Problem With Display Aspect Ratio

[Cunhambebe]

Hi there! Here I am once again :) I have bought the DVD Superman Returns (Brazilian version = exactly like the one released in the USA). What a good movie! I'd like to back up it to Xvid but I find some problems on how to find the correct aspect ratio. The box says its original aspect ratio is 2.40:1 and 16:9 transfer. DGIndex says it's 16:9. In fact resizing the whole thing to 640x360 makes things a bit shrunk (krypton, right at the beginning looks like an egg), on the other hand 640x272 seems OK. I thought about 640x266, which makes practically 2.40. I was just wondering if you coulkd help me find the safest/correct size. What should I do? Thanks in advance.
Cheers.

[CWR03]

DGIndex will always report either 16:9 or 4:3. You can't rely on it at all because it doesn't know if it's anamorphic widescreen or not.

It's very likely 2.35:1. 2.40:1 is an uncommon size. IMDB reports 2.40:1, but Netflix (which has been more accurate for me than IMDB) reports 2.35:1.

What should I do?
Perhaps use your own judgement in finding a suitable aspect ratio that suits your personal preferences instead of asking for opinions that are not likely to be objective?

[chilledoutuk]

The film aspect in not important there are two dvd aspects used in the industry 16:9 and 4:3 in both NTSC or PAL.

I personally would encode using full resolution and set the DAR (Display aspect ratio) to that of the coresponding format.

YOU CAN RELY ON DGINDEX AS ALL THAT MATTERS IS WHETHER THE DVD IS 16:9 OR 4:3.

From these you can calculate the corect display aspect you might need.

If you want to downsize the resolution i would first crop off any borders making sure your output is divisible by 16.

there are 4 key PAR's:
NTSC 4:3 =10/11
NTSC 16:9 =40/33
PAL 4:3 =12/11
PAL 16:9 =16/11

Using these pars and the following formula you can calculate the new aspect of any cropped video.

AR=aspect ratio
PAR= Pixel Aspec Ratio
CHR= Cropped Horzontal Resolution
CVR= Cropped Verticle Resolution

AR=(PARxCHR)/CVR

using this calcualted aspect ratio you can now resize to any resolution that follows this aspect and the film will display with the correct aspect.

[Cunhambebe]

Thanks to you both for taking time to respond.

CWR03
IMDB reports 2.40:1, but Netflix (which has been more accurate for me than IMDB) reports 2.35:1.
-Please, what do IMDB and Netflix mean? Thanks in advance.

chilledoutuk
f you want to downsize the resolution i would first crop off any borders making sure your output is divisible by 16
-That's what I've done. Y1= 56; Y2= -60
Using these pars and the following formula you can calculate the new aspect of any cropped video.

AR=aspect ratio
PAR= Pixel Aspec Ratio
CHR= Cropped Horzontal Resolution
CVR= Cropped Verticle Resolution

AR=(PARxCHR)/CVR
Thank you. In spite of the fact I flunked all my math exams, I'll try to do this :)

[CWR03]

-Please, what do IMDB and Netflix mean?
IMDB = www.imdb.com or the Internet Movie DataBase.

Netflix = an online movie rental service.

[Cunhambebe]

Thanks for the input, CWR03. In fact, I've googled it and found the sites. Thanks so much. I'm still trying all that math - ouch! lol :D
Cheers,
Mark

[professor_desty_nova]

For help you can use the "PARanoia" program. See http://forum.doom9.org/showthread.php?t=101070

[foxyshadis]

It's very likely 2.35:1. 2.40:1 is an uncommon size.

It isn't actually uncommon at all, I've found. Anything from 2.33 to 2.42 is quite common in that range, because there's a lot of leeway in the lensing and masking. 2.50 and up has definitely gone the way of the dinosaur though.

Cunhambebe, are you sure you want to shrink it so drastically? Watching something shrunk that much almost hurts once you get a bit larger screen, compared to a DVD.

[Cunhambebe]

First of all, thanks to all who took time to respond.

professor_desty_nova
-Thanks for the input on PARanoia. I've heard about that.

foxyshadis
It isn't actually uncommon at all, I've found.
-I do agree with you, it's pretty common.
Cunhambebe, are you sure you want to shrink it so drastically?
-You mean encoding the movie at 640x266? Well that's the right way to do it I guess; I mean, keeping it's original display.
Watching something shrunk that much almost hurts once you get a bit larger screen, compared to a DVD.
-So what do you suggest me do? I guess 640x272 would be OK as it's been suggested. :confused:
Thanks in advance

[chilledoutuk]

The best thing to do is not resize at all.
Crop the black borders off so that you still have a resolution thats divisible by 16 and then encode and set the PAR for your dvd source in XVID.
In fact not only is it better its easier as well saves time calculating aspect ratios after cropping and there is no error generated in the aspect which you sometimes get when trying to resize to a multiple of 16.

[Cunhambebe]

you still have a resolution thats divisible by 16
Could u please gives us an example for this movie?!
Thanks in advance
Mark

Edit:
The best thing to do is not resize at all.
-I guess resizing it makes you get a better encoding with a lower bitrate and no loss of quality at all.

[foxyshadis]

It depends, there's a few things to take into account. Resize itself will reduce the quality, sometimes a lot, but it'll also prevent blocking and ringing if that bugs you more. Strict cropping, no resizing, means anamorphic encoding and while I'd prefer that, it isn't universally supported. So you have to make sure your intended playback devices support it. Resizing up, or a little up (h) and a little down (v) like 864x320, will lead to more artifacts unless you give it a lot more bitrate, but the difference is amazing. After all, 640x272 is nearly VHS resolution, and it shows, compared to watching a DVD; at least, 720x304 (or 704x288 if it's only 704 wide) should look a little bit better. But as always, it all depends on the bitrate you give it and the matrix you use.

Compare the difference playing full screen of one scene, encoded at your desired bitrate, with different encoded resolutions. Use the most pleasing one, which might be the smallest, and might be a larger more detailed one.

[chilledoutuk]

it all boils down to as foxy said what you want to achieve.
If you want to get a film on a cd then your gona need some serious downsizing and probably noise removal as well.
If however you want to get 3 films on a standard dvd-r then as long as the films are not too long you can quite easily encode using anamorphic resolution.
This is how i recommend my brother uses recode in fact in recode its very easy to do all you have to do is make sure you crop to a divisible by 16 resolution and then disable resizing recode will automatically set the correct par for the video (assuming you used a mpeg2 source not .avs)
My brother used to use a program called vidomi which always downsized when i showed him some stuff i had done with recode lets hasnt gone back to non anamorphic encodes.

When you can get and old xbox and put XBMC which is based on mplayer on it i really don't see the value in some of these old divx players that are limited to avi containers etc.

TBH i wish megui had some PAR presets for the x264 codec as it would make anamorphic encoding in x264 much easier.

[Cunhambebe]

Thanks you guys.

foxyshadis
Resize itself will reduce the quality, sometimes a lot, but it'll also prevent blocking and ringing if that bugs you more.
-That's absolutely true. When I only crop the dark areas on the screen, leaving it to full resolution, I do get some blocking and this is very unpleasant, really.
After all, 640x272 is nearly VHS resolution
-Last month I encoded one of my own DVDs, The Big Blue as 640x272 and the outcome was 100% perfect. Of course I'm watching on a PC, haven't tried on a TV yet :o

chilledoutuk
...you can quite easily encode using anamorphic resolution.
-In spite of the fact I am encoding and resizing to 640x272, it is still anamorphic, isn't it?! :confused:

[CWR03]

-In spite of the fact I am encoding and resizing to 640x272, it is still anamorphic, isn't it?!
No, anamorphic is when the image must be stretched to display properly. What you're getting is a proper aspect ratio file.

Let's say for example that your source is NTSC, 720 x 480 (original aspect of 1.5:1), and you're working with the same film. You could encode it at the original resolution and use DAR signaling to have it display at 16:9. It would then display properly, even though the true aspect ratio is way off. THis method is used a lot for standalone players, but it's unnecessary for PC playback since your method will always display at the resolution at which it's encoded.

When I only crop the dark areas on the screen, leaving it to full resolution, I do get some blocking and this is very unpleasant, really
That's only because you've chosen a bitrate or filesize that's too low or small for so much information. I regularly encode movies at full width and proper DAR, although at 2.2GB, and the playback is nearly as good as the DVD.

[Cunhambebe]

Thanks for your help, CWR03.
No, anamorphic is when the image must be stretched to display properly. What you're getting is a proper aspect ratio file.
-Some people told me that encoding the way I'm doing, the video will display correctly - well, I guess I'm totally lost...
Anyway, cropping Y1 and Y2, gives me a full resolution of 720x362. Then what? Should I go to Xvid Configuration and on DAR guide, set it to 16:9?
Thanks :confused:

[henryho_hk]

i) Crop top and bottom black bars and make the height a multiple of 16.
ii) Encode to XviD using a PAR (pixel aspect ratio) of 16:9 (PAL or NTSC depending on your movie).
iii) Play your encoded movie in a player that supports aspect ratios properly (most do).

[Cunhambebe]

Thank you very much!

[Cunhambebe]

Encode to XviD using a PAR (pixel aspect ratio) of 16:9 (PAL or NTSC depending on your movie).
-Sorry, but where do I find that.?After some months without encoding, I guess I forgot where to find this option... Should I click on Display Aspect Ratio and choose 16:9 on the Aspect Ratio guide?
:rolleyes: Thanks in advance

Edit: to make it more concise, wouldn't it be better to encode at 720x480 (4:3 = 1.33:1), 720x360 (16:9 = 1.78:1) and 720x272 (21:9) at full resolution?