[mythtv-users] Ceton vs multirec questions

[f-myth-users at media.mit.edu]

    > Date: Wed, 28 Jul 2021 20:24:19 +1200
    > From: Stephen Worthington <stephen_agent at jsw.gen.nz>

    > This might be as a result of the new "Schedule as a group" option.  If
    > that is set, as I understand it, it overrides the setting for the
    > number of multirec tuners and the system will create virtual tuners as
    > required.  I have never used that option, but I understand it is on by
    > default in new installs.  You find it in mythtv-setup > Input
    > connections > select a tuner > Interactions between inputs.

Interesting.  I can find very little about this via a web search:
  mythtv "schedule as a group"
returns about three not-very-informative hits.  (Which is surprising,
since I'd swear I heard about this on the mailing list some time ago,
and I would have guessed that Google would return those messages.)

However, all six of the real tuners (the first six rows) in my
cpturecard table do have "schedgroup" set to 1.  (And all of the
later entries do not.)

If this really does override reclimit, then obviously fiddling with
that won't matter.  But what does schedgroup buy me?  Overlapping
(same-"channel", from pre/postroll) recordings sharing a tuner? 
(Hope so!)

The other reason I'm confused re multiplexes etc is that if I go to the
web interface for the Ceton, I can clearly see that each channel claims
a whole bunch of "program" entries, and it's a different list for each
individual channel.  (Some are mostly in the 1-10 range; some have half
a dozen entries like 1, 10, 2804, etc.)  My assumption was that these
were different streams multiplexed on the TS stream arriving for that
channel---if I record the card "by hand" using its web interface and
just dump the stream into a file using netcat, things like mpv will
report that there are are huge numbers of audio and video streams:

 (+) Video --vid=1 (mpeg2video 720x480 29.970fps)
     Video --vid=2 (mpeg2video)
     Video --vid=3 (mpeg2video)
     Video --vid=4 (mpeg2video)
     Video --vid=5 (mpeg2video)
     [ . . . ]
     Video --vid=13 (mpeg2video)
     Video --vid=14 (mpeg2video)
 (+) Audio --aid=1 --alang=eng (ac3 2ch 48000Hz)
     Audio --aid=2 --alang=spa (ac3 2ch 48000Hz)
     Audio --aid=3 --alang=eng (ac3)
     Audio --aid=4 --alang=spa (ac3)
     [ . . . ]
     Audio --aid=26 --alang=spa (ac3)
     Subs  --sid=1 (*) (eia_608)

...though only some of them seem playable with --vid=n.

So I don't know if this implies that there really are multiplexes
there that Myth can somehow take advantage of, or not.