[mythtv-users] Power to the Masses (CPU Power that is) - LONG!!

Brad Templeton brad+myth at templetons.com
Fri Mar 25 00:11:43 UTC 2005

On Thu, Mar 24, 2005 at 04:57:49PM -0500, Donavan Stanley wrote:
> On Thu, 24 Mar 2005 16:38:45 -0500, PAUL WILLIAMSON
> <pwilliamson at mandtbank.com> wrote:
> > 2.8 has been suggested as the lowest processor
> > you'd want to go with for HD.  I'm not sure
> > if the Pundit would do that...
> My Celeron 2.5ghz sits at 80% when watching 1080i...   
> The CPU quotes floating around the net are either out of date, for
> Windows, or just flat out wrong.

There was an improvement between .16 and .17 that allowed slower
processors to play HDTV.    Many things can play a role, including
if you do deinterlacing, and how much spare capacity you want to have.

My experience is I wouldn't want to run at 80% saturated because other
things can pop up on the system and cause stutters.   Live TV seems
more succeptible too.   For example, even though commercial scans are
run niced, they make the system more prone to stutters if you have a
slim margin.   I find that even my P4-3ghz-hyperthreading system can
still stutter on occasion when additional load pops up, though generally
it has more than enough.

xvmc support has been constantly improving.  Some have had it working
for a while, others have had problems but the problems are being slowly
ground out.  This changes the CPU equation as well.

There is some debate over how much better Pentiums are than Athlons
at mpeg decode, and why they are better, but they are a bit better.

Reasons include:
    a) mpeg decode takes more advantage of intel pipelining
    b) hyperthreading does its job well here (not on celerons of course)
    c) Intel CPUs run at ~ a 35% faster clock speed than AMD of the same
       number.  Sometimes the size of your clock does matter.

Idle times report major benefits for intel but are misleading.  However,
an improvement of the range of 15% is almost certainly real, and possibly
much more.

Intel CPUs run a bit hotter due to their faster clock.  AMD CPUs are faster
than Intel on other tasks even if slower on the particular task of mpeg
decode.   Of course mpeg decode is what you care about here!

More information about the mythtv-users mailing list