[mythtvnz] Pixellation Every ~ 20 minutes

[Curtis Walker]

On 16 October 2012 17:56, Noel & Diane <noel at igrin.co.nz> wrote:
> Random thought to ponder..
> If not a signal strength issue, maybe a thermal issue with the card?
> Perhaps the card components become out of tolerance when "warmed up" after
> 20 odd mins of operation....
> I would obtain the use of a digital signal strength meter & check the signal
> strength first & verify packet integrity before delving into potential
> internal hardware or software issues.
> Noel
>
>
> -----Original Message-----
> From: Brendan Dacre <bjdacre at gmail.com>
> Reply-to: MythTV in NZ <mythtvnz at lists.linuxnut.co.nz>
> To: MythTV in NZ <mythtvnz at lists.linuxnut.co.nz>
> Subject: Re: [mythtvnz] Pixellation Every ~ 20 minutes
> Date: Tue, 16 Oct 2012 10:14:57 +1300
>
>
> On 16 October 2012 07:32, Paulgir <paulgir at gmail.com> wrote:
>
> On Mon, 15 Oct 2012 16:13:03 +1300, Robin Gilks <g8ecj at gilks.org> wrote:
>
> Just a random idea...
>
> Has anyone with this problem tried to manual schedule a recording at odd
> start and end times to get away from any external effects being on the
> hour or half hour?
>
>
>
>
> I'm not sure there are actually on the hour or half hour.I think it is more
> like 20 to 30 mins after the scheduled recoding begins.Of course this looks
> like an hourly thing because the broadcasts are scheduled that way.
>
> -Paul
>
>
> Paul,
>
> I think the point of Robin's suggestion is this;
>
> If the problem occurs at the same time after the hour, then a scheduled or
> repeating event might be a likely culprit.
>
> If the problem occurs at the same offset into the recording, it may be a
> buffer overflow issue or something like it...
>
> Brendan
>
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Good random thought. I had the same one, and swapped out my GTX460 for
a spare GT430 - no difference.

I also - on balance of evidence and anecdote - now think this is a
buffer issue. Pixellation occurred while watching LiveTV today at
around the 20 minute mark (started watching at 17:15, so not an "on
the hour" problem or scheduling problem).

Stopping LiveTV as the pixellation starts and restarting it straight
away (signal 98%, SNR 2.4dB) resolved the issue. Problem occurred ~10
minutes later and was again resolved (or preempted from going to a
complete blur) by restarting LiveTV.

Now - how to find the cause .... ?