[MPlayer-users] Why 720x540 as opposed to 640x480?

[Jorge Fábregas]

Hello everyone,

I'm still learning about DAR's and PAR's...I'm now wondering why does mplayer 
upscales (vertically) my NTSC DVD to 720x540 as opposed to horizontal 
squeezing as in 640x480?  I know the goal is to obtain a 4:3 AR but isn't the 
latter best for interlaced material (still keeping the 480 lines)?

I'm just trying to understand this :)

Thanks,
Jorge