[mythtvnz] Pixellation Every ~ 20 minutes

[Curtis Walker]

On 18 October 2012 15:50, Paulgir <paulgir at gmail.com> wrote:
> On Thu, 18 Oct 2012 00:06:50 +1300, Steve Hodge <stevehodge at gmail.com>
> wrote:
>
> On Wed, Oct 17, 2012 at 11:17 PM, Curtis Walker <sultanoswing at gmail.com>
> wrote:
>>
>> The frontend playback log shows the problem - looks like it's some
>> sort of buffer-related problem after all (although I haven't had
>> LiveTV fail altogether before).
>
>
> The frontend log shows that there is a lack of video packets at that point.
> But we already knew that. It doesn't shed any light on the cause. The
> buffers it's talking about are playback buffers - they're not relevant.
>
> Have a look at the options for increasing the verbosity of the backend log.
> Also try the kernel logs.
>
> You said Mediaportal worked ok. So it's not hardware, but you haven't
> narrowed down which Linux software is causing the issue. Try to make a
> recording outside of MythTV but under Linux using dvbstream or something
> similar (I think you could use mplayer as well). That might tell you if the
> problem is in MythTV or if the problem is in the kernel drivers.
>
> You mentioned a fresh install of the very latest Mythbuntu dist. I don't
> think you've actually said, but I got the impression that this was a new
> problem for you, if so then I would be more inclined to try an older install
> (+ matching kernel) than a newer one. If you can narrow down the issue to
> the kernel or MythTV then try downgrading just that part.
>
> Cheers,
> Steve
>
>
> Here's a little more info based on my experimentation with this problem.It
> may be relevant.after I reduced the signal going into the tuner,TV3 shows 1
> or 2 second periods of minor pixellation but it never builds into the 30 to
> 60 second long event that get progressively worse till something resets and
> the picture suddenly comes right.
>
> -Paul
>
>
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Some more tests:

1) Fresh install of mythbuntu 12.04 (I recorded the Wimbledon Final on
July 9th without pixellation - so something has happened since that
time, I think) -pixellation problem occurred.

2) Back on Arch, I just watched half an hour of TV3 using VLC to open
the capture device. Pixellation at the 20 minute mark as per mythtv.
So - it's not something to do with Arch/MythTV (at least not
directly). A check of system monitor during this period showed CPU
usage actually fell, presumably as there was less info being presented
for processing.

So: a lack of frames / info being presented by the card - but only
under linux (not in Windows or to the TV tuner). Occuring every 20
minutes or so. Mine wasn't resolved by attenuating the signal (3-20dB
range) - although I could try again, I suppose to see if I can
replicate Pauls' findings.

Hopefully the USB DTV-B tuner will arrive tomorrow to test.