[mythtv-users] Sharing one STB output across two tuners---scheduler implications

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Sat Mar 3 03:14:08 UTC 2007

Is there some clever way of informing the scheduler that a single
STB's output is routed to the composite input of two different tuners,
to keep it from trying to change the STB's channel in inconsistent ways?

Here's the deal.  I do most of my recording via RF inputs to a batch
of PVR-250's, but I have a single STB whose output is split to two
of those tuners' composite inputs.  Myth understands that it can't
simultaneously use the RF and composite inputs of any given tuner, but
it doesn't understand that it can't simultaneously use both composite
inputs -if they're on different channels- because I don't see a way of
informing it of this situation.

Why would I do such a thing?  Because until Myth understands how to
write to two files simultaneously (and to deal with the resulting
scheduler implications), I can't do pre/postrolls for back-to-back
programming that comes from the STB---one or the other recording must
be dropped, or the postroll of the earlier one and the preroll of the
later one must be manually removed, etc.  And since there's enough
broadcaster jitter that I pre/postroll -everything-, well...

I typically manually schedule anything that's going to be coming from
the STB, and I don't record a huge amount from it, which means that so
far this hasn't been a huge problem.  But I'm going to be increasing
the amount of automatically-scheduled stuff from the STB, and that's
going to increase the chances of an unnoticed collision destroying a
recording (because the other input started recording on another STB
channel and snatched the channel out from under the first input).

I've done some searching for this scenario but haven't found anything;
perhaps I'm not using the right search terms, or perhaps this is rare
enough that nobody else has run into it.  Any clues?  [Note that I'm
running 0.18.1, but if this is fixed in a later release, let me know
and that'll be one more reason to transition.]

[If there's simply no solution in any release---at least until the
simultaneous-file-splitting stuff is implemented in the scheduler
(which would mean I don't even -have- split inputs any more, but which
otherwise might actually help my current problem), then I'll probably
have to write some code which queries the currently-scheduled stuff,
looks for overlaps, and at least alerts me.  Even better would be if
it automatically said "don't record this particular showing" iff that
program (a) was set to record one of that title at any time and (b)
there -was- another which exactly matched its description---that's a
fair bit more work, but if anybody had any skeletal implementations of
pieces, I'd certainly take them... :) ]


P.S.  I'm unsure if this is actually a question for -dev and not
-users, but I guess I'll start here; feel free to move it there if
you want & I'll still see the thread.

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