VGA is both a cable connection which you’re already familiar with and [COLOR=#000000]a resolution. I think the resolution aspect of it is throwing you off. If I’ve been following everything correctly, the signal has to be a minimum of 480p for the thing to work in addition to using the VGA cable.[/COLOR]
I think it’s designed this way so it has the space to insert the scanlines without taking away from the image of the game. Inserting scanlines into a 240p image takes away half of the artwork. Forcing scanlines in a 480i game has similar problems, as the entire image would be covered up half the time, since every other line is blanked and interlaced signals alternate between even and odd lines.
However if you upscale those images to twice to progressive scan, you end up with the redundancy necessary to insert a blank line. Basically the end result would be 2x2 blocks being turned into 2x1 blocks to emulate the space being taken up by the scanlines, instead of directly blanking out 1x1 blocks that you should be seeing.
It should first be noted that RGB signals are also outputted byt the SNS-001 and the Pal Gamecube. Nintendo stopped using it in North America 'cause they realized we didn’t actually have the means to benefit from it.
Though to answer the question, I’m not too well versed in how arcade tech works but I think insofar as home consoles go it emulates the scanlines you’d see in interlaced material on the CRT televisions these consoles were designed to run on as well. Since s-video, composite video and the RF switch produce a 480i signal, half of the image would be blanked out at any given time.
Granted, this doesn’t seem to alternate in a flickering pattern between even and odd lines as an interlaced signal would or at least so I would infer from the switch toggle needed to chose between blanking out odd or even rows of pixels. It’s an important part of the effect, as your mind would use the residual data from the last field to extrapolate what the image should look like going into the next. In this way you wouldn’t notice the blank and keeping in mind that pixels are a limitation of the monitor and not the mind, things may’ve theoretically appeared less blocky than they actually were as lines faded together.
Still it’s still a bit more authentic than seeing the whole upscaled image at once, where you’d have two rows of the same colors as either the pixels above or below duplicated with no space between the individual pixels that make up the image. I think your mind would still fill in the blanks to a degree once the mosaic effect kicks in when sitting a reasonable distance away from your monitor as a home based system would assume and more importantly, the colorspace should have greater acuity because you have more black to act as a counterbalance to the bright colors of the game generated footage.
For a more technical understanding of the jargon involved:
On another note:
I’m curious about this too. I think the XRGB throws in scanlines as part of the scaling process which is what allows it to upscale so quickly. Instead of guessing what color every second row should be filled with to make an interlaced signal into a progressive scan one, it just ignores the details and puts in black wherever the image is lacking. This appears to throw them in after the upscaled image has been outputted, giving this the more effect of a post-processing filter that infamously creates input lag. Then again, the process of blanking out every other line is so logically simple that I’m probably just splitting hairs here.
Even if it’s laggy and I’m not necessarily saying it is, it seems like a beautiful device to have for a screen capturing setup though, especially if you have a 15 khz syncing monitor with RGB passthrough… It may allow you to better emulate the experience you wish to share in ways not possible otherwise (while saving you much hassle and a pretty penny on importing the XRGB), as standalone scanline generators are otherwise unavailable.
Game Console>Monitor>BNC-VGA cable>Scaler>Scanline Generator>Screen Capture Device>PC>Hard Drive>Video File>Youtube HD video file.
Or how well would a VGA splitter work if I went from Game Console>Upscaler>Splitter>Monitor|Scaler>Scanline Generator… instead?
