Encode to non-square pixel xvid?

[rebl]

Hi all,

Assuming I have a pal dvd and I want to transcode to movie to an avi/xvid file preserving all the original pixels, I must keep the original pixel aspect ratio. So I want to make a 720x576 (SAR=5:4) xvid avi that will play as 4:3 DAR.
All the programs I've tried automatically set the PAR to 1:1 and then, in order to have 4:3 DAR I am forced to also resize to 4:3 SAR.
Is there any xvid/avisynth GUI like xvid4psp or mediacoder that allows specifically setting the PAR (or at least specifically setting both SAR and DAR- then PAR can be calculated from these).
I assume the PAR setting could be inserted in xvid-encraw command line, but this pretty much destroys the convenience of a gui.
I am not that lazy, or afraid of scripting and command line, but with all the needed steps (including pre-processing, cropping and so on) it's really conventient to use a gui. I just need to be able to control PAR (and aply avisynth denoise scripts ).
Until now I was working in xvid4psp and I am very content with the workflow, but the resize/crop settings are scarce and it gives no control to some of the command-line switches of xvid_encraw.
I've also tried avanti and megui, but I can't find the PAR setting and they both seem very hard to work with (like in not "ergonomical"). Especially megui, which forces you to first make an avs script...
Mediacoder has a very nice GUI, I like the workflow, it has the option to set par, but ... it does not work . I've always had problems with mediacoder and it seems to me it's very buggy. (Actually with the exception of some mp3 to AAC conversions, I never managed to do something in mediacoder - it either crashes or I get "no file output" error... or... some other bad thing happens).

So... any other gui would you recoommend that would be easy to use, offer full controll of all settings including setting PAR, and also offer the possibility to apply preprocessing avisynth filters?
Thank you in advance. (I hope I am not asking for the holy grail! )

[manono]

Am I correct in thinking that your main objection to using XviD4PSP is that you don't think it allows you to filter with it the way you like?

Since XviD4PSP allows for setting all that PAR/SAR/DAR stuff, what's so hard about editing the AviSynth script it prepares so you can add the filters you want? In addition, in Video->Resolution/Aspect you can crop and resize anyway you like.

I must be missing something.

[rebl]

On the contrary, the main thing i like in xvid4psp is that it offers me plenty of presets of avisynth denoise filters (that, and the convenient workflow).

The main thing I am unable* to do in Xvid4psp is specifically set the PAR not equal to 1:1 (end edit the xvid_encraw command line).
You are writing that "xvid4psp allows for setting all that PAR/SAR/DAR stuff"- but on the contrary -it does not!. It only allows you to set a "vaguely named" "aspect ratio" without specifying if it's DAR or anyting else. (I only assume it's DAR) and it automatically sets* the PAR to 1:1.

You can't enforce PAR non-square*.
* [LATER EDIT - ok, I assumed wrong. Actually, you set SAR by specifically setting the pixels ,such as 720 x 536, then you set the desired DAR such as 4:3 then the program will calculate a PAR that will fit the ecuation.
They should rewrite a little the interface to make the settings a little bit more clear! The program does its job, but it's hard to understand it does it.]
If you manually set 4:3 output and 720x576 SAR... wow! ! ! ... I was just doing this test while I was writing and I was sure the DAR will be ignored and I would get a PAR 1:1, distorted image. But no! I managed to get, according to gspot, a PAR 15:14 (1,063) image (SAR 5:4 and DAR 1,328).
I still don't get it why didn't it make PAR 16:15 (1,067) as it should for non-itu DAR.

By the way, is there any way to tell if the DVD is 4:3 (non-itu) OR ITU 1,3675 DAR?

[mgh]

AviDemux or Virtualdub using XVid codec-you can set what you want
in xvid4psp, you have to check save anamorphic aspect under settings-globalsettings-it will work with the PAR as indicated by your
source file

[rebl]

Strange, I managed to obtain non-square pixels (PAR 15:14 - quite inexact!) without the save anamorph setting checked.
I will try with that one checked too.
I still don't understand why the 15:14 ratio for PAR.
I thoughit it's 16:15 for PAL with DAR 1,33
and its a little different (a higher numbers ratio, not 15:14) for ITU DAR 1,3675 (according to FitCD, but i cant find the exact ratio)

L.E.
in the encoding log of xvid, with anamorhic setting enabled, the PAR is 803:753, wich is also to 16:15 but not the same

[rebl]

by the way, isn't "anamorphic" exactly the same as "having non-square pixels" and the same as PAR not equal to 1:1 ?

[TCmullet]

Hi. Am new to Xvid. This seems like an appropriate thread to post this (although not exact, but I don't think I'm hijacking). I've been encoding 720x480 (ntsc) videos and films to Xvid. But regrettably I've done them all w/square pixels. I've just done a short encoding test and found that my DVD player (Philips DVP 5992) DOES honor it when I change PAR from "square" to "4:3 NTSC". (The narrow black bars at top and bottom of TV disappear, and the people don't have that slight "fatness".) But I now have dozens of hours of DVD-R of xvid AVI with the square pixels. Isn't there some way to "fix/fudge the header" of the file to change the pixel ratio WITHOUT any real reencoding?? I have lost all the original source footage, and I don't want to reencode from xvid to xvid. Conceptually, it doesn't make sense that the pixel ratio has anything to do with encoding a video's pixels themselves.

Btw, I realize I could have prevented this by resizing to 640x480, but I really want to keep all that 720x info.

[jagabo]

So you encoded at 720x480 with a PAR of 1:1? If so, you can use Mpeg4Modifier to change the PAR/DAR flags and avoid reencoding.

[TCmullet]

THANK YOU, Jagabo! It's wonderful. Am still puzzled by a few things:

1. I was surprised it showed there was *nothing* specified in DAR. I guess if the player knows it is 720x480 and par is "4:3 NTSC", then it simply knows how to show it. Any thoughts as to why DAR has nothing. Am using the Xvid that works with VirtualDub.

2. The simple fix of PAR apparently will work fine for all my 720x480 stuff. (I've done it on interlaced 29.97 fps. I'm assuming it will work the same for 720x480 progressive 24fps.) Where I'm puzzled is what to do where I have an Xvid avi at 720x270. (It's a letter-boxed movie, and I've cropped the top & bottom away to leave 270.) What (if anything) should I do with DAR? And should I change PAR to "4:3 NTSC" as I did w/the full-screen clips?

3. Changing nothing (in my interlaced video file) except PAR, I notice the new file is 55K *greater* than the old. Why is it not exactly the same?

[jagabo]

Xvid has both a DAR and a PAR flag. The PAR flag describes the shape of individual pixels. The final display aspect ratio is then:

DAR = SAR * PAR

DAR = display aspect ratio (final shape of diplayed image)
SAR = storage aspect ratio (frame size)
PAR = pixel aspect ratio (shape of individual pixels)

In the case of Mpeg4Modifier the "4:3 NTSC" PAR means use the same pixel aspect ratio as 4:3 DVD (10:11).

The DAR flag tells the player to ignore the PAR and SAR, just do whatever is necessary to display the frame at the indicated DAR.

If you cropped a frame but didn't change the PAR you specify the PAR of the original source. So if your DVD source was NTSC 4:3 and you cropped away the black borders, leaving 720x270, and didn't otherwise resize the frame, your PAR in Mpeg4Modifier should be NTSC 4:3. (By the way, for best results the frame size should be mod8 or mod16. Some players won't play mod2 frame sizes correctly, so leaving 272 would be much better than leaving 270.)

The small change in file size has to do with the padding that different programs use to align video data. Some align on 1K boundaries, some on 2K, 4K, etc.

[TCmullet]

Ahhh, so it appears I should leave DAR alone. If it was empty before, I'll leave it empty now. What was difficult was to realize that at 720x270, I'm not really watching a 4:3. But the TV/DVD Player IS generating one by the player padding the x270 to make x480. I was worried I'd have to figure some custom values for DAR. Now that you've so eloquently explained the relationships, it's clearer. Wish the Xvid codec had docs like that.

This is all nice theory, but processing my x270 movie thusly will prove it all. Will work it out tonight.

Btw, I picked 270 as it seemed round enough. I knew that powers of 2 are better than odd numbers. I hadn't divided to see that 272 was a multiple of 16! I was leaning toward cropping all black as that would mean better compression. I wonder what they did on the DVD. (I don't know as this movie, Marooned, came off TCM, not a DVD).

And output buffers being different sizes makes perfect sense. As long as the AVI structure is properly maintained, it's all okay. I didn't even think that Mpeg4 Modifier was going to write a new file; thought it would update the header in the old. So when I see a different file size, that was a red flag.

Thanks for all the help. Now to consider whether some videos should use Mpeg quantizer or not..... (will search around some more, and do a little testing).

[jagabo]

The Mpeg quantizer is a little sharper than h.263 quantizer. But it takes more bitrate and generates a little more DCT ringing artifcacts.

[TCmullet]

(I've pasted the text of this post over to a more suitable thread. I'd delete this post here, but can't find a delete button. So I can only shrink the text.)