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06-30-2012, 08:40 AM
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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.

Thanks,
Charlie


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07-01-2012, 12:22 AM
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There's really no way to correct vertical image jitter after the signal has been digitized. Ideally, you need to use a better VCR. Quite often, you'll fight with the deck to maintain a proper tracking sync. The Panasonic AG-1980P (or comparable PAL model) is suggested for stubborn hard-to-track VHS or S-VHS tapes.

-- Important Note: This is not to be confused with "horizontal jitter", a technical video term that describes timing and sync error. Most notably, image tearing at the top of the screen. This thread is about the non-techincal use of the word "jitter", as it applies to a description of observed vertical bouncing and/or vibrational noise in layman's terms. --

Depending on the exact nature of the image jitter, sometimes a drop-frame deinterlace will remove steady frame vibration. Any number of editing errors can cause this. I've seen it from videos run through Toaster or VideoMate several times to date. Deinterlace is, however, quite destructive to image quality, creating aliasing and jaggies, which must then be re-filtered next. That's done with one of several Avisynth anti-aliasing methods. The end result is an image with relatively decent quality, and next to no jitter. But again, it only works when the jitter is consistently in the same odd or even field range.

For non-field based jittering, you're pretty much screwed. The methods from removing jitter are no different from motion shake (handheld camera shake), and rely on content analysis. I've tried VirtualDub's Deshaker filter, Premiere's now-defunct SteadyHand filter, vReveal's stabilizer, and Avisynth's DePan and DePanEstimate, with no usable results. Each of the filters works well maybe 80-90% of the time, but that other 10-20% entirely screws up the video.

The most potential method to date was the Avisynth script that would have merged QTGMC deinterlacing and Depan, but it the Avisynth filter didn't seem to function properly. Even when set to only address vertical motions, it would track horizontal, too.

Every few years (for more than a decade now), I bring this topic up on various sites.
The most recent time was in 2009 at Videohelp in this thread: http://forum.videohelp.com/threads/3...uction-filters
As always, nothing usable really came from it.

These methods are best reserved for short clips -- usually to help identify somebody in a video. Attempts to use this on an entire tape, episode or movie have utterly failed. It's quite annoying, but I still hold out hope that some mathematicians, statisticians, and/or engineers will one day figure out a better mouse trap for video jittering.

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