is a form of VGA. Its pixel resolution is 640×480. To make use of this signal, the consoles in question must be equipped with a component video cable or, in the case of the GameCube, a D-Terminal cable. If you run this format through a component-to-RGB converter, such as those manufactured by Audio Authority or Key Digital, you can plug your console directly into a VGA monitor. Games must specifically support this feature, otherwise the video signal is essentially 480i. The 480 refers to the number of lines on the screen. The "p" means "progressive" referring to the scan mode, and the "i" means "interlaced" for the reasons discussed earlier. A line doubler converts an interlaced video signal into a progressive video signal.
It is curious that all three of the current consoles could output a VGA signal if the designers had wanted them to. 480p is, as I have stated, VGA by another name. How hard could it be to produce a VGA cable for the GameCube or the Xbox? Yet, for some reason, Nintendo and Microsoft decided not to include this feature. Even Sony's PlayStation 2 can ouput a VGA signal, as evidenced by their Linux kit. It is accompanied by a VGA cable and it works with a VGA monitor. Despite the apparent success of Sega's Dreamcast VGA Adapter, the decision was made not to develop VGA cables for the current generation of consoles.
So it is that I find myself investigating products such as the Micomsoft XRGB-2 Plus, and gathering information with respect to the Audio Authority and Key Digital component to RGB converters. Should I ever get my hands on a one of the latter two companies' products, a review will be forthcoming.
This article is copyright (c) 2002, 2007 by Ken Gagne. All rights reserved. Not to be distributed without permission.
Original publication: Gamebits, 13-Mar-02