[mythtv-users] low def on Hi Def set (XvMC)

Rod Smith mythtv at rodsbooks.com
Fri Jan 1 03:51:59 UTC 2010

On Thursday 31 December 2009 01:37:12 pm Matt Graham wrote:
> Although I am sure that this subject has been touched on, I wasn't sure how
> to search for it.  I am considering finally getting a Hi-def screen.
> However, most of the content that I will be watching will still be
> low-def/SD.
> I have noticed that many of the more value oriented TV's do a poor job of
> upscaling SD content.  Sometimes making the low pixel count of the source
> content painfully obvious.

I haven't compared HD TVs side-by-side on this score. If you've done so and 
you see a difference, then I'll take your word for it. Perhaps the sets vary 
in the quality of their scaling and/or deinterlacing. OTOH, you can't expect 
miracles when viewing SD content on an HD set, no matter how it's done.

> Then it occurred to me, that if I am sourcing the content from my Myth box,
> then the Myth box will be doing the image processing (correct?)

It depends on how you set it up, but in general, yes. Certainly that's how 
mine is configured -- Myth scales to 1366x768 (my TV's native resolution) and 
that's all the TV sees. There is an option somewhere in the MythTV setup 
screens to use custom resolutions for different source file resolutions, so 
if you think your TV will do a better job of scaling, you could set up MythTV 
to enable doing it this way. I get the impression that most people don't use 
this option, though.

> I believe I have an Nvidia FX5200 and XvMC support compiled in,  will this
> be able to do a decent job of SD conversion?

I can't really comment if you're seeing differences between sets in a showroom 
and you want to know how your setup will compare. Certainly that hardware 
will be adequate for playing back either SD or HD content, provided your CPU 
is fast enough. Upgrading to a VDPAU-capable card can also help if your CPU 
is marginal for HD playback, and many people say that VDPAU provides superior 
picture quality. (My own system uses a built-in Intel chipset with no VDPAU, 
so I can't comment on that detail.)

Rod Smith

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