PLease help with Slowmo editing

[mywayrecordings]

Ok first off I know how to render 60fps to 30fps. im importing properly and all that. I know how to use FCP. The problem i have is with super slowmo. I put two links. First is video i shot with a gopro hero at 720 60fps. I rendered it properly to 30fps. Thats the first of three clips on first link. the second clip is cutting that slowmo in half to 50% and the third clip is going down to 10%. It is all strobbed at 10%. Problem. Ok the second link is shot with the same camera... i promise. Yes i know the gopro 2 they used can do 120fps...but NOT AT 720 so please dont say its that. that camera can only do 120fps in WVGA and if you look at the size of the video and video quality...you know its not WVGA. So all in all... both shots had to have been done at 60fps or 30. How do they get their video to almost stop without strobing. Thank you for anyone who can actuallly answer this properly with out giving me the obvious wrong answers.

http://www.youtube.com/watch?v=57uYRwjTgQs&feature=youtu.be
like i said this is shot at 60fps. rendered to 30. as the first clip. second is the first brought down to 50% play speed and the third is the first clip brought down to 10%

please help

http://www.youtube.com/watch?v=GUEZCxBcM78
Go to 2:12- 2:15 or 2:27-2:29 or the best example at 3:06- 3:24

[edDV]

What software/filter was used? Compressor for encode?

Post your camera original 60p file (just the motorcyle drop).

Do you expect frame interpolation to work at 10% speed?

How do they get their video to almost stop without strobing. Thank you for anyone who can actuallly answer this properly with out giving me the obvious wrong answers.

Who are "they" and how are they shooting?

[budwzr]

OK man, I'll give you the straight scoop. FCP can't do this because it's a toy.

[edDV]

I'm serious. Give us a 5 sec 60p clip (camera original) of that motorcycle drop and let us experiment.

[budwzr]

OK, it's Xmas day, so here we go.

When you convert 60p to 30p, you simply cut out every other frame and lose half the fields. That puts you in the hole right away.

The reason your frames are blurry is because you didn't turn off "frame blending", and playback rate before rendering. To avoid judder, keep your playback rates at the same multiple, like 30/60/120 etc.

This was done with 30p source (YouTube), so it judders, but this is what you're looking for, right? No frame blending. So just keep the video at 60p and adjust the playback rate instead of converting. Look up "undercranking" and "overcranking" at WiKi to get a better understandng of the concept.

[jagabo]

The second link you gave used a motion compensated algorithm to produce slow motion. If you look closely around the edges of moving objects you will see minor distortions. Also look at the blurring at the very edges of the frame during panning shots. Those are dead giveaways. They chose their shots very carefully to minimize those distortions.

The slow motion you are generating is simply blending frames, hence the blurred, double exposure look. Or maybe it is performing motion compensation but the motions are too complex for the software to handle.

[budwzr]

The second link you gave used a motion compensated algorithm to produce slow motion.

Are you talking optical flow interpolation?

Yes, and GoPro doesn't mention a word that you need special software to get this kind of result, and people think you can buy into a couple or three hundred dollar camera and do this at home.

The GoPro cameras ARE exceptional, for the price, and the small form factor, but the average user doesn't know how much overcrank equals how much "native" slomo you can expect.

Also, I think the slower you want to go, the number of raw frames needed goes up exponentially, not in a straight line. I don't think 120fps gives you "native" smooth 4X slomo at 30fps.

[jagabo]

The second link you gave used a motion compensated algorithm to produce slow motion.

Are you talking optical flow interpolation?

Yes.

[poisondeathray]

Also, I think the slower you want to go, the number of raw frames needed goes up exponentially, not in a straight line. I don't think 120fps gives you "native" smooth 4X slomo at 30fps.

Actually it is a linear relationship , and 120FPS gives you exactly 4x slo mo at 30FPS because 120/4 =30

240 FPS would give you 8x slow mo at 30 FPS , because..... ____________

But another problem that arises is shutter speed. If you don't prepare ahead of time, you might use the wrong settings and either get too blurry (motion blur) or too much strobing. The 180 degree shutter rule doesn't necessarily apply if you are planning to use slo motion

For interpolation , you generally want higher shutter speed, because it's easier to interpolate from sharp details as opposed to a motion blurry mess

[budwzr]

Actually it is a linear relationship , and 120FPS gives you exactly 4x slo mo at 30FPS because 120/4 =30


For interpolation , you generally want higher shutter speed, because it's easier to interpolate from sharp details as opposed to a motion blurry mess

Oh, it IS linear? That's good to know.

Hey, another question, the shutter speed consideration. My T3i just has a small blurb about using 60-125 shutter speed when shooting video, but no elaboration. Can you elaborate on that?

Besides exposure, is there some technical reason for not shooting at higher shutter speeds? Like sync or judder? I can understand 1/60 at the low end because if the shutter is slower than the capture rate all hell breaks loose, and 1/60 shutter is the lowest I can go.

[poisondeathray]

Hey, another question, the shutter speed consideration. My T3i just has a small blurb about using 60-125 shutter speed when shooting video, but no elaboration. Can you elaborate on that?

Besides exposure, is there some technical reason for not shooting at higher shutter speeds? Like sync or judder? I can understand 1/60 at the low end because if the shutter is slower than the capture rate all hell breaks loose, and 1/60 shutter is the lowest I can go.

Yes, Too fast shutter will give you sharp edges, with no motion blur. It will look too "strobey" and unnatural. Play with varying the settings, for some projects you might want that type of look . Too slow shutter will give you a smeary blurry look - again it might be a desired effect for some projects

The general rule is 180 degree shutter , so 1/60 for 30p , 1/50 for 25p etc... The consensus is that this closely emulates what film looks like

But it depends on your project and goals. You might use different settings for different types of looks

For indoor shooting, or if you have unnatural lighting, it's important to shoot in even multiples of the electrical grid frequency, or you will get flickering banding artifacts . e.g. For a 60Hz country like USA, 1/60 shutter would be fine, but a UK camera using 1/50 shutter in the USA will demonstrate those artifacts

[budwzr]

Yeah, I use my 52" LCD as a green screen, and it worked fine with my cheapo cameras, but it's giving me banding or moire on my Canon. I think you hit the nail on the head.

I think the refresh rate on the TV is 120, so I HAVE to use 1/60, right? Cool man, thanks for that.

[poisondeathray]

Yeah, I use my 52" LCD as a green screen, and it worked fine with my cheapo cameras, but it's giving me banding or moire on my Canon. I think you hit the nail on the head.

Moire is a whole different issue with the cannon DSLRs (T2i, T3i, 7D, 5DMk2) . They exhibit horrible moire patterns and rainbows. It's a sensor sampling issue, and not enough processing power, so they pixel bin from the large sensor , instead of doing a proper resize . So you're left with bunch of jaggies. They also lack an optical low pass filter, which most "regular" camcorders have

"Banding" might be a different issue as well. It depends on what type of banding you are referring to; There are several types of banding: 1) banding from poor compression (yep, canon's h.264 implementation sucks, it's actually macroblocking) 2) banding from low light / sensor noise - typically these look like linear color streaks 3) banding from 8bit depth (gradients aren't smooth) 4) banding from lighting/sensor sampling frequency mismatch - this looks more like regular undulating horizontal bars - this last one was the one I was referring to earlier