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Problem understanding over-cranked footage TIMEBASE

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simon cox
Problem understanding over-cranked footage TIMEBASE
on Apr 27, 2011 at 2:47:55 pm


I'm about ready to start editing a short promo, and have just received all the footage from the shoot - a combination of 5D and RED footage. Im having difficulty getting my head round my workflow. All the 5D footage has been shot 25fps, thats fine. However, all the RED footage has been shot with a timebase of 23.98. A lot of the RED footage is over-cranked slo-mo stuff. The idea originally was shoot and edit it all at 25fps, then conform the RED footage back to the .r3d files for the grade in color - a workflow I've done numerous times before, but now that the footage has come back at 23.98, i'm slightly confused about what route to take - and would appreciate any help or suggestions anyone has to offer.

I was thinking of conforming all my 5D footage to match the RED footage at 23.98, this would slow it down about 4% i believe? Then i considered trying to conform the RED footage up to match 5D at 25fps, but unsure about how to go about this, or if it's possible as I still need to go back to the r3d's to grade.

I feel like im either missing a really obvious step somewhere, or am I right in thinking this isn't going to be straight forward?

in short:
5D - 25fps
RED 23.98fps (over cranked at 100fps i think)
delivery - Web. Possibly PAL dvd too

thanks for any help in advance, its very much appreciated.

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Uli Plank
Re: Problem understanding over-cranked footage TIMEBASE
on Apr 28, 2011 at 5:50:30 am

First slap the camerafolks…

Then transcode the 5D footage to ProRes ans slow it down to 23.98 with the help of Cinema Tools. Changing the timebase of the R3Ds and still conform back to the original in Color could became a nightmare.

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts

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David Battistella
Re: Problem understanding over-cranked footage TIMEBASE
on Apr 28, 2011 at 7:25:00 am


RED treats overcranked footage exactly as film.

It goes like this.

The timebase is 23.98 (film is 24)

The number of frames you shoot in the time base is the over or under crank say 72fps.

What the RED does is capture 72fps (in 23.98 timebase) instead of the regular 24 fps in (23.98 timebase) so that when you play back the footage in a 2398 timeline you see it plays at 72 frames per second.

Film works exactly the same way. It captures more information in the same time base. One second is always one second, you are just telling the camera to capture MORE FRAMES in that one second.

So in film and RED you are capturing more information and you do not need to do anything other than drop the footage into a 23.98 time base.

What happens in a 5D (or panasonic HVX 200) is that they use the sensors 60 frame clock to capture the extra frames and then they have to post process the footage to play slow in a 23.98 timebase. (99.9% of all video based editing is 23.98 and NOT 24fps).

So my advice to you is to keep the RED footage as is and CONFORM the 5D footage to 23.98. Going the other way will result in you pulling your hair out.

Hope this helps.



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simon cox
Re: Problem understanding over-cranked footage TIMEBASE
on Apr 29, 2011 at 11:34:51 am

thanks guys. i really appreciate the advice/help

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