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Old 3rd February 2006, 13:33   #9  |  Link
SeeMoreDigital
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Join Date: Jun 2003
Location: Notts, UK
Posts: 12,219
If you can guys, try and calculate "everything" as a fraction, because converting fractions to decimals and back to fractions again "can" produce conflicting Aspect Ratio Signalling (ARS) values.

If your NTSC movie has an aspect ratio of 1.33:1, then this can be represented as a fraction of 4/3. Meaning: -
Code:
4     480     1920                    8
-  x  ---  =  ----  lowest dominator  -  Giving an ARS value of 8:9
3     720     2160                    9
If your NTSC movie has an aspect ratio of 1.77:1, then this can be represented as a fraction of 16/9. Meaning: -
Code:
16     480     7680                    32
--  x  ---  =  ----  lowest dominator  --  Giving an ARS value of 32:27
 9     720     6480                    27
If your NTSC movie has an aspect ratio of 1.85:1, then this can be represented as a fraction of 37/20. Meaning: -
Code:
37     480     17760                    37
--  x  ---  =  -----  lowest dominator  --  Giving an ARS value of 37:30
20     720     14400                    30
If your NTSC movie has an aspect ratio of 2.35:1, then this can be represented as a fraction of 47/20. Meaning: -
Code:
47     480     22560                    47
--  x  ---  =  -----  lowest dominator  --  Giving an ARS value of 47:30
20     720     14400                    30
If your NTSC movie has an aspect ratio of 2.40:1, then this can be represented as a fraction of 12/5. Meaning: -
Code:
12     480     5760                    8
--  x  ---  =  ----  lowest dominator  -  Giving an ARS value of 8:5
 5     720     3600                    5
For working out the "Aspect Ratio Signalling" values of PAL sources, simply substitute 480/720 to 576/720 and recalculate.

The same formula can be used to work out the "Aspect Ratio Signalling" values of cropped and re-sized encodes too by entering the relevant resolutions.


Cheers
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Last edited by SeeMoreDigital; 3rd February 2006 at 16:01.
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