Aspect Ratio Question

[EpheMeroN]

I have a DVD5 of a movie that is 4:3 Letterboxed. Is there a way that I could, after ripping it to hdd, flag the main video somehow without re-encoding it to make it true 16:9 again? Or is going into AviSynth and actually resizing it and re-encoding it the only way to bring it back to it's true widescreen format?

[2COOL]

I have a DVD5 of a movie that is 4:3 Letterboxed. Is there a way that I could, after ripping it to hdd, flag the main video somehow without re-encoding it to make it true 16:9 again? Or is going into AviSynth and actually resizing it and re-encoding it the only way to bring it back to it's true widescreen format? You can use PgcEdit. Clicking on "current domain stream attributes" in Pgc Editor dialog (http://www.videohelp.com/~r0lZ/pgcedit/doc/PgcEdit_manual_3.htm#PGC_Editor), deselect any checkboxes in Video section and have 16:9 option selected. Save and test.

[manono]

That assumes that it's just flagged wrong. If it truly is 4:3 widescreen, and you want to convert it to 16:9, it has to be reencoded. You won't gain any quality by doing that, though.

[EpheMeroN]

I hope it's just flagged wrong. It's quite weird what happens when I view it in MPC as well. I get a warning message that's in 4:3. Then I get the DVD Menu that's displayed as 16:9. Then when you play the main movie it's 4:3 Letterboxed. That's why I assumed it was just flagged wrong.

[Mug Funky]

a lot of DVD menus are made in 16:9 but set to pan-scan mode (not letterbox) with the intent that on a 16:9 TV you see prettyness on the sides, but on a 4:3 screen you see just the menu items needed and still a moderately pretty menu. kind of a design that works in both 4:3 and 16:9.

but of course, if you view on a computer or a 16:9 TV you'll end up with 16:9 menus but 4:3 feature.

[EpheMeroN]

Is PgcEdit the only app that can do this without re-encoding? I've never used it before and appears to be VERY complex.

[manono]

You can use IFOEdit. It's much more complicated. :)

Open the DVD in PGCEdit. Scroll down the list of stuff on the left until you come to the movie. You'll know it by its length. Double-click on it. In the lower-left of the screen that opens up, click on Current Domain Streams Attributes. In the Video portion of the new screen, you'll see 4:3 ticked. Tick 16:9, OK your way out of there twice, and then File->Save DVD. Play it to test. It probably won't work, though, because if it was really flagged incorrectly as 4:3, people would look tall and thin, and you would have noticed that, I think. After reflagging as 16:9, they'll probably look short and fat. What you just did is easy to undo. PGCEdit saves the original IFOs-just replace them.

[SeeMoreDigital]

Hi EpheMeroN,

Can you grab a still image from a well lit section of the movie and without correction (so it should either contain 720x480 or 720x576 pixels). And upload it please?


Cheers

[EpheMeroN]

Can you grab a still image from a well lit section of the movie and without correction (so it should either contain 720x480 or 720x576 pixels). And upload it please?
Is there an easy way to do this in MPC? Or is full-screening it and doing a Print Screen the best way?

[SeeMoreDigital]

Is there an easy way to do this in MPC? Or is full-screening it and doing a Print Screen the best way?Navigate to a part of the DVD you want, press pause and then select "Save Image..."

http://img158.imageshack.us/img158/9695/mpc5bo.png

You will be offered a choice of saving to either .BMP or .JPG... use .JPG. You can then use ImageShack (www.imageshack.us) to upload/display the image file on Doom9 - like I've just done above.


Cheers

[EpheMeroN]

Image #1:
http://img161.imageshack.us/img161/6163/snapshot200507021009156ni.jpg

Image #2
http://img66.imageshack.us/img66/5886/snapshot200507021011561ao.jpg

[SeeMoreDigital]

Your DVD transfer is without doubt "4:3 Letterbox" with a 2.35:1 image overlay!

So it can't be re-flagged to 16:9 anamorphic, it will have to be re-encoded.


Cheers

[EpheMeroN]

@SeeMoreDigital: Thanks for the help bud!

What about this source? It's pure coincidence that I ran across another dvd so similar and so soon. It's showing up in MPC as 4:3.

http://img335.imageshack.us/img335/1343/snapshot200507120059271rl.jpg

[SeeMoreDigital]

Okay,

The SAR (Storage Aspect Ratio) is 720x480
The IAR (Image Aspect Ratio) after cropping away the mattes is 720x350 approx

So that "frame grab" one is from an "16:9 Anamorphic" NTSC DVD, where the movie aspect ratio is 2.40:1.


Cheers

[EpheMeroN]

So I might be able to make it 16:9 again by re-flagging it I believe... I'll test using PgcEdit and report back. Btw, an AR of 2.40:1? That doesn't sound normal. I thought all widescreen movies either had an AR of 1.85:1 or 2.35:1.

[unskinnyboy]

So I might be able to make it 16:9 again by re-flagging it I believe... I'll test using PgcEdit and report back. Btw, an AR of 2.40:1? That doesn't sound normal. I thought all widescreen movies either had an AR of 1.85:1 or 2.35:1.
No, of course not. Have a look here (http://www.imdb.com/Sections/DVDs/AspectRatios/2.40_:_1/) and you can see that there are 101 DVDs which are listed as having an AR of 2.40:1 by IMDB alone. There could be more which IMDB hasn't listed or missed.

More info on 2.35:1/2.40:1 ARs here:
http://www.dvdanswers.com/index.php?c=27&s=8
http://www.widescreen.org/aspect_ratios.shtml
http://www.dvdtown.com/messageboard/topic/3/10697/

[manono]

Hi-

So that "frame grab" one is from an "16:9 Anamorphic" NTSC DVD, where the movie aspect ratio is 2.40:1.

You sure about that? Why can't it be 4:3, 1.85:1 or thereabouts? He already has one player that claims it to be 4:3. The easiest way to be sure of the DAR (to doublecheck MPC) is to open one of the vobs in DGIndex and run the Preview. You're much, much more likely to find a widescreen 4:3 DVD than you are a 16:9 one incorrectly flagged as 4:3.

It's pure coincidence that I ran across another dvd so similar and so soon. It's showing up in MPC as 4:3.

There's a ton of them out there, more in R1 than R2, though.

I thought all widescreen movies either had an AR of 1.85:1 or 2.35:1.

You thought wrong, as unskinnyboy shows. Then there are the 1.66:1, 1.78:1, 2.20:1, 2.55:1, 2.76:1 movies, and others.

[SeeMoreDigital]

You sure about that? Why can't it be 4:3, 1.85:1 or thereabouts? He already has one player that claims it to be 4:3. The easiest way to be sure of the DAR (to doublecheck MPC) is to open one of the vobs in DGIndex and run the Preview. You're much, much more likely to find a widescreen 4:3 DVD than you are a 16:9 one incorrectly flagged as 4:3.Damn it you are absolutely right manono.

The SAR (Storage Aspect Ratio) is 720x480
The IAR (Image Aspect Ratio) after cropping away the mattes is 720x350 approx

So that "frame grab" is from an "4:3 Standard" NTSC DVD, where the movie aspect ratio is 1.85:1.

The exact height for an 1.85:1 "4:3 Standard" image is, 346 pixels
The exact height for an 2.40:1 "16:9 Anamorphic" image is, 356 pixels

As you can see the pixel values are very close and I made the mistake of not correcting it's AR and checking the image by eye..... That's a total novices (over confident) mistake.... I should know better... There goes my credibility!

I apologise to you all

[Kika]

SAR, IAR? What's this?

All i know is:

SAR = Sample Aspect Ratio (it's about the sampling in Capture devices)
DAR = Display Aspect Ratio
PAR = Pixel Aspect Ratio

[SeeMoreDigital]

SAR, IAR? What's this?In respect to calculating the PAR of a given video file, SAR stands for "Storage Aspect Ratio" ie: The pixel frame size of a video file, before any form of AR correction has been applied.

In the case of DVD, the SAR pixel sizes would be, 720x576 for PAL and 720x480 for NTSC.


The calculations are obtained... like this: -

For 4:3 NTSC: -
When an DAR of 1.3333333 (ie: 4:3) is divided by an SAR of 1.5 (ie: 720/480). You get an PAR of 0.8888888 (ie: 8/9).
Likewise when an SAR of 1.5 (ie: 720/480) is divided by an DAR of 1.3333333 (ie: 4:3). You get an PAR of 1.125 (ie: 9/8).

So when you multiply, 720 pixels by a PAR of 0.8888888. You get 640 pixels
Or if you divide, 720 pixels by a PAR of 1.125 . You also get 640 pixels

For 16:9 NTSC: -
When an DAR of 1.7777777 (ie: 16:9) is divided by an SAR of 1.5 (ie: 720/480). You get an PAR of 1.1851851 (ie: 32/27).
Likewise when an SAR of 1.5 (ie: 720/480) is divided by an DAR of 1.7777777 (ie: 16:9). You get an PAR of 0.84375 (ie: 27/32).

So when you multiply, 720 pixels by a PAR of 1.1851851. You get 853.33333 pixels
Or if you divide, 720 pixels by a PAR of 0.84375. You also get 853.33333 pixels

For 4:3 PAL: -
When an DAR of 1.3333333 (ie: 4:3) is divided by an SAR of 1.25 (ie: 720/576). You get an PAR of 1.0666666 (ie: 16/15).
Likewise when an SAR of 1.25 (ie: 720/576) is divided by an DAR of 1.3333333 (ie: 4:3). You get an PAR of 0.9375 (ie: 15/16).

So when you multiply, 720 pixels by a PAR of 1.0666666. You get 768 pixels
Or if you divide, 352 pixels by a PAR of 0.9375. You also get 768 pixels

For 16:9 PAL: -
When an DAR of 1.7777777 (ie: 16:9) is divided by an SAR of 1.25 (ie: 720/576). You get an PAR of 1.4222222 (ie: 64/45).
Likewise when an SAR of 1.25 (ie: 720/576) is divided by an DAR of 1.7777777 (ie: 16:9). You get an PAR of 0.703125 (ie: 45/64)

So when you multiply, 720 pixels by a PAR of 1.4222222. You get 1024 pixels
Or if you divide, 720 pixels by a PAR of 0.703125. You also get 1024 pixels.

By-the-way, I've also seen SAR abbreviated for "Source Aspect Ratio"

With regard to IAR (Image Aspect Ratio), yes, I made this one up. But it refers to the SAR after cropping away the mattes - In hindsight I guess it would make more sense to abbreviate this to CAR (Cropped Aspect Ratio).


Cheers

[Kika]

Thanks, i know how to do the calculations, no problem so far. I've just never seen this shortcuts before.

Don't get me wrong, but i don't think we need new shortcuts. They may be confusing to newbies.

[SeeMoreDigital]

As far as I'm aware the "SAR" abbreviation is not new. And makes very good sense.

I even saw stegre (SteveG of GSpot fame) use it, way back in October 2004, in this post (http://forum.doom9.org/showthread.php?p=562532#post562532).


Cheers

[Inventive Software]

You have to remember that the 16:9 Letterboxed version usually has another Aspect Ratio next to it that refers to the Pixel Aspect Ratio (PAR). This is usually 1.85:1, 2.35:1, 2.40:1 etc. The 1.78:1 you sometimes see after it is 16:9, only without the letterboxing. Remember to do the 16:9 before you do the 1.85:1, 2.35:1 etc. So you get an image 1024 pixels wide and 576 pixels high (PAL) and all you have to do is crop the top and bottom to get the actual pixel ratio. The actual image size is as follows, and this only applies for the most common Pixel Aspect Ratios:

2.40:1: 1024x428 (divide 1024 by 428 and round up; the vertical pixel has to be even.)
2.35:1: 1024x436 (again divide 1024 by 436 and round up)
1.85:1: 1024x554 (divide 1024 by 554 and round up)

I hope this clarifies things.

[SeeMoreDigital]

Remember to do the 16:9 before you do the 1.85:1, 2.35:1 etc. So you get an image 1024 pixels wide and 576 pixels high (PAL) and all you have to do is crop the top and bottom to get the actual pixel ratio. The actual image size is as follows, and this only applies for the most common Pixel Aspect Ratios:

2.40:1: 1024x428 (divide 1024 by 428 and round up; the vertical pixel has to be even.)
2.35:1: 1024x436 (again divide 1024 by 436 and round up)
1.85:1: 1024x554 (divide 1024 by 554 and round up)

I hope this clarifies things.And things can get a little more interesting should you decide to generate full pixel height encodes with just the black mattes cropped away. Because, you'll need to encode to the nearest 16th pixel, meaning: -

1.85:1 will become 720x560 anamorphic (or 1024x560)
2.35:1 will become 720x432 anamorphic (or 1024x432)
2.40:1 will also have to become 720x432 anamorphic (or 1024x432)


Cheers

[Wilbert]

As far as I'm aware the "SAR" abbreviation is not new. And makes very good sense.

I even saw stegre (SteveG of GSpot fame) use it, way back in October 2004
With all respect. He used SAR refering to the MPEG-2 specs (afaiu it is not mentioned in the MPEG-1 nor in the MPEG-4 specs). As several people stated in this thread (http://forum.doom9.org/showthread.php?p=685658#post685658) in the MPEG-2 specs SAR means Sample Aspect Ratio, ie what is called PAR in the MPEG-1/4 specs and by most of us.

I don't mind we use an abbreviation for Storage Aspect Ratio (if needed), but imo we shouldn't call it SAR because that name is already used.

[Kika]

Wilbert is right. I did'nt know SAR as an abbreviation for a kind of storage size.
So i was a bit confused after reading this thread. ;)

[SeeMoreDigital]

As I know Wilbert already knows, Sharktooth is now calling the "AR Signalling" setting in his x264 GUI, "Sample Aspect Ratio" because: -Regardless of this discussion i will keep the "Sample AR" label coz the cli option is --sar and not --par or --dar ...
When and if the cli option will change name i'll modify vfw accordingly... I guess in reality the expression "Sample Aspect Ratio" can be used to describe the the x/y ratio of both the "input source sample" and the "output encode sample".

So "Sample" it is then....


Cheers

[Wilbert]

As I know Wilbert already knows, Sharktooth is now calling the "AR Signalling" setting in his x264 GUI, "Sample Aspect Ratio" because:
I didn't say it is better to call it Sample Aspect Ratio instead of PAR :) I think calling it PAR is much more clear to all people. SMD, is it clearly documented that -sar means Sample AR and that Sample AR = PAR?

[SeeMoreDigital]

SMD, is it clearly documented that -sar means Sample AR and that Sample AR = PAR?Would it not be more accurate to say: When SAR and DAR are correctly placed within a calculation, you can obtain a PAR value?


Cheers

[Inventive Software]

Originally Posted by SeeMoreDigital
And things can get a little more interesting should you decide to generate full pixel height encodes with just the black mattes cropped away. Because, you'll need to encode to the nearest 16th pixel, meaning: -

1.85:1 will become 720x560 anamorphic (or 1024x560)
2.35:1 will become 720x432 anamorphic (or 1024x432)
2.40:1 will also have to become 720x432 anamorphic (or 1024x432)

Why the nearest 16th pixel? Surely the nearest you'd need to get it is to the nearest 8th or 4th. I don't understand. Please explain more...

[SeeMoreDigital]

Why the nearest 16th pixel? Surely the nearest you'd need to get it is to the nearest 8th or 4th. I don't understand. Please explain more...Many encoding softwares (especially MPEG-4 SP/ASP) will only let you crop and/or select output pixel frame sizes using 16 pixel increments.


Cheers

[Wilbert]

Would it not be more accurate to say: When SAR and DAR are correctly placed within a calculation, you can obtain a PAR value?
Not if SAR means Sample AR, but perhaps i'm misunderstanding you.

Ok, i read the x264 thread again. As long as it is clear that SAR means "Sample AR" then it should be clear. But i had called it PAR, because the MPEG-4 specs doesn't mention SAR.

[jase99]

Hi there!

Hate to dig up such an old post but I would like to ask a question about these PARs (http://forum.doom9.org/showthread.php?p=686406#post686406)

Although I agree with the math, those PARs do not take into account the visible display. For example, in PAL the visible frame is 702x576 (the other 18 pixels are in the overscan area). It is the 702x576 visible frame that is 4:3.

Therefore (digging out some old notes), I believe these to be the correct PARs:

4:3 PAL --> 1:1: 702*(4/3) /(702/576)x576 = 702*(128/117) x576 = 768x576 | 128/117 = 1.09402 PAR
4:3 NTSC --> 1:1: 702*(4/3) /(702/480)x480 = 702*(320/351) x480 = 640x480 | 320/351 = 0.91168 PAR
16:9 PAL --> 1:1: 702*(16/9)/(702/576)x576 = 702*(512/351) x576 = 1024x576 | 512/351 = 1.45869 PAR
16:9 NTSC --> 1:1: 702*(16/9)/(702/480)x480 = 702*(1280/1053)x480 = 853x480 | 1280/1053 = 1.21557 PAR

I tried x264 encoding using these and the earlier posted PARs and I think mine look closer to the image displayed on the TV.

I would love to hear any comments you have on this.

EDIT: This resource may be helpful, it confirms (for example) 702x576 has dimensions 4:3 on PAL displays: http://lipas.uwasa.fi/~f76998/video/conversion/

[Brother John]

SMD’s posting shows the generic PAR numbers calculated with an active picture area that covers the whole PAL/NTSC frame. The »quick guide« calculates according to ITU-R BT.601 which has an active picture area that’s a little smaller than the whole frame. Hence the difference.

Which one to use depends on which one your individual source uses.

[smok3]

as Brother John wrote, it is the same standard, the one noted by SMD is fullscan (or 'digital') version of it, they should 'convert' with minimum/nul error to each other, example;
http://resizecalc.somestuff.org/index.php?ssmw=702&sar=1.094&sar2=&ssmh=576&CT=&CL=&CR=&CB=&trw=720&dar=1.06667&dar2=&mod=&padw=&padh=&css=&doit=true

[jase99]

Thanks guys, very helpful. Nice resize calculator :) I apologise, I should have mentioned my sources are standard definition DVDs. In summary, the PARs I posted are correct for the sources I am using. This is also confirmed in the examples here (http://www.doom9.org/index.html?/capture/par.html) . Therefore, I should continue, for example, to use --sar 128/117 (~1.094) when encoding a non-widescreen PAL DVD using x264 if I do not want to resize the source to 1:1. I should not use --sar 16/15 (~1.067).