PAL delay line free capture hardware?

[radorn]

I recently learned that PAL color decoding relies on a delay line do average current and previous line to compensate for possible phase errors during broadcast, which, unfortunatelly, also reduces color resolution...

Assuming this technique to be unnecesary for composite/s-video capture from a "local" device (game console to be more exact), I was wondering if there is any capture hardware that can decode each line by itself, without the delay line thing, and thus keeping the full color resolution across the vertical axis.

I actually have a Bt878 based card and I do notice color contamination from the upper lines, even when using a 240p console with no antialiasing, like the PSX , and having single pixel/line details (like a hud line across the screen) contaminate the next line:
http://img847.imageshack.us/img847/122/delayline.png
I may be wrong, but this seems to match the delay line "effect" that I read about in wikipedia and other places.

Strangely enough, I think it also does this when capturing NTSC color, from what I remember when seeing captured shots from an NTSC console I don't currently have at hand.

So, can PAL color be decoded without a delay line, and is there any capture hardware that does it?

In case of an affirmative answer, it would be nice if the capture hardware can also do 480p over s-video (even if this is non-standard) or even RGB, although I know rgb capture is EXPENSIVE... but these are just extras anyway, the main point is being able to do PAL color without the delay line technique and hence the loss of color resolution.

EDIT: SOLVED
http://img824.imageshack.us/img824/7290/nolinedelay.png
Using my Bt878 card with DScaler with "Even Comb" and "Odd Comb" unticked

This also explains why my NTSC captures also had the "line delay effect"

[jmac698]

You can do 480p capture already, probably. Just try it. If there's any picture, it will be the two frames side by side. You just need to unwrap it.

[pandy]

accordingly to Bt878 datasheet, chip allow to capture whole line (with sync) in VBI mode thus You should be able to perform http://www.techmind.org/vd/paldec.html (with modern CPU maybe even in real time)

This mean also that with tricky driver in theory TBC can be performed on BT878 purely in software for extreme high quality captures

[ChiDragon]

I actually have a Bt878 based card and I do notice color contamination from the upper lines, even when using a 240p console with no antialiasing, like the PSX , and having single pixel/line details (like a hud line across the screen) contaminate the next line:

You can't have single-pixel colors in subsampled YUV like YUY2, and as you say, RGB capture cards are rare.

Not sure what your "solution" is since your second capture is a color made of 2 lines.

[jmac698]

Pandy, two great ideas, that I've also thought of. Actually there is a way to do it easily with a filter graph and some filters like testline and dumpfile, I believe. There's opensource drivers we could tweak. I really wonder why no one has done this.
Also you can capture RGB as well with any card, you can also capture component with any card. As long as at least one signal has at least 480i or 480p (576) sync somewhat close to any video standard. Then just connect the other wires to it, to get greyscale, or wires one at a time, if the signal could be exactly replayed, or with a video distribution amplifier and to 3 cards at once, to get 3 signals. The result has to be reconstructed as an exact difference, since the voltage levels will cancel out.
I did this live from component to 3 VCRs and recorded a differenced video. Certain colors brought the signals too far out of spec for the VCRs however. Dark, highly saturated colors would be a problem here, causing a negative signal that could look like a sync.
On the other hand you can create custom video signals by tieing together a few video outputs.
I've tried mixing two video sources but they drift slowly.

[pandy]

I'm not a software guy and it is to late for me to start learning how to code especially drivers under Windows however 878 looks quite promising.

In ancient times (ie when hardware was slow and very expensive) this method was very popular - they use cameras with color filter then they at once grabbed only one component then change filter to second i capture second compensate then third etc - also they captured video tape with help so called time lapse VCR.