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Old 8th February 2006, 10:47   #61  |  Link
SeeMoreDigital
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If we are not following the ITU specification to the letter, which most (if not all) software players, don't appear to follow.... then the answer is yes
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Old 8th February 2006, 10:52   #62  |  Link
yaz
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sorry for my lame kick in, again. maybe i'm a dumbass but i feel some 'overcomplication' here. imho, u don't need anything else than the par value for making correct resizing.

the equation considered is :
dar = par x sar
where
dar : display aspect ratio (what ratio to be displayed)
sar : stream/sample aspect ratio (the original/non-cropped aspect ratio of the stream)
par : pixel aspect ratio
note, these all are given if your source can be played correctly !

actually, par is a multiplier giving how much the image must be expanded horizontally so as to get the correct/intended dar. that's what all players (should) do.

if the stream is cropped (whatever way !), the resulting dar value stays correct if the same par is used for resizing. of course, the picture will be higher or lower but not distorted.

it's quite easy to demonstrate. take your favourite dvd, make some different arbitrary but player compliant (say, mod16) cropping and than some short anamorphic encodes. (to go up to the studio logo is far enough for checking) set par value according to what shown on the dvd cover (can be 4:3 or 16:9only !). won't see any ratio distortion. (if someone would tell me how to upload images to doom9, i would show some demo pics, but it's worth to try personally )

the bests
y

ps if i get wrong what u're talking about, pls, forgive me
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Old 8th February 2006, 10:55   #63  |  Link
Seb.26
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Quote:
Originally Posted by SeeMoreDigital
If we are not following the ITU specification to the letter[...]
Please : Where could I read some papers about that ? ... I don't know what is it
[Edit] -> I will read all on your www ... it looks great !

Quote:
Originally Posted by SeeMoreDigital
[...] then the answer is yes
Ok, so I'm not fully idiot ...

My way looks really simple beside all your heavy-sci-math-computing

So if I'm wrong for 1 ou 2 pixels in height ... what the matter ?!

Thanks for answer SeeMoreDigital !
( from where is your avatar ? a movie, but which ? )

Last edited by Seb.26; 8th February 2006 at 11:06.
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Old 8th February 2006, 11:10   #64  |  Link
SeeMoreDigital
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Quote:
Originally Posted by Seb.26
( from where is your avatar ? a movie, but which ? )
It's from a TV show called "House"


Cheers
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Old 8th February 2006, 11:12   #65  |  Link
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thanks.
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Old 9th October 2019, 18:03   #66  |  Link
orion44
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Quote:
Originally Posted by SeeMoreDigital View Post
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
Thank you!

This helped me a lot.
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