James Richard Tyrer wrote:
Probably best to send 240 to the TV but only use the center 200 lines.
You are also going to need to increase the H blanking to compensate for
overscan, or is 640/720 enough? There is an official spec for overscan
somewhere. The usable area is called the "title safe frame".
IAC, if the VGA is outputting more lines than the TV we would need 2
different character generators or use line doubling for the VGA output.
So, yes you do need to know if you are driving a TV unless you have a
new HDTV that does 480p (accepts regular VGA with no problems).
To ramble on about this. You can send VGA as 480i to a TV set but you
aren't going to see the edges of the image. :-(
So if you are driving a TV set (with something other than a movie), you
should really use 640 H (of 910 total pixels per line) and 400 V (of 525
lines total) so that you can see all of the image. Pixels aren't
exactly square (.9375). :-(
--
JRT
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