[mythtv-users] How to minimize CPU usage

[Chris Ribe]

You could try reducing your color depth.  I have an older NVidia card that
didn't work well for HDTV, but I was able to get it working by changing the
color depth from "Millions of Colors" to "Thousands of Colors" in the
Display Settings.

On 1/28/06, Jerry Rubinow <jerrymr at gmail.com> wrote:
>
> On 1/28/06, Kevin Kuphal <kuphal at dls.net> wrote:
> > Jerry Rubinow wrote:
> > > I'm running myth with separate front/back end computers.  The frontend
> > > is a 2.8GHz P4 with 512MB ram, trying to display 720p HD, but I'm
> > > maxing out the CPU - myth ~65+%, X around 30+%.  The video is at times
> > > choppy when there's a lot of stuff changing in the frame.  What can I
> > > do to reduce CPU usage?
> > >
> > > Here's what I've done so far:
> > > -compiled myth with --enable-proc-opt (using SVN from less than a week
> ago)
> > > -using ratpoison for window manager
> > > -not using any deinterlacing
> > >
> > > Note: XvMC is not an option.
> > >
> > > I'm running FC4.
> > >
> > > mythfrontend -v playback reports that it's using Xvideo, format I420,
> > > using realtime priority, video timing method: RTC (glx vsync not
> > > supported in my driver).  Then I get a lot of video ahead of audio
> > > dropping frames messages, and then a lot of audio ahead of video
> > > messages.
> > >
> > > /proc/meminfo says there's 100MB free while running myth, so I guess
> > > it's not swapping.
> > >
> > > What might be causing the high CPU?  I've read about people with
> > > 2.4Ghz P4s not having a problem with HD, so it seems like there should
> > > be something I can do.  Would compiling my own kernel help?  With what
> > > options?  Anything else I can try first?
> > >
> > Try using libmpeg2 for your playback.  I'd suggest looking into
> > hyperthreading support in your kernel to see if it is enabled.  I
> > believe this means using an SMP kernel.  I'm not sure if that will make
> > a difference but it might.  And lastly, your video card and drivers do
> > help alot.  I've struggled with my choice of ATI on one of my frontends
> > and as I'm moving to HD, I'm biting the bullet and spending the $40 on
> > an Nvidia FX card and it will be one of the best $40 I've spent on my
> > system as it means HD playback on my 2.4ghz Celeron with XvMC.
> >
> > Kevin
>
> Sorry, I left out that I'm using libmpeg2.  Hyperthreading - hmm,
> unfortunately I just checked and my CPU doesn't support hyperthreading
> (it's a 533MHz bus 2.8GHz P4).  I tried going the FX 5200 route, only
> to discover that I I can't achieve the transfer speeds I need over PCI
> (my motherboard only has two slots, both PCI).  1280x720x(24 or 32)
> bits, 30 frames a second (or 60, even worse) - PCI's max throughput is
> 600 to 700 Mbits/sec.  I tried XvMC on the 5200 but it was always a
> bit glitchy.  The onboard graphics is AGP, but now instead of being
> limited by bus speed, it's by CPU speed.  Very frustrating, since it's
> soooo close to working properly.
>
> -Jerry
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