Strange shaking effect in recording while moving the videocamera

[anegroo]

Hi,

I recorded with my Canon HV20 a video which I want to slow down. So I set the camera to interlaced mode, and I use a script with MVTools:

Source(...myvideo.d2v)
Yadif(mode=1,order=1)
smoothfps(75)
assumefps(25)
function smoothfps(clip source, float fps) {
fp=fps*75
backward_vec = source.MVAnalyse(isb = true, truemotion=true, pel=2, idx=1)
# we use explicit idx for more fast processing
forward_vec = source.MVAnalyse(isb = false, truemotion=true, pel=2, idx=1)
cropped = source.crop(4,4,-4,-4) # by half of block size 8
backward_vec2 = cropped.MVAnalyse(isb = true, truemotion=true, pel=2, idx=2)
forward_vec2 = cropped.MVAnalyse(isb = false, truemotion=true, pel=2, idx=2)
return source.MVFlowFps2(backward_vec,forward_vec,backwar d_vec2,forward_vec2,num=int(fp),den=75, idx=1,idx2=2)
}

The resulted clip as you can see in this video (I put it on Mediafire too) is shaking in strange way. I tried to stabilize it with Deshaker but without succes, because different parts of the image moves in different directions. It could be a problem of mpeg2 encoding during the capture because of the constant motion of camera. What do you think? The uploaded video have two parts, in the first I only deinterlaced and resized the original, in the second part I used Bob, Slow motion script and resizing to 720p.
Thanks

[poisondeathray]

HV20 uses a CMOS chip which has a rolling shutter - different parts of a frame are exposed at different segments of time.

This makes it prone to jello shakes from vibrations, skewing on pans, and flash banding

CCD sensors are immune to this

Search for "rolling shutter" , "CMOS" , and "CCD" on google

Deshaker has partial rolling shutter correction (it can help reduce the skew) , but cannot help the "jello"

example of what skew looks like on CMOS camera
http://www.vimeo.com/6894404

example of CCD vs CMOS when vibrations are present
http://www.youtube.com/watch?v=UEaDrS-yzIE

[anegroo]

Thank you very much poisondeathray!

Now I understand the source of problem. I have found on this page (post#24) that in Deshaker we have to set the Rolling Shutter amount to ~40% for HV20. This way the results looks better, but no perfect because of "jello"as You warned. There are no other way to improve the correction?

Thanks

[poisondeathray]

No other way to improve it after it's been recorded. You can improve the skew by various methods, but not the "jello" very much

There is an expensive plugin for After Effects and Nuke, called RollingShutter by The Foundry, and it improves the jello a little bit (but still not perfect)

Jello is almost impossible to fix, because there are different motion vectors all moving at different velocities with different acceleration/deceleration

You have to pay more attention to shooting technique next time