[mythtv-users] Changing mythtv resolution to match HDTV output?

Michael T. Dean mtdean at thirdcontact.com
Thu Jan 12 23:15:10 UTC 2006


Paul Leppert wrote:

> I recently purchased a new TV with 1080p capabilities (HP md5880n) and 
> was looking for advice on how to set up mythtv to get the best image / 
> performance at the HDTV resolutions.
>
> Based on the capabilities of the TV, I can feed it a 480p, 720p, and 
> 1080p signal (and I'm assuming a 1080i signal as well, but not sure if 
> that is relevant).  I have a DVI to HDMI cable to feed it and have 
> confirmed I can send these three resolutions from my nVidia FX 6800 
> (mythtv box).
>
> Based on my understanding of mythtv, I have the option of setting it 
> up to use different resolutions based on what is being played back and 
> another resolution for the GUI.
>
> I would assume this would work out as:
>     1080i source -> 1080p output to TV
>     720p source -> 720p output
>     480i source -> 480p output
>     GUI -> 1080p output (probably doesn't matter much which resolution 
> to use for this)
>
> Is this how people use this capability?
>
> Is it better to have mythtv feed different resolutions to the TV based 
> on the source being played (and have the TV scale), or is it better to 
> have mythtv feed the highest resolution always (with mythtv scaling)?
>
> I have heard via this list that having mythtv feed a different 
> resolution (than the source content) will impact the performance since 
> the myth box will need to scale the image if it isn't the same 
> resolution.  I have an Athlon XP 3200+ and it has problems keeping up 
> with HDTV (if I don't use XvMC, which I would prefer not to use), so 
> CPU performance is probably my top concern. Does the CPU perform the 
> scaling or does the video card?  Anyone have any ideas on quantifying 
> the impact?

On any video card that has hardware scaling capabilities, scaling takes 
almost no CPU resources.  Your card does hardware scaling when using Xv, 
so you shouldn't notice any difference whether scaling on the Myth box 
or the TV.

Mike


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