[mythtv-users] combined HD frontend/backend on P4 3.2Ghz

[John P Poet]

On 11/21/06, Ali Asad Lotia <ali.asad.lotia at gmail.com> wrote:
> On 11/21/06, John P Poet <jppoet at gmail.com> wrote:
> > On 11/21/06, John P Poet <jppoet at gmail.com> wrote:
> > > On 11/21/06, James Armstrong <james at thearmstrongs.org> wrote:
> > > >
> > > > > In my experience, a 3.2 Ghz P4 can't even play back a single hi def
> > > > > stream reliably, so you are asking for trouble.  I wasted a LOT of
> > > > > free time trying to get this exact CPU to work.
> > > > >
> > > > > Dual core processors are cheap, I would suggest at least an x2 3800.
> > > > >
> > > > > Mark
> > > >
> > > > I have been running on a 3Ghz P4 for a few years it seems as a frontend
> > > > only and have had no problems decoding  / playing HD content. What makes
> > > > the difference is having an NVidia with Xvmc.
> > > >
> > > > - James
> > > >
> > >
> > > I just built a new myth system for my sister.  2.6 GHz HT P4
> > > (Northwood) with 1GB of 333MHz RAM.  With it I can record two HD
> > > streams and play back another without any problems at all.
> > >
> > > I cannot allow it to commflag at the same time as I am watching a HD
> > > program, however.
> > >
> > > John
> > >
> >
> > I should have mentioned that this is without XvMC.  This system is
> > just using Xv.
> >
> > John
> > _______________________________________________
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> > mythtv-users at mythtv.org
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> >
> what distro are you running?

Fedora Core 5.

> i wonder if the slightly faster
> clockspeed on my machine will allow commflagging to go on at the same
> time or if i will have to upgrade processors.

Linux stresses CPUs far more than XP does.  Makes it a bit harder to
have a stables, over-clocked machine.

> is HD commflagging as
> processor intensive as HD playback?

In a way, yes, but not really.  The commflagger has to decode the
show, just like it would to display it on your screen, however, it
does not have to do it in real time.

The commflagger can run at three speeds: High, Medium and Low.  High
speed means it uses all the CPU the scheduler will let it.  Medium
means it runs at a lower priority.  Low means it runs at a lower
priority, and will "sleep" a lot to make sure other processes get
plenty of CPU.

On the 2.6 MHz HT P4, even setting it run at Low kills performance too
much to watch a HD program.  I have a feeling this may have as much to
do with disk performance, as CPU performance.


> i love the performance of myth
> with SD and really don't want to have to deal with stuttering etc.
> when viewing content. i guess trying it is the best way to find out.


Yup.  As Mark Lehrer said, he has had a very hard time making this
work on similar hardware.  There are a lot of variables, including
disk performance, which go into the equation.  Even the BIOS on your
motherboard could influence how well this all works for you.


> thanks all for replying. any other input would be much appreciated.

Your welcome.

John