[mythtv] Failed DVB recording

Taylor Jacob rtjacob at earthlink.net
Thu Feb 10 19:49:03 UTC 2005


Quoting Tom Hughes <tom at compton.nu>:

> I had a DVB recording fail last night. The relevant log extract is:

> 2005-02-09 18:30:04.271 DVB#0 DVB signal 5300 | snr 5000 | ber 143af12 | unc
> 7961d18
> 2005-02-09 18:30:04.273 DVB#0 Status: LOCK.
> 2005-02-09 18:30:04.273 DVB#0 Multiplex Locked
> 2005-02-09 18:30:10.966 DVB#0 Timeout Getting PMT
> 2005-02-09 18:30:11.096 DVB#0 ERROR - Tuning for channel #4 failed.
> 2005-02-09 18:30:11.176 Changing from None to RecordingOnly
> 2005-02-09 18:30:11.237 DVB#0 Recorder: Card opened successfully (using PS
> mode).
> 2005-02-09 18:30:12.265 DVB#0 WARNING - No data from card in 1 second.
> 2005-02-09 18:30:13.316 DVB#0 WARNING - No data from card in 1 second.
> 2005-02-09 18:30:14.318 DVB#0 WARNING - No data from card in 1 second.
>
> Obviously it failed to tune the right channel due to a timeout
> getting the PMT from the multiplex. I don't know what the cause
> of that was, but what happened afterwards is that it continued
> to pretend it was recording and spew out those "No data" messages
> for the duration of the program.

Can you tune to this multiplex with zap and look at the PMT deltas?  There is
currently a 5 second PMT timeout when attempting to get the PIDs for the
desired channel.  The average PMT delta is .1 to .2 seconds, so I suspect that
there was some issue with the deilvery of it.

> In fact that's why I noticed what was happing because it was using
> far more CPU than normal and caused other things to slow down.

DVBSIparser might have gotten into a tight loop, but there is a usleep in there
to avoid that.  How much cpu was being consumed?

> Presumably something should have noticed that tuning failed and
> either tried again or given up rather than chewing up CPU for a
> long time and producing a zero length recording...

There are plans to change the entire tuning / timeout situation that will
hopefully avoid this down the road, but it hasn't gotten started yet.

Taylor


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