Crank

Stephen de Vere · June 14th, 2012, 05:22 AM

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.

Dan Keaton · June 14th, 2012, 06:15 AM

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.

You may call me. all of my numbers are listed at the bottom of this page, including my Skype number.

Support | Convergent Design

Since you are in a hurry, you could just record 720p50, then slow it down in post.

Stephen de Vere · June 14th, 2012, 02:59 PM

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 !

Stephen de Vere · June 14th, 2012, 03:08 PM

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) ?

June 14th, 2012, 05:22 AM	#1
Stephen de Vere Regular Crew Join Date: Mar 2011 Location: England UK Posts: 57	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.

June 14th, 2012, 06:15 AM	#2
Dan Keaton Inner Circle Join Date: Dec 2002 Location: Augusta Georgia Posts: 5,421	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. You may call me. all of my numbers are listed at the bottom of this page, including my Skype number. Support \| Convergent Design Since you are in a hurry, you could just record 720p50, then slow it down in post. __________________ Dan Keaton Augusta Georgia

June 14th, 2012, 02:59 PM	#3
Stephen de Vere Regular Crew Join Date: Mar 2011 Location: England UK Posts: 57	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 !

June 14th, 2012, 03:08 PM	#4
Stephen de Vere Regular Crew Join Date: Mar 2011 Location: England UK Posts: 57	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) ?