[mythtv-users] My HDTV woes

Daniel Kristjansson danielk at cuymedia.net
Mon Apr 3 02:39:14 UTC 2006


On Sun, 2006-04-02 at 16:29 -0600, John P Poet wrote:
> On 4/2/06, Mark Lehrer <mark at knm.org> wrote:
> > So, here's some info on my setup:
> > > Pentium 4 3.00GHz w/ hyperthreading (64bit chip, but 32bit install)
> > > 1GB RAM
> > This chip is nowhere near powerful enough to do HDTV.  Intel, in
> > general, is pretty worthless.  I recommend getting an Athlon x2 3800 -
> > that is the first chip I had that could do HDTV properly (my
> > definition of properly is playing back 1080i content with 2x
> > deinterlacing & at 1280x720).
> Huh?  I have successfully displayed both 1080i and 720p HD material
> with a 2.8GHz HT P4.  Never used XvMC, however, just Xv.

A 2.8Ghz HT P4 is enough for HDTV with XVideo; you just need to
use the --enable-proc-opt with configure before you compile.

My dev machine for HDTV is a 2.8Ghz HT P4. So MythTV can do HDTV with
a 2.8Ghz P4 w/HT even when compiled in debug mode, though of course
it does much better when compiled in release mode. I compile the
kernel with SMT support, and with preemption, and with a 1000 Hz
timeslice; all of those help a great deal in making things work
properly. Also if you have an nVidia or ATI card lower the pci
latency timer to 60 with setpci (see also lspci). My command:
  setpci -v -s 01:00.0 latency_timer=60

I do have a dual core AMD 64 4200+ machine now, but I haven't gotten
it to work properly for HDTV. I'm sure I will, it is close to working,
but in general I would say an Intel P4 series chip is superior for
MPEG decoding dollar for dollar. Mostly this is because the chips run
at higher frequencies and most of the critical path code is either
one cycle or half cycle floating point math code. I got the AMD 64
because I expect it to compile code quicker than an equivalent cost
P4 would have.

-- Daniel




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