@neuron2 - "Shake filter"

[DDogg]

First, so good to see you here!

I was wondering if you could speak a bit to the subject/theory/possibility of filtering hand held camera "shake". I do remember somebody did something like that sometime ago, but I seem to remember it either went commercial or it dropped out of sight.

IMO, *quality* re-encoding of DVCAM source to svcd is an unrealized dream (certainly for me) and is problematic due to the precious bitrate wasted by the frame differences due to the shake.

IYO, do you think a method of filtering/smoothing the frame difference is doable without adversely effecting the output?

I do realize no filter can ever fix silly fast pans and zooms caused by poor shooting, but I was hoping a specialized filter could at least moderate the huge hit on svcd encoding by removing some of the minor jitter.

DD

[OUTPinged_]

more to that.

I recently wrote to DGraft about a filter which could "stabilize" a small 1 pixel shakes on a poor mastered dvd source.

He told me the filter will be very complex and he doesnt have a time to make one. Any ideas on that one?

DDogg: it is commercial now afaik, if you have mentioned "digistudio's something stabilizer filter"

[DDogg]

Yes, I got a similar answer about the complexity involved. When DG is finished with DCOMB (great work) maybe he will have time to look at it. If anybody could do a filter for jitter I think it would be him.

[sh0dan]

A stabilize filter would involve some rather serious motion estimation algorithms similiar to MPEG.
For each frame there must be build a motion vector grid, that contains information about which direction the image is moving. Then a smart algorith has to see if there is a general movement in the entire frame.
The algorithm may not be confused by any part of the image moving and see this as general movement. On the other hand the algorithm will probably not be able to detect movement in flat-colored areas, so event though it seems like some part of the image isn't moving the filter may not think the entire frame isn't moving.

So you see, doing a stabilizer isn't an easy job, and the companies that sells software that does stabilizing has probably worked some time on this software. I'm not saying it's impossible - just that it isn't as easy as it may seem.

[trbarry]

I've thought about it from time to time but never come up with anything I really liked. It might be possible to correct single line vertical jiggle that only lasted for one frame but I'm not ever sure how easy that would be.

- Tom

[sh0dan]

The worst case scenerio would probably be a vertcal scrolling picture (end credits for instance). However if you intruduced a one frame lag the result should be ok.
However the very small amount of jumping you would be able to filter out would probably not be worth the big amount of processing time required. Do you have any movies or cases where if would be useful?

[trbarry]

The reason I considered single line vertical jitter the case where there is a sharp horizontal line. The smallest amount of vertical movement may be amplified as an entire scanline of motion.

But much or most visible jitter is probably just a result of interlace and the attempts to get rid of it.

I'm not actively working on this or even intending to try it in the near future. But over on AV Science they are talking about the new Terenex scalers that use motion compensated deinterlacing and it got me thinking about it again. For only a few tens of thousands of dollars you can have a home system with a supercomputer in it that will do all this. ;)

- Tom

[Taranli Maren]

it seems that in the case of the poor dvd mastering at least, that you wouldn't have to go the whole motion estimation route. Istead just overlay each frame on the previous, and adjust to the lowest possible difference around the edge.

I'm not a particularly competent programmer, so I could be completely wrong. I would very much like to see a filter that at least does this to some extent, even if it didn't work perfectly.

Taran'li Maren

[vidiot]

http://sandman_mmc.tripod.com/steady.htm

look there - it should deinterlace (main purpose) but could do (following the author) better stabilizing then comercial Versions for VD...

I forgot to mention: It´s a combined VD + Avisynth filter...

have fun

Harald

PS: Don´t make wishlist for Mr. Graft - I would like him to concentrate on Decomb...
(Just kidding) GREAT WORK by the way!

[ronnylov]

I have tested the steady deinterlace on my miniDV-source an yes it removes shaking from the video but it is also quite blurry when there is much motion like in my home videos. The steady deinterlace filter I tried was a virtualdub filter but avisynth was needed to feed it with field separated double framerate video.

Another option which does not have anything to do with avisynth is to use the software "Dynapel Steadyhand" which does a good job. There is a free demo available on their homepage but there will be a logo in the output from the trialversion.

http://www.dynapel.com

The dynapel can also handle interlaced video but the steady deinterlace removes the interlacing (not so strange becuase the purpose is to deinterlace). The output is double framerate (50 fps for PAL). I am a newbe when it comes to avisynth but is it possible to convert a 50 fps progressive video back to 25 fps interlaced using avisynth? I am also interested in how to best compress interlaced sources with divx in a progressive frame way that I can use to backup my DV-video and later restore the interlacing. Any good ideas of a avisynth script that can do this? The video does not have to be playable because if I need to restore the backup I will convert it back to DV-type AVI and back to tape. It's only for video backups on CD-ROM if it's possible.

[DDogg]

Damn, this dynapel really seems to work! I had a couple of sharp short jerky pans in a video my kids were doing. I was shocked to see them removed. Looks like they may have something here but I have only looked at it for a few minutes. Works on DV-Avi and other AVI.

Thanks very much for the link.