[mythtv-users] How to minimize CPU usage

Kevin Kuphal kuphal at dls.net
Sat Feb 4 17:26:16 UTC 2006


Jerry Rubinow wrote:
> On 1/30/06, Boleslaw Ciesielski <bolek-mythtv at curl.com> wrote:
>   
>> Jerry Rubinow wrote:
>>     
>>> PVRs have existed for a while, but not HD-resolution PVRs - they're
>>> pretty recent.  If X is in a 24-bit depth mode, then I don't see where
>>> my numbers are off - 24 (bit depth) * 1280 * 720 (screen res) * 30
>>> (fps) = 630+ Mbits/sec.
>>>       
>> 720p is (usually) 60fps.
>>
>> Bolek
>>     
>
> That's what I thought, but that would mean 24 * 1280 * 720 * 60 = 1260
> Mbits/second going to the video card.  There'd be no way that would
> work over PCI - it'd be dropping every other frame (not to mention
> that X reports 32 bpp, so 24 seems low), but it seemd like there was
> much less dropage than that.  So there's something I'm not accounting
> for, but I don't know what (this is without XvMC).
>
>   
But here's something.  If PCI HDTV tuners can write the data just fine 
to the disk, how is it that much harder for the video card to push that 
much data along the bus as well?  Assuming XvMC takes care of the CPU 
load, even if the data on the bus is the same, a PCI video card should 
be able to handle as much as a PCI HDTV tuner can...

Kevin


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