[mythtv-users] XvMC on NVidia with Myth .20 (Anyonegetting goodHD off a P4 3

Drew Bernat abernat at zathras.net
Mon Jan 8 20:10:14 UTC 2007


On Jan 8, 2007, at 1:23 PM, R. G. Newbury wrote:

> Right. Your "HDTV" cards will only do 'HD' if they are fed an HD
> definition signal. Generally, that means OTA with an antenna or you  
> are
> in the US, where you can get unencrypted HD over cable for local (OTA
> avilable) channels. If you are getting encrypted HD, then the output
> form the STB is either by firewire or S-video, and in either case,  
> will
> not use your HD card to tune the signal.

Right - I'm getting OTA HD. Sorry about not being specific.

> Whoa... XVMC is explicitly a video card driver thingy. It has  
> NOTHING to
> do with the tuners. XVMC makes use of the video card *hardware* to do
> stuff which would otherwise be done by the main CPU is producing the
> video output. Which is why you see discussions of the computer power
> needed to decode HD. You need either a pile of computer grunt, OR an
> Nvidia or VIa video chipset which supports XVMC.

Right. However:

HD-resolution show recorded via HD tuner card: XvMC works
SD-resolution show recorded via HD tuner card: unknown
SD-resolution show recorded via SD tuner card: XvMC doesn't work

This leads me to believe there is something about the _recording  
format_ off the card that causes XvMC assistance to break, and not  
the inherent resolution of the program. That's what I mean by tuner  
difference - that's basically the only varying component right now.

Drew

>
> Geoff
>
>
>
>
>
>>>> Also interesting that the S-video out ignores modelines. I know  
>>>> you can
>>>> futz with resolutions, but I thought you could also do refresh  
>>>> rates. I
>>>> guess not.
>>>
>>> Well, technically, I guess it has a hard wired modeline based on  
>>> NTSC or
>>> PAL standards... which include the refresh rate.
>>
>> Okay, so I can safely ignore the discussions on setting modelines  
>> and X
>> overhead.
>>
>>> Clean down your xorg.conf to either 800x600 or 720x480 and see what
>>> happems. Since you are using the S-video for output, remember to  
>>> set the
>>> output to 'CRT,TV' to get both.
>>
>> Will do, thanks!
>>
>> Drew
>>
>> -- 
>> Drew Bernat
>> abernat at zathras.net
>>
>>
>>
>>
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>>
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--
Drew Bernat
abernat at zathras.net


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