[mythtv-users] Bad Recordings - Choppy - on .25

Billy Macdonald billymacdonald at gmail.com
Tue Mar 6 03:36:24 UTC 2012


On Fri, Mar 2, 2012 at 1:44 PM, Dan Ritter <dsr-myth at randomstring.org> wrote:
> On Thu, Mar 01, 2012 at 11:52:10PM -0500, Billy Macdonald wrote:
>>    I've been troubleshooting some bad recording issues on .25 for the
>> past few days and haven't been able to figure out the issue.  I have
>> two HDHR & one HD Prime.  Seven total tuners.  Whenever I record more
>> than one or two shows, the logs (with -v record) will output tons of
>> the following messages.
>>
>>
>> 2012-03-01 23:45:16.849449 W [7383/7464] HDHRStreamHandler
>> dtvrecorder.cpp:1301 (ProcessAVTSPacket) - DTVRec(3): A/V PID 0x800
>> discontinuity detected ((1+1)%16!=6)  0.03%
>>
>> And the recordings end up in horrible shape.   There doesn't seem to
>> be any other mythtv activity around when the errors start/stop (they
>> come in clumps it seems).
>>
>> So far, I've validated that the cable feed is good, that I can watch
>> all the tuners fine through the HD config GUI, and that I can stream
>> four at a time to my mythtv BE using VLC without a single hiccup.  But
>> when I try to record in Myth, it falls apart.
>>
>> I was also seeing some similar issues on .24 before the upgrade, but
>> not even close to the same extent.
>>
>> Any ideas to help figure this out would be great.   I just upgraded to
>> Fedora 16 tonight hoping for some magical fix :)
>>
>> Also, CPU usage is extremely high recording from HDHR devices.  I'm
>> recording four tunners and mythbackend is running at 193% (AMD
>> Phenom(tm) II X4 960T Processor).
>
> Three things come to mind:
>
> - is your MySQL db on a different drive from recordings? It
>  should be, if possible.
>
> - are you having disk problems? Check dmesg
>
> - is your ethernet switch or NIC in trouble? Check dmesg and
>  run some bandwidth tests.
>
> -dsr-
>

I rolled back to .24 and was able to record 7 HD streams at a time.
Although I have a non-optimal setup with my MySQL and hard drive
setup, I'm pretty sure this is something specific to .25 and not a
general hardware issue.  I did verify network performance and checked
for errors in dmesg and other logs in /var/logs.

The high CPU usage during recordings on .25 is one of the concerning
issues.   Shouldn't HDHR recordings just be spooled to disk?  It's
like it was decoding the stream during recording based on the usage.


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