[mythtv] HD-PVR and multirec

[Klaas de Waal]

On Sun, 21 Feb 2021 at 17:19, John P Poet <jppoet at gmail.com> wrote:

>
>
> On Sat, Feb 20, 2021 at 10:40 AM David Engel <david at istwok.net> wrote:
>
>> 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
>>
>
> For capturing from a HD-PVR(v1) MythTV uses the mpegrecorder which does
> not support multirec. If we are talking about the newer HD-PVR2 then it
> works via an ExternalRecorder which does support multirec.
>
> At one point I worked on creating a multi-rec capable V4L2 recorder and
> the code is there, However, for various reasons I ended up removing all
> such devices from my system and cannot guarantee that code works or is
> complete. It has been on my TODO list to re-visit it, but I have never
> gotten around to it.
>
> John
>
>
> The summary is that MythTV-setup "Card Type" entries "V4L2 Encoder" and
"HD-PVR H.264 Encoder" both do NOT support any form of multirec, so they do
not support overlapping recordings. Recording multiple programs is of
course never possible with analog input.
The correct database configuration in table captureard for both card types
is then:
reclimit 1
schedgroup 0
It does not really make sense to make these values editable in mythtv-setup.
I'll have a go at checking this and fixing where needed.

Thanks for clarifying,
Klaas.
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