Quote:
Originally Posted by MoovyGuy
The mode called 480p is the lowest of the three HD TV modes, but it does not translate to 720x480, but instead 704x480
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704x480 is closest to the "real" dimensions of a full frame. While the active video area of an NTSC signal is actually 711x486, most digital video equipment chops off the bottom 6 pixels. With a height of 480 the ideal width for 4:3 AR is 702.2, and 704 is the closest value that is a multiple of 16.
720 is used to provide a margin for error when converting from analog to digital. See
this page for more than most people will ever need to know about aspect ratios
.