Film-Tech Forum ARCHIVE: Aspect Ratio Calculator

This is topic Aspect Ratio Calculator in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Paul Shuttleworth (Member # 9057) on 01-06-2019, 09:15 AM:

I have been asked to provide a pixel by pixel specification of aspect ratios ranging from Academy to Cinemascope.
(1:375, 1:66, 1:85, 2:39)

Is there a calculator or details of recommended ratio for a 2K projector online?

For example 16:9 would be 1920x1080

Posted by Scott Norwood (Member # 30) on 01-06-2019, 09:43 AM:

There is a discussion of this in an old thread. The conclusion seemed to be that these were the correct dimensions:

1.33: 1440x1080
1.37: 1480x1080
1.66: 1792x1080
1.78: 1920x1080
1.85: 1998x1080
2.39: 2048x858

There has been some variance on how 2.2:1 (70mm) is handled on DCPs. Some put it in the full container (does anyone know those dimensions?) and others pillarbox it into the scope dimensions.

[ 01-06-2019, 05:47 PM: Message edited by: Adam Martin ]

Posted by Paul Shuttleworth (Member # 9057) on 01-06-2019, 10:03 AM:

Thanks Scott,

That's brilliant!

Posted by Carsten Kurz (Member # 5396) on 01-06-2019, 11:49 AM:

Scott - there is no strict ruling in DCI or SMPTE, but:

---
ISDCF recommended practice that for aspect ratios under 1.85 (such as academy aperture 1.33) pillar box in a flat package. For aspect ratio from 1.85 to 2.30 letter box in a flat package. For aspect ratios above 2.30 letter box in a scope package.
---

So, 2.2:1 should come in a flat container, and be padded with black/letterboxed from 1998*908 to 1998*1080 for 2k.

e.g. http://www.cinematography.com/index.php?showtopic=67434

http://www.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=003059#000000

General consensus is that the 'C' Full Container should not be used for regular distribution content, only for test purposes or special applications.

- Carsten

Posted by Carsten Kurz (Member # 5396) on 01-06-2019, 04:43 PM:

BTW - in the above table, DCI Scope/2.39:1 is wrong, it is 2048*858

Posted by Scott Norwood (Member # 30) on 01-06-2019, 04:53 PM:

Typo. Thanks for the correction. Interesting about the ISCDF recommendations, but it makes sense as far as avoiding the need to create additional screen/lens files for common-height-masked cinemas.

Posted by Carsten Kurz (Member # 5396) on 01-06-2019, 05:53 PM:

Yes, I think that is the 'ratio' (pun...) behind it. Also, keep in mind that some systems generate format cues automatically from container flags (TMS spl generators/templates), so, using only F and S is the more robust scheme. Also, I am pretty sure that many human operators nowadays wouldn't know what to do if a 'C' turns up.

- Carsten

Posted by Adam Martin (Member # 641) on 01-06-2019, 10:13 PM:

quote: Carsten Kurz
many human operators nowadays wouldn't know what to do if a 'C' turns up

Call her a B and tell her to F off!

Thanks, I'll be here all week.

Posted by Carl Martin (Member # 1146) on 01-07-2019, 03:17 AM:

ha ha, thank you brother adam!

i've found that if it isn't 1.78, 1.85, or scope, all bets are off as to what dimensions will be used for the various ratios. i have so many damn screen and lens files for what some fool thinks is the best way to have "mastered" or "remastered" their movie.

Posted by Leo Enticknap (Member # 534) on 01-07-2019, 09:56 AM:

Another one: 1.19 ("Early sound special" (UK) or "Movietone" (USA) ratio) is 1,290 x 1,080 (2K) and 2,580 x 2,160 (4K).