[mythtv] HDTV CPU utilization

John Patrick Poet john at BlueSkyTours.com
Mon Jan 17 15:59:26 EST 2005


On Sat, 15 Jan 2005, Chris Mumford wrote:

> When I watch 1080i content my CPU is always pegged. I'm running the very
> latest source from CVS on a 3.0 GHz P4 with a NVIDIA 5200 with XvMC enabled.
> This CPU utilization is over twice what I see if I use MPlayer directly to
> watch a movie.
>
> When I run MPlayer I'm calling it like this:
>
>   Mplayer -fs -cache 8192 -vo xvmc:queue -vc ffmpeg12mc /dev/dtv
>
> This is also the line that I put into the TV Viewing setup section in
> MythTV. I did notice that if I take out the "-vo xvmc:queue -vc ffmpeg12mc"
> from MythTV that it has no difference with playback performance. Does MythTV
> playback with XvMC?


I am not sure what you mean saying that you put that line into the TV
Viewing section of Myth.  What Viewing setup section are you talking about?
Myth and mplayer don't use the same options.

If Myth is compiled with XvMC, then it will use it by default.  There is
also a checkbox on one of the setup screens to enable/disable XvMC.  You can
tell if XvMC is really being used, by the color (or lack there of) of the
OSD.  If the OSD is in black/white, then it is using XvMC.

That all being said, if you have a 3.0GHz HT P4, why would you want to use
XvMC?  That much horsepower is plenty to decode HD material without
resorting to XvMC, and the quality will be much better.  *Not* using XvMC
will result in most of your CPU power being used -- it should not be
"pegged", but it will use most of it..


> I have turned off all of the features that I think would require any kind of
> video processing like de-interlacing and commercial detection.


BoB deinterlacing does a VERY good job, and requires almost no extra CPU.


> Any suggestions?


My best guess is, that you are not actually using XvMC.  Is the CPU
"pegging" causing any problems?


John


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