[mythtv] HD-PVR and multirec

David Engel david at istwok.net
Sat Feb 20 17:40:05 UTC 2021

On Sat, Feb 20, 2021 at 05:13:06PM +0100, Klaas de Waal wrote:
> Hi,
> 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
> capturecard:
> 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.

I thought multirec is supposed to work for HD-PVRs.  I'm not sure
about other V4L tuners.  John Poet should be able to definitively
answer this.  My understanding is this should all be controlled by
CardUtil::IsTunerSharingCapable().  It doesn't currently include HDPVR
so I could be mistaken about it's capabilities.

David Engel
david at istwok.net

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