This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.

[INFO] About pixel aspect ratios,..
#1
We differentiate between three types of aspect ratio:
Display Aspect Ratio (DAR): the aspect ratio of the image as displayed.  ('4:3', '16:9', '16:11',...)
Storage Aspect Ratio (SAR): which is the ratio of pixel dimensions.  ('720:480','720:576','1920:1080')
Pixel Aspect Ratio (PAR): which is ratio of the pixels themselfes.  ('1:1', see below tables)

Here's how these three relate to each other: SAR × PAR = DAR
Meaning: If you multiply the shape of the pixels with their dimensions you get the display aspect ratio.

Since in video and image processing people can't make it simple there have been a lot of pixel aspect ratios definitions over the years, since the most common you will encounter are either the MPEG-4, ITU-R 601 or Generic defined values I will only list these:

MPEG-4:  (common for MPEG-4 based content)

DAR

PAL

NTSC
4:3
12/11
10/11
16:9
16/11
40/33


ITU-R 601:  (common for analog content)

DAR

PAL

NTSC
4:3
1150/1053
38800/42651
16:9
4600/3159
155200/127953


Generic:  (common for MPEG-2 based content)

DAR

PAL

NTSC
4:3
16/15
8/9
16:9
64/45
32/27


and the most common as pixel aspect ratio: Square Pixel 1:1, which means that the DAR and the PAR are the same. Smile

Side note:
Is content is encoded with a pixel aspect ratio that is not 1:1 it's called anamorphic.
A good read about the topic is The Ultimate Guide to Anamorphic Widescreen DVD (forDummies!) by Bill Hunt from The Digital Bits.

Cu Selur
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)