[mythtv-users] Live TV playback frustration

[Michael T. Dean]

On 08/24/2012 09:03 AM, Ian Wilkinson wrote:
> On 24/08/2012 11:50, Michael T. Dean wrote:
>> On 08/23/2012 03:15 PM, Ian Wilkinson wrote:
>>> You could setup a recording and watch it live from the recordings
>>> list (as is the recommended method in Myth).  However, if you were
>>> channel surfing and stumbled across it (perhaps you'd forgotten it
>>> was on but fancied watching it there and then), you could wind back
>>> to the start of the show without going to the recordings list.  It
>>> just used the recording file when you reached this channel when surfing.
>>>
>>> Does myth do this? No, it insists on creating two recordings of the
>>> same thing, because myth is not looking at providing the user with
>>> the content, myth is just looking at it as two different consumers
>>> that both happen to be receiving the same data.
>> In MythTV, Live TV has an implied contract that the Live TV viewer is
>> the "owner" of the tuner.  If you were channel surfing and stumbled
>> across a channel on which a scheduled recording is occurring and
>> MythTV noticed and instead started playing back the scheduled
>> recording, it would presumably "release" the tuner you were using for
>> Live TV.  And, unlucky you, your wife just happened to start Live
>> TV--and claim that just-released tuner--right before you hit channel
>> up, again.  Now you've lost your tuner, so what to do?
> Ok so in a two physical tuner system, when two recordings are taking
> place on two different mux, in LiveTV I'm limited to the channels on
> those two mux.  Same deal here, I'm limited to the channels that are now
> available.

No, that's different--you didn't lose your tuner, it only got locked to 
a mux, but you can still switch to any channel on that mux (or any other 
currently-in-use mux).  Being locked to a mux is the result of using a 
"software hack" to pretend you have more tuners than you do.  A physical 
tuner may be locked to a mux and prevent a Live TV user who's using one 
of its virtual tuners from changing channel (with that tuner) to one on 
a different mux.  However, the Live TV user stuck on that mux can still 
change channel between any of the channels on that mux without switching 
physical tuners.  (But in 0.25+, MythTV will actually switch to another 
virtual tuner on a different physical tuner, which may be locked to some 
other mux.)

> So if Myth did go to the tuner that was recording (which sounds like it
> might do with the change in 0.25-fixes that you mention later on), it
> doesn't actually have a different outcome does it?

No, MythTV attempts to change channels with the current Live TV tuner, 
but if the currently-in-use Live TV tuner is locked to a mux, MythTV 
will automatically switch to another tuner when the user requests a 
channel that's only available on another tuner.  Therefore, at the point 
that it has to switch to another tuner (such as the one in use for 
recording the show), the Live TV user was /already/ stuck on a mux.  So, 
nothing at all changed--except which mux the Live TV user is "stuck" on 
(but, in fact, it will also allow the Live TV user to switch back to any 
channel on any other mux that's in use).

> So the situation as you described it:
> I'm on tuner1 is watching something on mux 1, tuner 2 is recording a
> programme on mux 2, I surf to the channel that the recording is taking
> place on, mux 2, so the system changes over to tuner 2.

No, if tuner 1 wasn't already stuck on mux 1, it will change that 
physical tuner to mux 2 (so both tuners are now on mux 2).  (And, yes, 
note that this can--as can /any/ Live TV usage--result in causing tuner 
conflicts for upcoming recordings due to inefficient allocation of 
physical tuners...  But that's what happens when a user controls the 
physical tuner (the definition of Live TV) instead of letting the 
backend plan for usage.)

>    My wife wife
> starts LiveTV on tuner 1 on mux 3, whilst I'm still on mux 2 on tuner 2.
> So now if I try to surf back to mux 1, I can't, but I should be able to
> access anything on mux 2 or mux 3.

Well, your wife would only have been able to choose a channel on mux 1 
because the fact that your Live TV session switched tuners so it could 
view a channel on mux 2 implies that tuner 1 was already locked to mux 
1.  So you could happily go back to channels on mux 1.  However, since 
you only have 2 physical tuners, neither you nor your wife could switch 
to channels on mux 3.

> I think we'll all agree that scheduled recordings are more important
> than LiveTV, and probably most of us have the setting in myth set so
> that LiveTV does not cause rescheduled recordings (as you can't
> guarantee that the programme will be repeated).
> On this basis, how is that different from the following on a system with
> two physical tuners but only one FE:
> I'm on tuner1 is watching something on mux 1, tuner 2 is recording a
> programme on mux 2,  I surf to the channel that the recording is taking
> place on, mux 2, so the system changes over to tuner 2.  A recording now
> starts on tuner 1 on mux 3, whilst I'm still on mux 2 on tuner 2.
> So now if I try to surf back to mux 1, I can't, but I should be able to
> access anything on mux 2 or mux 3.
>
> Neither of these is any different from the original situation when two
> recordings are taking place on two different mux, in LiveTV I'm limited
> to the channels on those two mux.

Again, Live TV only switches tuners if it /has/ to because the physical 
tuner in use for Live TV is already locked to a mux.

>> What you describe is easy to implement in a single-system setup.
>> MythTV is a multi-system DVR that may have more than just one
>> concurrent user on any of potentially many frontend systems.  We need
>> a way to ensure that Live TV continues to work like Live TV even if
>> you surf through channels with scheduled recordings.
> Hopefully from my examples above, I've demonstrated that it is not a
> multi-user problem,

I completely agree.  In your examples, the problem is using virtual 
tuners and assuming they are a valid replacement for a physical tuner.  
:)  That said, your examples don't play out quite like you thought 
because we only switch tuners in 0.25+ if we have to because the tuner 
in use is already locked.  Once this is understood, you'll see that we 
try our best to maintain the contract that a Live TV user owns the 
tuner--and it's only when a Live TV user is using a virtual tuner on a 
physical tuner that's locked to a mux (an "already hobbled" tuner) that 
Live TV switches tuners.  (Or, technically, we'd also switch tuners if 
you requested a channel on a different Video Source that's unavailable 
on the current tuner.)

>   you get the same issues on a single system when it
> can be recording at the same time as you want to view Live TV, and that
> it can be easily resolved by using the existing functionality of limited
> the user the the channels available on the two already tuned mux.
>
> Granted, Myth is a much more complicated system than my single user,
> commercial PVR, but the issues in this case are the same and can be
> resolved in a similar way.
>
>
>>> Don't get me started with the problem with two recordings on the same
>>> mux using both tuners and stopping LiveTV from receiving any other
>>> mux, or the fact that you have to /Manually/ change input to use an
>>> inactive tuner, or to see channels on the other mux if two recordings
>>> are in progress.  My wife asks almost every week why it won't let her
>>> see something on ITV2 when she knows it's recording ITV1 and BBC1,
>>> the Topfield just worked and sorted it out and she knew she couldn't
>>> get to channel 5, etc, but was happy with the experience.
>> 0.25-fixes and above should automatically switch tuners when another
>> tuner is available.  It sounds like you're still on 0.24-fixes or below.
> Yes, I'm still on 0.24-fixes, I've looked at upgrading to 0.25 several
> times, but the number of issues that people seem to still be
> experiencing has put me off.  I just don't need the grief at the moment.
>
> Does this change in 0.25, now resolve the issues around having freeview
> and freesat where some of the channels are available on both platforms,
> but both also exclusive channels?  Previously couldn't just surf from
> "Dave" on Freeview to "CBS Action" on freesat without going into the
> menu and manually changing source.

Yes, MythTV 0.25+ Live TV will allow switching to any available 
channels.  If the channel requested is only available on another 
physical tuner (whether it's due to different Video Sources--i.e. the 
channel is only available from DVB-S but the user is currently watching 
DVB-T--or due to the Live TV physical tuner being locked on a mux and 
the requested channel is on another mux), MythTV will switch tuners.  
(Note, also, that this was the way it was always supposed to work, but a 
couple of devs actually went to the trouble of fixing the bugs that 
prevented it.)

Mike