What is the proper resolution for a resized 16x9 DVD to 4:3

[FulciLives]

Hello

I know a NTSC DVD is 720x480 but if it is 16x9 enhanced and you want to resize it to 4:3 then what does the resolution become? My calculations are 720x352 but I'm not sure if that is correct. So if anyone knows

Also I know a PAL DVD is 720x576 so what would the resolution be when you do 16x9 to 4:3 in that format?

Thanks!

- John "FulciLives" Coleman

P.S.
I need to encode at DVD resolutions in 4:3 from DVD resolution 16x9 sources so I thought I would resize first (to make the aspect ratio correct or in other words from 16x9 to 4:3) and then addborders to get the proper height (480 total for NTSC and 576 total for PAL). I intend to do this using an avs script. THANKS IN ADVANCE!

[killmore]

I got 720x303...

[FulciLives]

Hello

Well after looking at a post I found on another forum along with a recalc by none-other-than myself (hehehe) I have come to the conclusion that the correct aspect ratio for a 720x480 16x9 DVD is 720x360 (so that it looks normal on a 4:3 display).

That solves NTSC but what about the PAL format?

I'm still not sure what it would be converted from 16x9 to 4:3 so ...

Any and all help is appreciated

- John "FulciLives" Coleman

[Vejita-sama]

You are confusing DAR (display aspect ratio) with resolution. This is a fairly common (and confusing) aspect of digital video. You can have any DAR at any resolution (although you may have to letterbox).

For example, supported DVD resolutions are 720x480, 352x480 and 352x240 (NTSC). You can have a 4:3 image thou at ANY of those resolutions.

Take a look at:

http://www.doom9.org/aspectratios.htm

http://www.thedigitalbits.com/articles/anamorphic/aspectratios/widescreenorama.html

for more info. But here's a short primer:

There are three DARs that you are likely to work with:

1:1 PC
4:3 TV
16:9 Film and widescreen TVs

Under teh 16:9 DAR flag there are actually several ratios including:

1.85:1 academy flat
2.35:1 anamorphic wide screen
1.77:1 widescreen TVs

Notice that resolution is not mentioned at all in the above. Now, on the PC (since it has a 1:1 DAR) resolution = DAR. But this is not true for TV (standard or widescreen).

720x480 is the standard DVD resolution. But doesn't that have a DAR of 1.5:1? Actually no, the DVD player takes the 720x480 MPEG-2 stream, multiplies the vertical resolution by the aspect ratio (480*16/9=853 =~850) which gives you the horizontal resolution for a properly stretched movie. So the 720x480 stream will be stretched horizontally to 850x480 during playback. (read more about anamoric DVDs for DAR flags)

So the question becomes how can I perserce the aspect ratio of my source when I encode? The answer 9/10 is letterboxing (or pan scanning, or cropping the edges off the screen). (again read more on letter boxing or anamorphic DVDs).

So to answer your question, what resolution do you encode a 720x480 16:9 movie to, if you encode to a 4:3 MPEG. Will the question is what do you want to do: letterbox or crop? But you can do this at any resolution.

However, it's best to choose a supported NTSC (or PAL) resolution:

VCD - 352x240
CVD - 352x480
SVCD - 480x480
DVD - 720x480, 704x480, 352x480, 352x240

if you want to be able to play it on your TV Hope that helps some (might not I'm pretty tried).

[FulciLives]

Hello

Thanks for the post Vejita-sama but ...
That still doesn't answer my question

I want to take a NTSC 16x9 DVD and convert it to 4:3 without cropping. As I am sure you already know the 16x9 aspect ratio is approximately 1.78:1 and that is how a 16x9 DVD is stored. If the movie in question has an aspect ratio that is wider (say 2.35:1) then it is still encoded at 1.78:1 but with black above and below the picture. Also the 16x9 is of course stretched making every look too tall and thin on a 4:3 display.

So ...

Without cropping the original 720x480 16x9 source what DVD complaint resolution would I use to make it look normal on a 4:3 display. That is the question! My understanding is if I resize it from 720x480 to 720x360 that I will be getting the correct aspect ratio on a 4:3 display. I am doing this in an avs script so I am adding the ADDBORDERS command to pad the height to 480. So I resize then addborders above and below to get a full 720x480 resolution. So right now using my figure of 360 as the corrected height my script reads like this (this is simplified of course)

Resize (720x360)
AddBorders (0,60,0,60)

Now my formating there is off a bit (I'm not looking at my avs script) but you get the point. I'm resizing then adding borders above and below the image to get back to 720x480

My only question is ... am I right about the 720x360 resolution?
Also what would it be in PAL since a PAL source is 720x576 (not 720x480) I assume the PAL value would have to have a height greater than 360 (which is my NTSC figure).

Does that make more sense now?

- John "FulciLives" Coleman

[SeeingMole]

With NO cropping involved, the correct resize would be:

NTSC from 720x480 to 720x352
PAL from 720x576 to 720x422

Then as mentioned, you'll have to add black borders top and bottom to get it back to 720x480 or 576.

PS. The calculations above has ITU standard enabled.
If disabled, the number would be 720x360 and 720x432, but as you can read on Doom9's site, it is recommended to enable the ITU standard.

Oh, and I don't see the point in doing this at all because you could simple re-encode as anamorphic widescreen. Your DVD player will resize and put black borders for you so it'll fit on a 4:3 TV anyway.

[FulciLives]

I don't see the point in doing this at all because you could simple re-encode as anamorphic widescreen. Your DVD player will resize and put black borders for you so it'll fit on a 4:3 TV anyway.

1.) I thank you VERY much for providing these vaules especially both with and without the ITU standard.

2.) I need to do this in order to create a XVCD using mpeg1 but with non-standard VCD settings. It is my understanding that the stand alone DVD player will not properly decode a 16x9 XVCD (only a DVD) and I only have standard size 4:3 televisions. If I had a 16x9 TV then I probably would encode it that way but I don't so I have to convert it to 4:3 in the encoding process.

Anyways ... thanks again!
Much appreciated

- John "FulciLives" Coleman