Aspect Ratio

[peterk]

Some time ago, I can't remember where, I read that video should be resized to 720x480 NTSC and 720x576 PAL. This is what I have been doing if I needed to but it has just occurred to me that true 4:3 is 640x480 and 768x576.
Why or when would 1.5 or 1.25 be used instead of 1.33333 (4:3)

[paglamon]

One reason is that the pixel is not square in NTSC or PAL DVD.
See here for basic understanding:http://www.transcoding.org/cgi-bin/t...e?Aspect_Ratio