[mythtv-users] Scheduler seems to think I am recording too many programs at once

David Engel david at istwok.net
Thu May 2 18:26:44 UTC 2013


On Fri, May 03, 2013 at 03:01:42AM +1200, Stephen Worthington wrote:
> On Thu, 02 May 2013 09:25:17 -0500, you wrote:
> 
> >On Fri, May 03, 2013 at 12:04:03AM +1200, Stephen Worthington wrote:
> >> On Thu, 02 May 2013 07:18:50 -0400, you wrote:
> >> 
> >> >On 05/02/2013 12:56 AM, Stephen Worthington wrote:
> >> >> I was just checking the scheduling for the new EPG received today, and
> >> >> I found that one program "Seven Sharp" was not recording at its usual
> >> >> time of 19:00 on TV ONE, but instead was recording at 20:00 from the
> >> >> TVONE PLUS1 channel which retransmits TV ONE an hour later, but in SD
> >> >> instead of HD.  I have occasionally seen this sort of thing happen
> >> >> before, always when I am recording lots of programs at the same time.
> >> >> It has always seemed to me that the scheduler must have some limit for
> >> >> the number of programs it will record at one time and when it goes
> >> >> over that limit, it tries to reschedule one or more of them.  If I add
> >> >> an override to force "Seven Sharp" to record from TV ONE at 19:00, the
> >> >> scheduler is happy to do that and does not seem to make any other
> >> >> changes.
> >> >>
> >> >> Here is the schedule for that time period, without the override:
> >> >> [Time]       [Callsign]-[Program name]
> >> >> 17:30:18:30  DISCO - Mythbusters
> >> >> 18:00-19:03  TV ONE - One News At 6pm
> >> >> 18:00-19:03  TV3 - 3 News
> >> >> 18:30-19:03  ChoiceTV - Bath Crashers
> >> >> 19:00-19:33  TV ONE - Seven Sharp  (yellow, "Find Daily -3 Later
> >> >> Showing")
> >> >> 19:00-19:33  TV ONE-S - Seven Sharp (yellow, "Find Daily -7 Later
> >> >> Showing")
> >> >> 19:00-19:33  TV3 - Campbell Live
> >> >> 19:30-19:33  TV2 - Police Ten 7
> >> >> 19:30-20:30  HISCH - Mysteries At The Museum (yellow, "Channel Record
> >> >> +0 Later Showing")
> >> >> 19:30-20:30  KNOWLGE - Who Do You Think You Are? Aus
> >> >> 19:30-20:33  PRIME - Great Rift: Africas Wild
> >> >> 19:30-20:33  TV3 - Grand Designs Revisited
> >> >> 20:00-20:30  CRIME&  - Traffic Blues (yellow "Channel Record +0 Later
> >> >> Showing")
> >> >> 20:00-20:33  TV2 - RBT
> >> >> 20:00-20:33  TVONE PLUS1 - Seven Sharp
> >> >> 20:29-21:33  TV3 - Bones
> >> >>
> >> >> In the above, TV ONE, TV2 and TVONE PLUS1 are transmitted on the same
> >> >> DVB-T multiplex, PRIME and ChoiceTV are on the same DVB-T mux, and TV3
> >> >> is on the third DVB-T mux.  TV ONE-S is an SD version of TV ONE on a
> >> >> DVB-S mux.  The other channels are all on Sky TV which is recorded
> >> >> from a set top box via one S-Video card (so there is only one tuner
> >> >> for those channels).  The three DVB-T muxes are on one source, the
> >> >> DVB-S muxes on another source, and Sky TV is on the third source.  All
> >> >> the DVB-T and DVB-S tuners are set up with 4 multirec virtual tuners
> >> >> each, and I have 3 DVB-T tuners and 2 DVB-S ones.  Since I have as
> >> >> many DVB-T tuners as there are DVB-T muxes being transmitted, I should
> >> >> never have to use the TVONE PLUS1 channel at all as I should always
> >> >> have enough tuners to record everything I need on the first showing.
> >> >>
> >> >> So, does anyone know if there is some sort of limit in the scheduler
> >> >> on the number of programs that will record at any one time?  And if
> >> >> so, what it is and how it works?  Is there a setting I can adjust for
> >> >> it?
> >> >
> >> >No limit.  The only limit is the number of tuners (physical and virtual) 
> >> >you have.  MythTV will gladly work your system so hard that the hardware 
> >> >fails to keep up and everything fails miserably if you tell it to.
> >> >
> >> >> I have 5 recording drives, so whatever is causing this sort of
> >> >> rescheduling is not taking that into account, as I can easily record
> >> >> at least 10 programs simultaneously, and probably more, as long as the
> >> >> recordings use all the drives (and they normally do).
> >> >
> >> >It is almost definitely a priority modifier on the other showing causing 
> >> >it to be preferred.  This could be channel or input or HDTV or any of a 
> >> >number of other priority modifiers.  You can see what's happening by 
> >> >running:
> >> >
> >> >mythbackend -v schedule --loglevel debug --printsched
> >> >
> >> >before the shows air and without the override in place.
> >> >
> >> >> Also, is there a way to mark the TVONE PLUS1 channel as SD and the TV
> >> >> ONE channel as HD and tell the scheduler to always record the HD
> >> >> programming unless there is an actual clash?
> >> >
> >> >No, there's no such thing as an "HD" channel--only channels that have 
> >> >programs which may or may not be HDTV.  So, it's up to your guide data 
> >> >to properly mark programs as HDTV or not.
> >> >
> >> >You can set priority modifiers on channels (and starting with 0.27, 
> >> >they'll work the way you think they would work), but then again, 
> >> >priority modifiers you've already set are probably what's causing MythTV 
> >> >to record shows in such a way that you think the scheduler is wrong...  ;)
> >> >
> >> >Mike
> >> 
> >> The --printsched option looks like it is really useful.  I have put
> >> the result on my web server here:
> >> 
> >>   http://www.jsw.gen.nz/mythtv/sched.txt
> >> 
> >> If I paste it into a post, its gets word wrapped and unreadable.  For
> >> readability I also cut down the output to just the bit between times
> >> where there is nothing recording, so in theory nothing before or after
> >> the bit posted would affect the scheduling at the problem time.
> >> 
> >> If, as I am assuming, the P=Priority column is the fully calculated
> >> priority value for the scheduled recording, the I do not understand
> >> what is going on.  The "Seven Sharp" scheduled to actually record from
> >> TVONE PLUS1 has a priority of -4, but the one that is not going to
> >> record from TV ONE has a priority of -3.
> >> 
> >> The channel priorities are: TV ONE is 0, TVONE PLUS1 is -1, which
> >> explains the difference between the two recording priorities.  But it
> >> is still going to record the wrong one.
> >
> >I'm pretty sure Mike meant that to be --testsched and not
> >--printsched.  And don't snip any of the output.  It's the cryptic
> >details that explains what is going on and why.
> >
> >David
> 
> OK, that has a lot more detail.  I have put it here:
> 
>   http://www.jsw.gen.nz/mythtv/testsched.txt

Here's what's happening in a nutshell.  In the initial scheduling
pass, none of the HD showings can be scheduled due to conflicts.  In
the first retry scheduling pass, none of the conflicting programs can
be moved.  In the second retry pass, lower priority showings are tried
and the SD showing at 20:00 is chosen.

The reason adding an override sometimes works is it essentially limits
the second retry pass to the current showing.  FWIW, there are some
minor changes to this area in master (aka pre-0.27).  They might or
might ot help in this particular case.

David
-- 
David Engel
david at istwok.net


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