[mythtv-users] DVB(S) tuner sensitivity (and my other) experiences

Dave dave at 0bits.com
Sun Feb 18 11:56:11 UTC 2007


Possible one of two things.

1. Your disk is taking all the interrupts whilst recording and your not 
getting anything for your dvb or vide card. Try unmasking interrupts for 
your disk, or shuffle your interrupts as described.

2. Or, likely your 'nvidia' driver is sharing interrupts with some other 
critical hardware and the 'nv' driver isn't. I believe the nvidia quadro 
cards are woefully inadequate and supported only by legacy nvidia drivers ?

Have you looked at vmstat to see your cpu/interrupt usage ?

Cheers
Dave
-------- Original Message --------
Subject: DVB(S) tuner sensitivity (and my other) experiences
Date: Sun Feb 18 11:39:55 UTC 2007
To: mythtv-users at mythtv.org

Dave wrote:
 > Hi,
 >
 > thought i'd post so people will realise that often it's not myth's fault.
 >
 > I built a mythtv system with a variety of components in a relatively
 > small form factor box (thermaltake vc7001sns) and a Technotrend S1500
 > budget dvb card. Everything went well, but for the life of me i couldn't
 > watch a decent picture from the satellite as i was getting constant
 >
 > [mpeg2video @ 0x86b3238]ac-tex damaged at 13 26
 > [mpeg2video @ 0x86b3238]concealing errors
 >
 > errors and stuttering blocky video images and pip and squeak audio every
 > minute or so. I was so depressed as the WAF (wife approval factor) was
 > tending to zero having parted with my dreambox only recently.

<snip>

 > This was a public service announcement
 > Dave

Some interesting ideas there.  One more to add to the list; I have an
HVR3000 along with an NVIDIA Quadro graphics card in a small form factor
case.  I've found that I can record from DVB-S in perfect quality so
long as I'm not watching anything at the same time.  As soon as I try to
watch at the same time as recording (either watch what I'm recording, or
watch something that was previously recorded) I start to get errors in
the DVB stream.

I think I've narrowed this down to some sort of conflict between the
HVR3000 and the NVIDIA binary drivers.  If I use the "nv" driver for
graphics, then I don't see this problem, but mythfrontend is sooo slow
using "nv" on my system it's virtually unusable so this isn't really an
option.

Robert.




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