[Cin] SAR, DAR, PAR - oh, my!

Terje J. Hanssen terjejhanssen at gmail.com
Sun Jan 7 23:52:39 CET 2024

Den 07.01.2024 23:35, skrev Andrew Randrianasulu:
> пн, 8 янв. 2024 г., 01:31 Andrea paz <gamberucci.andrea at gmail.com>:
>     I don't quite understand how ffmpeg considers the various aspect
>     ratios. However from the site lurkertech you pointed to (and from
>     which I had taken some definitions put in the manual) PAR and SAR are
>     not the same thing: PAR is about pixel shape and size; SAR is about
>     frame shape and size.
>     To change the manual I would like to be sure that ffmpeg really
>     considers PAR=SAR.
> lets wait until ffmpeg-users reply to just send email :)

The wikipedia article section "Confusion with display aspect ratio" 
points out:
Pixel aspect ratio is often confused with different types of image 
aspect ratios; the ratio of the image width and height. Due to 
non-squareness of pixels in Standard-definition TV, there are two types 
of such aspect ratios: /storage aspect ratio/ (/SAR/) and /display 
aspect ratio <https://en.wikipedia.org/wiki/Display_aspect_ratio>/ 
(abbreviated /DAR/, also known as /image aspect ratio 
<https://en.wikipedia.org/wiki/Image_aspect_ratio>/ and /picture aspect 
ratio <https://en.wikipedia.org/wiki/Picture_aspect_ratio>/). Also, 
/pixel aspect ratio/ (/PAR/) is also known as /sample aspect ratio/ 
(abbreviated /SAR/) in some industrial standards (such as H.264 
<https://en.wikipedia.org/wiki/Pixel_aspect_ratio#cite_note-2> ) and 
output of programs (such as /ffmpeg 
<https://en.wikipedia.org/wiki/Pixel_aspect_ratio#cite_note-3> ). Note 
the reuse of the abbreviations /PAR/ and /SAR/. This article uses only 
the terms pixel aspect ratio, display aspect ratio and storage aspect 
ratio to avoid ambiguity.

And in Note 3
"ffprobe shows PAR as SAR" <https://trac.ffmpeg.org/ticket/1776>. 
ffmpeg.org. Retrieved 2022-06-10.
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