[mythtv-users] Scheduled Recordings are keyed off of the callsign field

[Bruce Markey]

Nick wrote:
> On 28/01/06, David Whyte <david.whyte at gmail.com> wrote:
>> Howdy,
>>
>> I went and adjust some of the channel names in mythweb so that they
>> showed up down the left of mythweb a little different (to save space
>> more than anything).  The text I changed was the 'callsign' field in
>> the mythweb > Settings > Channels page.
>>
>> Anyways, I just noticed that all of my schedules had been cancelled
>> and immediately realised why, however I don't understand why it is so.
>>  I thought each channel would have had a unique ID which is what we
>> would key off so this 'callsign' field can be updated however.
>>
>> I am sure there is a logical reason for why this has heppened, I am
>> just hoping someone can explain it to me.  Everything is OK, by going
>> and updating them back they have come back.  (Although I had to
>> restart the backend for the changes to take effect, which is why I
>> didn't pick up the problem sooner).
> 
> Without wishing to step on Bruce's toes (he may decide to provide one

Not at all. I cut my big toe last night so it would have been
extra painful ;-) but this is a good explanation. 

> of his extremely useful explanations), callsign is used in the
> scheduling process in order to determine whether channels with
> different chanids are in fact the same station. The value of callsign
> is recorded in the record table, so it is likely that by changing the
> callsign values without similarly updating it in record will result in
> failed rescheduling when the rules search for the old callsign values
> which have now changed.

Correct. This applies to rules that care about the station. "All" and
Find* rules match without checking the station but Single, Timeslot,
Weekslot and, of course, Channel all do care. These rules will no
longer match if the rule's station doesn't match the new callsigns.
However, there is a trick you can use to fix these without having
to recreate all the rules. The trick is that when you save changes
to a rule, it stores the information from the showing that you are
editing including the callsign. Therefore:

- In mythfrontend, go to the Recording Priorities (AKA Set Priorities)
page. Rules that have matching showings are in green (or the "Will
Record" color for your theme). Rules with no matches are white and
say "(Recording 0 of 0)" below the title.

- Highlight a white title that you know no longer matches because
of the callsign change.

- Press "I"nfo for the recording options page. Change the record type
to "Record at any time on any channel" for now then "Save these
settings".

- Back on the priorities list, press "O" for the upcoming episodes
list. These now all match the rule. Highlight the single showing
or a showing in the timeslot that you want to record.

- Press "I"nfo for the recording options page. Change the record type
back to the intended type then "Save these settings". This save
will update the rule with the current station(!).

- Rinse and repeat for the other rules affected.

This same trick is useful for other things like changing a timeslot.
Say I record a 10pm showing of a show each week but there is a 2am
rebroadcast which usually works out better. I can change the type
to all, select the 2am showing and change the type back to Weekslot.
It's now set to record at 2am each week with all the same parameters
as before.

--  bjm