[mythtv-users] hdhr3-cc and recording quality

Gary Buhrmaster gary.buhrmaster at gmail.com
Wed Mar 26 12:44:16 UTC 2014

On Wed, Mar 26, 2014 at 12:04 PM, Leo Butler <leo.butler at member.ams.org> wrote:
>>   On Wed, Mar 26, 2014 at 2:25 AM, Leo Butler <leo.butler at member.ams.org> wrote:
>>   ....
>>   > What is going on here?
>>   One important detail is whether this is a new installation,
>>   which has never worked properly, or is this a recent change
>>   in behavior (without you (knowingly) making any other
>>   changes to your configuration).
> Neither. The myth system is just over a year old, running 0.25/12.04
> mythbuntu. For 10 months I had a single pvr150 recording analogue
> cable from charter; there were essentially no flaws in those
> recordings. Charter changed over to an encrypted digital signal in
> mid-January and I changed to an hdhr3-cc with a cable card and tuning
> adapter.
> The new tuning system has never provided flawless recordings in 2
> months of operation, but my subjective evaluation is that the gaps
> have been increasing in number and length of time.
> I don't see any indication of the gaps in the hdhr logs, only in the
> backend log, and only at the end of a recording. I have looked on the
> silicondust fora, and I didn't see mention of similar problems.

Ok, what I interpret what you are saying is that this is a new installation
(of a HDHR) for purposes of MythTV, and that it has never worked

I would suggest upgrading your MythTV version.  0.25 is no longer
supported (and I am not sure it would have been current even a year
ago), and there have been many fixes (including some with
stream handling) that could have an impact if your system is at
the edge.

To simplify and debug, one should take MythTV out of the picture
for initial testing.  Using the hdhomerun command line utilities,
tune to the channel (the vchannel that you nominal have problems
with) and save the resulting transport stream.  While doing so,
check the status, vstatus, and the debug values.  Check the
values a number of times.  After a few minutes, cancel the
save, and look at the reported values for errors.  Ideally, the
errors will be zero, and the signal and quality level(s) reported
near 100.  If the error numbers are high, or the signal percentages
low, or the signal values change substantially over time, you need
to look at your cabling.  Some of the values can be seen via
the hdhr web interface, if you prefer.

btw, since this is Charter, are they using a Cisco Tuning Adapter
in your area?  Cisco TAs have a well known failure mode where
the internal amp dies, resulting in a signal that is (around)
3.5dB lower power.  If the signal was marginal to begin with
that can push things over the limit.  Checking the signal level
(as above) would tell you if the signal levels are low.  Remove
the TA from the patch to the HDHR and see if the signal
levels return to a reasonable value, even if you cannot tune
to it (some people add a splitter before the TA, and do not
use the TA pass-through port, to eliminate the potential
failure mode, but that presumes your signal is adequate).


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