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Dejitter video without affecting pans and zooms?

hi there,

I was reading a discussion you had in the forums regarding fixing a jittery video that resulted from VHS tracking issues. I too have been having a lot of problems with this myself doing VHS to digital format conversions. It really is frustrating to say the least. I wonder if you've found any kind of a solution or a program that helps to fix this or minimize the jitter without affecting pans and zooms that are part of the video?

Any information you could help with would be greatly appreciated. Feel free to shoot me an email at xxxxx@gmail.com.

Thanks,
Charlie

Note: charlie92155 comes before the @gmail

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Quote:

Originally Posted by via Email or PM (Post 22247)

I wonder if you've found any kind of a solution or a program that helps to fix this or minimize the jitter without affecting pans and zooms that are part of the video?

I wish. :(

However, that's something I'm actively working on, with forum member jmac698. I'll be sending him some sample tapes and discs this month, for this very purpose. I've come across a perfect test clip, and we may be able to come up with a way to alter existing demotion Avisynth scripts.

At the moment, all "dejitter" filters work by using demotion algorithms, which have a habit of falsely picking up pan motion. Even when you limit the axis to adjust vertically only, it'll confuse pans as jitters, and mess up the motion of your clips. The existing filters need to be made more content aware. Demotion filters are really rather basic at the moment, even the ones that impress users.

I have several Avisynth scripts that I've worked with, but none of them are flawless in this regard. At best, I've mitigated damage to extreme motion, like car chases, people dancing, or a person getting up from a chair. Those scenes tend to be a bit bouncy on the screen, as image edge borders leak into the visible image/screen area. But it's the best that can be done right now.

If you want, I can share those scripts.

This is the bane of my existence too.

These days I often just locate all of these frames in my video (usually just a handful) and simply translate the frame back into position. Sometimes you have an instance where you get a bit of a timebase error too, which will cause a slight blur on the bounce, but it is much less noticeable when the frame is not deviating so much from its position.

Here's my script:

Code:

avisource("c:\myvideo.avi")



ConvertToYV12()

QTGMC(Preset="Slow")

SelectEven()



mdata=DePanEstimate(trust=1.0,dxmax=4,dymax=20,range=1,pixaspect=1)

DePanStabilize(data=mdata,cutoff=0.2,dxmax=4,dymax=12,method=1,mirror=0,pixaspect=1)



ConvertToRGB32()

Notes:

(1) You must deinterlace before you can de-jitter. That's one immediate weakness. Of course, by using QTGMC in slow mode, the damage is minimal, if at all. It's also harder to notice issues on already-problematic live-action videos. It's easier to see deinterlacing artifacts on animation and geometrical lines/shapes.

(2) This video has no just vertical motion, but horizontal vibration, hence the inability to set dxmax at 0. To truly "dejitter" the motion, I had to give it some slack.

This method should either be enhanced or dropped/replaced with something newer and better. At the moment, I think this is the best option we have.

To fully dejitter to perfection, you'd do well to automate with this method, then manually scrub frames in an NLE like robjv1 suggests. But the goal would be to fully automate the process, making painful time-consuming picture-by-picture editing unnecessary. You can fix most errors frame by frame. Automation is what matters, because you have 10s of thousands of images.

Discuss. :)

@jacm698: This is the dejitter/demotion portion of the script, as run on the main sample I'm sending you.

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