pixel aspect ratio issues

[Ernest Burden III]

I am finding several aspects of digital video to be difficult and confusing. The first is encoding--best codec, size, bitrate, etc.

 

The second is pixel aspect ratio. There are a variety of formats and some expect aspects other than 1.0 I have been animating stuff for at least a decade, with a variety of rendering software, and they ALL output assuming aspect 1.0 . Isn't that how we look at renderings--a 800x800 image is square? Not to Premiere.

 

In setting up a project to use square pixels I have template choices, I notice that NTSC standard is 720x480 with a PAR of .9 and NTSC widescreen is 720x480 with PAR of 1.2 Hummm, I rendered to 720x480 but with PAR of 1.0--so which is it?

 

I set up the project to use square pixels, each imported shot sequence (about 25 for 1:30 of anim) must be 'interpreted' to 1.0 as it defaults to .9 Great--but now on export, when I try to use standards like WindowsMedia it will change the pixel count to adjust for the .9 or 1.2 PAR. I can use a codec like Indeo5 and spec everything which works, but not as good an output. So far, Quicktime is the most obedient encoder. I'm going to try some of the MPEG/DVD output formats, too.

 

In Photoshop CS you can change the PAR, could be done batch to all frames.

 

Does anyone have any wisdom on pixel aspect ratio?

[Chad Warner]

For a standard NTSC television screen, you want to use 720x480 at .9. TV's have rectangular pixels. I don't know about the program you use, but viz and max both have the capability to render at .9.

 

For typical widescreen, you want to either use 720x480 @ 1.2, or 864x480 @ 1. (if you do the math, they pixel counts are identical). The only reason I would do one over the other is that premiere recognizes 1.2 PAR as widescreen, so there is no interpreting the images.

 

But, if you are encoding this to be played on a computer, you want to use square pixels.

 

More confusion?

 

-Chad

[Ernest Burden III]

But, if you are encoding this to be played on a computer, you want to use square pixels.

More confusion?

 

Yes.

 

Does that mean YOU understand this? I mean, I do understand how Premiere is incorporating the PARs of .9 vs 1.2 to make either standard or widescreen, but the point is aren't most of us producing video to be shown on a computer?

 

So advise please--I rendered 720x480 at 1.0 PAR for 30fps (not 29.97) progressive-scan output to be shown on a computer. What format to output?

[Chad Warner]

Do I understand it? Not in the least. I just know that it works. You should be able to force premiere to use square pixels for the export part of the movie, as well as set the project settings to use square pixels as well. That way, you use the NTSC as a starting point, and then override it fro square pixels.

 

Actually, we do most of our video work on VHS or DVD output, so square pixels aren't too much of an issue. You are lucky you don't have to deal with fields. THAT is something I still have no idea how it works.

 

-Chad

[Ernest Burden III]

You should be able to force premiere to use square pixels for the export part of the movie, as well as set the project settings to use square pixels as well. That way, you use the NTSC as a starting point, and then override it fro square pixels.

 

I found that to be a lot easier to do in Premiere6. The new one (Pro) does not have the 'project settings' pop-up table, and I am having trouble forcing anything.

 

On output, I find that certain formats--not all--do not have the ability to force sq. pixels. Windows Media being one of them.

 

Fields. Yeah, an animation I did last year reportedly fell apart upon being transfered to a fields format. Not that anyone ever told me that they were going to do that. Anyway, I sent them a set out output frames (the final edits/fades) and a matching .wav file so they had a completely uncompressed version to use in their video setup.

 

Oh, and I just tested the squareness of my Lightscape-rendered frames by rendering a square polygon seen straight-on. It is indeed rendering sq. at PAR of 1.0 Photoshop CS uses various pixel aspects ratios, but it is a display variance, not a file change--just so it 'looks right' on screen. I could do a non-proportional re-size to account for the .9 or 1.2 PAR, but at a cost of image quality.

 

It's good to have standards.

[STRAT]

maybe a little off the subject, but this is a usefull plugin for C4D m8 -

 

http://www.3dweave.com/plugins/DPI_to_PIXel_convert_C4D.php