720x480 -- SD and Widescreen not 4:3 or 16:9

Question

Hi,
This is one of those topics that I've not seen answered definitively.
NTSC DV is 720x480 square pixels.
If it's NTSC SD, the final display is 640x480 -- a 4:3 "frame" or screen aspect ratio. The pixels are squished (taller than wide) such that the pixel aspect ratio is .9091. But if you multiply 720 by .9091 you get 654.552. What happens to those extra 14.552 pixels?
If it's NTSC widescreen, the final display is 853.333x480 -- a 16:9 "frame" or screen aspect ratio. In this case the pixels are stretched (wider than tall) such that the pixel aspect ratio is 1.2121. But if you multiply 720 by 1.2121 you get 872.712. What happens to those extra 19.37867 pixels?
Thanks to whomever clears this up or points me to a definitive answer.
Jeff S

Answer 1

The DV NTSC pixels have a pixel aspect ratio of 0.91 (nonsquare). DV pixels, which are always rectangular, are vertically oriented in systems producing NTSC video ...
Ann,
I should have worded my initial statement differently. But, it is essentially correct. It should say:
NTSC DV starts its life as 720x480 square pixels.
NTSC displays those pixels at a frame ratio of 4:3 (SD) or 16:9 (Widescreen). Those pixels are altered -- stretched wider or narrower -- to accomodate those frame ratios. But, those pixels taken on their own -- when they are just pixels and not displayed as NTSC signals -- are square.
A nifty way to see this, is to use the Export Frame feature in the P Pro Program Monitor. Use it on an NTSC SD clip (in an SD sequence) and on an NTSC Widescreen clip (in a widescreen sequence). In both cases the resulting image will be 720x480 square pixels.
Jeff