The most difficult shot ever…

[James Dubendorf]

A few more thoughts. Is this the dreaded “jello effect,” caused by object movement rather than camera movement? If so, is there a way I could have manipulated a variable like shutter speed- can having too fast a shutter speed, for example in bright light, make the effect worse?

Thanks,
James

[Mike Kujbida]

James, can you post a link to a YouTube Clip so that we can see what the problem looks like?

[James Dubendorf]

Mike,

I certainly can. The video is here:

https://www.youtube.com/watch?v=Ic44eC5wSe8

and I would say the most obvious issues are exemplified by the clip from 1:16 to 1:22.

Again, I don’t see what I understand to be interlacing artifacts per se (horizontal lines, mice teeth, etc.)- just occasional hitches in the movement of the chair that are obvious and might be otherwise invisible except for its absolutely constant rate of motion across the screen.

Should I consider shooting in progressive for these kinds of images? Altering shutter speed? I’m ready to try anything!

Many thanks for your thoughts.

James

[Matt Crowley]

It looks like you’ve got velocity envelopes or time stretch/compress on a lot of events/clips in that video. Do you have a slight time stretch/compress on that clip at 1:16?

If yes, and it’s only a small change of speed, then you might just be seeing the jerkiness that results from dropped/added frames. There’s not a lot you can do about it in Vegas, but if you disabled resample on that event, try enabling resampling – that allows Vegas to blend frames to produce intermediate “fill-in” frames instead of just dropping/adding full frames. It might give you a blur or smear kind of look, though.

For ultra-smooth speed changes, you need to consider something like Twixtor which synthesises intermetiate frames using motion tracking and all sorts of image processing that Vegas can’t provide natively.

[James Dubendorf]

Matt,

Thanks for your input. The video does have some velocity changes in it, but not that particular clip. Also, it was set on smart resample. When I view frame by frame on the vegas timeline, there is obvious doubling of the moving elements i.e. the chairlift armbar. Not a lot of blurring, however- the doubled parts of the image are both fairly crisp and distinct from one another. This makes me wonder whether a slower shutter speed might improve things, lose some clarity but gain some smoothness?

I know of Twixtor, but have not used it. Do you think this clip slowed down slightly, and processed through Twixtor, might improve in quality? Can Twixtor improve the quality of clips playing at their normal rate?

Many thanks,
James

[Lori Freitag]

I think the plug-in you are thinking of, that could help this shot, isn’t Twixtor, but RSMB which doesn’t currently work in Sony Vegas but works on many other applications.

[Lori Freitag]

Just wanted to add a little more info..

Two things:
– Twixtor can do a better job at velocity changes than Sony Vegas. When you say there are “double moving elements” that is the result of frame blending that Vegas does. So in this case Twixtor will probably do a better job and improve the quality of the slow-mo footage.

– A slower shutter speed in the camera will produce more motion blur because the shutter is open longer. You were wondering if you will get better results if there is more motion blur in the original clip when you retime it in Sony Vegas because it will smooth the results of the frame blended results Sony Vegas gives. Personally I wouldn’t do that because then everything will be soft even when not retiming with Vegas. You should try Twixtor.