#Field Rendering
09-Apr-95 13:48:13
Sb: #163773-#Field Rendering
Fm: david W. mennenoh 71561,2343
To: Glenn Zimmerman 76247,3660
Glen, As someone else pointed out to you the extra lines are used for
the vertical retrace. I'm not an engineer, and can offer no more on
that issue. Actually it is 486 lines vertically. Horizontally really
doesn't matter it can be anything from 512 – 752 or even higher using
a Vista or something. Yes, field rendering renders every other line.
But the two fields are always combined to make one frame. There are
always two fields in a video signal. If you render to frames instead
of fields then those two fields are just the same. Your NTSC device
displays the first 243 lines in 1/60 of a sec. then goes back and
displays the other 243 lines. That's why if the images being displayed
have field info. (rendering to fields) the output appears smoother. I
don't exactly follow your question about rendering two fields
seperately, they are always combined. The only difference is where
you view a field rendered image. A still on a TV will flicker and it
won't on your computer monitor.