[mythtv-users] Input Group Question For Two Dual Tuners

[Joseph Fry]

>
> >This is probably a very old problem, but google isn't turning up anything
> useful that's recent.   I have the backend set up to record a few minutes
> early and a few minutes late for all recordings.   When two shows are
> scheduled to record back-to-back, the second show doesn't record despite
> having four Hauppauge tuners (2 dual pci-e tuners) and separate disks
> dedicated to recording shows.
> >
> >I'm hoping that input groups will solve recording two shows back-to-back,
> but I can't figure them out.
> >
> >I tried adding two new input groups and adding a tuner to each. The
> result was I couldn't watch TV or record and I could not undo the changes
> in the gui. I recreated the 0.28 backend, so currently there is no cruft
> from years of in place upgrades and no fancy settings/setup.  Four tuners
> are minimally configured.
> >Thanks in advance.
>
> Input groups are for tuners that are multi-function, such as DVB-T and
> analogue in the same tuner.  Usually, only one of the two functions
> can be used at the same time, but the two tuners appear as separate
> tuner devices.  So you create an input group and put both tuner
> devices in that group and then mythbackend knows to only use one of
> the tuners at once.  So it is not at all what you want.
>

Stephen is correct, input groups are not what you want.


> To fix your original problem with back to back recordings needing
> overlap, the usually way that is done is to use multirec tuners.  That
> is where each physical tuner has multiple virtual tuners assigned to
> it, all of which can be recording at once.  This is the normal setup
> for DVB-T and DVB-S tuners, where a tuner is capable of tuning to one
> frequency at once, but that frequency can broadcast several channels
> of data multiplexed together.  So you frequently need to record from
> more than one of those channels at once, and it would be very wasteful
> to use a physical tuner for each channel.  MythTV supports up to five
> multirec tuners per physical tuner.  Multirec tuners are also used to
> do the overlap for back to back recordings.  One recording is running
> on one multirec tuner, and the new recording for the same channel gets
> started on a different multirec tuner.
>

MultiRec is not required for back-to-back recordings to function properly.
The way it is supposed to work, and always has on my system, is that:

- if back-to-back shows are on the same channel, it will simply ignore the
extra recording time.
- if back-to-back shows are on different channels, and enough tuners are
available, it will use different tuners.
- if back to back shows are on different channels, and all tuners are in
use, it will ignore the extra recording time at the transition between
shows.

I suspect that the problem is that you set your extra recording time in the
wrong place.  Mythtv has both hard and soft padding.

Hard padding is set in your recording rule for a particular show.  It says
that the scheduler must add X minutes to the beginning/end of the whatever
the guide data says during scheduling.

Soft padding on the other hand is configured under the Video/General setup
options; "Time to record before start of show", "Time to record after end
of show"

Soft padding gives the scheduler flexibility... however it means that every
recording may include the additional time before and after.

I use hard padding to add 60 minutes to sporting event recording rules, in
case they go into overtime or there is a delay during the game.  But I use
soft padding to add a minute to the beginning and end of all my recordings
because occasionally the networks like to start a tad early or end a bit
late.

Additionally, there are settings in the same screen where you apply soft
padding, to apply extra soft padding to recordings in particular categories
(such as sporting events).  I have never used this feature, but then I
don't record many games.

I hope that helps.
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