[mythtv-users] Input priority

[Michael T. Dean]

On 01/20/2010 09:23 PM, Rod Smith wrote:
> On Wednesday 20 January 2010 06:18:04 pm Kevin Ross wrote:
>   
>> Michael T. Dean wrote:
>>     
>>> [Lots of useful information]
>>>       
>> Okay thanks for clearing that up.  I guess the best way to give one input
>> preference over another is just make sure it has a lower ID (i.e. is added
>> first in mythtv-setup).
>>     
> For INPUTS, yes. For CHANNELS, not necessarily. For instance, my cable company 
> provides digital SD and HD versions of many channels (Science Channel, 
> National Geographic Channel, etc.), so they come over the same input 
> (Firewire in my case). My cable company gives the SD channels lower numbers 
> than the HD channels, so the SD channels get favored by the scheduler. I 
> suppose it would be possible to renumber these channels in MythTV, but then 
> they wouldn't match the numbers used by the cable company, which could be 
> confusing.
>
> I've begun dropping the priority of SD channels with exact HD counterparts 
> when I run into problems with SD being favored over HD. This restores HD 
> recordings in most cases; since the SD and HD channels carry identical 
> content, no recording is lost because of this change,

It still can be.  See the last part of my response to Robin in this thread.

>  although in my case 
> there can still be conflicts (I've got just one cable box, so it's 
> occasionally a scheduling bottleneck). If the SD and HD channels were to 
> deviate in content, then lost recordings would become a possibility; but 
> since the HD channel's priority is unchanged, the two have identical content, 
> and only one can be recorded at a time, the only way I can think of to lose a 
> recording this way is via a record-by-channel rule on the SD channel.
>
> Going further, when the SD and HD channels are on different tuners but they 
> have identical content, a conflict will result in the SD channel being 
> recorded unless there are other shows scheduled at the same time on the SD 
> input. (For me, this is very unlikely; I've got three analog SD tuners, which 
> seldom get used any more.) If a later showing is available and there's no 
> conflict at that time, though, it will be rescheduled for HD recording if the 
> SD channel's priority is reduced. If I simply reordered the tuner cards in 
> the setup and left all channel priorities at 0, this situation would cause 
> the analog station to be recorded in SD at the earlier time. Which behavior 
> is preferable is of course a personal matter, and might also depend on the 
> shows being recorded.
>   

Exactly.  But anyone messing with channel or input priorities needs to
understand what exactly they're telling MythTV--and that what they're
telling MythTV may result in missed recordings.

> Finally, I'm not too worried about conflicts causing problems I never see, 
> since the MythTV scheduler flags conflicts in red. (The color varies with the 
> theme in use.) Conflicts are therefore easy to see when I review upcoming 
> recordings, so spotting them is easier than spotting suboptimal recording 
> quality because the tuner's recording SD when an HD channel is available.
>   

You need to look not just at conflicts, but also at Later showings. 
Those are the problems you never see.  You can have Later's even without
conflicts when differing priorities are involved.  Everything looks
great today, the network changes the schedule, the later showing is
dropped, you have a missed recording an never had a conflict.

However, your use of negative priorities is the better approach if you
are using channel priorities.  You have a good idea of what they do, so
as long as you're willing to live with (and not complain about--or
worse, file tickets about) the consequences, using them is fine.

Mike