Film-Tech Forum ARCHIVE: Picture cut-off in scope

This is topic Picture cut-off in scope in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Bernardo McLaughlin (Member # 7267) on 06-22-2014, 02:10 PM:

Hi, we just upgraded to DCP and I haven't had a real, proper training yet so that's why I'm gonna sound like a layman here.

I haven't had a chance to fiddle with this yet, but the problem is that the aspect ratio of this movie ("Next Goal Wins") seems a bit off. Despite having it set in scope, the picture is still cut-off a bit at the top and bottom. Ordinarily might not be a problem, but portions of it feature subtitles.

Thanks for any tips and I'm happy to answer any clarifying questions.

Posted by Victor Liorentas (Member # 5272) on 06-22-2014, 02:28 PM:

You will have to give us projector make and model.
Sounds like scope is not set to spec.

Posted by Brad Miller (Member # 2) on 06-22-2014, 02:30 PM:

First, are you sure the movie IS in scope? Remember in digital flat is "letterboxed" within scope (in the simplest form) and there is no anamorphic squeeze, so you can't just look at people in the image and tell if you have the right lens based upon whether they are overly fat or super skinny like you could with 35mm. Try switching to flat. If it fills the height of your screen, that's your problem...it's a flat movie. If it doesn't fill the screen vertically, then you COULD temporarily run it in flat and present it "letterboxed" so at least the customers can see the subtitles.

Are your screens curved? That's a great way to lose subtitles due to the typical "smiley-face" distortion.

Did you have a real technician install this system? We always go in and rework the screen masking so as to achieve spot-on aspect ratios, but most people just crop and walk away.

Also it is possible you don't actually have the proper lens. I see this a lot also with many install companies where they order the lens they think is right, but it actually won't quite reach one end or the other so they simply crop off parts of the picture or scale it (which kills the quality) as opposed to doing the right thing and swapping the lens out for the correct one.

The projector make/model would help.

Also is the image spilling off of the screen onto the masking, or does it look like it is being cropped off like an aperture plate would so those parts of the image never leave the projector?

Posted by Bernardo McLaughlin (Member # 7267) on 06-22-2014, 02:51 PM:

The projector is NEC's NC900C

The operating system is OS-SA3K-3.0.48

I'm reasonably sure the film is supposed to be in scope. The screen is not curved. We did have a real technician install our system, but as far as I know he didn't mess with the screen besides installing the sound system behind it. The picture is not spilling off the screen, it's more like the aperture plate scenario you described.

Posted by Brad Miller (Member # 2) on 06-22-2014, 03:37 PM:

Try running it in flat first before we continue.

Posted by Frank Cox (Member # 6258) on 06-22-2014, 04:15 PM:

It wouldn't hurt to post the actual filename of the film, too. Most dcp filenames follow a specification that includes the format of the film, among other things.

Posted by Bernardo McLaughlin (Member # 7267) on 06-22-2014, 04:44 PM:

Says scope on the packaging and the file name contains an 'S' where it would usually indicate scope.

Posted by Frank Cox (Member # 6258) on 06-22-2014, 05:13 PM:

Don't bet your life that it's scope. I haven't had it happen with digital (yet), but I remember playing One Hour Photo. It said scope on the labels on the cans and every one of the reel leaders had "scope" printed on it, too.

It was flat.

Posted by Brad Miller (Member # 2) on 06-22-2014, 05:27 PM:

We've already come across MANY DCPs that were improperly labeled. This could be another example.

He will find out once he tries to play it in flat.

Posted by Carsten Kurz (Member # 5396) on 06-22-2014, 05:44 PM:

'Next Goal Wins' 2014 documentary seems to be referenced on various sites to be scope AR/1:2.4

https://s3.amazonaws.com/tribeca_cms_production/uploads/document/document/5345cf3d55ce63efcc000002/NEXT_GOAL_WINS _press_notes-1.pdf

The YouTube Trailer also clearly has a scope AR.

As Brad suggests, play it in flat. Pause it, change lens preset on the NEC to scope, then see what happens. If significant top/bottom parts of the image disappear when switching to scope, there is something wrong with the installation.

Download these test patterns und store them on your server for a quick check:

http://www.freedcp.net/dcp/test/xdc/xdc_test_pattern_XYZ_1-85.zip

http://www.freedcp.net/dcp/test/xdc/xdc_test_pattern_XYZ_2-39.zip

- Carsten

Posted by Steve Guttag (Member # 268) on 06-22-2014, 06:06 PM:

If it is JUST the subtitles that are wacked (off the screen)...(but credits and such are all appearing okay...people's heads are not chopped off)...then watch out on the PCF file being used. NEC normally has people use the "Auto" file and there is nothing auto about it. It is full-container with the pixel size defined as 0 x 0. Subtitles use the image size as the reference and if your server (which you didn't specify) hands off the image as a 4K file and your NEC is only a 2K projector (which it is), then the subtitles will be in the wrong place since they are referenced off of the bottom and center of the image.

In the Titles, the PCF should be set to define scope as 2048x858 with an AR of 2.39 or Auto-Square Pixels. Likewise on Flat, make sure the PCF has the defined resolution of 1998x1080 and an AR of 1.85 or Auto Square Pixels.

If you have an IMB system (most are now), then it is important that it is set up as a 2K output only.

Posted by Leo Enticknap (Member # 534) on 10-30-2014, 07:49 PM:

Many thanks Steve. We were having precisely this problem playing a 2K scope subtitled DCP (Waiting for August) through our DSS200, cat745 and NC3240S, and changing the PCF settings as you suggest and creating a "2K Scope Subtitled DCP" title/button for them has solved it.

Posted by Peter Castle (Member # 1997) on 10-30-2014, 08:55 PM:

Not quite on the same topic, but we tried to display an OCAP version of a DCP recently. The movie was "Annabelle", server GDC and projector NEC3240 - and the feature was scope. The captions had the second line's descenders off screen - in the unused pixels of the DLP. Is there a way of moving them or is it, as our installer felt, a production error?

Posted by Dave Macaulay (Member # 813) on 10-30-2014, 10:22 PM:

Are you certain that the captions were outside the 858 height of the scope image? If so, this is a production error. I believe that OCAP versions have the captions already in the image files, they are not inserted "on the fly" - so the PCF setting would have no impact on them (although it really can bugger up CCAP captioning).
It is pretty unusual to crop scope images from top or bottom but it could be done, especially if keystoning is extreme. Try setting a screen file with Y cutting off <111 and >969, zoom to see the entire height of that image, and see what's on screen.

Posted by Peter Castle (Member # 1997) on 10-30-2014, 11:09 PM:

If we display the scope image with a flat setting, the descenders are there - in the black below the image.

Posted by Gavin Lewarne (Member # 5397) on 10-31-2014, 03:56 AM:

I have come across a number of titles where the subtitles are rendered literally to the very bottom pixel of the scope container.

This causes a problem at our screen, because we physically cannot have the projector squared off to the centre of the screen, we have a little "skew". We are able to set our scope image to only have about 3 pixels masked off on each side to hide it, but for those titles with the subs at the very bottom I have to compromise a bit and have created a preset on our barco where the entire scope container is visible on screen, but it leaves the skew slightly visible.

If anyone has a workaround for that I would be interested to know it.

My normal procedure for setting the image formats to deal with the skew is to zoom the image so the border of the format is just-barely-touching the masking on all four sides then mask it.

Posted by Carsten Kurz (Member # 5396) on 10-31-2014, 04:36 AM:

Hmm, strange, it's a 4k projector, and a Scope DCP, and 2k I guess. I wouldn't understand how the subtitles can get below the container bottom in that scenario, at least if the cropping hasn't been completely over the bottom ;-) But you certainly would have noticed that before. Maybe it's really a production issue. Can you check picture properties of that feature, e.g. container size? Is the scope image falling into the proper masking?
Is the NEC running on current software? Maybe there is still something wrong with the PCF files/4k/2k/IMB settings.

The Doremis have options to do their own subtitling and also configure feature specific offsets. I have never heard the GDC can do that as well.

I think it is bad the subtitle offset can not be adjusted for projector generated subtitles. At least the offsets should be corrected by the projector automatically based on the crop setting, not the image container geometry. But as has been shown in many cases, TI is just not interested in doing real improvements on the subtitle engine. Sometimes I think they are deliberately sloppy on this so that server manufacturers pick up the issue so TI get's rid of that duty completely.

- Carsten

Posted by Marco Giustini (Member # 4544) on 10-31-2014, 05:43 AM:

As Carsten says, open the XML files and check where the subs are supposed to be. If they are at the bottom of the picture, report it back.

I remember having the same issue with subs on 35mm prints sometimes.

Posted by Jim Cassedy (Member # 4115) on 10-31-2014, 09:38 AM:

quote: Marco Giustini
I remember having the same issue with subs on 35mm prints sometimes.

Yea- but whenever I ran into that issue in 35mm, I'd run the print with the
1:85 aperture plates but use the 1:66 lens. It gave a slightly smaller
image on screen, but it at least kept the cinematographer's composition
intact, and you didn't have to come up with some framing compromise
between seeing the subtitles or cutting off the tops of people's heads.

Steve G gave an excellent explanation of the 4k output/2k projector
issue. Last time I ran into it was at the Telluride Film Fest this year,
where the subtitles on one of the films were off from where they
should have been.

For a number of reasons, we didn't have time to work out the issue
before showtime, so we screened that program off of an HDCAM
backup tape that had burned-in subs.

I couldn't tell the difference between the HDCAM & DCP on the 30ft screen.