...maybe using DePan and MVTools in conjunction?

maybe you try yourself?

Why, is a purely theoretical discussion a sacrilege?

Hi, IMHO Depan is not useful (modern mvtools make global compensation too). Perhaps a limited de-jittering could be done after 2x horizontal/vertical resizing, mvcompensating with a blksize of 4 and resizing to original size again. But practise is the best master.

dejitter for AVS and vhs sync restore for VDub only seem to work with hard thresholded values for the beginning of the active video area. But this is bad if the active video starts with a slow envelope. thi means: if the video contents are bright it recognizes a earlier (more left) start and if the contents are pretty dark it recognises a later (more right) start of the (virtual)sync. so both are more or less useless of low jittered sources (one or two pel offset)

there's a dial for contrast too :) clouded had a pretty good looking solution a while ago, but i don't think it was released. that involved strong vertical blur + GMC on each line. i'm sure that could be sped up considerably...

i think what would be really cool is a way to get at the data that capture cards work with - record it in a similar way to PCM audio. then a codec could be designed that performs these operations on the actual sync data. not sure if this is possible at all, because as far as i know most hardware doesn't allow access to that kind of info.

It can be done to a certain extent. Virtualdub's bt8x8 tweaker allows the left border to be pulled out far enough to see the color reference signal, which in theory should be at the same horizontal location for each line. For more damaged sources (when the card can't find hsync) it's possible to hack the drivers to at least get something back besides a blue screen.

TBC built into capture cards 

Here's a practical idea then, put the unstable source through various devices that might have a good chip (called a video encoder). For example a set top cable box (analog in to firewire out), a dv camcorder (analog in to firewire out), or of course any bt848 or bt878 based tv card. I recall, some high end Sony consumer decks had digital still frame, and probably built-in TBC. So just record on some good equipment. If it's already digital and can't be re-recorded, I would say find the black pixels from either edge and resize to 712/704 pixels line by line. If the picture is black you can't find the edges, but then you don't need to worry :) I agree with scharfis_brain's idea. I don't agree that you need to see the original sync, the rec.601 is extra wide on purpose (720 pixels instead of 711) to be able to capture the transition pixels. A TV broadcast is very highly stable, the VCR is highly unstable *over small time periods*, and detecting the active line should be all that is necessary, sync just makes it easier to detect. You're not losing information. Adjusting to rise time can be calibrated to the source by examing some white or dark lines. Resizing must be done with a sinc based resizer such as lanczos. You can adjust brightness and contrast to see blacker-than-black but at the same time not wash out the picture. I've been able to see a few pixels of not sync but purposely blacked out inactive area from a source this way.