There are two fields in NTSC. So it's not 525 - 21. It's 262.5 - 21 and 262.5 - 20.5. That's 483.5, which is rounded to 480 for computer (and MPEG macroblock) convenience. TTFN, Mark cbenham@xxxxxxxxxxx wrote: >I'm confused. >525 lines minus 21 in the VBI (I'm including line 21 because today it's >used for closed captioning) >equals 504 lines. Where are the other 24 lines >going which reduce line count to 480? > > > ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.