Adobe After Effects - Difference between PAL aspect ratio

Author

Difference between PAL aspect ratio

Yuhan_Lin@adobeforums.com

2006-12-06, 8:15 pm

Hi all,

Am currently working on a DVD program utilizing only still images and no video footage. And my current composition settings is PAL D1/DV Sq Pix, 768*576. Hence I am wondering what's the difference if I actually switched the settings to PAL D1/DV, 720*576.
I understand that there's square pixels and blah blah. But I just want to know what happens when we view the FINAL output (on DVD) if the settings are different. (ie. squashed?)

Much Appreciated,
Han

Aaron_Cobb@adobeforums.com

2006-12-06, 8:15 pm

Ultimately, the DVD video will have to be PAL D1/DV PAR. It's just a matter of whether you generate a square pixel master and then have your DVD compression software resample to D1/DV pixels for you, or if you set your comp up in AE to output D1/DV pixels
from the get-go. You'll get a very subtle degradation if you choose to use square pixels and resample, but not anything the human eye can pick out, I suspect (I work in NTSC-land where D1 pixels get resampled vertically, and as long as you are rendering
to whole frames nobody will notice the difference).

For my money, native D1/DV PAR = fewer pixels = less render time, but your mileage might vary.

Yuhan_Lin@adobeforums.com

2006-12-06, 8:15 pm

Thanks Aaron :)

so the general rule of thumb here is "there's no difference" between the two D1/DV versions for PAL: 768*576 and 720*576. Am i right? And it's all converted into the "correct aspect ratio" by the DVD authoring software. But what's the standard that everyo
ne else is using? 768 or 720?

Andrew_Yoole@adobeforums.com

2006-12-06, 8:15 pm

You misunderstood Aaron's post. PAL DVD material MUST be 720x576 pixels. Some encoders/authoring tools will convert from square pixels on-the-fly, but not all. And some of them do a much worse job of it than After Effects will.

For my money, native D1/DV PAR = fewer pixels = less render time, but
your mileage might vary.

I agree entirely with Aaron here. Unless there's a specific reason NOT to work at native 720x576 D1/DV, why wouldn't you?

Aaron_Cobb@adobeforums.com

2006-12-06, 8:15 pm

You misunderstood Aaron's post.

There seems to be a lot of that going around lately. I should probably take it as a sign.

I wasn't aware that some encoders won't resample. That's really lame.

I do know some folks who simply hate working in non-square PAR's. I can sympathize: AE's Pixel Aspect Ratio Correction is really crude for no particularly good reason (AE eats scale transformations for breakfast, why does PARC just drop/add columns of pix
els?) and working in a 3D world in which the axes aren't the same scale can get really hairy, particularly if you are using expressions. But in most cases losing the additional resample wins out for me.

Yuhan_Lin@adobeforums.com

2006-12-06, 8:15 pm

Thanks guys! Much appreciated :)