[mythtvnz] Pixellation Every ~ 20 minutes

[Pieter De Wit]

On 4/10/2012 22:34, Nick Rout wrote:
>
>
> On Oct 4, 2012 8:07 PM, "Curtis Walker" <sultanoswing at gmail.com 
> <mailto:sultanoswing at gmail.com>> wrote:
> >
> > Odd problem this.
> >
> > On all TV recordings, after around 20 minutes, the picture starts 
> becoming pixellated. Over the next 30 or so seconds it becomes more 
> and more pixellated until it looks like an impressionist painting. The 
> sound is generally OK, but does have the odd, brief "glitch" (a noise 
> like a modem negotiating). After no more than a minute, the picture 
> and sound suddenly return to normal.
> >
> > I'm fairly sure this is not a reception issue, since it seems to 
> occur so regularly, and at roughly the same time in each recording, 
> and for the rest of the recording picture and sound are perfect. 
> Signal strength and SNR are fine (98% and 2.3dB respectively, and this 
> is representative). Same thing occurs on all channels.
> >
> > It doesn't appear to be related to the playback, as the same 
> pixellation occurs in the same place whether viewing the recording on 
> desktop (nvidia) or Laptop (intel integrated), although it sounds 
> similar to symptoms reported by others on mythtv <0.25 which people 
> ascribed to vdpau and buffer settings.
> >
> > Could be some scheduled process is running every 20 minutes or so on 
> my disks? Although why it occurs ~20 minutes into a recording, and 
> never at other times, doesn't seem to fit with this either.
> >
> > Hmmmm ....
>
> I have seen similar stuff. I thought it was to do with the networking 
> between my HDHR and my backend. I should indicate further.
>
>
Quite correct Nick. If you drop a few packets from the h264 stream, it 
does this, the more your drop, the worst the result (logical, I know :) 
). I used to see this with program changes (I am sure most of you have 
seen my rants on the main list), but since then I took a certain 
supplier to task on a $99 deal for a 120gig SSD, problem gone :)

Why this happens at the 20 min mark is hard to say, can you tell us more 
about your setup ? Perhaps more details around CPU,memory,disk,mount 
points ?

Cheers,

Pieter
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/mythtvnz/attachments/20121005/821a476b/attachment.html>