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Old May 4th, 2005, 07:54 PM   #1
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Uncompressed 60p = no 24p?

Would converting the uncompressed 60p out from this cam to 24p result in great hassle/image loss? How hard would this be in post? And would the image be degraded in the way that most 24p post conversation processes are?
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Old May 4th, 2005, 09:36 PM   #2
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Quote:
Originally Posted by Glenn Gipson
Would converting the uncompressed 60p out from this cam to 24p result in great hassle/image loss? How hard would this be in post? And would the image be degraded in the way that most 24p post conversation processes are?
If you were to implement an uncompressed capture system, with its attendent analog capture card and high-speed RAID array, it wouldn't really be too hard at all. The JVC can output 24P within a 60P stream, so you could capture the 60p output and drop out the duplicate frames, giving you a genuine 24p file.

As near as I can tell, the 24P of the JVC is output to 60p by simple frame duplication: two 24p frames are output as five 60p frames, so 24p frames a,b,c,d get written out to 60p as aa,bbb,cc,ddd. You'd have to capture the 60p frames, and then drop 6 out of every 10 frames, leaving one copy of a, one copy of b, one copy of c, and one copy of d.

There should be none of the image degradation you get with other systems, because there's no frame interlacing/combining/field blending going on. It's raw distinct progressive frames.
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Old May 4th, 2005, 10:30 PM   #3
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Thanks for the clarification Barry, but is there software readily available for this? Or is this a simple NLE function?
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Old May 4th, 2005, 11:59 PM   #4
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Well, no, probably not; but then there's really nothing simple about capturing uncompressed HD either. The whole process is somewhat overpowering; I mean, you're talking about needing a RAID that can sustain over 166 megabytes per second (or 6 seconds per gigabyte).

But presumably, if you were to build an uncompressed capture station, the 60p->24p conversion should be very simple to do. I imagine Graeme Nattress or Marcus Van Bavel could write up such a utility in less than a day.
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