[mythtv-users] How to minimize CPU usage

[Kevin Kuphal]

Steven Adeff wrote:
> On 2/4/06, Kevin Kuphal <kuphal at dls.net> wrote:
>   
>> Steven Adeff wrote:
>>     
>>> On 2/4/06, Kevin Kuphal <kuphal at dls.net> wrote:
>>>
>>>       
>>>> 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
>>>>
>>>>         
>>> DVB cards send an mpeg stream through the PCI bus, the data being sent
>>> from the cpu to the  video card is "raw uncompressed" video
>>> information.
>>>
>>>
>>>       
>> So I guess the question still remains, does XvMC make a difference in
>> this case...
>>
>> Kevin
>>     
>
> >From what I understand of how XvMC works, it should, as much of the
> "decompression" of the video data is done on the card.
>
>   
I'm not going to be driving an HDTV with this card, just sending HD 
content scaled to my SD TV.  I don't know if that makes any difference.

Kevin