[mythtv-users] Enabling multirec borks usability a bit.

Simon Waldman lists at firecloud.org.uk
Wed Apr 21 07:09:04 UTC 2010


On Tue, Apr 20, 2010 at 18:47, Michael T. Dean <mtdean at thirdcontact.com> wrote:

> If you're not the sole owner/user of the physical tuner from the point you
> enter Live TV until you exit Live TV, you're not in control of when/if you
> can change channels and what channels are available.  If MythTV just
> switches the active tuner on you during Live TV, you're likely to have some
> very confusing situations arise.  If other people are watching Live TV at
> the same time, your actions and their actions may cause both Live TV users
> to get stuck on a mux neither cares to watch (or cause the other guy to
> steal control from you even though you started watching Live TV first).

Thanks for the explanation. I think what I, and many posters here,
were missing, was the extra complications that are introduced by
having more than one FE using LiveTV at the same time. I'm guessing
that the most common configuration for MythTV is a single combined
FE/BE, and so many of us forget that multiple FEs can be used :-)

This does make it a more complex problem in terms of working out the
optimal behaviour and in designing the UI to make things clear to the
users, when a scheduled recording requires somebody to give up their
LiveTV channel. However, I think that we're looking at two different,
if related, issues, and this is perhaps causing some confusion.

Issue 1: If LiveTV does not have its own dedicated tuner, then logic
and UI issues arise when a scheduled recording requires a tuner that
is in use for LiveTV. These issues are more complex if there is more
than one FE using LiveTV, because there are (potentially)
exponentially more possible actions. However, these already exist in
the current code - if somebody doesn't have enough tuners to dedicate
one to LiveTV, then they can already be presented with the "cancel the
recording or change channel" choice. I don't *think* that any of the
users here are complaining about this, although many of us probably
don't appreciate the complexity of getting it right.

Issue 2: For those of us who can't dedicate a tuner to LiveTV, who are
quite prepared to channel-hop within the confines of the muxes that
are tuned for recordings, channel-hopping does not work between
inputs. I suspect, from this thread, that this is a result of the
"LiveTV needs a dedicated tuner" philosophy, something which I imagine
made much more sense in the days of one-station-per-channel. The
extreme example that has already been given is that if somebody has
one tuner per mux, they should never hit a restriction. The fact that
they can and do indicates that the system currently makes inefficient
use of resources in the multirec world.

I think that each of these two issues exacerbates the other, and that
they are probably best solved together. Without knowing much of Myth's
architecture, I suspect that what may be needed is a wholesale rethink
of the philosophy of scheduling and tuner allocation - I'm guessing
that the current system was designed for a one-tuner-per-station
world, and think that maybe it needs redesigning with multirec in mind
from the beginning - it seems to me that neither the scheduler nor
LiveTV should need to care which tuner it is using, so long as the
station that it wants is available on a tuner somewhere.
Or, maybe I'm wrong. I'm no system architect.

Either way, I thank those who have got Myth to its current state, and
I thank those who are working to improve it in this way or others -
please don't get the impression that I'm not grateful. I just wish,
sometimes, that this sort of discussion was possible without an
immediate assumption of "you're doing it wrong".


-- 
Simon Waldman
swaldman at firecloud.org.uk


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