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720 60p or 720 24p
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[doka15] “The camera Shoots at 60 fps all the time”
No. The camera shoots as many frames as you tell it to. It can shoot 60 if you want, or 24, or 2. Let’s use two as the example, because 2fps makes it so much easier to understand what’s happening.
If you choose 2fps as your capture rate, the camera itself will image a distinct frame twice per second. Two frames per second. The shutter will open, the camera will capture the image for 1/2 of a second (assuming 350-degree shutter) and then the shutter closes. All the motion blur that happens during that frame will be imaged properly, exactly as a film camera would.
So you end up with two distinct frames per second, and only two frames per second.
If you recorded this in 720/24pN mode, the unit would record those two frames per second, and only those two frames per second.
If you recorded this in 720/60p mode, the 720/60p mode demands that 60fps be recorded. But the camera SHOOTS two frames per second. So each frame gets duplicated 29 times. Each of those two frames will actualy be recorded 30 times, so two frames shot per second get recorded 60 times per second.
What I can’t wrap my head around yet is why if I import a 60 fps stream and have FCP convert that to 24 it will be mushy and not the same thing as shooting in 24p.
Well, let’s compare shooting 2 fps (and recording into a 60fps stream) vs. shooting 60fps and converting that to 2 fps. If you shoot 60fps, 60 individual pictures are imaged, each distinct and standing alone. If you tried to convert that to 2fps, you’d have to blend and mush 30 frames all together to create one big hodgepodge mishmash that sort of tries to emulate what one properly-shot 2fps frame would look like. It’s not the same thing, not at all.
And while it’s theoretically feasible to try it anyway, let’s show why it’s totally not appropriate to try to do it from 60p to 24p. In that scenario you don’t have an evenly-divisible frame cadence. You’d have to do one of two things: either extract frames at varying intervals (say, the second frame, the fifth frame, the 8th frame, the 10th frame, etc) and just call that “24p” (even though the intervals between frames wouldn’t be consistent whatsoever) or you’d have to try to mush and blend frames, so that the first two frames get blended to create one, and then the next three frames get blended to create another one.
Obviously this is going to produce a result much less satisfactory than if you’d shot 24fps to begin with, which would result in 24 distinct frames being imaged, and each one being imaged at 1/24th of a second intervals.
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OK I got it now. I didn’t know that when you shoot 2 frames per second that even though the camera shoots 60 FPS it duplicates those 2 frames 29 times like you said “The Filler”. I thought it was 60 seperate frames that it pulled 2 frames from and the full 60 ‘Stand alone frames’ were still there.
I understand it better now so there is light at the end of the tunnel. I still think that since there can be seperate 60FPS that you can convert that to 24PN perhaps with After Effects or something else and then have the computer do the 3:2 math for you if you are going to to tape. This is if you shot the 60 and decided down the road that you wanted the 24p look.
Thanks for all your help. I have a better picture of what is happening with the footage.
-Lars
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[gary adcock] “Just to be clear here -this 720p24 over 60 workflow predates the HVX200 and has been in use since the varicam arrived on the market 5 years ago.
FCP knows what to do for 2 reasons”
Gary my response was not related to 720p24 over 60. It was in response to Lars asking if he shot 720/60p and then tried to convert that to 24p in FCP.
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[doka15] ” This is if you shot the 60 and decided down the road that you wanted the 24p look.”
That is specifically, exactly, 100% not what you want to do. That will lead to the mushed frame situation.
The camera does not always shoot 60fps. It shoots however many frames you want, just like a film camera does.
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Get the most from your DVX camera. The DVX Book and DVX DVD are now available on ebay and at Amazon (https://www.fiftv.com/db)
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