[mythtv-users] MythTV experience with Intel Sandy Bridge graphics
kpyle at austin.rr.com
Sun Jan 15 22:49:12 UTC 2012
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.
CPU: Intel i5 2405S (2.5 GHz)
MB: MSI Z68MA-ED55 (HDMI, DVI-D, VGA)
Memory: 4 GB
Drive: Intel SSD (caught a good! Black Friday sale)
OS: Gentoo Linux x86_64 3.1.6
3D driver: mesa 7.11.2 (plus one patch)
2D driver: xf86-video-intel 2.17.0-r3
C library: glibc-2.12.2
MythTV Version : v0.24.1-27-g30993d6
MythTV Branch : fixes/0.24
Network Protocol : 63
Library API : 0.24.20110505-1
QT Version : 4.7.2
Display: Samsung C8000 series plasma
Video and audio are over HDMI. We're using the on-board Z68 graphics
(no add-in video card) and the classic mesa driver.
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.
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 not a video engineer (nor do I play one on TV),
there are no apparent video defects and playback is completely smooth.
CPU load is up to ~25-30% on one core playing a 1080i HD recording from
the backend. Audio quality is good as well.
We have not experimented with libva yet.
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.
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