PAL and NTSC video is stored in non-square pixels.
DAR = display aspect ratio, often referred to simply as "aspect ratio" (or "AR")
SAR = storage aspect ratio, and is not often mentioned or talked about. 720x480 (NTSC), for example, is 3:2 aspect. However, you'll never watch it this way. 352x480 is something like 11:20 aspect. I forget the PAL SAR's, don't know them offhand, because I work more with NTSC and have those memorized. This information is only useful in certain scenarios. For example, when you want to crop off pixels in a non-4x3 editor (
VirtualDub's crop feature), but maintain final aspect (both SAR and DAR).
The two generally have no overlap.
720x576 = 4:3 AR (DAR), and something else for SAR
720x480 = 4:3 AR (DAR), and 3:2 SAR
352x576 = 4:3 AR (DAR), and something else for SAR
352x480 = 4:3 AR (DAR), and 11:20 SAR
... same for 352x240, 352x288, 704x576, 704x480, 480x480, 480x576, etc
You'll see SAR when you use 1:1 square pixels. But that's not proper NTSC or PAL video encoding -- that's non-format video sizing.
640x480 = 4x3 @ 1:1 square pixels
320x240 = 4x3 @ 1:1 square pixels
... and there are MANY more possible combos. Just pick a number a and multiple it by 4 and by 3, and it will be a valid size where both are divisible by 8.
Just remember that the pixels of video data for NTSC and PAL video are not square.
- Good computer player software will show the pixels properly.
- Bad computer player software will squish/stretch the video in odd ways, forcing the rectangle-shaped pixels into improper little squares.
- Editors can vary in how their preview works, so pay attention to aspect settings when setting up a project, or when viewing the preview windows. (In VirtualDub, for example, you can right-click the preview to show it 4:3. In Premiere, you set up the project to have proper AR.)
That's really all there is to it.