[mythtv-users] Live TV playback frustration

[Ian Wilkinson]

On 24/08/2012 16:39, Michael T. Dean wrote:
> 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.)

Right, ok sorry again I didn't make myself clear.  I was suggesting that
if Myth did as you had suggested and swapped onto the tuner that was
recording the programme, when you tried to change channels afterwards
that it wasn't any different to the current situation on a dual tuner
system when both tuners are already in use and you try to start Live TV.

I will concede that if you have a dual tuner system and only allow one
recording per physical tuner (why would you want to do this?) that you
do have a slightly different situation.  However, I still don't see
what's wrong with subsequently being restricted to only viewing channels
on the 2 mux.  If no tuners are free myth when selecting Watch TV, it
should either drop you into one of the recordings and allow you to surf
to the other, or just give you the two choices, rather than telling you
that no tuners are free.

As most of your response seems to be from the point of view of what Myth
does do, rather than what it could do if we swapped to the other tuner,
I've snipped it...

<snip>
>>> 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.)

Why do the tuners have to be allocated at all to a user?
Why can't myth simply treat the tuners as mux sources, and assuming
enough available backend capacity, allow a user to watch any channel in
those available mux?

Or more importantly, why should a user /Care/ about tuners?  When they
hit Watch TV, it should just work and let them view either of the
currently recording programmes, or something else from those mux.  There
shouldn't really be a need to tell the user that a tuner isn't available.

I'd agree that the virtual tuners are a hack to provide additional
recording ability, but in reality it should be enough to setup the
physical tuners then myth should just test to see what the realistic
bandwidth limit is from a tuner and also what the maximum simultaneous
bandwidth is from all tuners and allow myth to create any virtual
devices to fix problem of having to allocate a tuner to a recording
before it takes place.

I have two physical tuners setup as 4 virtual tuners, but I've no idea
what my hardware could cope with as I don't want to be responsible when
the recordings start to fail.

I just figured as the old commercial box used to let us have three
simultaneous streams (two recording to disk and one to watch) from two
tuners so the new one should be able to do at least one better than that.


>>
>>>> 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.)
>
A big Thank You to the (unnamed) Devs!  When I do upgrade I will finally
be able to add the freeview channels into the freesat setup I've got at
the moment without having to take my wife through the additional steps
of changing tuners.

Hum, so in a dual tuner system, one DVB-S and one DVB-T system, with no
virtual tuners.  With no recordings taking place, I can start Live TV
and I can surf from DVB-S to DVB-T and myth will go from one tuner to
the other, if my wife then starts Live TV as well is she then limited to
DVB-S and I become limited to DVB-T?

Ian.