[mythtv-users] mythTV, Kaffeine and Twinhan DVB-T

[Nick Crabtree]

On 3/15/06, Rudy Zijlstra <mythtv at edsons.demon.nl> wrote:
>
> Nicklas Bergfeldt wrote:
>
> >Hi,
> >
> >I'm using the following system:
> >Linux 2.6.15-gentoo-r1 #9 SMP PREEMPT Wed Mar 8 00:50:22 CET 2006 i686
> >AMD Athlon(TM) XP 1800+ AuthenticAMD GNU/Linux
> >with 1 GB RAM and 2 Twinhan DVB-T cards.
> >
> >Software:
> >*  media-tv/mythtv
> >      Latest version available: 0.19_p9163-r1
> >      Latest version installed: 0.19_p9163-r1
> >
> >*  media-video/kaffeine
> >      Latest version available: 0.7.1
> >      Latest version installed: 0.7.1
> >
> >Live TV is working perfectly in Kaffeine (no errors in the picture), but
> >in mythTV "hickups" / "jerks" / "squeeky sounds" is very common (i.e. 1
> >approx every 30 sec)...
> > - One could say that the errors in mythTV could result from bad
> >reception, but that do not explain why the picture in Kaffeine (always)
> >is perfect and the picture in mythTV (always) displays "jerks" every 30
> >sec or so...
> >
> >
> >
> The main difference i see, is that Kaffeine is not buffering at all,
> whereas with Myth you always are buffering via HDD (thus you can pause
> etc.). I would check your disk performance / I/O schedular etc.
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>

To see whether buffering is the issue, you could try activating laptop mode,
which groups disk write activity into "chunks" that are spaced at larger
intervals than they normally would be. Although this is intended as a power
saving idea to let a laptop's hard drive spin down, it would in this case
check whether the 30second interval jumps are due to disk cache flushes.
emerge laptop-mode-tools to install it, and run /usr/sbin/laptop_mode start
to start it.

Of course, if you are running other stuff and don't have the free RAM for
more than 30 seconds of TV then you will still get disk activity and laptop
mode won't help.  But on a quiet system (no web browser or email client
running, for example) then you should have plenty of spare RAM for this.

You might also want to try benchmarking using interbench
members.optusnet.com.au/ckolivas/*interbench*/

--
Nick Crabtree
nickcrabtree at gmail.com
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