[mythtv-users] Random Stuttering

Garry Cook garrycook at gmail.com
Fri Sep 21 04:19:37 UTC 2007


I have the same problem with my PVR500. I was running an ancient version of
MythTV, .17 I think, on FedoraCore 3. Once I got my LCD TV, the output was
crappy and distorted. I lived with this for a while, as I was too busy
(lazy) to upgrade. Then, when zap2it went away, I was pretty much forced to
do it.
I grabbed MythDora4 after stopping by Jarod's site to see what I was going
to have to do to upgrade. Man, did that make things easy. Not only was the
install easy as hell, but it fixed all the lingering issues that I had.
However, it did introduce a new problem with the PVR500. All of my
recordings on those two tuners are 'stuttered'. It's pretty annoying.
Does anyone have any idea what the problem might be here,and how to fix it?

On 9/16/07, George Mari <george_mythusers at mari1938.org> wrote:
>
> Bryce wrote:
> > Hi All,
> >
> > I have an issue with my myth system that i'm struggling to get working.
> >
> > I have a backend system thats an AMD Semperon 3000+ with 512MB Ram
> > 10Gig boot disk and 2x200GB disks for media.
> > This has a Dvico DVB card for free to air TV (in australia) and a
> PVR-500
> > for foxtel.
> >
>
> Are your 2x200GB disks IDE or SATA?
>
> > I then have a frontend system thats a Pentium D 2.8Ghz, 1Gb Ram
> >
> > The problem i get is that I get random stuttering of video
> recording.  It
> > might work fine for 30 mins then 2-3 seconds of stuttering or I might
> get
> > stuttering ever few minutes.  It seems random.
> >
> > I can't see anything happening out of the ordinary on either system when
> > this occurs.  the only thing is that if i have a terminal window open on
> my
> > backend system and ping the frontend, during the stutering the ping
> times
> > jump up to over 1000ms for that few seconds - but the terminal windows
> on
> > the box don't freeze or anything like that.
> >
> > 64 bytes from 192.168.16.11: icmp_seq=249 ttl=64 time=0.326 ms
> > 64 bytes from 192.168.16.11: icmp_seq=250 ttl=64 time=2156 ms
> > 64 bytes from 192.168.16.11: icmp_seq=251 ttl=64 time=1156 ms
> > 64 bytes from 192.168.16.11: icmp_seq=252 ttl=64 time=156 ms
> > 64 bytes from 192.168.16.11: icmp_seq=253 ttl=64 time=0.132 ms
> >
> > But pinging other boxes, or pinging the backend from a 3rd box does not
> do
> > this.
> >
> > I've also tried to play the videos via samba on my windows machine and
> it
> > seems that its the actual videos that have the stuttering in them, not
> the
> > playback, so that makes me think its probably a backend problem, not a
> > frontend problem.
> >
> > The stutering happens on both high definition and foxtel.
> >
> > The backend does not seem to be working too hard:
> >
> >
> > top - 13:49:51 up 14:49,  1 user,  load average: 0.20, 0.10, 0.06
> > Tasks:  58 total,   2 running,  56 sleeping,   0 stopped,   0 zombie
> > Cpu(s):  0.3%us,  0.7%sy,  0.0%ni, 96.7%id,  0.7%wa,  1.0%hi,  0.7%si,
> > 0.0%st
> > Mem:    451472k total,   446396k used,     5076k free,     1356k buffers
> > Swap:   500464k total,      116k used,   500348k free,   356172k cached
> >
> >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> >  4569 mythtv    18   0  251m  20m  13m S  0.7  4.7   1:46.77 mythbackend
> >  4360 mysql     15   0  140m  29m 4744 S  0.0  6.8   0:04.55 mysqld
> >    71 root      10  -5     0    0    0 S  0.0  0.0   0:01.06 kswapd0
> >   784 root      21  -4  1908  704  376 S  0.0  0.2   0:00.84 udevd
> >  6568 root      23   0     0    0    0 S  0.0  0.0   0:00.55 nfsd
> >  6564 root      15   0     0    0    0 S  0.0  0.0   0:00.51 nfsd
> >  6565 root      15   0     0    0    0 S  0.0  0.0   0:00.44 nfsd
> >
> > I dont' see major conficts for interuppts
> >
> > wolverine ~ # cat /proc/interrupts
> >            CPU0
> >   0:   13429809    XT-PIC-XT        timer
> >   1:          8    XT-PIC-XT        i8042
> >   2:          0    XT-PIC-XT        cascade
> >   5:     519423    XT-PIC-XT        ivtv0
> >   7:      89130    XT-PIC-XT        cx88[0], cx88[0]
> >   8:          2    XT-PIC-XT        rtc
> >  10:          0    XT-PIC-XT        ivtv1
> >  11:    5155231    XT-PIC-XT        sata_via, eth0
> >  12:        130    XT-PIC-XT        i8042
> >  14:      34189    XT-PIC-XT        ide0
> >  15:      65054    XT-PIC-XT        ide1
> > NMI:          0
> > LOC:   13430083
> > ERR:          0
> > Any advice or suggestions would be greatly appreciated.
> >
>
> If your media drives are SATA, the fact that your SATA controller shares
> an interrupt with your ethernet device might explain your high ping
> times during the episodes of stuttering, but may not explain the cause
> of the stuttering in the first place.  Any other network-intensive
> activity happening on your backend during recording?  I see it's running
>   the NFS daemon - any other boxes writing or reading a lot of data to
> those drives?  If so, you may want to work on separating those two
> devices so they do not share an interrupt.
>
> If your media devices are IDE, are you sure DMA is turned on?  (See the
> hdparm utility)
>
> What level of logging are doing with mythbackend?  I have an
> underpowered backend that could not cleanly serve up one video stream to
> a remote frontend client with mythbackend running verbose -all logging.
>   If I turned off all logging, it was fine.  I've since upgraded the
> disk I/O capabilities of the backend.
>
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