Slow motion in postpro.

H

hal9000

Member
Until now I used a interlaced video camera and now with my DVX100AE I am testing the slow motion in progressive mode.

I notice that the postpro mode in Premiere is quite poor and specially in progressive mode jittering is evident with 25% speed and even with 50%.

I found Motion Perfect from DynaPel, and I realize of a very nice result, output is now excellent (at least to my eyes)

Do you use this tool too? do you have another to recomend just for slow motion ?

Thanks
 
Re: Slow motion in postpro.

After Effects is pretty good at anything related to this. May want to check that out. I know for the matrox system with premiere, matrox re-wrote the speed changes in the software to make it much nicer. Don't know if you can get your hands on that though. I'd say, AE is your best bet if you want better results and want to stick with premiere.
 
Re: Slow motion in postpro.

.. i use the dynapel product.. works great for things that arent moving too fast to begin with, but it lacks proffessional control to deal with regional "gloopiness" when the software gets screwed up.. unfortunately in order to have the tracking mattes in the software.. all the other programs are about 50 times the price.. so i really like being able to use it for quick and easy stuff.- twixtor rocks for when you need somthing solid though.
 
Re: Slow motion in postpro.

If I wanted to match normal-speed 24P Std footage with slow motion footage, should I shoot the the footage that will be slowed down in 24P, 24PA, 30P or 60i?
 
Re: Slow motion in postpro.

If you're wanting a somewhat slow-mo effect, you can always shoot in 30P and then slow it down to 24P, then add a 3:2 pulldown. It will give you a subtle slo-mo effect, but it will be TRUE slow motion, you had simply recorded more frames per second.

If you shoot in 60i, you'll have even MORE motion samples per second, but because you'll have to interpolate the interlaced frames, you'll get a softer picture. Might be what you want, though...
 
Re: Slow motion in postpro.

Thanks. Now, if I shot in 60i, given good lighting, what shutter speed would you recommend?
 
Re: Slow motion in postpro.

As you're going to recreate progressive material from interlaced footage, I suggest you get as crisp images as possible, which means rather brief exposition time.
Depending of course on the type of movement you wanna capture, I think you shouldn't shoot under 1/120.
Once again, check out this article :
http://www.rarevision.com/articles/slow_motion.php
 
Re: Slow motion in postpro.

In my testing, the best SLOW slow-motion results came from 60i footage. For mild slow motion, 30P is best. For slow slow motion, you can't beat shooting 60i. I always shot with 1/60th, but I can see why you might want to shoot 1/120.
 
Re: Slow motion in postpro.

Now, when you say 60i, is that 60i (scene setting 1-3) or is that 24p standard (scene setting 4)???
 
Re: Slow motion in postpro.

60i means sixty interlaced fields per second, so it would not be one of the 24P or 30P modes. You could use the same preset (F5 or F6) but just turn "progressive" to "off" for the slow-mo shots.
 
Re: Slow motion in postpro.

ok, but does 60i footage work, or look, the same as 24p footage when slowed down?
 
Re: Slow motion in postpro.

60i footage, when played back at 40% rate, will look like film footage that was shot at 60fps and played back at 24fps, except that it will be lower vertical resolution.  But it will be higher temporal resolution.

24P, played back at 50% slow motion, jitters.  60i, played back at 40% slow motion in a 24P timeline, looks smooth.  If you make sure that all your settings are identical in all other ways, and shoot at 1/120 on the 60i footage, it should blend in fairly seamlessly with your 24P footage, providing a nice smooth slow motion effect.
 
Re: Slow motion in postpro.

I just shot some 30p footage with the intent to slow it down to 24 fps timeline.

It's not working, here's what I did.

Took a song, sped it up 25%

Lipsynced to that song filmed at 30p.

Imported the 30p footage at 80% speed into a 24 fps timeline.
Had the song at its normal speed in the 24 fps timeline.

It's not syncing up. My calculations say that 24p footage needs to be sped up 25% to make it to 30 fps, then slowed down only 20% to get back to 24 fps.

It seems as if my 30 fps footage is still too fast.  Right now I am running 23.98 and 29.97 should I try this again with 24 fps and 30 fps, would this make a difference? Anyone know what's going on? I'm going to try different things, but any help ... would help! Thanks.
 
Re: Slow motion in postpro.

What program are you using to edit with?

It's late, and I'm trying to wrap my brain around this. Let's see... if you shoot 1 minute of 30P and import that into a 24P timeline, frame for frame, it will play for 75 seconds. At 30 frames per second, 1 minute of footage will yield 1800 frames. 1800 frames divided by 24 frames per second yields 75 seconds.

If you sped up a 75-second song by 25%, that sped-up song would play for 56.25 seconds. Meaning, if you made the song last for only 75% of its regular time, you'd get 56.25, which is obviously wrong -- you'd need the song to last 60 seconds. You would need to speed the song up by 20%, not 25%. Or, let me put it a different way: you'd want the new duration of the song to be 80% as long as the old duration of the song. So, again, a 75-second song, re-timed (sped up) so that it lasts 80% of its original time, would have a new duration of 60 seconds.

So, then, you would shoot 60 seconds' worth of 30P, timed to the 60-second sped-up song. Then, in post, you would put the original 75-second song on the timeline, and you would pull in the 30P footage and play it at 80% speed. That should give you frame-accurate sync.

So, looks like you made the sped-up song too short. Go back to your original calculations and see what percentages and ratios you get, and see if there's a way to salvage it -- maybe you can try to re-time the song to match the duration of the footage?
 
Re: Slow motion in postpro.

Barry,

whoa. I didn't get that at all. I think ...no, nope didn't get it.

So I speed up the song 20% ...

and I slow down the 30p footage 20% ...

Seems like it would make sense.....

I don't know what I was thinking before.

I'm using FCP, and digital performer.

The footage need not be salvagable, I was just recording stuff to learn how to do it.

ooohhhkay. I think I get it now. Thanks!!
I'll try it again when I have another day free. ;)
 
Re: Slow motion in postpro.

Let me try it again, this time in one clear sentence instead of a dozen muddled paragraphs...

You want both the footage and the song to last 80% as long. So you change the song's speed so that it lasts 80% as long as its real length (i.e., if it's a four-minute song, which is 240 seconds, you'd speed it up so that its new duration is 192 seconds). Then you'd shoot 192 seconds of 30P video, which will give you 5,760 frames. You tell your editor to play that video at 80% speed, which will give you 240 seconds' worth of footage at 24 frames per second.

The only tricky part is figuring out how long the sped-up song should be. And all you have to do is figure out how many seconds it is, and then multiply by .8 to get the desired new duration.

(okay, I couldn't do it, can't just type one clear sentence, gotta go on and on... sorry...)
 
Re: Slow motion in postpro.

I've tried this technique of capturing 60i and converting it to 24p. It works really well (although I didn't shoot at 1/120).

Has anyone tried this in Final Cut Pro? Any success? I want to avoid having to go out of that program to create the needed slo mo footage.

Any ideas?
Russell
 
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