Any thoughts?
always
Can you go into more detail about this, or point me to a review you might have written that describes this? I re-read your explanation above, and it wasn't too clear.
I haven't put it in a review before, but talked about it quite a few times here on board. Let me try to explain it again.
Before we have a look at true hi-res material (Naomi) think for now about genuine 240p titles running linedoubled through VGA. This includes Capcom and SNK titles running on a Dreamcast, early Cave titles on the 360 or the majority of titles within MAME. On a perfect conversion (let's take Futari or Deathsmiles) every single pixel gets represented by a 2x2 Pixel cluster.
If you perfectly linedouble a 240p signal (without interpolation) you always get 2 identical lines next to each other. 1+2, 3+4 and so on. To downconvert to 240p the Genious throws out every second line, which is no problem, since no information is lost. It also gets you back the original lines of the 240p image. The UVC and Emotia on the other hand, blend the lines. If you blend red and red you get red, so blending lines 1 and 2 into one would be fine, 3 and 4 into one as well, but unfortunately, that's not what the units do. They blend lines 2 and 3 and 4 and 5. Lines coming from different lines of the original 240p image and that is what causes the misalignment and missing "kick" (in terms of sharpness and pixel perfection).
By shifting the incoming image one line up or down before handing it over the the Emotia/UVC you can correct this. Add a black line on top (it's ignored anyway) and make lines 2 and 3 identical, so blending them will result in a perfect match.
This would especially be a problem on diagonal lines, throwing away 1/2 the resolution will result in jagged lines/edges. Blending will not be as sharp as the 480p source, but the line will look smoother / more realistic.
And here you're talking about someting completely different. You're no longer thinking of MAME or the arcade versions of Futari or Deathsmiles, but you're thinking of "real" hi-res titles - something like Guilty Gear X, Gradius V or the 360 versions of Akai Kaitana or Mushihimesama.
Here I am completely agree with you, downconverting those to CGA/240p doesn't make any sense. On a tri-sync cab, I would keep those at 31khz. On an older cab, either 24khz or 15khz INTERLACED is the best option. 24khz downconverts from 480 to 384 lines, which can look nice, but you already lose quite some details. 15khz interlaced (480i) keeps most of the details at the expense of a little flicker.
In the end it's matter of your sources. A down conversion to 15khz progressive is something for titles which have originally and genuinely been 240p no matter what. While a few people would play Guilty Gear X in 240p, I would definitely recommend another approach for those "hi-res" titles.
