[mythtv] [mythtv-commits] Ticket #1872: Backend stops recording in middle of program

Bill Cizek cizek at rcn.com
Wed May 31 03:01:06 UTC 2006

>  On Fri, 2006-05-26 at 23:00 +0000, MythTV wrote:
> > #1872: Backend stops recording in middle of program
> > 
> ---------------------------+------------------------------------------------ 
> > Reporter: cizek[at]rcn.com | Owner: danielk
> > Type: defect | Status: new
> > Priority: minor | Milestone:
> > Component: mythtv | Version:
> > Severity: medium |
> > 
> ---------------------------+------------------------------------------------ 
> > Attached is a log for a USA DVB recording which should have run from 
> 9:30
> > - 10:00. The log indicates the show is being recorded properly, but the
> > file stops being written at 9:46. As well, there are a slew of "Writing
> > PAT & PMT" messages in the log files until 9:46. After that time there
> > are none of these messages.
> >
> > This is on SVN 10005. If there is anything else useful let me know.
> Is this slave backend?
> If so, were the clocks on the master and slave in sync?
> Other than that, this looks suspicious:
> 2006-05-26 09:46:28.433 0xacdfbbb0 bool
> DVBRecorder::ProcessTSPacket(const TSPacket&) DVBRec(1): PID 0x40
> discontinuity detected522 2006-05-26 09:46:28.433 0xacdfbbb0 void
> DVBRecorder::WritePATPMT() Writing PAT & PMT @7b6f0a54 + 19e30523
> 2006-05-26 09:46:28.434 0xacdfbbb0 virtual void
> DVBRecorder::StartRecording() DVBRec(1): Resetting Demux Filters524
> 2006-05-26 09:46:28.443 0xacdfbbb0 int debug_thread_create(pthread_t*,
> const pthread_attr_t*, void*(*)(void*), void*, const char*, const char*)
> PTH: Created run_dummy_video(0xa8a6bbb0) from StartDummyVideo
> The discontinuity itself could be due to some problem at the
> transmitter, or reception problems, so it's not so fishy, but
> this is not the PMT for our program, so the demux filter reset
> looks strange.
> -- Daniel

[Snip from "DVB recording failed on MGT"]

> On Mon, 2006-05-29 at 16:18 -0500, Bill Cizek wrote:
> > recording startup processing. The reason it never returns true is that
> > it's waiting for MGT data - matchingMGT.IsGood() is always false.
> > Beyond this I'm not sure what should be happening.
> You should try rescanning your channels in mythtv-setup. This means it
> can't find the channel you're trying to record on the frequency it is
> supposed to be on.

Thanks for the help, Daniel.

This all runs on a single Master backend.  I've got a pair of frontend 
only systems, but I doubt
that matters...

Both of these problems happen on the same channel. I rescanned my 
channels and I'm running
some test recordings now,  but... I took a look at the my database and 
the only things that changed
after the rescan were the call-signs and names for three channels, none 
of them on this specific
channel that I have problems with.

As well, I've tried dvbsignal, which consistently shows 90% + signal 
strength, and this channel has worked
fine on the older code (svn 9759). It just seems kind of weird that this 
stops working for exactly 30
(or 60) minutes, and then comes back fine afterward. I've done some 
background research about ATSC
and DVB, but I barely scratched the surface. What is actually required 
to record a program? (PAT, PMT, MGT ??)

Are there any other obvious things I should try before pulling out my 
copy of "DTV Decoding for Dummies" (tm)?


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