> IMHO here lies a problem. Nearly all capture cards, where not designed to capture the > "whole" frame. Even in the Firefox thread, you will not see such a capture (starting > with page 1). Professional equipment will capture VBI data, but not the whole frame. > You may achieve this with hacked videodrivers, but this is not recommended and a > ideal solution at all. I consider it very hard to do it the right way, especially if > you want to keep the interlace/fields intact, which would be crucial for further > processing. To be honest, i could be wrong here as i never seen the original > captures, but i think the captures from Aaron have errors regarding this topic. We > only need to know, which lines of the VBI data are needed, but we dont need the whole > frame, this will cause only trouble. This is the reason why i asked if the software > for proving captures, could be rewritten. Professional equipment doesnt work that way > (cheap stuff neither), like it is expected in the article of Aaron. So the approach > of the LD tool in MAME is wrong, regarding the VBI data, as it is expecting the > "whole" frame (525lines). > > Which brings me to the last point. Yeah, you can hack all kind of stuff, like the IR > remote for exact frame jumping and what not, capturing straight from the laser lens > to your eye. I think we should avoid as much as possible of this hacks. The > interlace/fields, analog sources/noise, VBI data etc. all of this, is very delicate > and very picky and with a single shifted scanline, you will break all your capturing > effort into useless shit. Keep it simple, treat the source right, capture it > uncompressed/lossless and thats it.
Could you expand on this please? As I understand it, part of the issue with laser disc support is the ongoing discussion of accuracy.
Disclaimer: I'm not presuming to question MAME design decisions, I'm just wondering about a different path.
What caught my attention is this: What you're proposing sounds to me like you're discussing the capture of the parts of the "frame" that are relevant to the game and disregarding the parts of the "frame" that are present only because of the requirements of the co-opted technology (Laserdisc).
I'm wondering if that is an interesting discussion point as MAME doesn't attempt to emulate all of the intricacies of the underlying technology (Not counting discrete circuits). MAME isn't attempting to emulate any frequencies outside of the human range of hearing for example, so I'm wondering if not grabbing unused frame information might be similar?