Changing Aspect Ratios?

vbimport

#1

:confused: Anyone know if you can easily change the aspect ratio of the image before you burn a copy on DVD? eg. Change a letterbox title movie to a 2.35 image?


#2

There are only 2 different aspect ratios, 4:3 and 16:9. A 2.35:1 is just a 16:9 with black bars encoded into the picture at top and bottom.


#3

i think ifoedit is able to change it when you rip the dvd to your hdd (as vobs, ifo’s etc)


#4

“There are only 2 different aspect ratios, 4:3 and 16:9. A 2.35:1 is just a 16:9 with black bars encoded into the picture at top and bottom”

Sorry but this is plain wrong, unless you refer to TV ratio standards.

You are mixing TV/VIDEO ratio systems (4/3 and 16/9) and movies aspect ratios.

Movies aspect ratios are numerous, and are generally between 1:33 (which corresponds to the ratio of a 4/3 TV) and 2:35.

16/9 refers to a horizontally shrinked (at the mastering stage) widescreen image, expanded at the viewing stage (generally by a 16/9 TV), so no horizontal line is lost. This improves vertical resolution.
This process is know as anamorphose (thus 16/9 is sometimes referred to as “anamorphic”).

In 4/3, there is no shrinking, to maintain widescreen there is a loss at the top and bottom of the image, it will fit a 4/3 TV but has to be zoomed on a 16/9 TV thus loosing a fair amount of resolution.

4/3 and 16/9 = VIDEO/TV SYSTEMS
1:33, 1:85. 1:88, 2.33, 2:35… = ASPECT RATIOS

A 16/9 TV has a 1.85 aspect ratio.

As to Murray’s question, please be more precise, as “Change a letterbox title movie to a 2.35 image?” doesn’t make sense.
A 2.35 movie will be letterboxed anyway, even on a 16/9 TV!
“Letterboxed” (opposed to “fullscreen” on 4/3 TVs) refers to an image with horizontal black bars… :slight_smile:


#5

eg. when I refer to changing aspect ratios:
Many of the Rogers & Hammerstein movies are stretched beyound the normal 2.35 image and to get the aspect back to a true 2.35 shape screen one has to use the ZOOM control on the player. This inturn looses resolution and thats why Im wondering if it could be changed in the burning stage to prevent doing it in the playing stage? When you have to use any form of stretch/zoom when using a projector the quality really suffers! :sad:


#6

@Francksoy: I think what ChickenMan meant was that as far as DVDs are concerned there are the two aspect ratios that he metioned. Obviously there are 4:3 titles that fit the 720x576 ratio where no stretching is required. Other ratios are encoded such that when stretched back out they give the correct viewing ratio and are encoded to do so.

Regards

TZ


#7

Hello all,

First sorry Chickenman for my rather unfriendly sentence at the beginning of my post, I was in a bad mood. :slight_smile: - no offence intended.

Well I still have to say that it is a mistake to use the term “aspect ratio” when it comes to 16/9 - 4/3, specially for DVDs.

Why? Because both 16/9 and 4/3 formats, on DVDs, will actually fill a single 1.33 aspect ratio image anyway! There is NO other “aspect ratio” when it comes to the image actually recorded. A 16/9 image is only a widescreen image horizontally shrinked to fill the 1:33 frame, then this image will be stretched during playback, either by the DVD player or the TV set, so to restore the widescreen.
But in both cases, the raw aspect ratio of the image recorded, before stretching, still is 1:33!!

That’s why I state that 16/9 and 4/3 don’t refer to aspect ratios, but are two video formats/systems to manage the aspect ratios of recorded pictures.

I hope that I make myself clear enough so you can understand that I’m actually discussing a point of terminology.

This is a rather complicated subject and is difficult to explain only with words…

I found this interesting page http://www.hometheaterinfo.com/video1.htm but sadly there are no drawings.

update found this page too, more “in-depth” and with drawings: http://members.aol.com/ajaynejr/vidwide.htm

Now to the question from Murray and (or?) Rapallo, now I get it :), but sadly I can’t help simply because I do’nt know any software that will perform a high quality zoom/resampling of a 4/3 letterboxed image, then shrink it horizontally with the proper algorithms to fill a 1:33 frame that will be recorded to DVD… put in other words, transform a 4/3 image into a 16/9 image without changing the aspect ratio.

Maybe such a software exists that I’m not aware of. I’m very interested if someone knows such a software, even if I guess that the whole process would use huge processing power and take ages, unless a dedicated chip handles the task…

Personally, I can live with the resolution loss from zooming a 4/3 widescreen picture, because my 16/9 TV set is not huge. But I guess that this would indeed bug me if, like Rapallo, I used a projector…

Cheers :slight_smile:


#8

“That’s why I state that 16/9 and 4/3 don’t refer to aspect ratios, but are two video formats/systems to manage the aspect ratios of recorded pictures.”

Correct but 90%+ of people dont see it that way. We are talking DVD’s here and you can check any DVD you like and the pic size is always 720/704 x 480/576 with them all :slight_smile: As you say, the subject is extremely complex, but a dvd will playback in only one of 2 forms, either 4:3 or 16:9.


#9

Hi Chikenman :slight_smile:

“As you say, the subject is extremely complex, but a dvd will playback in only one of 2 forms, either 4:3 or 16:9”

Sure! :iagree: But I think Murray’s question gets deeper than that, as from what I understand he’d like to get a better resolution from a 4/3 widescreen/letterboxed image than what is achieved by simple zoom (performed by the TV set or the projection in the case of a video projector).

Actually now that I think about it I don’t see how this would be possible. No software would improve the actual resolution of the image! It could apply complex anti-aliasing algorithms while expanding, though.

In the case of TV viewing, the quality of the zoom maybe depends on the quality of electronics, so maybe a dedicated high-quality software treatment to expand the image before burning would improve things (if such a software ever exists).

In the case of a projector, though, the zoom is optical (from what I guess…?), thus analogic, so how on earth would any electronic or software pre-zoom, applied before burning the DVD, give better results? :confused: makes no sense to me.

Cheers :slight_smile:


#10

Thanks guys for all your help, looks like I opened up a can of worms!:cop:

And yes, I was trying to avoid so much ZOOM at the projection stage. Using ZOOM on projectors looks terrible, the resolution is not good:sad:

Sorry to confuse you but I had to change my user name as somehow I got locked out and couldnt sign into the forum! Anyway back online again:eek:


#11

“In the case of a projector, though, the zoom is optical (from what I guess…?), thus analogic, so how on earth would any electronic or software pre-zoom, applied before burning the DVD, give better results? makes no sense to me.”
Very true, thats why I havent really wasted any of my time on the whole issue.

Original request was to “Change a letterbox title movie to a 2.35 image?”, thats not zooming in, thats zooming out. I see absolutely no point to it what so ever, it would only make the situation worse, not better. If it was the other way around, then that would make total sence. But to achieve that, you need to chop off some of the left and right sides of the picture to expand the rest up to 16:9 keeping everything in correct aspect ratio. The end result would be better than using optical zoom on you OP. I would use DVD2SVCD (it works !) with modifying the avisynth script. Read my dvd to svcd tutes as all the setting are in there, just use 720 as the width and not 480. The doom9 forum in the dvd2svcd Q&A section also has heaps of scripts on how to achieve letterbox 2.35:1 to 16:9.


#12

I have a dvd that was encoded as ntsc 3.85 not 4.43. The picture is not lining up properly. I see the very top edge of my picture at the bottom of my screen under a thick black bar. Have any idea how I correct this?


#13

Let’s assume that you have a movie that it is 600x420.
Now that is not a 4:3 but you know that its real correct format is a 4:3, since 4:3 is simply a 1.3 report, you need to make 600/1.3 that gives you 560. So the correct resolution for the ratio 4:3 would be 560x420.

It’s not hard, now to change it without re-encoding there’s now way. I am not aware of any freeware that can rencode enough powerfully but since i run a photography business i know what i am talking about

You should google for a software called " Aspect Ratio Video Resizer " .

I will not post the link first of all because it’s not permitted but also because i don’t like to spm. So far that is the best price/quality combo i could find