[mythtv-users] DVB-S2 and DVBT2 via SAT>IP

[Stephen Worthington]

On Mon, 10 Feb 2025 12:11:56 +0000, you wrote:

>Hi Everyone,
>
>I've been experimenting with minisatip on a system that has a TBS Dual 
>S2 card, a TBS Dual T2 card and a Hauppauge DVB-T card. I've been 
>collecting logs and wireshark captures, with various combinations of 
>enabled interfaces, to find out why DVB-S and DVB-T don't work 
>together.  I'm finding that I can get DVB-T to work or DVB-S, but not 
>both together. My aim is to have the host system be a SAT>IP server and 
>run MythTV backend on a VM. It should simplify backend upgrades.
>
>In one of my tests I had two DVB-S2 interfaces enabled and one DVB-T2. I 
>used MythTV to run a DVB-S2 channel scan.
>
>minisatip logs the DVB-S2 request from MythTV like this:-
>
>minisatip[733468]: [02/02 18:32:38.786 main]: detect_dvb_parameters 
>(S)-> 
>fe=1&src=1&freq=11428.00&pol=h&ro=0.35&msys=dvbs&mtype=qpsk&sr=27500&fec=23&plts=auto
>
>A subsequent channel scan of the T2 interface is logged by minisatip 
>like this
>
>[02/02 18:48:09.572 main]: copy_dvb_parameters -> src=1, fe=1, 
>freq=474000, fec=0 sr=0, pol=0, ro=3, msys=3, mtype=0, plts=2, 
>bw=8000000, inv=2, pids=, apids=NULL, dpids=NULL x_pmt=NULL
>
>wireshark captured this request as
>
>rtsp://...:554/?fe=1&freq=474.00&bw=8&msys=dvbt&tmode=auto&mtype=auto&gi=132&fec=auto
>
>This second scan of the T2 source fails with "no channels found".
>
>Notice that in both the S2 scan and the T2 scan, MythTV requests fe=1.
>
>I initially asked about this on the minisatip github and the suggestion 
>from there is that MythTV should omit specifying fe= parameter in its 
>SAT>IP requests. Instead the msys= parameter be used to identify the 
>type of tuner being addressed. I'm aware that there is also a session 
>id. I'm not fully familiar with the SAT>IP Specification, however, I do 
>see the fe= parameter used in many examples in that Specification.
>
>I've kept all the logs and wireshark captures in case they are useful. I 
>could re-run some of my tests, possibly also using dev-fe-tool to track 
>which tuner is actually getting addressed.
>
>Although to me it seems suspicious that, although fe=1 appears in both 
>the S2 and T2 scans, that does not explain why a system with just two 
>S2, or just two T2 tuners is working.
>
>Thoughts???
>
>
>Thanks
>
>Ken

My experience is that minisatip will normally assign tuners as
required, on demand.  I have two MythTV systems sharing seven DVB-S2
tuners from minisatip, and in all cases I have seen, when both MythTV
systems request channels on the same DVB-S2 multiplex, minisatip will
use the same physical tuner to provide the channels.  But since I set
this up before MythTV supported SAT>IP, I am using SAT>IP via IPTV
channels where I set up the URLs, and they do not include an fe=
option.  So I think that the MythTV SAT>IP code should probably be
doing that too, at least as an option.  The same minisatip also has
two DVB-T2 tuners that get used (only occasionally) from DVBViewer on
my Windows box or a third test MythTV setup on another Linux box.

Here is a selection of the URLs that I am using:

MariaDB [mythconverg]> select * from iptv_channel limit 10;
+--------+--------+--------------------------------------------------------------------------------------------------------------------------------------+------+---------+
| iptvid | chanid | url                                                                                                                                  | type | bitrate |
+--------+--------+--------------------------------------------------------------------------------------------------------------------------------------+------+---------+
|     79 |  10008 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12608&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,303,1003,1103,8183 | data |       0 |
|     78 |  10007 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12358&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,307,1007,1107,1907 | data |       0 |
|     77 |  10006 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12581&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,304,1004,1104,8184 | data |       0 |
|     76 |  10005 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12331&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,308,1008,1108      | data |       0 |
|     75 |  10004 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12295&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,307,1007,1107,1907 | data |       0 |
|     74 |  10000 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12519&msys=dvbs&plts=off&fec=34&pol=h&ro=0.35&sr=22500&mtype=qpsk&pids=0,1069,1006,1106,8186 | data |       0 |
|     81 |  10010 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12267&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,305,1005,1105      | data |       0 |
|     82 |  10011 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12707&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,304,1004,1104      | data |       0 |
|     83 |  10014 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12608&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,1079,1007,1107     | data |       0 |
|     84 |  10015 | rtsp://satip.jsw.gen.nz:554/?src=1&freq=12707&msys=dvbs2&plts=off&fec=23&pol=h&ro=0.35&sr=22500&mtype=8psk&pids=0,303,1003,1103,1903 | data |       0 |
+--------+--------+--------------------------------------------------------------------------------------------------------------------------------------+------+---------+
10 rows in set (0.000 sec)

They use msys=dvbs2 or msys=dvbs, or msys=dvbt or msys=dvbt2 to select
the type of tuner needed.

If MythTV sends fe=, I believe that it is effectively claiming
exclusive use of a tuner, and that is bad if you want multiple systems
to access the same SAT>IP tuners, as I do.