[mythtv] HD-PVR and multirec

Klaas de Waal klaas.de.waal at gmail.com
Sat Feb 20 16:13:06 UTC 2021


The HD-PVR is a card that encodes an incoming video signal.
It does not have a tuner, it does not receive a multiplex and hence it
cannot support recording different programs
from one multiplex. It might in principle support simultaneous recordings
of the same channel; this can happen
when recordings of different programs are scheduled to overlap.

MythTV behavior for multirec is controlled by two fields in table
reclimit         This is the "Max Recordings" option in mythtv-setup
schedgroup  This is the "Schedule as Group" option in mythtv-setup
The default value for reclimit is 2.
The default value for schedgroup is 1 (true).

For DVB capture cards, with tuners, the reclimit and schedgroup values can
be edited in mythtv-setup
page "Input Connections" / "Interactions Between Inputs".

For HD-PVR cards the "Interactions Between Inputs"  page does not show the
"Max Recordings" and the "Schedule as Group" fields.

When "Schedule as Group" is selected then the scheduler will create
additional virtual tuners (capturecard entries)
when needed for multirec.

When a new HD-PVR tuner is created there is only one entry added to
database table capturecard.
The value of reclimit is 2 which indicates there should also be a second
entry. For DVB cards there are two entries after the "Save and Exit".
The value of schedgroup is 1 (true) which indicates that additional virtual
tuners (entries in capturecard) can be created dynamically.
This currently fails on HD-PVR cards.

Overlapping recordings on the same channel is supported for DVB cards.
I think that this should also be supported for HD-PVR cards.

If this is supported for HD-PVR cards, or if it will be supported, then the
mythtv-setup page needs to be changed so that the
"Max Recordings" and "Schedule as Group" fields can be configured.
Also the number of entries in capturecard will then be what is configured
in "Max Recordings".

If overlapping recordings on the same channel is NOT supported for HD-PVR
cards and if this will not be added then the
mythtv-setup page is correct but the value for "Max Recordings" must then
be 1 and the value  for "Schedule as Group" must be false.

I would like to ask if my understanding of the HD-PVR and the current
behaviour of MythTV with this card is correct,
and what the idea is of what the correct behavior should be.
The next step is then of course to fix it.

N.B. SImilar problems have been reported for "V4L2 Encoder" capture cards,
This has reportedly been fixed by setting reclimit to 1 and schedgroup to 0.
 I might take that along as well.


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