[mythtv-users] XvMC on Mac Mini?

[Todd Ignasiak]

On 4/7/07, Bill Omer <bill.omer at gmail.com> wrote:
> On 4/7/07, Dan Brown <dan at familybrown.org> wrote:
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> > I've set up MythTV as a combined frontend/backend (though most of the
> > backend work is done on a different machine) on an Intel Mac Mini under
> > Ubuntu 6.10.  I notice that video playback (live TV, recordings, or DVD)
> > is using 100% of one of my cores, so I tried to enable XvMC.  According
> > to the wiki at http://www.mythtv.org/wiki/index.php/XvMC, the i810
> > driver supports XvMC.  However, when I launch mythfrontend, the log file
> > indicates "XvMC output requested, but is not supported by display".
> >
> > A web search indicates that XvMC needs to be enabled in xorg.conf, but I
> > haven't found any indication of how to do that.  Is there a setting I
> > need to enter in xorg.conf, or something else I need to look at?
>
>
> Are you using the i810 driver or vesa?  I had to compile MythTV from
> SVN and forcefully enable xvmc, it was only after that when I was able
> to use XvMC on my Intel Mac Mini.

XvMC has two portions of the MPEG decoding that it offloads,  Motion
Compensation (MC), and Inverse Discrete Cosine Transform (iDCT).   I
am pretty sure the Intel drivers only offload MC, which is a small
portion of the overhead.  The iDCT portion is what saves the majority
of the CPU overhead.    So, you may not see a large difference in CPU
utilization.

There was a recent post about an effort led by intel, to make a new
video offload API, which would provide better acceleration, support
for other codecs (MPEG4, H.264, WMV).  This would presumably work on
the Mini's integrated GPU, but it is in the early stages, so I'm not
sure when code will be available.