On Nov 26, 2005, at 10:45 PM, Brad Barnett wrote:
A few months ago, I mentioned to this list some strange mpeg artifacts
that I was experiencing. Someone mentioned that I should try the
following:
/usr/local/bin/ivtvctl -c dnr_temporal=0 -d /dev/videoX
This helped, but it also uncovered the primary source of the
problem. My
PVR-500 had noise, RF noise.. interference of some sort, on any
input I
used on it. That is, if I used cable, video or s-video inputs, an
interference pattern was always present from both my satellite
receivers
and my cable.
This noise pattern on my PVR-500, existed even if I took the inputs
I was
using for my PVR-250 or PVR-350.. noise free inputs, and plugged
them into
the PVR-500.
My natural assumption was that my PVR-500 was damaged. I spoke with
someone at Hauppauge, explained the debugging that I had done, and was
given a fairly quick replacement.
Here's the problem, however. The noise still exists on the
replacement.
This leads me to believe that the problem is not the particular
card I had
(I have been assured by Hauppauge that the card is a different unit (I
should have marked my old card, to be sure)). So, considering that
this
card is a new replacement, it would mean that something odd is
going on.
The type of noise I am seeing, again, is RF noise. It is not an mpeg
artifact, but it does _cause_ mpeg artifacts, for obvious reasons.
When I
turn temporal off, I can see this noise but with temporal on, I see
nothing.. just the mpeg artifacts (more than on my 250 or 350 inputs).
I've installed this card in a different box, a test Windows box I have
here, and I do not see the noise _or_ mpeg artifacts.
Unfortuantely, I
have no idea as to how I can turn off dnr_temporal using the Windows
drivers.
So, I'm wondering if anyone has any comments on this? Does anyone
else
notice any RF noise pattern when turning off dnr_temporal, on a
PVR-500?
I keep dnr_temporal at zero on my PVR500 and see no noise. I would
do some serious power noise testing on your box if I were you,
although the working pvr250/350 is a bit perplexing. Here's what I
would do :
1. Remove every other component from the power. Unplug other cards
and move hard drives and fans to another power supply temporarily.
Fans are the most likely culprits of introducing noise in your power.
2. Try a different power supply in the same case. Pull the one from
your Windows machine temporarily or something. Possibly repeat
number 1.
My obvious next (reluctant) step is to buy a hard drive, install a
version
of Linux on this drive, and use some box I have around here to test
the
PVR-500 under Linux. This would at least allow me to likely rule
out my
individual Myth box as the fault.
However, I do not see how my box would effect the PVR-500 and not
the 350
or 250.. I suppose it could be a difference in shielding...
Alternatively, does anyone know how I can turn of dnr_temporal with
the
Windows drivers, so I can get an MPEG stream on the current Windows
install that might show this noise?
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