Loogs wrote:How about an XRGB upscan converter? I'm not sure about the compatibility with US systems/TVs. Apparently, it acts as a soft mod for the original signal (composite or S-video) to output in a sharper VGA, and can act as a hub for plugging in all consoles.
OK, lets get a few things clear first:
For starters, you can't get signal quality for free. Plugging an S-Video connector into a XRGB (or any other upscan converter) doesn't gain quality. Your output signal is only as good as the weakest link in your chain. If S-Video is the weakest link, then that's the quality you'll get out of the VGA output. There's no "soft mod" or any such nonsense happening there.
All the XRGB does is double-scan the signal. So for every line it gets via input, it pushes two lines as output (simplified explanation for standard PAL/NTSC progressive scan low res modes - interlaced modes are slightly different, but the idea is much the same). You can't magically make the signal better just by double-scanning.
It's like taking a low-res image and resizing it in a graphics program like GIMP or Photoshop. Scaling the image doesn't add resolution, it just scales pixels. Likewise if the original image was blurry and ugly, the resulting image will be just as bad.
If you want good quality signals out of your consoles, you need to take the best, native signal it can produce. There's no magic way to take a crap signal and make it better ("shit in, shit out" as they say). For most third generation and younger non-HD consoles, that means RGB, falling back to S-Video in a pinch.
A lot of these consoles will allow you to get RGB straight out of their multi A/V outs at the back. For my own setup I've made a generic RGB/SCART plug for my arcade monitor so I can just buy a SCART cable for most of my consoles and get output directly that way. For older consoles that didn't offer the RGB out, there's usually some way to hijack the signal off the main video encoder chip and add your own connectors directly.
In order of quality (worst to best) you are looking at:
1) RF (arial connectors) - All video and audio signals mashed in together and transmitted over radio frequency. Lots of interference, and ugly.
2) Composite (typically yellow RCA "A/V" plugs). Video is transmitted as Luminance (Y), or the brightness (i.e.: the black and white image, just how black and white TVs worked), Chrominance (C), the colour part, and finally the sync signal. These signals are sent down the same wire. Audio is on separate wires which makes the signal much better than RF.
3) S-Video. The Luminance (Y) + sync, and Chrominance (C) are split into dedicated cables, giving less interference in each signal. The end result is a noticeably better than composite. Some consider this a type of "component" cable (as the signals are broken into components), but I consider it somewhere in the middle.
4) Component. And here's the silly part. In marketing language, component is how they refer to YPrPb cables. Technically speaking anything that breaks a signal into components is a component cable, but to avoid confusion I'll stick with the marketing name. Signals are broken up into Luminance (Y) + Sync, Chrominance shift from red (Pr) and Chrominance shift from blue (Pb). The end result is a signal that requires much less bandwidth than RGBHV, but should give a mathematically identical signal quality. This compression technique (called YUV or HSV in colour space terms) is also used in other systems like JPEG and MPEG compression (which is partly why it's been so readily adopted by media systems, as going form DVD to YPrPb meant less effort). The upside to component is that it can carry both low def and high def signals easier than RGB. The downside is it requires an encoder/decoder chip pair in order to do it fast enough to be considered realtime. And not many older consoles support it.
5) RGB (also RGBHV, i.e.: Red, Green, Blue, Horizontal Sync, Vertical Sync - and sometimes the H+V are combined into a "composite sync"). It's worth noting that "RGB" can be transmitted over many different sorts of cables. SCART is a common one for low resolution (15KHz) RGB (which uses composite sync by default). High res requires better cabling, and is usually left to VGA cables (which by default requires separate H and V syncs). Some older systems sent RGBHV over BNC connectors as well (anyone who did CAD in the 90's will remember BNC connectors on those giant fixed-frequency monitors). There are plenty of proprietary RGB connectors as well from the likes of Apple and Sun, which are all highly annoying if you need to use them with generic monitors.
Technically speaking YPrPb and RGB give the same quality signal. However I prefer RGB for consoles as it's easier to work with due to being the "native" system for monitors themselves, meaning it's generally very easy to hack into a good quality arcade or broadcast monitor.
6) All digital signals. DVI, HDMI, etc all fall in this category. But they don't make sense for analogue displays like CRTs. I have seen CRTs with DVI ports on them, but for the added cost you're not getting any benefit (unless your device ONLY has digital out, and you're hell bent on using an analogue display, but I can't think of any device with only digital out).
