PAR and After Effects

[Hans Van vliet]

Hey,

I always work in squared and let AE take care of turning it into a non-square setup for output. If there is quailty loss none of my editors have noticed it at all (niether have I) .. Good luck

..::hunz..

[Nicholas White]

Hey,

I’m fairly new to video editing, only seriously got involved about 2 years ago, and I can’t think of any time where I’ve had to worry about PAR; like Hunz said, let the software do the work for you.

Is the PAR thing that everyone talks about a hangover of older softwares, or is my limited experience with only DVD’s and DV tapes not exposed me to potential problems with other formats?

Take care,

Nick

[Steve Roberts]

(This also applies to widescreen, but with different numbers.)

Computer monitors display square pixels.
TV monitors display rectangular pixels.

As a result:
1) We know a standard computer monitor has a 4:3 aspect ratio. Its resolutions fit that ratio: 640×480, 800×600, 1024×768 and so on. This is because the pixels are square.
2) A standard TV also has a 4:3 aspect ratio, but the digital standard calls for non-square pixels. 720×480 or 720×486 fill a 4:3 screen, but those numbers are not 4:3.
3) 720×540, 640×480 and 648×486 are all 4:3. When creating graphics in computer graphics apps that are not compliant with non-square pixels, you should create TV images using one of those frame sizes. Older versions of Photoshop are like that.
4. On a square-pixel computer monitor (all of them) the 720×480/486 images will look too wide. Make drawings on graph paper to check. However, those images will look fine on TV.
5) Some video editing apps (maybe all) squeeze the image so it looks normal on the computer and the TV. AE has recently added this capability: pixel aspect ratio correction. If you use it, switch it off before rendering.

If you want to know more, search the COW for Rick Gerard’s Dr. Strangepixel article.

Hope that helps,
Steve

[Jim Wilcox]

Steve,

Thanks for the response. I feel quite comfortable with how AE deals with incoming files and interprets square vs non square. Rick’s Strangepixel is a great piece and I’ve had it in my file for quite awhile. I’m just curious with Photoshop and AE capabilities of allowing you to view in square pix even when working in non square pix, if folks are now working more in non square. And if so, are there any problems I’m overlooking that may bite me in my southbound region! Just seems like I should now be working at 720×486 in PS and AE since that’s what I am going to output. And with tools that can allow us to see results square pix on the computer as we work…why not. But I can’t shake the feeling that I am somehow going to compromise my work. That’s all…Thoughts?

[Nicholas White]

Hey,

I think that when you tell programs like PS and AE that you want to work at a .9 PAR but display at a 1.0 PAR, you are actually working with non-square pixels. The software is just smart enough to show everything as square pixels while you’re working, but in reality they’re non-square.The real test is to look at your work on a non-square display like a TV or special monitor…if it looks ok, you’re probably doing fine.

There’s a great book by Richard Harrington called ‘Photoshop for Non-Linear Editors’, it does a great job of explaining all the pitfalls of square and non-square pixel problems you might have or worry about…it was one of the first books I bought when I got into doing video stuff with Photoshop, After Effects and Premiere and calmed my nerves after a few reads. It should be required reading for anyone new to video : )

Take care,

Nick