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Incorrect DAR of 2.40:1 instead of 2.39:1 ? #612

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Sami32 opened this issue Sep 16, 2017 · 3 comments · May be fixed by #829
Open

Incorrect DAR of 2.40:1 instead of 2.39:1 ? #612

Sami32 opened this issue Sep 16, 2017 · 3 comments · May be fixed by #829

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@Sami32
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Sami32 commented Sep 16, 2017 •
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https://en.wikipedia.org/wiki/Aspect_ratio_(image)

The motion picture industry convention assigns a value of 1.0 to the image’s height; an anamorphic frame (since 1970, 2.39:1) is often incorrectly described (rounded) as 2.40:1 or 2.40 ("two-four-oh").

This aspect ratio of 2.39:1 was confirmed by the most recent revision from August 1993 (SMPTE 195-1993).[5]

http://www.arri.com/?eID=registration&file_uid=7737

Unfortunately, everyone was so used to calling anamorphic films 2.35:1, that many still use that aspect ratio erroneously, even when talking about films shot after 1970. Similarly, 2.40:1 is an incorrect, unfortunate and unnecessary rounding up; a proper rounding up would be 2.4:1. The correct aspect ratio for anamorphic films shot after 1970 is 2.39:1.

Samples:
audio-issue-sample-file.mkv.txt

EDIT: Feel free to close this issue if it is not pertinent, relevant.
@Sami32 Sami32 changed the title DAR of 2.40:1 instead of 2.39:1 Sep 16, 2017
@Sami32 Sami32 changed the title Incorrect DAR of 2.40:1 instead of 2.39:1 Sep 16, 2017
kieranjol added a commit to kieranjol/MediaInfoLib that referenced this issue Mar 31, 2018
@kieranjol
File__analyze_streams.cpp - Change for 2.39:1 DisplayAspectRatio/String
eff9bb8 
MediaArea#612
@kieranjol kieranjol linked a pull request Mar 31, 2018 that will close this issue
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@kieranjol
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Hi, I just noticed this issue. DisplayAspectRatio/String displays aspects ratios almost exactly how we would like:
mediainfo -f --Language=raw *.mov |grep -i aspectratio/string

DisplayAspectRatio/String        : 1.85:1
DisplayAspectRatio/String        : 4:3
DisplayAspectRatio/String        : 2.40:1
DisplayAspectRatio/String        : 16:9

The only exception being our 2048x858 DCP files, which have a ratio of 2.39:1 but it is listed here as 2.40:1. i've attempted to fix in #829
@mivk
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mivk commented Oct 4, 2020

Note that 2.40:1 is not just a rounding of 2.39. It is also actually used for BluRay. A scope film on a 2K DCP will be 2048 x 858 ( = 2.3869... =~ 2.39:1), but on BluRay it will be resized and cropped to 1920 x 800 = 2.40:1.
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