[mythtv-users] Choppy hd live tv playback with HD3000

Mark Johannessen mfjlaw at gmail.com
Tue Dec 20 14:55:36 EST 2005

Thanks for the tips.

Because others have mentioned CPU usage is higher using mythtv as
opposed to xine and mplayer, I looked at CPU usage this morning and
found that when playing live hdtv mythtv absolutely pegs the CPU at
what looks like 100% (and this is a 2.66gHz Celeron).  I noticed the
jerkiness increases as the screensaver kicks in.   This all indicates
to me that the CPU is doing most if not all of the playback work, even
though the system has an HD3000, a Nvidia e-GeForce MX4000 AGP, and a
Soundblaster audio card.  From prior posts, it appears that CPU usage
is the last resort for playback if appropriate video hardware can't be
found.  This leads me to believe my video card or the drivers that
control it aren't being properly recognized or there is some
configuration setting I'm missing.  Does this seem to be a reasonable

In any event, I will follow your suggestion and wait until .19 is
released prior to changing out hardware.

Mark Johannessen

On 12/19/05, Daniel Kristjansson <danielk at cuymedia.net> wrote:
> On Mon, 2005-12-19 at 19:44 -0800, Mark Johannessen wrote:
> > On 12/19/05, Daniel Kristjansson <danielk at cuymedia.net> wrote:
> > > The audio can often be addressed by turning on "Extra Audio buffering" in
> > > the frontend settings, but sometimes requires the purchase of a new audio card.
> > I was afraid that this might be a hardware problem.  I've tried
> > turning on "Extra Audio buffering" and no change.  If it makes any
> > difference, the sound and the video studder together and not
> > independently (same rate, etc.)
> It's really hard to tell what causes the problem on any particular
> system. Generally people try swapping in an old audio card try using
> the motherboard audio if they were using an sound card. I had one
> motherboard that had the audio causes stuttering problem, and I
> installed an old SoundBlaster audio card which cured the problem.
> My current motherboard has built-in ICH5 audio and I haven't had
> any problems with it.
> > I'm sorry - what is "SVN"?  Does the ./configure relate to a kernel recompile?
> SVN is the code repository for MythTV. There are directions for using it
> at http://svn.mythtv.org  Generally I wouldn't recommend SVN to novice
> users, but for HDTV there have been a lot of improvements since 0.18.1.
> > > I recommend against using XvMC with nVidia cards for HDTV unless you can't
> > > get MythTV to work without it. If you do need it, you need to enable it in
> > > ./configure, and in the frontend settings under:
> > >   "Setup"->TV Settings"->"Playback"->"Preferred MPEG2 Decoder"
> > I don't see the "Preferred MPEG2 Decoder" on my system.  Does
> > ./configure relate to a kernel recompile?
> No ./configure relates to a MythTV recompile. The steps are:
> ./configure [configure options]
> qmake
> make
> su [type root password]
> make install
> There are more directions in the docs at http://www.mythtv.org
> If you can wait, I would guess the next release (0.19) will come before
> the new year. But it most likely will not be compiled specifically
> for you CPU, which you may need to get HDTV working. It only adds about
> 10 to 25% to the speed at which MythTV runs, depending on the CPU. But
> that may make the difference between stuttering and not stuttering.
> > I've installed almost everything from scratch using yum and I would
> > hate to go manual unless absolutely necessary.  For me, it will be
> > much simpler to ditch an incompatable nvidia and sound card than to go
> > through another weekend of config hell - which I very likely would
> > face if I tried to modify the kernel.
> There is no need to modify the kernel, but you will most likely need to
> uninstall the MythTV installed by yum, so that there are no conflicts.
> > On that point, is there a listing anywhere of sound and display video
> > cards that are known to work with myth and the HD3000, and hopefully
> > the playback settings in myth to use?
> No, not really. If you search the archives some cards and motherboard
> audio that don't work well are mentioned. For display cards, nVidia
> cards work pretty well, just not in XvMC mode with 1080i video. I
> use one in XVideo mode everyday without problems (though I need to
> use the 6629 drivers, rather than newer drivers, for it to use my
> 1920x1200 LCD at full resolution.)
> -- Daniel
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