[mythtv-users] Can MythTV support the new raspberry pi dvbt hat - cheap network tuner?

[Stephen Worthington]

On Sun, 6 Oct 2019 22:33:51 +0100, you wrote:

>I can shed some light on this thread:
>https://lists.gt.net/mythtv/users/620466#620466
>Specifically
>Original post from zackjones88:
>Raspberry Pi have announced a DVBT2 Hat for Pi devices. It is selling for
>approximately 22€. Does anyone know if MythTV can support this
>somehow? Would really like to move to a network tuner so this could be a
>cheap method of giving it a try.
>https://www.raspberrypi.org/products/raspberry-pi-tv-hat Thanks
>
>StevenAgent then replied:
>I do not know specifically about Pis or that tuner. But the general
>rule is that MythTV on Linux supports any tuner that has Linux drivers
>that conform to the Linux DVBAPI specification. So if the tuner has
>drivers that create a /dev/dvb device that looks like this:
>
>root at mypvr:/tmp# ll /dev/dvb/adapter0
>total 0
>drwxr-xr-x 2 root root 120 Oct 8 04:31 ./
>drwxr-xr-x 18 root root 360 Oct 8 04:31 ../
>crw-rw----+ 1 root video 212, 32 Oct 8 04:31 demux0
>crw-rw----+ 1 root video 212, 33 Oct 8 04:31 dvr0
>crw-rw----+ 1 root video 212, 35 Oct 8 04:31 frontend0
>crw-rw----+ 1 root video 212, 34 Oct 8 04:31 net0
>
>then it is likely to work. And so will almost any other Linux
>software that supports DVBAPI tuners.
>
>I've got a raspberry pi 3b with a TV Hat and Raspbian Buster + MythTV-Light
>v0.30, as a slave backend (master on Ubuntu bionic with MythTV v0.30).  It
>doesn't QUITE work.
>The /dev/dev entries are exactly as above, but net0 is missing.  So I guess
>the TV Hat driver doesn't fully implement the Linux DVBAPI specification.
>
>Within MythTV, I can define the card and scan for channels (and it finds
>the channels, including HD channels), but the tuner status shows as
>"errored" in the system info.
>Unless I've done something wrong, then it doesn't appear to work with
>MythTV at present.
>TVHeadend works and can stream TV.

The absence of the net0 device should not be a problem - I do not
think MythTV uses it.  See here for what the devices do:

https://linuxtv.org/downloads/v4l-dvb-apis-new/uapi/dvb/intro.html#linux-digital-tv-devices

If TVHeadend works, then MythTV should.  And if scanning works, the
tuner should work for recording also.  So I am not sure what the
problem is.  Did you make sure that TVHeadend was shut down when you
ran mythbackend?  What user did you run mythtv-setup as?  What user is
mythbackend run as?  What user is TVHeadend run as?

I can see that the ownership and permissions on your tuner devices
looks right, but is the user that runs mythbackend part of the "video"
group?  Or is mythbackend run from root?  One or the other is required
to be able to access the tuner.  To see what groups a user belongs to,
use this command:

groups <username>

It is possible to use the tuner via TVHeadend, as a network tuner. But
then scanning using that tuner does not work and you have to set up
the channels manually unless you have another tuner that does work for
scanning.

I think you will need to delve into the log files to see what the
problem might be.  I am not sure where the mythbackend.log file is on
a Pi, but in Ubuntu it is found in /var/log/mythtv.  To get more
logging of how the tuners are used, add this option to the mythbackend
command line:

-v record

At startup, mythbackend tests each tuner to see if it can use it, and
if that test fails, the tuner is marked as unusable and shows the
error state.  So this is likely what is happening with your tuner.
With the -v record option, the testing of the tuners is logged.

>(As a new user I hope I have done this reply correctly - I wasn't able to
>access the original email to reply to it so had to quote it from the
>archive.  Apols if this is not the right way).