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Old 2nd September 2014, 23:10   #1  |  Link
asarian
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DAR of "2.40:1"

There used to be this great online resize tool, but it seems gone.

So, on a PAL DVD, at "720x576", with a DAR of "2.40:1", should I upscale to 1920x800? That feels too wide, but is really what my calculations keep telling me. Or did I forget to factor something in?
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Old 2nd September 2014, 23:16   #2  |  Link
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Why would you need to upscale? Just let the video player handle it.
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Old 3rd September 2014, 00:18   #3  |  Link
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Crop the borders first since DVD only allows 4:3 or 16:9 flags, but yeah. 2.39:1 and 2.35:1* work out to 1920x800 and 1920x816 (accounting for mod), respectively.

*deprecated since 1970 but still occasionally shows up
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Old 3rd September 2014, 00:37   #4  |  Link
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1920x800 is 2.40:1, did you crop before upscale?
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Old 3rd September 2014, 00:39   #5  |  Link
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Originally Posted by qyot27 View Post
Crop the borders first since DVD only allows 4:3 or 16:9 flags, but yeah. 2.39:1 and 2.35:1* work out to 1920x800 and 1920x816 (accounting for mod), respectively.

*deprecated since 1970 but still occasionally shows up
Thank you! Read up on SAR/DAR/PAR, etc., and you hear 10 different stories. Guess I remembered it right, for a change.
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Old 3rd September 2014, 01:21   #6  |  Link
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Originally Posted by feisty2 View Post
1920x800 is 2.40:1, did you crop before upscale?
No cropping.

Different players are playing it differently, though (often at ca. 1920x1040), which actually looks more natural.

Although the DVD VOB container pegs it at 2.40:1, other sites list the same PAL DVD ("Cherry 2000") at 1.85:1, which would, indeed, come down to 1037p. And that *does* indeed make it far more natural. Hence, my confusion.

EDIT: I just checked, it actually says 1.85:1 on the cover of my box too, LOL. Guess the VOB had it wrong. :P
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Old 3rd September 2014, 02:21   #7  |  Link
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Try this. I'm not sure where it gets it's ITU pixel aspect ratios. They're slightly different to the ratios most other programs use, although the difference is very tiny. Most 16:9 DVDs would probably use straight 16:9 resizing anyway, so you'd uncheck the ITU resizing option. It's an exe, but it's safe.

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Old 5th September 2014, 08:30   #8  |  Link
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Originally Posted by asarian View Post
There used to be this great online resize tool, but it seems gone.

So, on a PAL DVD, at "720x576", with a DAR of "2.40:1", should I upscale to 1920x800? That feels too wide, but is really what my calculations keep telling me. Or did I forget to factor something in?
A DVD has no DAR of 2.40:1. The movie maybe .

There are two approaches on how the movie is stored.

One is to put the movie inside a fullframe (or 4:3). In this case you'll have some 300 pixels for the whole vertical field. This is the worst solution, and therefore found mainly on budget movies/studios/countries.

The other one is to have the DAR of 16:9. This will give you another 100 pixels. Sensibly better image. This is usually found with better editions (premium, collector, platinum etc). All values must be corrected for overscan, in particular the horisontal one.

Either way, the final resolution for upscaling would be 1920 x 800. While the horizontal definition is not greatly affected by the upscaling (it's only ~2x) the vertical ranges from ~3x to ~2x, accordingly. Non-integer ratios yield more artefacts.

And either way, the upscaling algorithm must be good, as you'll have to live with the result. Meanwhile the hardware scalers, as found in BD players and TV sets, improved a lot and became incredibly cheaper, thus available even in budget gear.

Like creaothceann I'd leave this to the player-TV combination. Unless one has to edit sequences from old movies into a HD project.
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Old 5th September 2014, 15:59   #9  |  Link
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Am I not correct in saying that there is a 3rd DAR (Full frame) for DVD, 2.21:1 or something like that,
although I have never seen one like that ?
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Old 5th September 2014, 16:31   #10  |  Link
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Originally Posted by Ghitulescu View Post

Either way, the final resolution for upscaling would be 1920 x 800. While the horizontal definition is not greatly affected by the upscaling (it's only ~2x) the vertical ranges from ~3x to ~2x, accordingly. Non-integer ratios yield more artefacts.
Turns out, like I said above, it was actually a DAR of 1:85:1 (this is why I always manually inspect things first). Which gave me a 1920/1.85 = 1037.8 vertical res (I used 1040, btw, as I think that's what it's actually supposed to be).

Quote:
And either way, the upscaling algorithm must be good, as you'll have to live with the result. Meanwhile the hardware scalers, as found in BD players and TV sets, improved a lot and became incredibly cheaper, thus available even in budget gear.

Like creaothceann I'd leave this to the player-TV combination. Unless one has to edit sequences from old movies into a HD project.
I simply prefer my own scaling, especially when I'm post-processing the movie to begin with.
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Last edited by asarian; 5th September 2014 at 20:02. Reason: I wrote 1337, instead of 1037
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Old 5th September 2014, 16:39   #11  |  Link
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Originally Posted by StainlessS View Post
Am I not correct in saying that there is a 3rd DAR (Full frame) for DVD, 2.21:1 or something like that,
although I have never seen one like that ?
Knock yourself out: Previous and currently used aspect ratios
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Old 5th September 2014, 18:16   #12  |  Link
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2.21:1 is not a valid DVD aspect ratio flag (DVD only allows 4:3 and 16:9 flagging), but all the MPEG-2 encoders I've ever seen have a setting for doing 2.21:1. Which makes me think it's defined as an 'official' ratio in the MPEG-2 spec (and the aspect ratio listing above confirms it was in the MPEG-2 part), but since it's not used very much at all day-to-day, it was left out of the DVD specifications. I mean, to my knowledge, no widescreen TV ever had a 2.21:1 ratio, since (as per that link) it was developed as a film ratio in the 1950s but was still rarely used. Most, if not all, widescreen televisions and monitors are 16:9 or 16:10, although I'd imagine some ultra-widescreen models exist that are 2.39:1 to match the common film ratio.

Case in point, if you try to make HCenc use 2.21:1, it tells you it's not DVD compliant.

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Originally Posted by asarian
(I used 1040, btw, as I think that's what it's actually supposed to be)
Technically speaking, that's not what it's supposed to be. When speaking in absolute terms, you don't round the result (actual 16:9 at 480p is a width of 853.3 repeating, but it's usually rounded to 848 to account for mod16*, 856 for mod8, 852 for mod4, or 854 for mod2). But encoding programs don't like having non-integer (and in many cases, a non mod-[32|16|8|4|2] number), so it has to be rounded by necessity, and generally, human eyes don't tend to notice the relatively minor distortion that results (1.85 is close enough to 16:9 that in many cases it gets rounded down or cropped when put on DVD). The alternate tactic would be not to divide the width by the ratio, but to multiply the height by it. In which case, you'd get 1998x1080 for 1.85:1, or if you were dead-set on a height of 1040, 1924x1040.

*which also includes mod8, mod4, and mod2, but going 5 pixels down makes less sense when using the others because they can get closer to 853 than mod16 can. With mod16, you can use 848 or 864, and 848 is closer. 1.85:1 at 480p is 888x480, which is compatible with mod8, 4, and 2, but not 16 (which needs 880 or 896).
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Old 5th September 2014, 20:01   #13  |  Link
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Originally Posted by qyot27 View Post
Technically speaking, that's not what it's supposed to be. When speaking in absolute terms, you don't round the result (actual 16:9 at 480p is a width of 853.3 repeating, but it's usually rounded to 848 to account for mod16*, 856 for mod8, 852 for mod4, or 854 for mod2). But encoding programs don't like having non-integer (and in many cases, a non mod-[32|16|8|4|2] number), so it has to be rounded by necessity, and generally, human eyes don't tend to notice the relatively minor distortion that results
At 1.85:1, I should probably have rounded that 1920/1.85 = 1037.8 to 1038, but keep in mind that those 2 extra lines I used (1040), aka 1 extra line on top, and 1 extra on the bottom, is something I'll never ever see.

Besides, I took a still of the DVD, scaled it properly (1.85:1), and it gave me exactly 1040p; so I figured I would just use the same.
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Old 5th September 2014, 20:31   #14  |  Link
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Originally Posted by asarian View Post
At 1.85:1, I should probably have rounded that 1920/1.85 = 1037.8 to 1038, but keep in mind that those 2 extra lines I used (1040), aka 1 extra line on top, and 1 extra on the bottom, is something I'll never ever see.

Besides, I took a still of the DVD, scaled it properly (1.85:1), and it gave me exactly 1040p; so I figured I would just use the same.
Just to double-check what you're doing:
PAL DVD flagged as 16:9.
720x576 -> 1024x576

Crop off the letterboxing/pillarboxing.

Scale up based on 1.85:1, getting 1920x1040 when accounting for mod16.
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Old 5th September 2014, 20:41   #15  |  Link
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I mean, to my knowledge, no widescreen TV ever had a 2.21:1 ratio
There are TVs with such a ratio. It is called Cinema 21:9. But the dvd specs doesn't seem to allow for such a DAR. On wikipedia there is a rumour that the upcoming revision of the Blu-ray specs will support it.

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Old 5th September 2014, 22:53   #16  |  Link
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There are TVs with such a ratio. It is called Cinema 21:9. But the dvd specs doesn't seem to allow for such a DAR. On wikipedia there is a rumour that the upcoming revision of the Blu-ray specs will support it.
As stated by the Wikipedia article you linked, '21:9' (which is the marketing name for 64:27) is 2.37:1, not 2.21:1. It would fall under the other thing I said:
Quote:
although I'd imagine some ultra-widescreen models exist that are 2.39:1 to match the common film ratio.
Also on the other Wikipedia page listing past and present aspect ratios:
Quote:
2.20:1 (11:5, 22:10): 70 mm standard. Originally developed for Todd-AO in the 1950s. Specified in MPEG-2 as 2.21:1, but hardly used.

2.37:1 (64:27 = 43:33): TVs were produced with this aspect ratio between 2009 and 2012[8] and marketed as "21:9 cinema displays".
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Old 5th September 2014, 23:09   #17  |  Link
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Originally Posted by qyot27 View Post
Just to double-check what you're doing:
PAL DVD flagged as 16:9.
720x576 -> 1024x576

Crop off the letterboxing/pillarboxing.

Scale up based on 1.85:1, getting 1920x1040 when accounting for mod16.
Yup, that's exactly what I did.
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Old 8th September 2014, 09:24   #18  |  Link
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Originally Posted by qyot27 View Post
2.21:1 is not a valid DVD aspect ratio flag (DVD only allows 4:3 and 16:9 flagging), but all the MPEG-2 encoders I've ever seen have a setting for doing 2.21:1. Which makes me think it's defined as an 'official' ratio in the MPEG-2 spec (and the aspect ratio listing above confirms it was in the MPEG-2 part), but since it's not used very much at all day-to-day, it was left out of the DVD specifications.
The DVD specs do not encompass exactly those of MPEG-2. The same as with Blu-ray or even with its predecessor, the VCD. In fact DVD can also accommodate MPEG-1.

MPEG-2 on the other hand is a generic algorithm. It can be used on computers, cellphones, whatever.

The problem with digital (one of them) is that the display is fixed, ie it has a finite and exact number of pixels. Any pixel costs money, so one would not make screens of eg 123x71 pixels, because no application would use it.
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Old 8th September 2014, 10:14   #19  |  Link
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when I'm dealing with ntsc dvds, I would add 6 pixels blackborders at vertical direction first, then resize them to 720*540 then crop all blackborders, it's a reverse process of how dvds were made from broadcast ntsc mastertapes

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