aspect ratio 16:9 and 2.11:1

[kheperi]

there seem to me to be a (small) problem with those 2 aspectratio's

My calculator tells me 16/9 = 1.7778
But this ratio (DAR3) is also often called 1.85
Which one is the right one?

And the ratio 1:2.11 (DAR4) is also named 1:2.35

What is the real value that dvd players use to reconstruct the intended aspectratio?

[amni]

so don't bother too much.

when you convert the backup and resize,
raseize to approximate ratio (eg, ratio + - 10% comparing to the
original). For example 16:9 can be resized to 640x336 pixels.

[kheperi]

well i did a test with a dvd. I opened it with a dvd player (on my computer) and then i opened my dvd2avi project and resized it with virtual dub.
i used an x-size of 512 and then resized the dvd-player window to match the width of the preview screen of the resizefilter. Then i tried to match the y-size closest as possible. Of course i only matched the used part of the picture and not the black edges.

And indeed it seems that the suggested y-sizes on Doom9's site are too low! he suggests 512x272 but 512x288 is much better! still a bit too small but very close to what the dvd-player shows.

[kheperi]

and 640x336 is not good. Its much to low. You can choose between 352 or 368. the correct value would be 360, but thats no multiple of 16.

As far as i can deduct right now the factor for 16/9 indeed is 1.78 and not 1.85

That may seem a small difference but its not that small. Like your example: your 336 is a bit lower then the by Doom9 suggested 352, but its even more low related to the (probably) right size of 360.

Well anyway i will check any dvd i back up from now with the methode i described above

[Zhnujm]

btw, not all soft dvd players resize correctly...

[kheperi]

so... what IS the correct factor?

[kheperi]

(found on Nicky guides)

(quote)
There are a myriad of possible ratios for widescreen. But probably the most used of them for DVD's will be 1.85:1 (American), 1.66:1 (European), 1.77:1 (British) and especially CinemaScope at 2.35:1 (worldwide). CinemaScope are also sometimes called Panavision or just WideScreen. Of course, it could be a mistake to say any aspect ratio is just British or just American etc., because studios just use the ratios they feel are best for their audience.
(/quote)

hmmmmmmm..... since i live in Holland i guess most 16/9 dvd's here are 1.66 (or 1.67) indeed, as i already found out. And american are 1.85, as Doom9 uses in his examples.

Confusing... Does a dvdplayer know the difference?

(excuses for me talking so much to my self :-)

[saVe]

i'm european. i use 640x352 or 640x272. it's always one of those. there are two kinds of movies here. most are 640x272. some are 640x352. both are labeled 16:9. that's how it is over here.

sorry, too much information for long sentences...

[Doom9]

you're mixing up DARs (display aspect ratio... the aspect ratio of your display device : TV / PC monitor) and ARs (aspect ratios) of the actual movies. A movie on DVD has both an AR and a DAR. the DAR indicates how the picture has to be stretched during playback, the AR indicates how much of the vertical pixels are used for the actual movie in relation to the horizontal resolution.
for more info please refer to http://www.doom9.org/aspectratios.htm

On an additional note: the 1:1 and 2.11:1 DARs are never used on DVDs.