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34 fps instead of 24 fps mixup.


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#1 Scott Willis

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Posted 04 March 2008 - 12:47 PM

alright. shooting a student 16mm project and we had a little mishap and accidentally rolled at 34 fps instead of 24 fps for a few shots.

It took months of wrestling to get the purchase order paperwork through for the processing so by the time i got the footage back i had completely forgotten about this. Transfered to DVCAM by the way.

The problem being now that for 3 shots I have a terrible strobing effect.

I've been playing around to try and boost the speed back up, which helps with synching the sound but the strobing is still distracting.

Anyone else be able to clean something like this up in post? I'm cutting on avid media composer right now and not quite sure how to work on this.


Is the problem fully built into the negative or could I get the lab to retransfer it and adjust for the fps mess up?


help.
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#2 Scott Willis

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Posted 04 March 2008 - 12:50 PM

i guess i should also mention that the shots in question were shot at night with tungsten lights.
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#3 Phil Rhodes

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Posted 04 March 2008 - 03:41 PM

You should look at a solution which does proper motion interpolation - something like Twixtor at the high end, as a plugin for After Effects, or a similar thing. They do smart interpolated speed changes and will probably do the best job possible on sorting out your mistake. I doubt it will ever be perfect.

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#4 John Sprung

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Posted 04 March 2008 - 06:54 PM

Is the problem fully built into the negative ....?

Yes, unfortunately.

But it's only three shots. The right solution is to re-shoot or cut around it.




-- J.S.
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#5 David Mullen ASC

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Posted 04 March 2008 - 07:15 PM

What strobing effect? If it was transferred at 23.976 fps, it would look slightly slow-motion and have a 3:2 pulldown added for 59.94i. But I don't understand why it would be strobing.
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#6 Scott Willis

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Posted 04 March 2008 - 07:39 PM

my guess was that it's strobing because the light source (which was honestly just a parking lot overhead mercury vapor light) was on a 60-htz circuit.

the stuff under the same lighting setup shot at 24fps looks just fine.
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#7 Phil Rhodes

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Posted 04 March 2008 - 08:37 PM

Ah.

That's tought to fix. I assumed by "strobing" you meant that you'd sped it up to normal speed for sound sync, and that the result was jumpy (which I would expect).

If the strobing light source is the only one in shot, there are several approaches - the simplest one, but one I've found to work really quite surprisingly well, is a Virtualdub plugin called "deflicker". It's free, and you could try it.

Unfortunetly, if your flickering source is one of many in the frame, and you can't separate them, you are thoroughly buggered.


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