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Old December 27th, 2010, 09:24 AM   #1
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Combining footage from 3 different cams at different fps???

Hi Guys,

I have had a good look through the forum but cant find a simple answer to this ( as im sure there isn't one!).

I was just wondering if any of you could answer this question and/or point me in the direction of threads or resources that can help.

I have a small project coming up that will need the use of all 3 of my cameras at once. They are:

5DmkII
1D mkIV
GoPro HD

The short involves a static spoken scene and then quite a bit of running/fast movement.

-I will be recording the static scenes with the 5D at 1080p/24

-The GoPro can only record at 60p or 30p. I would like to shoot 720p/60 with the GoPro as it will be chest mounted on an actor during the action so the 60fps will help with slowing action if needed.

- I was going to shoot 720p/60 with the 1D as well since this will also be following the action, panning from the side.

I want to keep the 24p "look". How can i combine the three video sources so that they playback correctly at "realtime" speed in a 24p timeline? Or will i have to scrap 24p and move to 60p?

I will be recording audio seperately on a Zoom H3n which i believe also records against a 24p timing?

This is my first multicam project so have no idea what to do for this.

Sorry if this is really obvious to you guys, I just need some help before the start date comes around!

Thanks in advance,

Rob
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Old December 28th, 2010, 03:06 PM   #2
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You can interpret the footage as off speed footage, and then convert it to 24 fps - how you do this depends on what system you are editing on.

Many if not all NLE timelines these days have a level of multiframerate support in that if you put footage of differing framerates on the timeline they will automatically interpolate the footage to the timeline framerate. However, this sort of interpolation is not perfect and often results in instances of slightly weird, stocatto type movement or a frame blended look (especially when going from a high speed 60fps with accompanying motion blur characteristics back down to 24fps.)

This is less of an issue with slow mo footage, although in a system like the go pro where I am unsure if you can set any sort of shutter angle then you might still have incongruity between the motion blur of one set of footage to the other.

The real issue here though, is that you are looking for 24fps playback. It doesn't matter how the footage is originated, if you run playback at 24fps, and you have high motion panning, then without introducing significant motion blur in post to hide it you will still get choppy/stocato pans, even if the footage has been acquired at 60fps, because it is the distance visual pointers in the frame move before refreshing that creates the choppy look. By shooting 60 you'll be able to do more frame interpolation that could help that, OR you could theoretically manually select each frame out of the 60 in the pan/fast movement to try and create the smoothest pan out of the frames you have (incredibly laborious and I don't believe would yield much of an improvement unless motion blur was a real issue for you)

All in all, if shooting footage for 24fps display - you need to follow the rules for 24fps panning.
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Old December 28th, 2010, 06:31 PM   #3
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Sorry Craig, forgot to mention i am editing with the Premier Pro & After Effects CS5 ( plus the rest of production suite).

So what you are saying is that i should be doing smoother/slower pans even with the 60fps to account for teh 24fps playback?

Sorry if I am being dim - i am just new to this!

Thanks for your help!
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Old January 6th, 2011, 03:16 AM   #4
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Sorry for taking a while to get back to this - Yes, if your end footage is not going to be played back in slow motion (i.e 60FPS playing back at 24fps) but instead is going to have frames removed so that it plays back at 24fps (60FPS playing back to match the footages original duration and speed, but in a 24FPS timeline) then you would need to pan with 24FPS delivery in mind.

But because of pull down etc, even smooth panning might run into trouble here. It's generally not a great idea to run something shot at 60 for 60 playback in a 24FPS timeline if perfect temporal scaling/motion is vital. However, as with anything - you can obviously make it work, either because you have to (access to only those cameras) or you want to (trying to achieve some specific look).

In either case experimentation and testing always makes a big difference.
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