[mythtv-users] Silly question about live tv and two tuners

[Ronald Frazier]

On Sat, Aug 13, 2011 at 2:52 PM, Larry Finger <Larry.Finger at lwfinger.net> wrote:
> The selection of tuners for recording is based on the entries in the "Capture
> Cards" section. Thus I have listed /dev/video2 first, followed by /dev/video1.
> That setup will do what you want. Recording a single program will select tuner 2
> leaving 1 available for a second recording or live TV.

That doesn't really accomplish what you are suggesting it does. Yes,
it will leave /dev/video1 available, but assuming he's using myth to
do all the recording (vs some outside program explicitly selecting
/dev/video1) he's going to be back to the same situation. Live TV will
select the 1st tuner (which points to /dev/video2) and recordings will
also select the 1st tuner (agaiin, /dev/video2).


> I believe the best procedure is to add each physical tuner as ONE
> tuner, ie no virtual tuners. This makes the two physical tuners number
> 1 and 2.
>
> Then once you have done that, go back and add the virtual tuners,
> which will be 3 and upwards.
>
> Then when you go from tuner 1 to tuner 2, you go to the next physical
> tuner, not the next virtual one.

I'm not positive that's the best idea either. Before I continue, I'll
add the disclaimer that I haven't actually tried multirec in 0.24
(only in 0.22), so it's possible the scheduling algorithm has been
upgraded to make what I'm about to say obsolete.

The problem with adding your real tuners as 1 and 2 and then having
the virtual tuners be 3+ is that myth doesn't seem to have any
preference for using a multirec capable input when possible. If you
have a recording going on tuner 1, and then start a 2nd recording,
myth will pick the next tuner (tuner 2) for the recording, even if the
2nd program is on the same multiplex. It won't care that tuner 3 would
have been a better choice. If instead you group the physical and
virtual tuners together, myth will always use the virtual tuner when
possible, and only fall back to using the 2nd physical tuner when
necessary.

The current version of the wiki also supports this suggestion:
http://www.mythtv.org/wiki/Multirec#Setup_Tuners_.2F_Capture_Cards

-- 
Ron Frazier