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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » DCP Creation -1.78 (Page 1)

 
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Author Topic: DCP Creation -1.78
Eugene Lehnert
Film Handler

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From: New York, NY
Registered: Jul 2012


 - posted 08-21-2014 11:10 AM      Profile for Eugene Lehnert   Author's Homepage   Email Eugene Lehnert   Send New Private Message       Edit/Delete Post 
Is it best to place a 1.78 film into a 1998x1080 container or a 2048x1080 container?

Thanks!

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Scott Norwood
Film God

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 - posted 08-21-2014 12:03 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Wouldn't the result be the same (a 1920x1080 image)?

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Eugene Lehnert
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 - posted 08-21-2014 12:19 PM      Profile for Eugene Lehnert   Author's Homepage   Email Eugene Lehnert   Send New Private Message       Edit/Delete Post 
Yeah. I guess I'm trying to figure out if one resolution or the other can affect the size of the image during playback? Is a projector zoomed into the screen differently for the different resolutions? Would a 1.78 in a 1998x1080 look larger on the screen than a 1.78 in a 2048x1080 container?

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Manny Knowles
"What are these things and WHY are they BLUE???"

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From: Bloomington, IN, USA
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 - posted 08-21-2014 03:20 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
Both aspect ratios (1.85 and 1.78) use the maximum height of the full (2K) container -- 1080 pixels. So, they are the same, in terms of height.

Since 1.78 is not as wide as 1.85, it will appear smaller in that dimension, which is to be expected.

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Stefan Vogels
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From: Aarle-Rixtel, Noord-Brabant, Netherlands
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 - posted 08-21-2014 03:29 PM      Profile for Stefan Vogels   Email Stefan Vogels   Send New Private Message       Edit/Delete Post 
It would look the same, however not every cinema probably will have the 2048x1080 preset configured. They do have 1998x1080 as Flat ratio.

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Eugene Lehnert
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From: New York, NY
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 - posted 08-21-2014 03:35 PM      Profile for Eugene Lehnert   Author's Homepage   Email Eugene Lehnert   Send New Private Message       Edit/Delete Post 
Right. But when you have a projector set to 1998x1080 do you through a larger image onto the screen if you fill the screen horizontally? If you were to fill the screen horizontally with a 2048x1080 the vertical length would be shorter?

So a 1.78 in a 2048x0180 container would have to be enlarged where a 1.78 in the 1998x1080 container would not need as much enlarging?

I haven't worked as a projectionist so I was guessing that theaters are set with a standard setting for 1.85 and 2.39. I'm just worried how this 1.78 will be interpreted on the big screen by projectionists.

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Manny Knowles
"What are these things and WHY are they BLUE???"

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From: Bloomington, IN, USA
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 - posted 08-21-2014 03:45 PM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
According to DCI spec, you're supposed to fill either height, width, or both.

Full width is not an option for this aspect ratio. For 1.78, you need to use the full height dimension. There's no real difference between packing it within 1.85 versus full container. You will end up with the same resolution, and the same amount of unused container on either side.

I think you're worrying needlessly.

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Marcel Birgelen
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 - posted 08-21-2014 04:25 PM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
According to DCI specs you're quite right, you shouldn't have to worry...

The problem is the reality out there. Many locations don't have any presets for "full container", just scope and flat... If you deliver them content in another container they might start to do stupid things.

So, if you're not going to be present at the screening(s) yourself, I think it's best to put it in a 1998x1080 container, to avoid the locations with "limited skill-sets" messing up.

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Steve Guttag
We forgot the crackers Gromit!!!

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From: Annapolis, MD
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 - posted 08-21-2014 04:34 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Marcel is right on the money. It is absolutely safest to list it as "F" or you will get unpredictable results in the cinemas. Current naming conventions would have you put in an "F-178" into its name. While the actual ratio is an "optional" piece, it would go a distance to ensure that when the image didn't fill the width of the 1.85 masking setting, the reason would be known.

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Scott Norwood
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quote: Marcel Birgelen
So, if you're not going to be present at the screening(s) yourself, I think it's best to put it in a 1998x1080 container, to avoid the locations with "limited skill-sets" messing up.


What could they do wrong? The picture size would be the same either way.

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Monte L Fullmer
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From: Nampa, Idaho, USA
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 - posted 08-21-2014 09:19 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
When using the "DCP-o-Matic" DCP creation program, it give you the option to choose how your file will look in certain containers and will gives you a description, in words and sample image, of how the container is filled.

Thus, a 1.78 formatted file being ready to be placed in a FLAT container will show to the user of the image having slight black bars on the side since it's filling the vertical part, being the 1080p, to top and bottom of the frame.

-Monte

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12631
From: Annapolis, MD
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 - posted 08-21-2014 09:54 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Scott...not knowing what "C" means, they could also use "Scope" and thus would have an 858 x 1920 image cropped in height and not filling the width of the image.

Calling it "F-178" removes all ambiguity including for automated TMS systems.

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Monte L Fullmer
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From: Nampa, Idaho, USA
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With the above comment, the program mentioned also puts the lens (_F_, _S_)factor in the content file naming string when all the presets in making the DCP is completed.

Thus, removing any possibility of wrong lens format used with the produced content when used within an assembled SPL.

-Monte

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Manny Knowles
"What are these things and WHY are they BLUE???"

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From: Bloomington, IN, USA
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 - posted 08-22-2014 01:42 AM      Profile for Manny Knowles   Email Manny Knowles   Send New Private Message       Edit/Delete Post 
I'll agree that the uncommon (yet legal) "C" designation could confuse some users. However, for the record, the OP was not asking about how best to name the DCP.

Essentially/technically, placing 1.78 inside 1.85 is the same as placing it inside the full container. Labeling also has no real effect. The result would be the same either way.

As others have pointed out, labeling is an important consideration, in terms of short-circuiting user error. But only in that regard.

I would recommend "F-178" as Steve suggested.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12631
From: Annapolis, MD
Registered: Dec 1999


 - posted 08-22-2014 05:30 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Manny,

Since the OP clarified that a concern was the size/magnification of final result as it would appear in theatres...how an end-user, that may be an automated TMS too, using "C" sets one up to have an unpredictable result. While within the DCP itself, it is the same regardless of F or C.

Now I wish for 65/70mm dupes that they would use C-220 as the format! But that is another discussion.

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