[mythtv-users] Stuttering after frontend has been running a while

Manuel McLure manuel at mclure.org
Tue Jan 12 19:43:44 UTC 2010

I have a problem with stuttering and the dreaded "prebuffering pause".
The symptoms are as usual - start playing a recording and suddenly it
starts stuttering. If I then set a bookmark, restart the frontend and
play the exact same recording from the bookmark (or from the
beginning) there is no stutter. But once the frontend has been running
a while, there's a chance that a recording will start stuttering.

I've gone through the
http://www.mythtv.org/wiki/Troubleshooting:Prebuffering_pause page and
haven't found anything that seems to apply.

The MythTV version is 0.22-fixes SVN revision 23069 on Gentoo Linux
64-bit. I'm using the Gentoo ebuild with the patch from
http://svn.mythtv.org/trac/ticket/6581 applied since audio sync is
always 150ms off.
Hardware is an Athlon X2 5050e with an NVidia 9500GT 512M video card
using HDMI output.
NVidia driver 190.53
This happens both with the VDPAU High Quality and VDPAU Normal profiles.
Recordings are stored on a Western Digital Caviar Black 1TB drive
using the XFS filesystem. The filesystem has less than 3%
Audio output is AC-3 passthrough to SPDIF on a  C-Media Electronics
Inc CM8738 sound card.
Recordings are mostly 1080i h.264 - my TV provider uses IPTV which I
record directly using the freebox recorder. The recordings don't seem
to be the best shining examples of h.264 perfection, as noted by the
number of messages of the form

[h264 @ 0x7f23184198a0]number of reference frames exceeds max
(probably corrupt input), discarding one


[h264_vdpau @ 0x7faa84a378a0]non-existing SPS 1 referenced in buffering period


[h264_vdpau @ 0x7faa84a378a0]mmco: unref short failure

that show up in mythfrontend.log.

Any ideas? It seems like there's something that gets triggered after
mythfrontend has run for a while.
Manuel A. McLure WW1FA <manuel at mclure.org> <http://www.mclure.org>
...for in Ulthar, according to an ancient and significant law,
no man may kill a cat.                       -- H.P. Lovecraft

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