Converting 640x272 to 16:9 fullscreen (Star Wars Episode 2)

[DJRumpy]

I'm finding alot of DIVX posts in this resolution, and I'm not sure why. The size doesn't scale to 720x480 (it comes out to 720x320something). Can someone shed some light on this. How do I get this back to animorphic 16:9 widescreen, without letterboxing?

[LeeBear]

Simply put movies are never shot at a 16:9 (1.77) aspect ratio. Most movies are filmed at a ratio of 1.85, 2.25, and even 2.78. As you can see there will always be a small black bar at the top and bottom even if you encode to anamorphic. It's the same for anamorphic DVD's there's usually small black bars. Sometimes if the movie was shot at a 1.85 aspect ratio the studios will crop a bit off the sides when they put out the DVD so there won't be any black borders. It works if the movie was shot at an 1.85 aspect ratio because its pretty close to 1.77 (16:9) nothing important should be lost. If the films wider then that they'll usually put the black bars in. Anamorphic just means it's encode to the 16:9 aspect ratio. There's only 2 valid aspect ratios for DVD's the other being 4:3, so anamorphic doesn't always mean no black borders, it just means it's encode with a 16:9 aspect ratio. Episode 2 was filmed using a 2.25 aspect ratio, so you're still going to have to letterbox it or crop out a fairly large chunk of the edges.

-LeeBear

[Mr Walker]

Do you still want Divx or do you want to convert the movie to vcd or svcd?
This movie is perfectly in it original aspect ratio 2.35:1, and for info regarding AR and anamorpich (I don't agree with all the info here), take a look here:
http://www.thedigitalbits.com/articles/anamorphic/index.html

[DJRumpy]

It just irritates me. I'm the proud new owner of a Sony 57" Widescreen HDTV. It's such a waste of realistate.

[snowmoon]

I think it would irratiate you more that with such a nice set you would bother to watch a movie that's had the edges cut off!

[DJRumpy]

It would. What I didn't tell you is that I've been encoding the DIVX in 720x480. What I didn't know is that I should have simply resized the video to 720x480, leaving it looking all squished, and my DVD would have put it up in full screen animorphic (thanks for the link MrWalker...very informative, and it answered my question perfectly).

I was manually adding the letterbox back in to maintain the aspect ratio (I can't stand pan & scan). Now I find that I didn't need to add it in, and I've wasted the last 24 hours.
The only benefit I'm getting from exercise now, is to determine if I can successfully encode a DVD and retain the 5.1 surround sound that came in the DIVX.

I'll be re-encoding again, this time in true 16:9, sans the letterbox.

[snowmoon]

Makes more sense now.

[Mr Walker]

Hmm.. As the movie is in an aspect Ratio of 2.35:1 you still need a little "letterbox" even at anamorphic encoding. If you want to use 720*480 then the movie should be 720*360 to maitain th AR of 2.35:1 This will look a little stretched but nice on a 16/9 tv with a little "lettebox" to maintain the AR.
If you want to convert the picture to 16/9 you need to cut to 480*272 (80left- & 80right-side) and then resize to 720*480 and you will get the movie in anamorphic with the AR of 16/9, this way you fill the screen but loose some info on the sides. But it's all within the eye of the beholder.

[DJRumpy]

I'd much rather have the little bit of letterboxing than lose some of the height.

How does the math work for reverse engineering a video back to it's original aspect ratio and DVD size? In other words, knowing that I want a target size of 720x480, and my movie is 640x272, how did you come up with 720x360 + letterboxing for the full 480 vertical?

[Mr Walker]

Well You stated that you want 720*480 (or maybe i missunderstood you??)
anyway, If you have a movie wich is in the AR 2,35:1 this is about 56% of the height in a 4:3 picture ((2.35:1)/(4:3) wich meen the letterbox is calculate of the vertical resolution*0,56 (this works everytime Pal,NTSC,vcd,svcd etc.)
But 16:9 is 75% of 4:3 (all anamorpic dvds are in a strethed 4:3) and therefore you use 75% of the vertical resolution (480*0,75=360) to get an anamorphic version of a 2.35:1 movie.

Look's like a big mess, hope you know what i mean.

[DJRumpy]

Yes. It makes sense. Thanks!

[DJRumpy]

Just an update. I ended up resizing the mpeg to 720x352 (someone told me to use multiples of 8's..dunno why). I'm kinda worried, because the final output looks like the correct aspect ratio, while the info I read suggested it should actually look a little squeezed in from the sides. I filled the remaining vertical area with letterboxing.

[Bel]

I am having this same problem... I want to convert to dvd, so I resized to 720*480, and display it in 16:9 aspect ratio. However, as was discussed in this forum, the picture is a bit stretched. Not unwatchable but noticeable.

Does anyone know what filter I would use to add some black lines to the top and bottom so that when displayed in 16:9 the aspect ratio will be correct? Also, how many lines or pixels (or however the filter works, I've played around with virtualdub but I can't find one) would I add to the top and bottom so that it was displayed in the correct 2.25 aspect ratio. I found an addborders filter in AVISynth, which I think should do the trick, although I don't know the math or the command I would use to maintain the aspect ratio. Thanks.

EDIT Well, I think I figured it out... I ended up using the resize filter setting the size at 720/320 and then checking the border box and making that 720/480. I originally was reversing the numbers, and the filter wouldn't let me do anything, presumably due to the fact that the letter box was smaller than the size of the actual video. This makes the aspect ratio appear correct when viewed through a 4:3 aspect ration on my dvd player (at least it looked correct).

2 things, does anyone know the resize command for doing this manually in AVIsynth, and if I wanted the dvd to be in 16:9 aspect ratio instead of 4:3 anyone know what numbers I would plug in for the size of the video? My math was never very good...

[Mr Walker]

DjRumpy when played on a 16:9 tv in the "wide"-mode everything should look good, but as a 4:3 picture it's streched vertically. Don't really know about the multiple-story but i assume it's the whole picture incl. the letterbox(480) that are supposed to be a multiple of 8. Anyway 360 or 352 will harldy be noticeble, did it look good then it's good

[Bel]

Mr Walker,

I finally understood your post regarding the 75% of 480 for a ratio of 2.25 which seems to do the job perfectly for an anamorphic clip. While we have your attention (and I'm impressed with you math skills), can you tell me what the percentage would be for an anamorphic movie in 1.85 aspect ratio? Or 2.78 for that matter... Thanks.

[Mr Walker]

As I see it you should only use 16/9 or 2.35:1 as aspect ratio. I'ts higly possible that the movie you got at 2,75:1 really is 2.35:1 but altered when encoded to divx or something else, I would encode that as 2.35:1. but if you want to try 2.75:1 it would be about 48,5% letterboxed and about 65% anamorphic.
And as for the 1.85 i think many of those are really cut to 1.78:1(aka 16/9) and if not so there is a verry little difference (3,9%) so i'd encode that to 16/9 directly wich mean 100% for anamorphic and and 75% for letterboxed.

[Bel]

I see what you mean... Thanks

[DJRumpy]

Back again. Just to clarify, I meant that my output file, at 720x360 looks like a "normal" aspect ratio while being watched in 4:3. That's why I was worried. The info you gave me suggested it should look squeezed in from the sides, but it doesn't appear that way. It looks like the correct aspect raitio in 4:3.

I read another guide on resolutions, and found out why they are using this 640x272. It would appear to be a reduction of 2.35:1 using a 4:3 aspect ratio.

The math works like this.

Target horizontal resolution / aspect ratio
or
640 / 2.35 = 272

That's how they came out with the final resolution of 640x272.

if you use the same math, putting it back, it would come out to:
720 / 2.35 = 306

I need to know the same formula, but with the ratio being 16.9:1 instead of 4:3

Mr. Walker, where do you get your percentages? I'm not sure what the actual math looks like for this part: ((2.35:1)/(4:3)
or in my case:
((2.35:1)/(16.9:1)?

It's been too long since high school...

[DJRumpy]

{*DOH!*}.
Correction:

That would be 16:9, not 16.9:1, wouldn't it...

I think I found my own answer. Mr Walker, can you verify if this is correct?

720 * 9 / 16 = 405 ( rounded to the nearest 8 = 408 )

So I should be resizing my movie to 720 / 408, with the additional in letterbox? This looks like a good representation of what your link shows me. The image when viewed in 4:3 is somewhat squeezed, while still showing the letterbox at the top and bottom.

The other way, which is what your showing me is:

2.35 * 9 / 16 = 1.32

272 * 1.32 = 359.04 (or 360 give or take).

This way doesn't look squeezed in 4:3.

Help!

[Bel]

720x360 letterboxed from 720x480 works for anamorphic 16:9. The margins are identical to the way the avi looks (Proven by some well placed post-it's on my monitor). I assume we have the same avi. In 4:3 at this ratio it still looks good, and like the normal letterbox margins but remember that at 2.35:1 the black letterbox will cover more screen space as compared to a 1.85:1 letterbox.

Your 306, I think, would be the proper resolution for 4:3 display, and to be honest, I didn't follow how Mr. Walker came up with the percentage that he used, that's why I asked about the other ratios for future reference. However, after plugging his numbers into my filter and doing a test encode and author, I'm convinced he's right. It gives the exact same ratio as the avi at 640x272, and that is what we're trying to replicate right?

[DJRumpy]

Correct. I think I've figured out how he got his numbers. See my post above.

Take the aspect ratio (2.35 in this case), and multiply is time the target aspect ratio: 2.35 * 9/16 = 1.32
This gives you the difference between the two ratios, which in turn, gives you the size of the necessary letterboxing.

Multply that difference ( 1.32 ) times the vertical resolution, since this is where we're making up the space:
272 * 1.32 = 359.04
or
480 / 1.32 = 363.64
Round to the nearest 8: 360

I think it's right. Mr Walker will need to verify for me. I'm resizing it in virtual dub right now. I'm trying two different resolutions. 720x380 and 720 x 360, to see which looks better on my 16:9 tv.

[Bel]

Cool... I see where you went with the math. Seems like it works. Although, you left out the parenthesis, as you need to do the division first

Why are you trying the 380, where did that number come from? Let me know how it looks, cause I'm still stuck with an old 4:3 TV. I just want to make sure I'm ready for the future...

[DJRumpy]

I just added a bit to the vertical resolution to see if I could minimize the amount of letterboxing I see. It doesn't come from any of the math, it's just an experiment. :P

[Mr Walker]

Here.s how I see it (and i'm not sure how it actually work but this seems to give the right AR)

A 16/9(1,78)picture has a difference from 4:3(1.33) with 75% (1,33/1,78=0,75)
meaninng on a 4:3 tv a movie in 16/9 75% is movie and 25%letterbox.

Same apply for 2.35:1 (1,33/2.35=0,56) but here it's 56%.

example:
720*480 16/9 movie 480*0,750=360 will be 720*360
720*480 16/9 anamorphic well just do it 720*480
720*480 2.35:1 leterboxed 480*0,56=268 will be720*268

720*480 2.35:1 anamorphic would be like this(try to keep up) 480*0,56=268(letterboxed version) *0,75=358 (to get the anamophic)
to make it simply use vertikal *0,75 even for this.

I don't know anything about programming but i got an little excel-file to do the math if you would like to try it.