[mythtv-users] Hauppauge PVR questions

[Michael T. Dean]

On 10/13/2013 02:41 PM, Jay Ashworth wrote:
> From: "David Engel"
>> The hostility in the past has been because the suggestions were to
>> save cardid/inputid. Those values can change when tuners are added,
>> removed or renumbered making them less useful. The input displaay
>> names can be more descriptive, so using them can solve the tuner
>> change problem. Of course, it's still up to the user to add
>> sufficiently descriptive names.
> And that's patently ridiculous: how often are tuners *actually* changed
> on production machines?  Every 3 or 4 years?

Every boot on some machines (like mine)--depending on which tuner gets 
which number from the kernel.  I have no need for any udev or other 
rules to lock a physical card to a specific kernel number because every 
single one of my cards is "identical" (meaning they're all DVB-API cards 
that are attached to the same Video Source)--despite being 5 distinct 
physical cards from 2 manufacturers with 3 models of card.

In other words, the problem isn't the user changing/swapping/removing 
tuner hardware, but that the only identifier we have in MythTV is /not/ 
necessarily associated with any static value that's useful over time.  
I.e. MythTV's numbers don't necessarily equate to the same physical 
hardware on every run of MythTV.

Plus--and far more importantly--users shouldn't have to do direct 
database queries to figure out what inputid matches up with what 
physical input, so if /any/ code exposes (internal) database ID numbers, 
that code is wrong (and, yes, I know there is code in MythTV that does 
so, and, yes, that code is wrong, too, and needs fixing).

And, FWIW, we also need user-specified card names (to replace the 
"Encoder 4" or whatever on backend status page and Upcoming Recordings 
list).

So, storing the user-specified card input display name would be OK--but 
only if we are sure to make it completely clear that the name can *only* 
match up to the exact same physical hardware if a) the user has only one 
capture device or b) the user does external (non-MythTV) configuration 
of the underlying system to make sure that the physical device matches 
up to the same kernel device on every reboot.  (Which is why we've taken 
the "use the logs" approach in the past--because the value stored to say 
which card my system used in 2006 to record that episode of New Yankee 
Workshop is meaningless information, today, even though I still haven't 
watched the recording and, therefore, still have the recording and its 
metadata.  Having the value in the logs, only, helps to enforce the idea 
that the information is ephemeral, as is the configuration of the system 
at any given time.  That said, I won't complain if someone stores the 
card input display name the user has configured, but *only* of someone 
else explains to them the intricacies of udev and kernel numbers and 
that they can't assume that today's configuration is the same as the one 
that existed a year earlier.  I will complain loudly if someone exposes 
the (database-internal) card input ID to the user. :)

Mike