How can I over/under crank to slo mo or fast look in XL2?
 

Hi guys,

I'll be shooting a music video soon and I'm trying to achieve the slow motion look and be able to lip sync audio with that slo motion.
Is there a way to get slow motion look by over cranking or fast motion by under cranking in XL2? Is it something to do with Shutter Speed?
Is there any other way to achieve slow motion?
Any help or tip would be greatly appreciated,
Thanks in advance,

Zia

The XL2 does not have the capability to do under or over crank.

The only thing you can do is shoot in interlaced (50i or 60i) and then de-interlace it in the edit (this splits the two fields and two frames) this will give you 50 or 60 fps.
Steve

Hey thanks Steve,
Does the audio need to be playing at a faster rate during the shoot to match the video in post?
I guess my ? is,
Should the audio be played at 200% during the shoot with XL2 at 60i?
What shutter speed should I use?
What percentage do I change the video speed in FCP to sync with audio playing at normal speed?
Thanks once again,

Zia

Perhaps I'm wrong, but that doesn't sound right. I don't think shooting interlaced and then deinterlacing in post adds extra frames or changes the framerate. You still have 30 (for NTSC) discreet images per second, they're just handled differently. When they're interlaced, you're seeing two images at once, in a sense, on any given frame, when they're deinterlaced, there's only one image. They software will interpolate based on your settings on how they missing field is created. But it's still 30 images (in NTSC) per second. You might try playing with higher shutter speeds (1/250, or 1/500 or something). This is technically not giving you more frames per second, but it can give the appearance of that, since you see motion much more clearly (motion blur will be eliminated, giving all your movement a very clean look). This might aid in better results if you slow it down in post. As for how fast to play the sound, etc., just experiment. Find a video setting in the camera that gets you the best results (maybe I'm wrong and Zia is correct), and then try different things with the playback to see what fits best.

This is a good guide: RAREVISION - New Media & Broadcast

The solution there is to shoot 50i (Pal) with a shutter speed of at least 1/120 and deinterlace it to 25p and make it 200% faster (read 50p). It will give you nice slowmotion but not as great as native.

My bad. But you have to have after effects or another plugin to do this, right? Not just simply converting your interlaced footage to progressive in FCP or Vegas and then adding slo-mo would accomplish the same thing, would it?

It looks like the key to the method is the "interpret footage" function in AE, that tells the program to create whole frames from the fields and therefore extra frames instead of just deinterlacing the footage and keeping the framerate the same.

And do not forget that using this method you decrease vertical resolution to half of the original as you use odd field to make first frame and even to make second one and so on.
You will finish with 720x288 resolution footage. Sometimes using Twixtor or even After Effect's frame blend you will get better results. SOMETIMES is very important word here :)

I thought the program could fill in the missing field, and maintain resolution?

How would it get this extra resolution that was not recorded?

I thought it was possible the software could see what two given lines in a field looked like, and guess what the missing line between them would look like, and fill it in.

Hi Josh. Well it can upscale the 288 lines back to 576 but there is no new information added so the image will definitely be softer compared with having 576 lines to start with.

There are other ways of deinterlacing that don't just separate the fields, but in general they also have drawbacks such as smearing of moving objects because the data from different fields is blended.

Richard

But Josh is basically correct, in that you don't end up with anything like a hlaf resolution image, the missing lines are interpolated, this is why some programmes are better at it than others, they "guess" the missing lines better. No editor myself but I have heard people saying good thing about the likes of Twixtor.
Even without the resolution issue though, there does always seem to be something odd with the look of de-interlaced material, there always seems to be some sort of jitteryness. Same is true of progressive 25P footage slowed in Smoke.
Steve

Here is a few films that’s overcranked:

Tyv
Ingerstrand
Bullets

All these where shot with a SGpro.

In theory this could be done with any 50i PAL or NTSC camera.

Ah. I am illuminated.

Good evening,

This is a slightly older threadbut still of interest to many I am sure.

First, with an xl2 why would you Shoot interlaced and then deinterlace when you can shoot in progressive (30P)to start with.

Then go to a program like vegas which interpolates the frames to give you reasonable slow motion, definitely better than adobe (I use both) where it adds duplicate frames and will appear as slow motion.

The best slow motion effects I have seen is with the program Twixtor!!

I believe the new sony xd cam, ex 3 or such allows over and under cranking.

With most software you are building addative frames.

I personally shoot for slow motion and never shoot faster than 120th of a second and often prefer 1/60th. It makes for smoother movement and certainly more resembles slo mo from a film camera.

Would like to hear thoughts on this!!!

They're saying that if you shoot in 60i and deinterlace later, you get 60 fields which can be converted to whole frames, giving you 60 fps, while shooting 30p in the first place will only yield 30 discreet frames.

half to full frames
 

Josh,

I am not sure I underestand this. If you converted the 60 1/2 interlaced frames to full frames it would still play at the desired 30/second (right?) and it would not run the 60 which would make it twice as slow if you could do that.

it would be cool if you could rebuild the half frames to accurate full frames and then run it at the normal 30 frames a second. If this is doable how and what software???


I am intrigued!!!!

It seemed weird to me too.

Someone earlier in the thread posted this link. . .this is what I was referring to:

RAREVISION - New Media & Broadcast

Sometimes this stuff hurts my brain, but the idea is, I think, if you have 30 frames per second and turn it into 60, you essentially have two seconds worth of frames representing one second's worth of motion; in essence, slow motion. So yes, you play it back at regular speed. If you wanted it faster than 50% of the original speed, you'd speed up the 60fps footage to your liking.

The Canon XL2 can shoot overcrank, i have been doing it for a few years now. I actually shot a video today with it. Check it out.

YouTube - White Rain

Can you explain? I have an XL2 and the only thing I know how to do (as far as slomo/overcrank) would be either the 60i method above, or shooting at a 1/250 or faster shutter and applying slo mo in post. If it shoots higher framerates than 30fps I'd be surprised to know about it.

Josh,

Yes, you are correct. Technically, overcranking refers to the speed of the media across the lens system. It's not as though we can run a 60 minute digital tape through the camera faster than 60 minutes. So sometimes folks imply they're overcranking by varying the shutter speed and compensating in post, but that's not really overcranking the cameras motor.

Regards, Michael

Thanks. I'd still like to know if the method in the article could be done in something like FCP.

Final cut method:

two duplicate layers of video (shot 60i) speeds set to 50% with no blending.

top layer has de-interlace filter applied (even fields or odd fields) and a blink filter set to 1.

If the footage ends up looking jumpy, switch the field order in the de-interlace

Thanks! I will give this a try.

Question
 

cole,

do I have this straight: shoot interlaced, import to track one. import and deinterlace same footage and add to track two, then time stretch or interpolate 50% morre frames.??

If that is the case what does the second track layer of deinterlacing actually do for the footage, as apposed to shooting progressive and then interpolating or time stretching 50%?

I use vegas and Pr Pro


thanks.

vegas and premiere I don't know...

The reason for the 60i footage is that it's a real collection of 60 images/sec... rather than 30/sec being stretched or guessed into 60. The drawback to this is that you lose half your resolution to get it... which if you're de-interlacing anyway happens regardless.

If shooting on a canon, shooting progressive loses 30% of the image anyway compared to shooting interlaced. But the promise of actual timeslices rather than created ones makes me happy.

The first piece of footage is imported, then speed adjusted to 50%. The second track is deinterlaced even and the bottom odd (I think I missed this part last time)... the blink filter reveals the lower clip every other frame (1/30 sec)... again if the result appears to flutter, the even/odd fields need to be reversed.

I think Vegas uses field deconstruction and de-interlacing to slow their footage down (could be wrong, but there's lots of threads on this forum on this subject - I'm in lots of them). Premiere, no idea.

Thank you cole,

I am going to tinker on this and see what I can get.


No one has ever totally explained the 30% loss to me, and I have asked several times.

If a ccd has full resolution and receives one full frame, how is that different from a full frame of interlaced?