Residual interlacing and other VHS capture issues

[ajk]

Hello guys,

For some reason finding an answer to my question has been surprisingly difficult by just searching the forums so I thought I would ask directly for a change.

I have been doing some PAL VHS captures lately and there is one thing constantly bugging me. When capturing material that is originally of film source, I always seem to be left with a little bit of combing between the two fields (I use a Panasonic VCR that has a TBC of some sort in place, but I haven't been able to overcome the issue in hardware. Tape was originally recorded on some other VCR). Usually it isn't a steady 1 pixel shift or anything either but fluctuates slightly.

Now, what I'm asking is, not the "best", but let's say a conceptually correct way of getting rid of these combs. Obviously most smart deinterlacers will remove the effect, but all also seem to involve some manner of blending or interpolating which seems to soften the image overall. Is there a method that would actually be able to move the lines around for a best match so to speak? This isn't actual interlacing after all, just a problem with the field based nature of the capture/recording. I'm thinking a motion compensated bob would probably handle this somehow but have yet to try it out due to the horrible CPU needs.

http://users.tkk.fi/~akorhola/combing.png

A screenshot there and a small lagarith clip (http://users.tkk.fi/~akorhola/clip.avi) of some example capture.

There are also other problems in the image, haloing, colour bleed and stuff that I will have to tackle, I have had more success there but any tips are still welcome.

[Boulder]

I don't know if there are any comb filters for PAL..try VInverse perhaps? You should be able to find it using the search, I think tritical made a plugin out of Didée's original function.

EDIT: here's VInverse : http://bengal.missouri.edu/~kes25c/vinverse.zip. Here's the thread where it emerged from: http://forum.doom9.org/showthread.php?t=82264&highlight=vinverse&page=20

[davidhorman]

With such a source, I think you could do a lot worse than just vertically blurring followed by a little sharpening:

http://img14.imgspot.com/u/07/158/06/decomb.png

The chroma noise could do with a cleanup beforehand, though.

David

(hope you got to see that before imgspot mysteriously deleted it)

[Malcolm]

tomsmocomp(0, -1, 1).lanczosresize(clip.width, clip.height) does a good job too! You can choose different resizers to vary the degree of blurring.

greetings,
Malcolm

[ajk]

Thanks guys,

I was really after some method that could actually gently bump the lines back in order (if feasible), but considering the other qualities of the source all of the above solutions seem to be quite fine. Time to encode!