[mythtv-users] HD 1080i Jerky playback while recording

Steve Malenfant smalenfant at gmail.com
Fri Jan 13 18:02:45 UTC 2006


I've resolved my problem... but not too sure what actually did it. 
I've changed the buffer, but than we got electric glitches in the
neighborhood and my OS drive died (not totally).  I able to recover
the mythconverg database so I re-installed on FC4 (was FC3) on an old
9 gigs drive (/mnt/store is on a 200GB drive).  I was watching ER last
night on NBC no problem.

The buffereing was probably the cause because it would happen every
few seconds.  Although it was nice to see that my ATSC card was
supported by the 2.6.14 kernel.

Buffers are now at 9400, down from the 14100 value.

Steve M.

On 1/6/06, Steve Malenfant <smalenfant at gmail.com> wrote:
> The harddrive is a brand new samsung 200GB.  Although, the HD Ring
> Buffer might be set a bit high "14400" and maybe the jerkyness happens
> when that buffer is written to disk.
>
> I'll try to lower that quite a bit to see if it makes a difference...
>
> Is there a way for mythfrontend to buffer more data so it doesn't
> starve when mythbackend is busy doing something else?
>
> Steve
>
> On 1/5/06, Steve Adeff <adeffs at gmail.com> wrote:
> > On Thursday 05 January 2006 23:02, Steve Malenfant wrote:
> > > Scenario :
> > > - Backend recording NBC in HD 1080i
> > > - Frontend playing the NBC show in 1080i
> > >
> > > Result : Jerky playback
> > >
> > > As soon as the show finish recording, the playback is fine.  If I do
> > > the same on a recording in 720p, it doesn't happen.
> > >
> > > The only I could see is that the CPU is used at 45% and the "wa" state
> > > uses the rest (0-1 % idle).
> > >
> > > Usage when recording on backend and watching on frontend :
> > > top - 22:58:38 up  4:21,  4 users,  load average: 1.90, 1.19, 1.13
> > > Tasks: 117 total,   1 running, 115 sleeping,   0 stopped,   1 zombie
> > > Cpu(s): 41.7% us,  3.3% sy,  0.0% ni,  0.3% id, 51.3% wa,  3.3% hi,  0.0%
> > > si Mem:   1035872k total,   936812k used,    99060k free,     6528k buffers
> > > Swap:   690752k total,      708k used,   690044k free,   579356k cached
> > >
> > >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> > >  6293 root      15   0  379m 147m  19m S 42.3 14.6   1:19.09 mythfrontend
> > >  3026 root      15   0  194m  60m 7720 S  1.7  6.0   3:09.03 X
> > >
> > > Usage when not recording and watching the same show :
> > > top - 23:01:19 up  4:24,  4 users,  load average: 2.40, 1.76, 1.35
> > > Tasks: 117 total,   3 running, 113 sleeping,   0 stopped,   1 zombie
> > > Cpu(s): 43.2% us,  0.7% sy,  0.0% ni, 55.1% id,  0.3% wa,  0.7% hi,  0.0%
> > > si Mem:   1035872k total,   936116k used,    99756k free,     6788k buffers
> > > Swap:   690752k total,      708k used,   690044k free,   576456k cached
> > >
> > >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> > >  6293 root      15   0  382m 149m  19m S 42.0 14.8   2:59.47 mythfrontend
> > >  3026 root      15   0  194m  60m 7720 S  0.7  6.0   3:19.36 X
> > >
> > >
> > > Any ideas why the "wa" is using so much of the CPU time only when the
> > > backend is recording?
> > >
> > > wa: Time spent waiting for IO. Prior to Linux 2.5.41, shown as zero.
> > >
> > > Steve M.
> >
> > sounds more like your harddrive is unable to keep up.
> >
> > --
> > Steve
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >
>


More information about the mythtv-users mailing list