[mythtv-commits] Ticket #9794: Remote frontend temporarily pausing during playback of recorded or live tv

MythTV noreply at mythtv.org
Fri May 20 13:28:34 UTC 2011


#9794: Remote frontend temporarily pausing during playback of recorded or live tv
-------------------------------+--------------------------------------
 Reporter:  lists@…            |           Type:  Bug Report - General
   Status:  new                |       Priority:  minor
Milestone:  unknown            |      Component:  MythTV - General
  Version:  0.24-fixes         |       Severity:  medium
 Keywords:                     |  Ticket locked:  0
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 I'm having a problem with playback of recorded material on a remote
 frontend in 0.24-fixes.  Playback hangs momentarily during start/stop of
 recordings on the backend, during a reschedule on the backend, or during
 expiration of recordings from the backend.

 I've gone through my configuration to try and debug this problem and
 consider there must be some kind of problem with locking in the backend
 code which I cannot work around.

 I noticed that there was a peak in hard drive access on the backend during
 a pause and a bit of digging showed that mysql was creating a temporary
 table on disk, so I put the temp dir for mysql on a ramdisk and this
 shortened the length of the pauses.  It seems to me that the backend is
 locking on the result of a database query which starves the frontend of
 data.

 I tried tuning mysql using mysqltuner.pl and things got much better, but
 the pauses (which are much shorter now) still occur.

 I've also tried mounting the recording directory via nfs (using nfs-
 kernel-server) but this hasn't improved the situation.

 I can play back local or network mounted HD files (big buck bunny) on the
 frontend with other software using vdpau and have no issues.  There were
 no issues with this hardware for versions of mythtv prior to upgrading to
 0.24-fixes.

 The load on the backend is low with little other software running.
 Stressing up this machine via dd or other operations does not cause a
 pause on the frontend.

 Reception gives a 100% lock when viewing live tv in the frontend, and
 recordings play back fine on other systems.

 My config:
 - 2 x HD Homerun DVB-T (multirec, 4 tuners per physical = 16 in total)
 - As I'm in Australia, DVB-T broadcasts MPEG2
 - I transcode to H264 via a custom transcoding job with a locally built
 ffmpeg.
 - Gigabit network

 Whitebox backend (Ubuntu 10.04) with:
 - Xeon CPU 3040 @ 1.86GHz
 - 4G ram, 92 kb of swap used after weeks of running
 - xfs recording filesystem on hardware raid 1
 - ext3 filesystem on a separate hardware raid 1 for the database
 - Hardware raid can easily sustain 50 MB/s sustained read and writes with
 other activity happening on the machine.

 ION frontend (Mythbuntu 11.04) with:
 - nothing fancy, just a 250G sata drive
 - vga output to component feed in to old crt widescreen hdtv (720p) via a
 converter box (audio-authority unit)

 I've tried pretty much all the debugging I can, but can't seem to solve
 the problem.  If there is any other information I can provide, please let
 me know.

 Backend Version (frontend running the same version from the mythbuntu
 daily build repository):

 Please attach all output as a file in bug reports.
 MythTV Version   : v0.24-287-g8dd67eb
 MythTV Branch    : fixes/0.24
 Network Protocol : 63
 Library API      : 0.24.20110505-1
 QT Version       : 4.6.2
 Options compiled in:
  linux debug using_alsa using_oss using_pulse using_pulseoutput
 using_backend using_bindings_perl using_bindings_python using_directfb
 using_dvb using_firewire using_frontend using_hdhomerun using_hdpvr
 using_iptv using_ivtv using_joystick_menu using_lirc using_mheg
 using_opengl_video using_opengl_vsync using_qtdbus using_qtwebkit
 using_v4l using_v4l2 using_x11 using_xrandr using_xv using_bindings_perl
 using_bindings_python using_mythtranscode using_opengl using_vdpau
 using_ffmpeg_threads using_live using_mheg

 Note:  This is my first bug report, so I'm not sure I've done this all
 correctly.  I have searched the list of tickets already and didn't find
 any that were duplicates of this one.

-- 
Ticket URL: <http://code.mythtv.org/trac/ticket/9794>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center


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