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Expert
Posts: 134
Registered: ‎02-04-2015
Message 11 of 19 (1,545 Views)

Re: Best way to deal with rolling shutter


pmcstudios wrote:

If you want to avoid this in the future shoot such moves slower or at 48 frames instead of 24 assuming you shot your project in 23.975p. Then when you drop the clip on your timelime in your NLE just speed it up 2x and it will look smooth compared to your 24 frame tilt move. It doesn't have to be 48 frame, bye the way, it's just easy to deal with. Experiment.

 

Kent


Could you elaborate on that? Why would you shoot in slow motion and then speed it up to bring it back to the same speed? 

Specialist
Posts: 75
Registered: ‎09-25-2015
Message 12 of 19 (1,541 Views)

Re: Best way to deal with rolling shutter

You are doubling the frames. 48 vs 24 in my example. The reason 60i looks much smoother than 24p is that there are more images over the same amount of time. Yes there is interlaced vs progressive (another discussion).

When I am building an After Effects comp and want to stay in progressive mode I never build it in 24 frame. Swish pans and other quick camera moves often look terrible without a lot of motion blur applied because of the 24 frame shutter effect. I build it in 48f or 60f.

These frame rates delt with correctly on your NLE timeline won't be in slomo. They will appear in regular motion but with greater motion clearity. Without stutter. I don't use this technic for everything. I want the 24 frame filmic look for most stuff I shoot.

So if you are shooting at 24p (or 30p) for smoother motion, shoot the shot at twice the frame rate in S&Q mode 48p (or 60p). If you drop it on your NLE timeline you will see it plays back in slomo. The usual desired effect. In this case we want regular speed motion so simply apply 2x speed to the clip. Now you have regular motion without the 24 (or 30) frame shutter effect on quick camera moves.
Expert
Posts: 134
Registered: ‎02-04-2015
Message 13 of 19 (1,538 Views)

Re: Best way to deal with rolling shutter


pmcstudios wrote:


These frame rates delt with correctly on your NLE timeline won't be in slomo. They will appear in regular motion but with greater motion clearity. Without stutter. I don't use this technic for everything. I want the 24 frame filmic look for most stuff I shoot.

So if you are shooting at 24p (or 30p) for smoother motion, shoot the shot at twice the frame rate in S&Q mode 48p (or 60p). If you drop it on your NLE timeline you will see it plays back in slomo. The usual desired effect. In this case we want regular speed motion so simply apply 2x speed to the clip. Now you have regular motion without the 24 (or 30) frame shutter effect on quick camera moves.

Still don't understand how a "greater motion clarity" is possible assuming your timeline's baseline framerate is 23.98p. If that's the case then the motion simply can't be represented with a greater temporal resolution as in a result it is represented with the same number of fields (there are only 24 stages of motion per second). It would only work if your timeline's baseline frame rate was greater than 23.98p, for example 60p but then the part with slowing it down does not make sense, not to mention that why wouldn't you simply shoot it in 60p to begin with? 

Expert
Posts: 466
Registered: ‎12-01-2014
Message 14 of 19 (1,514 Views)

Re: Best way to deal with rolling shutter

This sounds interesting but I don't get it either unless the playback had 2 fields, but as its  a progressive tineline it shouldn't right? Or am I missing smething ?

Not a post expert, but I once had lots of problems with stuttering on pans of  models ships with vertical rigging details against a black background. Nothing seemed to help though - not a slower shutter speed, switching to 23.98 nor shooting in interlace. Looked horrendous to me but the client loved it. Would love a solution for next time.

Expert
Posts: 2,286
Registered: ‎11-23-2012
Message 15 of 19 (1,498 Views)

Re: Best way to deal with rolling shutter

I don't get it either as ultimately if the playback is 24fps or 30fps progressive that will be the limiting factor. Shooting at 48 fps and playing it back at 24fps will give less juddery pans, but then so to would shooting at 24fps and halving the pan speed.

 

One key factor with stutter is sharpness. Our visual system can't see a solid color move, all it can see is edges. So you see edges or fine lines skip from one frame to the next. The sharper those edges the more noticable it becomes. So as resolution and contrast increases the problem becomes worse (black text on a white background is going to flicker/judder much more than colored text on a colored background).

 

Also when down converting from a higher resolution to a lower one without proper anti-aliasing the flicker will increase as the edges become more defined (an edge that is a 4 pixel slightly soft gradient in UHD/4K becomes a 1 pixel wide instant move from one level to the next). Shallow DoF is a huge help as only a narrow part of the image is in sharp focus so flicker in the background is reduced significantly. It's one of the reasons why modern video tends to flicker more than film. Film stocks were typically 100ASA so required large apertures no matter what you were shooting. Most video cameras now have 1600 ISO + sensors and often matched with f4 or slower lenses. Shoot anything wide and the DoF is huge, so lots of potential for things in the shot to catch your eye and flicker.

Enthusiast
Posts: 5
Registered: ‎01-06-2017
Message 16 of 19 (1,484 Views)

Re: Best way to deal with rolling shutter

OK, Alister, what you're saying makes a great deal of sense. I have been shooting 3840x2160 29.97p.  AND,  the most pronounced stutter came from using the Sony F4 lens that came from the camera.  So, I'll try different combos of ISO and Frame rate. Meanwhile, you mention adding proper anti-aliasing when downconvering.  I'm using Sony's Catalyt Browse to downconvert to ProRes for editing in FCP.  I don't see any option for antialiasing. How can I add that step?

Expert
Posts: 2,286
Registered: ‎11-23-2012
Message 17 of 19 (1,473 Views)

Re: Best way to deal with rolling shutter

You would probably get a better result by editing at UHD and then downconverting on export from FCP. I don't think the down conversion within Catalyst is very sophisticated and this may be a part of the problem.

 

I think you'll find that it is a combination of all the factors discussed here that is leading to the problems you are seeing. So the whole workflow needs to be looked at. Shooting at 24fps or 30fps even with progressive should be OK. Use a 1/60th shutter so you reduce motion blur without adding un-necessary stutter. Don't add any in camera sharpening. Shoot with a reasonably wide aperture to keep the DoF slightly shallow so backgrounds are a touch soft. Then be careful with your pan and tilt speeds. The speeds that work best will depend on the focal length. Very fast pans are typically OK, as are very slow pans. It's the in between speeds that can cause the biggest problems.

 

Then look carefully at the workflow. Use a very high quality downconversion to HD. If you find the HD looks jaggy, over sharp or jittery try adding a very slight blur to the UHD (1 to 3 pixel blur) BEFORE you down convert it, this acts as an antialiasing filter. It's amazing how much difference there can be between down conversion processes. I use Adobe Premiere and it's media encoder and this does a pretty good job most of the time.

Rookie
Posts: 2
Registered: ‎03-18-2017
Message 18 of 19 (999 Views)

Re: Best way to deal with rolling shutter

 

still issue ??

 

 

www.tecradar.in

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Expert
Posts: 303
Registered: ‎03-29-2013
Message 19 of 19 (974 Views)

Re: Best way to deal with rolling shutter

I would shoot 29.97 not 23.98... so many things just look funky at that frame rate.  And then you distibute on broadcast TV all kinds of thing can go wrong. 

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