[SeeMoreDigital]

Originally Posted by bkman

That would explain a lot, but as you say it is arguable and may not always be the case. So there is a choice when calculating the SAR in that respect, I think, where some might think it is more correct to do it one way, and others the other.

Thanks for your help with my questions, btw.

When you read my posts you will see I tend not to mention terms such as SAR, PAR and DAR. This is because people tend to pre-assume their values are always "fixed".... Which they are not!

The level of "Aspect Ratio Signalling" (ARS) you will require will change in relation to your source "Movie's Aspect Ratio" (MAR) and your "mod16" pixel frame size (after cropping and resizing).

Here's an "extreme" example of what I mean. If you had an MPEG-4 file with say, a resolution of 496x464 but you knew it should be displayed at 2.35:1 shape, you could use the following calculation: -

MAR    FAR                              ARS 
47     464     21808                    1363
--  x  ---  =  -----  lowest dominator  ----  Giving an ARS value of 1363:620
20     496      9920                    620

EDIT: I forgot to include the "Extreme Example" sample.


Cheers