[mythtv] Change proposal

[Jerry Rubinow]

I'm running a system with a firewire input (for HD), svideo input for
digital channels that are encrypted over the firewire, and an analog
cable input.  The latter two are through a PVR-500.  The firewire and
svideo both come from the tuner on the cable box, so they are mutually
exclusive.

I'm running into problems when it's recording something over firewire
and I go into live tv and it changes channels on the cable box for the
svideo input, messing up the firewire record.

It would be nice if myth knew that two different inputs were going
through the same tuner and could not be used at the same time. 
Consider the following change:

Have another property on each input, a numeric field.  Let's call it
SourceID.  By default it's the same as the input number, but the user
can set two inputs to have the same SourceID.  In the program logic
where it checks if a tuner X is currently in use, also check if any
tuners which have the same SourceID as tuner X are in use.  If so,
consider tuner X as in use.

So questions for the devs: I'm not that familiar with the code - would
this be feasible?  It doesn't seem like it should be a difficult
change.  Just alter the UI for the input setup in mythtv-setup, add a
field to...would it be channelbase?, and change the IsRecording method
in TVRec.  I'm making a ton of assumptions here since I'm not that
familiar with the code - I'm sure it would be more complex than that. 
Plus it means another database table entry, so I won't be surprised if
this isn't acceptable.

But if it is acceptable, it would make things a lot easier for people
who are trying to do the above.  I'd be up for making the change.  Or
attempting it anyway.  I know programming, but not myth, so there'd be
questions.  But if one of the devs wanted to do it, all the better.

-Jerry