Hmm... yes. You guys are spoiled with this SCART
thing :-) SCART has
separate sync? RGBHV? Not hard to build a sync separator I suppose.
Use a LM1881.
I'm thinking a guy could make a major project out
of this and use three
high speed A/D ahead of some ARM based board that could acquire the video,
scale and convert to taste and then output on HDMI. Should be able to
handle lots of legacy analog formats that way.
This exists, and works even for vector displays!