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Old June 14th, 2012, 06:22 AM   #1
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Crank - dropped frames

Dan,

I expect this has been answered many times, apologies, but I am in a rush just starting using Crank and initial test produces dropped frames when 25p crank is set to anything in the range 26-49. 50 works fine for 2x slo-mo but nothing else in-between. Always get some missing frames in those other rates.

Perhaps I have set too high a bit rate ? Haven't got time today to test more yet. I have been shooting for months at 50 long-gop and 100-140 I-frame 1080p without issues, using SanDisk Extreme 60MB/s UDMA cards.

The Crank mode that works fine set at 50 for 2x slo-mo for 25p I have been setting Bit Rate on the Nano at 220 and getting 110mbps 720/25p fine.

Sony EX3 set in Pal and 720/50p mode for all this.



Thanks.
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Old June 14th, 2012, 07:15 AM   #2
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Re: Crank - dropped frames

Dear Stephen,

Please help me understand what you mean when you say you are getting dropped frames.

Since your camera is set to output 720p50, cranking drops frames on purpose to produce the number of frames per second that you have requested.

For example, if you set cranking on, feeding the nanoFlash 720p50, then setting crank to 25,25 (just as an example, every other frame will be dropped).

If you select 25, 45, fewer frames will be dropped.

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Since you are in a hurry, you could just record 720p50, then slow it down in post.
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Old June 14th, 2012, 03:59 PM   #3
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Re: Crank - dropped frames

Ah, ok, I understand it now, thanks for clarifying. It is working as it should - the problem is my thinking it would work by converting in the same way as the Varicam (and as film cameras), which is unrealistic for a unit that can only do as much as the camera's output allows.

I have indeed been shooting 720/50p and 720/60p a lot and also 1080/30p sometimes and conforming it all down to 25p in post which allows using the Prebuffer mode at the same time which is absolutely wonderful.

Sometimes I like the Nanoflash so much, I expect just too much more from it !
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Old June 14th, 2012, 04:08 PM   #4
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Re: Crank - shutter speed / motion blur

One thing - that is very hard to set up a test for - when shooting 720/50p for slowing down to 25p in post should I set the camera shutter to 90 degrees instead of the usual 180 or is that already taken care of inherently in the 2x sampling rate of the 720/50p signal (ie. in the same way it would naturally occur in a film camera) ?
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