[mythtv-users] 50Hz PAL over VGA at 60Hz (again) - how does Windows MCE do it?

Charles Mason charlie.mas at gmail.com
Sat May 5 14:17:39 UTC 2007


On 5/5/07, Ben Lancaster <lists at benlancaster.co.uk> wrote:
> Hi all,
>
> OK, so a while ago I started a discussion about how video playback
> wasn't as smooth as I'd expected with 50Hz PAL over VGA @ 60Hz (a
> limitation of my TV), and the answer was, as expected, because
> there's interpolation with duplicate frames to compensate for the
> addition 10 frames required. It's most noticeable when you get
> panning shots, or lots of movement, it's by no means a showstopper,
> but it's quite irritating.
>
> So my new question is this: how does Windows MCE do it? A friend of
> mine has the exact same TV (Samsung LE32... something-or-other), but
> he uses Windows MCE to play UK Freeview (i.e. 50Hz PAL) over VGA at
> 60Hz, yet video playback on his is silky-smooth. What is MCE doing
> differently? And is there any way to replicate this on Linux?
>
I know on how they used to do it. When you want to full screen mode it
drooped the screen refresh rate to 50Hz. This used to cause me big
problems when I was at uni as my room was small (so I was close to the
monitor) and this refresh made my eyes hurt on my old CRT monitor. I
found a registry hack to stop it drooping the refresh rate and from
then on I had pain free TV viewing at uni.

If I remember correctly I stopped needing the registry hack when I
upgraded to 2005 edition. Although soon after that I got an LCD
monitor so I may have just left it untill then.

As far as I can see the only thing they can do is either drop the
refresh rate of the output device, or interpolate the extra frames. It
may be they have found some way to improve the interpolation algorithm
which looks less obvious.

Charlie


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