[mythtv-users] What should be the minimum video card memory I should look?

Niels Dybdahl Niels at Dybdahl.dk
Wed Apr 19 06:48:38 UTC 2006


On 4/18/06, Jonathan Rogers <jonner at teegra.net> wrote:
> Niels Dybdahl wrote:
> > Most LCD TVs will scale the input from the HDMI while they will not
> > scale input from a VGA, so you could get better picture via VGA than
> > HDMI.
>
> If you think about it, you'll realize that an LCD TV will have to scale
> the VGA input anyway, since it's an inherently analog signal (unless
> it's smart enough to divine where the video card divides between
> pixels). The VGA scanlines may be mapped directly to panel lines, but
> the TV isn't going to know exactly where columns start and end.
>
> Specifically, my cheap LCD TV has composite, SVideo, component, VGA, and
> DVI inputs and always scales them all. It has a VGA autofit button,
> which works, but is annoying because you have to do that every time you
> turn the thing on. On the other hand, the DVI modes I'm using fit pretty
> well since I tweaked them with xvidtune; the TV doesn't even know what
> the mode is; it just spits the pixels up there, which is why it would
> make more sense if it didn't scale the image.
>
> I wish I could get it to turn off the scaler, since mapping pixel to
> pixel is one of the main reasons to for the existence of DVI. Also, I
> know that the native resolution is 1366x768, as many LCD TVs are, but
> video cards don't like modes with dimensions that aren't divisible by 8,
> so I have to use 1360x768 or 1368x768. Since those are so close, the
> pixels almost line up. If I move an xterm horizontally, I can see about
> five vertical "stripes" across the screen where columns of pixels from
> the video card bleed into each other, but between those regions, they
> appear to match exactly.

I have never had the opportunity to watch HD shows on a LCD TV.
What happens if you show a 720p (1280x720 pixels) recording on a LCD
TV with 1368x768 pixels ? Is there any way to avoid scaling ? If not I
would imagine that the best result would be to run the video out in
1280x720 and only have one scaling which would be in the TV.

I have noticed that a DVI connector has analog signals in addition to
the digital. If a TV has DVI in, can I be sure that it will use the
digital signals or might it default to the analog ?

Niels Dybdahl


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