[mythtv-users] tuner priorities

[Michael T. Dean]

On 12/28/2012 04:50 PM, Tom Hayward wrote:
> On Thu, Dec 27, 2012 at 9:38 AM, Michael T. Dean wrote:
>> I'm making this distinction so that others reading the thread or the
>> archives find the right settings.  Generally speaking, no one should set
>> Input Priority (popularly called "tuner priority").  It's pretty much just a
>> way of saying, "This input is broken but I'd rather get the occasional bad
>> recording out of it than fix my system."
> Sorry to hijack the thread, but how would you classify this use case
> (broken system / sub-optimal configuration / optimal):
>
> I have an HDHomeRun Dual connected to antenna receiving ATSC. Channels
> are generally 12-16 Mbps MPEG2.
>
> I have an HDHomeRun Prime connected to cable receiving QAM. Channels
> are generally 9-12 Mbps MPEG2.
>
> I give the HDHR Dual inputs higher priority because the picture
> quality from ATSC is better. The picture quality from cable isn't bad,
> just not as good as ATSC. Is this optimal or is there a better way to
> encourage programs to record from the higher quality steam?

This is almost definitely a misconfiguration.

The reason is because (as I described in my previous post) priority 
tells MythTV *what* to record--not where to record it.  With your 
configuration, you're telling MythTV, for example, that you'd rather 
record New Girl airing on HDHR Dual/ATSC than record The Walking Dead on 
the HDHR Prime/cable--and, though New Girl is a pretty good show, I'm 
sure no one in their right mind would actually want it over The Walking 
Dead.  ;)  (Because with Input Priorities, you're not saying, "The 
Walking Dead on ATSC is better than The Walking Dead on cable," you're 
saying, "Any garbage on ATSC is better than anything (even different 
shows) on cable,"--of course, to the point of the priority change.  
This, I think, is the reason people expect Input Priority is what they 
want to use--because they think it compares only one show to the same 
show on the other input.  In fact, it compares everything on that input 
to everything else on the other input.)

What you do want to do is tell MythTV the priority of shows (using 
recording rule priorities)--so you can say that The Walking Dead is 
preferred over New Girl--but then tell MythTV that when assigning tuners 
for recording, it should use them in an order that starts with the HDHR 
Dual/ATSC inputs and then goes to HDHR Prime/cable.

When MythTV schedules recordings, it will always put the 
highest-priority shows on the most-preferred (first-ordered) available 
input.  So, it finds the highest-priority show airing, then goes through 
your Schedule Order to find the first-ordered input on which it can 
record that show.  Then it finds the 2nd-highest-priority show airing at 
that same time and assigns it to the 2nd-ordered input.  So, if you set 
your Schedule Order to be HDHR Dual/ATSC #1, then HDHR Dual/ATSC #2, 
then HDHR Prime/cable #1, MythTV will get your favorite shows off 
ATSC--where possible--and only use cable when it has to--which I'm 
pretty sure is exactly what you were trying to tell it to do when you 
set Input Priorities.

If you try to ab^H^Huse Input Priorities to tell MythTV where to record 
shows, you'll end up missing some show you like a lot, then posting a 
thread, "Strange scheduling," or "Scheduling problem," or "Scheduler not 
working," and--after spending a lot of time discussing and looking over 
your scheduler output--our scheduler expert will tell you the problem is 
that you've set Input Priorities such that they told MythTV not to 
record the show you really like.  You may say that's not what you mean 
when you set them, but that's what you're saying when you set them.  If 
you haven't seen this problem, yet, you've either been lucky, or you've 
just failed to notice it, and you'll likely see it one day.

Note, too, that if you've been ab^H^Husing Input Priorities this way and 
you remove them (Delete all capture cards, re-create capture cards, 
re-connect inputs--and doing so won't affect channels or video source 
nor require rescanning, so it's a very quick process) and rely on the 
Schedule Order, you may see changes in the way MythTV schedules things.  
If so, it simply means that you had adapted your recording rule 
priorities in an attempt to take into account the way that Input 
Priorities were breaking scheduling (and ended up with an unstable 
equilibrium, with everything balancing on a needle point), and you may 
need to fine-tune them, again, back to where they should have been for 
it to schedule properly (such that each rule priority tells MythTV how 
much you like that show compared to others).  (So, if you remove the 
Input Priorities and things don't seem to work, please don't say, "It 
doesn't work," without actually looking at/fixing your rule priorities, 
too.  Though, chances are, you won't see this issue--if you were pretty 
good at setting rule priorities in the first place.)

Input Priorities are meant to say, "I'd rather miss a show than record 
it from this tuner."  So, if you have a PVR-150 connected to a digital 
TV converter box or DTA via RF-modulated (channel-3 output) connection, 
and have a couple of HDHR Prime tuners and an HD-PVR (for example), you 
may actually want to reduce the priority of the PVR-150--in which case 
you're saying, "I really don't want to watch any show recorded off the 
150," at which point, you may want to consider why you actually have the 
150 connected (versus just getting more Primes or HD-PVRs or ...).

Similarly, Channel Priority may actually be used to say, "I'd rather 
miss a show than record it off this channel on this input"--for example, 
because the signal you get over the antenna for that channel is really 
poor and results in audio cut-out and picture breakup consistently 
throughout the show.  If all the other channels on the antenna come in 
well, leaving the input connected is still appropriate, though you may 
want to consider removing the "bad channel" from the Video Source, instead.

Mike