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

[Nick Rout]

On Mon, Jan 16, 2012 at 2:35 PM, Matt Garman <matthew.garman at gmail.com> wrote:
> 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

As a casual observer, this may have something to do with under performance?

Have any of you used the combination of master and vaapi?

> 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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