[mythtv] Idea for interlaced playback.

[Cory Papenfuss]

> I got the following numbers directly from the PAL signal specification:
>
> Horizontal Frequency = 15.625kHz
> Vertical Frequency = 50Hz
> Horizontal lines (total) = 625
> Horizontal lines (visible) = 576
> Horizontal Front Porch = 1.5µs
> Horizontal Sync Width = 4.7µs
> Horizontal Back Porch = 5.8µs
> Horizontal blanking period = 12µs
> Vertical Front Porch = 0.16ms
> Vertical Sync Width = 0.16ms
> Vertical Back Porch = 1.28ms
> Vertical blanking period = 1.6ms
>
 	Wherever you found that doesn't happen to have the NTSC specs, 
does it?  I've looked for them and found conflicting numbers... another 
datapoint would be good.

> Nvidia restrict some of the values in their modelines to multiples of
> 8. Taking that into account this is the closest possible modeline for
> 720x576 to the PAL spec for an nvidia based card:
>
> ModeLine "720x576pali" 13.875 720 744 808 888 576 581 586 625 -hsync
> -vsync interlace
>
 	Yes, that's quite annoying that they restrict it.  Make sure the 
dotclock gets changed to compensate.

-Cory

-- 

*************************************************************************
* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
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