[mythtv-users] live TV program overrun causes loss of recording

Tue Jun 28 07:41:43 UTC 2011

On Tue, 28 Jun 2011, Michael T. Dean wrote:
> On 06/27/2011 10:35 AM, blind_Pete wrote:
> > Something interesting just happened this evening.
> >
> > A TV program that I was interested in popped up on the guide, so I clicked on it for a single recording.  Earlier in the evening a live to TV program overran its schedule, by about 10 minutes, causing both the program after it and the program that I was interested in to be delayed as well.
> >
> > The first thing that I noticed was that MythTV had decided that the program was not listed an would not be recorded - despite it being clearly visible in the guide.  First the start time and program length changed, then later the end time changed and the program length returned to its original length.  I did not see the raw data for the guide.  (I'm not even sure how to get it.)  I don't know if the program length really changed or just the inferred length between adjacent start times changed.  A few program s have "gone missing" in the past, and this mechanism now seems highly suspicious to me.
> >
> > What is MythTV supposed to do in this situation?
> 
> Exactly what it did--you said to record a specific showing (which means 
> a show on a specific channel ID with a specific start and end time).

It did NOT record anything.  Although at this stage I'm not sure if that is because I fiddled with it, or because there is a bug.  I strongly suspect that I have lost other programs due to this.  Now that I have noticed something I'll be looking for it.  

I take it that you think it should have recorded whatever happened to be showing on that channel at the time specified when I click on the guide.  (Option 2 below.)  In retrospect I also think that that is what it should have done.  So, are we agreed about what it should have done?  

Upcoming recordings showed "not listed" and the guide continued to show the name, first with the forecast times then with the corrected start time and finally with the corrected end time.  

Off Topic: 
Would it be possible to indicate manual recordings and "lost" time slot recordings on the guide?  Perhaps an open green box drawn over the guide from start time to end time so that you can see if it matches any program and if so, which program it matches.  

> >    I can't really complain that it is not doing what it is supposed to do before I find out what it is supposed to do.  Presumably one of the following is designed and maybe documented behaviour.
> >
> > 1) The change in schedule is detected and tracked, recording the program when it is broadcast.
> >
> > 2) The change in schedule is ignored and the original time slot is recorded, possibly still recording the entire program if a big enough lead out time was configured.
> >
> > 3) The change is detected and found to be too confusing - allowing the now unused tuner to record a lower priority program on another channel.
> >
> > 4) The change is detected and found to be too confusing - and the tuner is left idle for the duration of the program.
> 
> 5) the change to the listings is detected and the show you asked it to 
> record no longer exists, so it doesn't/can't record that show.

You missed the point.  The program does exist, but something has changed.  How should it respond?  "Something has changed" is a reasonable start, with three sub-categories; (4) don't record anything, (3) don't record this, but release the tuner, and (2) don't care, we have a channel, a start time and an end time - this seems to be what it should do.  

(5) is just a restatement of (4) or (3), depending on what happens to the unused tuner.  

If there is a next time, I will set some other programs to be recorded with a low priority.  

> > The data is coming from the free to air guide, but it is not an EIT problem because downloaded guides should be updated too.  It is just that the EIT data is updated more often and in this case at least reflected reality.
> >
> > I'm using a pre-compiled binary, mythtv-backend-0.24-20110303.1plf2010.2.x86_64.rpm
> 
> If you're using a listings source that changes start time frequently 
> (such as EIT), you should not use "timeslot" or "this episode" recording 
> rules--and, in general, even where people use "less-frequently-updated" 
> listings sources like XMLTV or Schedules Direct, you still shouldn't use 
> timeslot or "this episode" rules, except for very specific shows which 
> typically lack episode details (such as The Daily Show).

No, if the source can not change there is no problem.  If the source can be corrected or updated then there is a problem, which might be extremely rare or annoyingly common.  

It is quite apparent that I have been using the wrong option.  "Record one showing of this title" was what I should have selected, not "Record only this showing".  I would expect those to behave like (1) and (2).  

Off Topic again: 
Would it be sensible (or even possible) to change those strings to, "Record one showing of [title]" and "Record from [start time] to [end time]" and replace the stuff in the square brackets with data?  Better still, change the first one to "Find one showing of [title]".  

> You should, instead, use "find one" rules--which allow you to record the 
> show, regardless of the start or end times.  Unfortunately, this means 
> you'll also have to watch for other showings that would match the "find 
> one" rule--which may mean, especially when setting up the rule a long 
> time before the airing, that you'll need a custom rule to get the right 
> episode.  (I'm pretty sure, though, that 0.25 will include an ability to 
> do a find one for a specific episode of a series.)

Next silly question, what would have happened if I had selected the correct option and the preceding program had under run by ten minutes?  More generally, what do the find daily and find weekly options do if the particular episode clicked on was a delayed one?  Say it was scheduled for 7:32 when most episodes are scheduled for 7:30.  Does it start the hunt "a bit" before the expected start time?  What is a sensible fudge factor here?  One third of the program length including padding?  

More experimentation is needed.  

> See, also, http://code.mythtv.org/trac/ticket/4879 --especially comments 
> 6 and 8 by gigem/David Engel (where he's currently doing the, "One idea 
> I have percolating is to add custom recording clauses that could be 
> enabled or disabled easily in the recording rule editor for regular 
> rules," part, which is what will allow find one for a specific episode).

Comment 2 reported a "did not record anything".  It looks like a bug.  I think that the reporter would like "find daily" where the search starts "a bit" before the scheduled time - maybe 15 minutes.  

Maybe I should read up on custom rules, but then there is another thread that goes of on an interesting tangent about /The Cathedral and the Bazaar/.  

> 
> Mike
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Thanks for your response Mike.  

blind Pete