MythTV fails to record (because of late EPG change?)

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njsharp
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Australia

MythTV fails to record (because of late EPG change?)

Post by njsharp » Sat Mar 30, 2019 9:36 pm

OS:Ubuntu 18.04 up to date wef March 30 2019
MythTV: 29
Usually recording Australian ABC channel 20 (full HD)

Sometimes when I set up a recording from the Programme Guide I then find at the time of the broadcast this failure:
"This showing was not recorded because this rule does not match any showings in the current program listings"
and an 'N' against it in the Scheduled Recordings listing.

If I am at the machine near the start of the program time, I can force MythTV to record, and I lose nothing because I use a start 5mins early setting (and a 10 mins late at the end). But having to be there at the time somewhat detracts from the expected automation!!!

I am fairly sure this most annoying (and common) occurrence is due to the EPG times being changed by the broadcaster a very short time before broadcast.

For example, yesterday (2019-03-30) I set up recording of:

The Bletchley Circle: San Francisco (start due 7:31pm) followed by
Delicious (start due 8:17pm)

I then tracked on mythconverg as follows (you need to be mysql aware to do this):
select starttime,title from record where title like "%Bletchley%" and chanid="1020";
08:31:59 | The Bletchley Circle: San Francisco

and for quite a long time:
select starttime,title from program where title like "%Bletchley%" and chanid="1020";
2019-03-30 08:31:59 | The Bletchley Circle: San Francisco
but about ten minutes before program start time it changed to:
2019-03-30 08:32:07 | The Bletchley Circle: San Francisco

'record' is the table showing recording choices.
'program' is the table showing the latest EPG data.

Quickly, using the standard mythtv actions I deleted the recording rule, and recreated it so it then read:
select starttime,title from record where title like "%Bletchley%" and chanid="1020";
08:32:07 | The Bletchley Circle: San Francisco

and the recording started OK. I feel sure it would have failed with the "This showing ..." message otherwise.
I guess I could have tweaked the 'record' table entry directly, but I'm not that great at mysql.

It is annoying, to say the least. It seems the entry in the table 'record' is created with the start time from the EPG AT THE TIME of making the entry, and then if the EPG data is changed later to give a slightly different time: FAILURE!!

Over a decade ago, in:
rule does not match any showings in the current program listings
https://code.mythtv.org/trac/ticket/5360
this was offered:
"There's not really much we can do if the broadcaster sends out updated program information that changes the program we were planning to record to something else. However if the program is still being shown at that time, i suspect the program information may have changed slightly to make it no longer match up with the recording schedule."

though in the case described here, it is the time that has been changed, albeit by just a few seconds, which still causes a mismatch.

I noted that the same change of time happened to the following program 'Delicious' but that change happened less than 5 minutes before start, so since I record with a 5mins early setting, the program had already started recording!! Hooray!

I really don't see an agreeable solution to this problem. E-screaming at the broadcaster is likely to elicit the response "go buy the DVD". Setting up recordings using Manual Schedule is almost certain to work perfectly, as long as the program does go to air ROUGHLY when expected, but is a PAIN.

Any thoughts?

perkins1724
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Re: MythTV fails to record (because of late EPG change?)

Post by perkins1724 » Mon Apr 01, 2019 12:47 am

I strongly recommend using "record all" rules instead of "record this day and time / this time / this channel / single" rules. A compromise might be to use a "find one" rule if you are using EIT data which might be quite low quality.

See this for more info on record types: https://www.mythtv.org/wiki/Scheduling_ ... _decisions

njsharp
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Joined: Tue Mar 08, 2016 7:30 pm
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Re: MythTV fails to record (because of late EPG change?)

Post by njsharp » Mon Apr 01, 2019 2:55 am

Thanks perkins1724, I'll try that. The link you mention seems not to contain 'record all' though.

I guess I will get offers to record from other channels too, and need to go through nixing those.

perkins1724
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Joined: Tue Nov 18, 2014 7:44 am
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Re: MythTV fails to record (because of late EPG change?)

Post by perkins1724 » Mon Apr 01, 2019 4:16 am

My fault - I meant to link to a different part of that page. Try this one: https://www.mythtv.org/wiki/Scheduling_ ... cord_Types

Edit: yes you will possibly / probably get a lot of extra recordings if you use EIT. I use a customised version of Shepherd to provide a very detailed EPG in xmltv format which helps MythTV make excellent scheduling decisions.

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dizygotheca
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Re: MythTV fails to record (because of late EPG change?)

Post by dizygotheca » Mon Apr 01, 2019 12:45 pm

"Record this showing" creates a time-based rule, which will fail on EIT changes.
I suspect the "Record this time (and date)" might actually fail less often as they have a larger time tolerance than "Record this"

"Record All" is good for series, but for single showings "Record one showing.."/Find One is what you want.
Both create title-based rules so the scheduler should handle EIT time changes automatically.

"Record One" will also delete itself a week after recording, like "Record this".

Also beware of using "Record this" when creating overrides to adjust Myth's choices when there are repeats: you'll be back at square one.
A safer strategy is to use "Do not record this showing" on the alternatives until Myth chooses the one you want!

njsharp
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Joined: Tue Mar 08, 2016 7:30 pm
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Re: MythTV fails to record (because of late EPG change?)

Post by njsharp » Wed Apr 24, 2019 9:54 pm

I have given up trying to understand exactly what is going on! Sometimes recordings happen perfectly. Sometimes they just disappear with no explanation. I have watched the timings on the 'record' and 'program' tables in the database. Sometimes they differ close to going to air, even though of course they were identical at time of adding the program to the 'record' list. Sometimes the difference occurs after my 5min buffer (see #1 below), so perhaps the recording started before the difference occured, so no worries. Sometimes no recording happens. Sometimes I get TWO recordings, with one starting a lot later, eg past the start of the content. Hmmmph!

SO! I have taken to using manual record. Notes about that:
1 My default template includes a 5min buffer at start and a 10min buffer at the end, to allow for poor broadcaster timings. These buffers ARE added to the manual record timings. I'm happy with that.
2 If I wish to record two consecutive programs on the same channel, I tend to set up just one manual record for both. This avoids switching recording input device, though I doubt that much matters. I nearly always record now from ABC 20 (Full HD: MPEG4) Afterwards, I use mythtv's 'E' editor to determine the keyframes for start and end of content, then MKVToolNiox GUI to copy the .ts recording into one (or more) .mkv files containing just the content required
3 FYI, If I view entries in the 'program' table I actually see the manual record entries between the EPG lines, eg:

| BletchleyMidwife (Manual Record) | 2019-04-27 09:30:00 |
| The Bletchley Circle: San Francisco | 2019-04-27 09:31:50 |
| Call The Midwife | 2019-04-27 10:17:13 |

...an example of #2 above.

It is my belief that a manual recording happens at the time specified in the 'record' table entry without any reference to the related 'program' entries, so no concern now about what the EPG says.

Hope this helps somebody!

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