[mythtv-users] MythTV experience with Intel Sandy Bridge graphics

Matt Garman matthew.garman at gmail.com
Mon Jan 16 01:35:20 UTC 2012


On Sun, Jan 15, 2012 at 04:49:12PM -0600, Keith Pyle wrote:
> There has been frequent discussion about the state of Intel graphics
> and their Sandy Bridge chip capabilities, so I wanted to share our
> recent experiences.  Here's the hardware and software being used for
> the MythTV front-end system.

I am working on a similar system.  Here are my specs:

    CPU: Intel i3-2100 (dual core 3.1 GHz)
    MB: Asrock H67M-ITX
    Memory: 4 GB
    Drive: Kingston SSD
    OS: CentOS 6.1, kernel-ml 2.6.39-4.1 (elrepo-kernel)
    Video drivers
        3D driver: mesa 7.11-12.1 (elrepo-testing)
        2D driver: xf86-video-intel 2.17.0-1 (elrepo-testing)
        libdrm:    libdrm-2.4.27-1 (elrepo-testing)

    MythTV Version   : v0.24.1-106-g31e9528
    MythTV Branch    : fixes/0.24
    Network Protocol : 63
    Library API      : 0.24.20110505-1
    QT Version       : 4.7.2
    
    Display: Panasonic tc-p65v10 (plasma)

> Myth experience: We started with the CPU++ standard playback
> profile (ffmpeg & Xvideo).  There was a noticeable horizontal tear
> about half way down the screen, most apparent during vertical
> panning of a scene.  This wasn't surprising given prior reports of
> similar problems.

I have very slight horizontal tearing across the top 1/10th of my
screen.  It's not constant; exists in some scenes, and not in
others.  I can *almost* ignore it.

I tried enabling the XvPreferOverlay setting in xorg.conf that was
suggested here; that had no effect.  Same goes for the
i915.powersave=0 module param that I read about somewhere else.

> We tried switching to ffmpeg & opengl, but Myth would crash on
> starting any playback.  A bit of debugging identified a
> null-pointer dereference in the mesa video driver, which we
> reported to freedesktop.org.  They fairly quickly posted a
> proposed (simple) patch which we have now incorporated.  With the
> patch, playback works *very* well with ffmpeg & opengl.  While I'm

Do you happen to have a link to that patch?  Or if it's small enough
can you post it?  I too have the "crash when using opengl" issue.

> Power profile: At idle on the X desktop, the system pulls 31.2
> watts, as measured by a Kill-a-Watt meter.  With all 4 cores
> spinning at 100%, the load is 66.1 watts.  Playing a video via
> mythfrontend draws 34.4.

This is why I'm really interested in getting a Sandy Bridge-based
FE going.  I underclocked my memory from 1333 to 1066 and
undervolted it to 1.325 Volts.  With a PicoPSU my idle system pulls
about 18 Watts (also measured with a Kill-a-Watt).  Watching videos
puts me in the 25--30 Watt range (depending on the video).




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