Over Cranking and SDI at DVinfo.net

James Huenergardt · October 25th, 2007, 06:36 AM

Hi,

Not sure how this works, but if I 'overcrank' a shot but am capturing the footage using SDI, how does that work? Or, am I stuck with having to capture to the Express cards in 4:2:0?

Thanks,

Jim

Craig Seeman · October 25th, 2007, 07:17 AM

My hunch is that it comes out SDI at 29.97 (or 59.94) or 25fps. Of course that begs the question how does one remove the "unnecessary" frames.

I think, for example, on the HVX200 you can over/under crank and then downconvert that to DV tape inside the camera. I wonder what people do (if anything) to extract the desired frames in their NLEs.

Of course the answer in both cases may be that you do simply have to use the cards if all you want are the raw frames. Since, unlike 24/23.98 there's no method to remove the pulldown (or is there?).

Alexander Ibrahim · October 26th, 2007, 11:00 PM

The applicable standard is SMPTE 292M, for HD-SDI.

http://en.wikipedia.org/wiki/Serial_Digital_Interface

The HD-SDI interface supports a number of frame rates directly. Supported formats include 1080i60, 1080i59.94, 1080i50, 1080p30, 1080p29.97, 1080p25, 1080p24, 1080p23.98, 720p60, 720p59.94, and 720p50

I think the EX1 records and plays back all the non-integral rates. (i.e. 23.98 fps, but not 24fps)

If you are capturing at some other frame rate you should probably record straight to SxS and import footage using an IT workflow if you want to avoid extra frames.

If you need your over/undercranked footage to be captured over the HD-SDI, because you need 4:2:2 then you have to be able to control the frame rate at the recorder/capture end. That means using a system like Sony's SR Motion

http://bssc.sel.sony.com/Broadcastan...ta/index.shtml

This is available on the SRW-1 recorder- I don't know what that costs, but it ain't cheap. Also, you will give up the SR Motion's ability to control the camera, but you should be able to manage controlling the SRW-1 itself just fine.

(By the way, I think its awesome that you get many of the features of SR Motion on the EX1, even if you are stuck with 35Mbps XDCAM instead of 440Mbps HDCAM SR.)

If you simply need to get the video out over SDI, then the camera will play back the effect from the SxS cards at any rate, thus creating your effect for you in camera. i.e. if you wanted slow motion and overcranked, to 60p, but want playback at 24p the camera will do that for you.

That can leave you with lots of "extra" frames in the case of undercranking, but my take is that if its the effect you intended you are golden. (In the case of "overcranking" you don't get extra frames, it just takes longer to get at the frames you did record.)

Not certain I've been clear, but I hope that helps.

EDIT
Turns out I wasn't clear, I missed telling about a crucial part of the picture. Thanks to Barry Green. I added more info below to clarify.

Barry Green · October 27th, 2007, 11:17 AM

Quote:

Originally Posted by James Huenergardt

Not sure how this works, but if I 'overcrank' a shot but am capturing the footage using SDI, how does that work?

It doesn't. All monitoring is disabled when overcranking or undercranking.

Alexander Ibrahim · October 27th, 2007, 11:48 AM

Quote:

Originally Posted by Barry Green

It doesn't. All monitoring is disabled when overcranking or undercranking.

I knew I was skipping something vitally important. That's what I get for posting at 1am.

The camera only outputs SDI when its set to one of the rates supported in SMPTE 292M- that's why I posted that part.

That's why you have to use an external system if you want 4:2:2 capture over SDI.

You have to have the camera set up to output 720p59.94, 1080p29.97 or 1080i59.94. Then you can take the footage in with the SR Motion system at any frame rate it supports, which I think is up to 1080p60.

October 25th, 2007, 06:36 AM	#1
James Huenergardt Major Player Join Date: Nov 2005 Location: Chehalis, WA Posts: 513	Over Cranking and SDI Hi, Not sure how this works, but if I 'overcrank' a shot but am capturing the footage using SDI, how does that work? Or, am I stuck with having to capture to the Express cards in 4:2:0? Thanks, Jim

October 26th, 2007, 11:00 PM	#3
Alexander Ibrahim Major Player Join Date: Oct 2001 Location: Washington D.C. Metro Area Posts: 384	The applicable standard is SMPTE 292M, for HD-SDI. http://en.wikipedia.org/wiki/Serial_Digital_Interface The HD-SDI interface supports a number of frame rates directly. Supported formats include 1080i60, 1080i59.94, 1080i50, 1080p30, 1080p29.97, 1080p25, 1080p24, 1080p23.98, 720p60, 720p59.94, and 720p50 I think the EX1 records and plays back all the non-integral rates. (i.e. 23.98 fps, but not 24fps) If you are capturing at some other frame rate you should probably record straight to SxS and import footage using an IT workflow if you want to avoid extra frames. If you need your over/undercranked footage to be captured over the HD-SDI, because you need 4:2:2 then you have to be able to control the frame rate at the recorder/capture end. That means using a system like Sony's SR Motion http://bssc.sel.sony.com/Broadcastan...ta/index.shtml This is available on the SRW-1 recorder- I don't know what that costs, but it ain't cheap. Also, you will give up the SR Motion's ability to control the camera, but you should be able to manage controlling the SRW-1 itself just fine. (By the way, I think its awesome that you get many of the features of SR Motion on the EX1, even if you are stuck with 35Mbps XDCAM instead of 440Mbps HDCAM SR.) If you simply need to get the video out over SDI, then the camera will play back the effect from the SxS cards at any rate, thus creating your effect for you in camera. i.e. if you wanted slow motion and overcranked, to 60p, but want playback at 24p the camera will do that for you. That can leave you with lots of "extra" frames in the case of undercranking, but my take is that if its the effect you intended you are golden. (In the case of "overcranking" you don't get extra frames, it just takes longer to get at the frames you did record.) Not certain I've been clear, but I hope that helps. EDIT Turns out I wasn't clear, I missed telling about a crucial part of the picture. Thanks to Barry Green. I added more info below to clarify. __________________ Alexander Ibrahim http://www.alexanderibrahim.net Last edited by Alexander Ibrahim; October 27th, 2007 at 11:51 AM. Reason: Missing information.

October 25th, 2007, 07:17 AM	#2
Craig Seeman Inner Circle Join Date: Feb 2004 Location: Brooklyn, NY, USA Posts: 3,841	My hunch is that it comes out SDI at 29.97 (or 59.94) or 25fps. Of course that begs the question how does one remove the "unnecessary" frames. I think, for example, on the HVX200 you can over/under crank and then downconvert that to DV tape inside the camera. I wonder what people do (if anything) to extract the desired frames in their NLEs. Of course the answer in both cases may be that you do simply have to use the cards if all you want are the raw frames. Since, unlike 24/23.98 there's no method to remove the pulldown (or is there?).