Resizing woes

Sereenie · Post by **Sereenie** » Sat Jan 20, 2007 8:43 pm

I'm in a bit of a pinch.

I am going to mix 16:9 and 4:3 sources and want to use anamorphic resolution. Easy, right? I only need to crop 60px up and down my 4:3 footage and resize to 720x480.

Well, not quite. I have now switched to Premiere Pro 2.0, and really would love to take this opportunity to use its new feature which allows me *not* to scale everything to frame size. I wouldn't have to decide ahead of time what part of a frame I'd want to cut out to fit anamorphic proportions–or to apply the same "cut" to a whole segment; I could just do it straight in Motion, thus saving time and aggravation. So I want to upscale my 4:3 progressive footage to use it as much as I can.

The problem is, I have no idea how to calculate how to resize the footage. I tried using Trythil's Resize calculator, but it only goes as high as 528x480 (after cropping 8px left and right to remove garbage).

I then tried using those numbers as a basis to calculate the resize manually (knowing that the final width must be 720), but that didn't work either, as I ended with an uneven number. I'm looking for perfect proportions, so without knowing how much I need to crop off and where, I'm getting nowhere.

I know that the easy way out would be to work in square pixels. But I like to make my life difficult! More importantly, I want to be able to export my work on a DVD afterwards as well as for online distribution, so I want to avoid multiple resizings.

So, has anyone sle tried to do this before and figured out the calculations?

Thank you!

S.

Zarxrax · Post by **Zarxrax** » Sat Jan 20, 2007 8:58 pm

I don't quite follow. You are saying you want to let premiere sort out the aspect ratio stuff, right? Then why do you need to resize anything at all?

Sereenie · Post by **Sereenie** » Sat Jan 20, 2007 9:15 pm

Because when I export it all, it needs to use a single aspect ratio, no?

That being said, I don't really want Premiere to work out the aspect ratio: I just plan to use Motion to drag the 4:3 footage up or down so the frame picks the relevant part of the footage. So no resizing is invloved there if everything already is at the same AR. If I am not mistaken, Premiere should crop any excess to 720x480 when I export.

Plus, since I mean to upscale, resizing in Premiere wouldn't give me results as good as if I first resize in Avisynth, before applying the filters. I also think that having all my footage at the same AR will allow me to be sure that anything I apply to it will come out as I mean it to.

It's a bit weird, because I realise that I am making my life hard right now so as to make it easier while editing and exporting!

S.

Zarxrax · Post by **Zarxrax** » Sat Jan 20, 2007 10:13 pm

Export from premiere at 848x480 with square pixels.
The widescreen stuff will be perfect, and the 4:3 stuff will have borders on the sides.
In motion, crop it to 640x480 or whatever, so that the 4:3 stuff is good, then you can move your widescreen footage around.

Zarxrax · Post by **Zarxrax** » Sat Jan 20, 2007 10:18 pm

Oops you want the final thing in widescreen.
It seems to me that the thing to do would be to upsize your 4:3 footage before you edit. If you are keeping your widescreen stuff at 720x480 though, seems like it would be a bitch to calculate.

Seriously, just save yourself some trouble and resize to square pixels before you edit. Widescreen to 848x480, 4:3 to 848x640. OR widescreen to 640x352 and 4:3 to 640x480. So much simpler the entire way through...

Sereenie · Post by **Sereenie** » Sat Jan 20, 2007 10:42 pm

Zarxrax wrote: It seems to me that the thing to do would be to upsize your 4:3 footage before you edit. If you are keeping your widescreen stuff at 720x480 though, seems like it would be a bitch to calculate.

hehe! That's *exactly* what I was trying to explain and what my problem is about, but I just could not express myself properly! Thanks for rewording things in an intelligible manner!

I know that the square pixels is the easiest way, and it *will* be my last resort if I can't find an answer about this. But I'd really rather avoid it, because I'd have to resize down again to 720x480 afterwards for the DVD. Just as I try to avoid colour space conversions, I try to do so with resizing. By keeping everything 16:9 throughout, I'll get a cleaner copy both online and on my TV.

Plus, I guess that if someone has figured out that cutting 60px up and down before resizing to 720x480 makes 4:3 into 16:9, then it has to be possible to know what that height should be without (or with minimal) cropping. Or maybe there is some sort of tool or application than can help calculate those things, a bit like the Resize calculator. I have tried looking around, but have found nothing to help me about this. Heck, I don't mind calculating by hand if need be! I just don't have the right formula to get to the final result...

Thanks again, Zarxrax!

S.

Sereenie · Post by **Sereenie** » Sun Jan 21, 2007 2:03 pm

Ha! I think I figured it out, thanks to you!

You gave me 848x640 for square pixels 4:3, which basically provided me with the last piece of info I needed to calculate that darn thing.

I'll skip the details, but my solution is the following (keeping in mind that I use 768x432 for square pixel 16:9 instead of 848x480–only because I'm anal about AR!):

Crop(8, 0, -8, -0)
LanczosResize(768,576)
(Filter chain)
LanczosResize(704,640)

Knowing that I would cut out 8px on each side of my anamorphic footage anyway after exporting from Premiere, it's really not a problem to simply do it before I start working on the project. So I'll be working with 704x480 instead of 720x480.

Just to be sure I was right, I exported a frame and cropped it in Photoshop to keep only 704x480 (thus mimicking what Premiere would do while exporting), then resized it to 768x432: perfect! I can post before and after shots if anyone's interested.

As far as I know, the exact same script could be used with the standard 848x480 by using that for the first resize.

Sure, two resizes isn't ideal, but it still gives good results, especially by sticking the filter chain in-between, thus correcting imperfections before downscaling. After all, isn't that more or less what SSXSharpen (among others) does? And I did all this using the horrible uncensored first season of Sailor Moon, so if it looks great with *that* footage, I can't imagine that it wouldn't be the same for anything else.

So there! If anyone else wants to use PP2.0's Motion to move 4:3 footage around instead of cropping it ahead of time, that's how I did it. ^_^

S.

trythil · Post by **trythil** » Sun Jan 21, 2007 4:10 pm

Sereenie wrote: I'll skip the details, but my solution is the following (keeping in mind that I use 768x432 for square pixel 16:9 instead of 848x480–only because I'm anal about AR!):

True, 768x432 is closer to 16/9 by about 0.011..., but another aspect of the image that you may want to take into account is vertical resolution.

The reason why 848x480 is so popular is because it preserves all 480 vertical lines of a 720x480 image, vs. 768x432, which mashes them together.

Sereenie · Post by **Sereenie** » Sun Jan 21, 2007 4:25 pm

Oh, I realise that! I only use that resolution when I manage to make my footage totally progressive. Live action in particular looks great when using it.

But when there is still some interlacing, even occasional, then I stick to 848x480. I should have mentioned that. My bad!

That being said and since you have crossed my path, may I ask if you considered the possibility of updating the Resize calculator? Upsampling footage seems to become more frequent around here, especially for HD, but calculations pertaining to 4:3 resolution stop too "soon." When using only 4:3, it's not a problem, as it's fairly easy to calculate, but when mixing ARs, as I was trying to do, it gets a bit messy...

Thanks for the warning, though! I would hate to have caused anyone to mess up their footage. ^_^

S.

trythil · Post by **trythil** » Sun Jan 21, 2007 4:38 pm

Sereenie wrote:That being said and since you have crossed my path, may I ask if you considered the possibility of updating the Resize calculator?

I've been meaning to do that for...uh, years now :P

At this point I think it'd be more realistic to expect someone else to take over its development. It's not that I'm disinterested; it's more like "so many projects and so little time", or "wow I'm easily distracted -- oh look, shiny".

The source code is available, and I think I can walk through how it does what it does, if you or someone else is interested.