[mythtv-users] Upgrade old or cut my losses and buy new?

Calvin Harrigan charriglists at bellsouth.net
Mon Mar 5 19:46:11 UTC 2007

Yan Seiner wrote:
> Phil Bridges wrote:
>> On 3/5/07, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
>>> On 3/4/07, Brian Wood <beww at beww.org> wrote:
>>>> On Mar 4, 2007, at 6:22 PM, Yan Seiner wrote:
>>>>> Steven Adeff napsal(a):
>>>>>> If your motherboard supports it, you can try overclocking the
>>>>>> Sempron,
>>>>>> you probably don't need much to get it decoding 1080i.
>>>>>    I tried that.  Seems that the limitation isn't the CPU clock
>>>>> cycles,
>>>>> it's the pitiful cache that AMD put on the chip (128K L2 and no L1).
>>>>> Basically, the CPU spins its wheels waiting on data.  More wheel
>>>>> spinning isn't going to help.  :-(
>>>>> Also, that mobo has only one stick of DDR400 memory.  Would there
>>>>> be any
>>>>> advantage to a second stick?  (Other than more ram, of course.)  The
>>>>> system has 512MB RAM.  If I can improve performance for < $100 well
>>>>> enough to run HD, I'll be happy.
>>>> 1GB RAM would of course be nice but if you're not doing anything else
>>>> it should be enough for playback, use free or top to see if you're
>>>> swapping excessively though.
>>>> If you *really* want to know more about RAM and HD decoding check out:
>>>> http://www.cs.princeton.edu/~chenhan/papers/icme2002t.pdf
>>>> A bit out of date but the concepts are of course still valid.
>>>> I seriously doubt that CPU will do what you want though.
>>> yea, I'm gunna have to agree with Brian here (per usual...). I would
>>> assume a 3000+ on a frontend only machine should be fine for HD,
>>> though I wonder if its enough to enable Bob during playback?
>> I run an A64 3000+ frontend/backend doing HDTV fine without XVMC.  I
>> believe my X/mythfrontend CPU usage stays around 50-60% while watching
>> live.  IIRC, I don't have any deinterlacers working, but I'd have to
>> check my machine to be sure.
> Does the CPU load come from decoding the MPEG2 stream or from sending 
> the data to the video card?
> I have an Athlon XP 2000+ that does HD just fine (60% CPU load), but it 
> is using the s-video out on a 5200 card.  I am assuming that some 
> percentage of CPU horsepower goes to decoding the stream, some to 
> rescaling to the appropriate screen resolution, and some to shoving the 
> data out to the card?

The scaling is done on the video card.  With a XP 2000 you are probably 
using XVMC.  I was able to do hd out to a 720p display with an XP 1800 
using xvmc on a 5200.  The data streams sent to the card depends on 
whether or not you are usng xvmc.  Not sure which is more, I'd lean 
towards xvmc requiring less data.
> I am definitely not a video hardware kind of person, so I'm not really 
> sure if the above even makes sense, but hopefully someone can puzzle it 
> out enough to answer.  :-)
> --Yan
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