[mythtv-users] HDTV modeline frustrations

[Jim Paris]

> 720p.  This will probably be my eventual goal.
...
> stable, but much more overscan than I'd like.

You won't be able to adjust the overscan, at least not for the
top/bottom.  You're giving the TV 720 lines and it's up to the TV
where to display them.

> 1.  My primary question is about Dot Clocks.  As I work through
> the adjustments and formulas, most sites seem to assume the
> clock is constant.  Its nearly impossible to make significant
> improvements in overscan (720p) keeping the clock constant.

Dotclock doesn't matter, only horizontal and vertical refresh.  Keep
those constant if you want your TV to be happy.  Adjust dotclock to
adjust the total horizontal resolution in a given scanline.

> What symptom would I see if I'm over-driving the clock on the TV?

There's no concept of "over driving" the dotclock.  You're just
feeding analog data.  The TV will sample it whenever it wants.

> I don't think my HDTV tuner at 720p has this much overscan?

Check.  With a proper input signal, overscan is a function of the TV,
not the signal.

-jim