Potential issue about pilots setting and potential fix

[homer314]

Hello Team,
i would like to share my experience with minisatip about Pilot Symbols and listen for your point of view:

My hardware setup is the following:
2x WideBand LNBs -> dcss / Jess multiswitch -> (2 ways Inverto Unicable II IDLU-USP1O5-OUO2O-OBT Splitter) -> DM920 4k with FBC DVB-S2X tuner

My software setup, instead:
minisatip (v2.0.99~b16d810) running on the dreambox with PurE2-Image Enigma2 Image.

minisatip -j 0:4-0985 -d *:1-0 -e 0 -o 127.0.0.1:9000 -R /usr/share/minisatip/html -x 8080 -y 554

My LNBs are pointed to Eutelsat 16 and Hotbird 13: most of the transponsders come with Pilot Symbols disabled. I've no problem scanning or tuning channels on Enigma2. However, for some reason i'm not able to figure out by myself, minisatip's clients are not able to scan or play channels until Pilot Symbols are enabled. This behavior introduce several caveats:

• i need to manually update every single TP in order to enable Pilot Symbols
• clients like Android Apps that don't provide a way to modify this parameter are broken.

Is this something potentially related to my setup?

Side note: I created following patch to mitigate/address this, but i did not create any PR yet because i really would like to get your thought on this first. Thank you!

src/dvb.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 
diff --git a/src/dvb.cpp b/src/dvb.cpp
index e7a5e25..31c53b4 100644
--- a/src/dvb.cpp
+++ b/src/dvb.cpp
@@ -1221,6 +1221,12 @@ int setup_switch(adapter *ad) {
 #define USE_DVBAPI3
 #endif
 
+// Ignore the pilots setting requested by SAT>IP clients and always let the
+// demodulator auto-detect it. See the comment at the DTV_PILOT property below.
+// Set to 0 to honour what the client asks for (the upstream behaviour), which
+// is needed if the demod does not implement PILOT_AUTO.
+#define FORCE_PILOT_AUTO 1
+
 #define ADD_PROP(prop, opt_val, def_val)                                       \
     {                                                                          \
         if ((opt_val).has_value()) {                                           \
@@ -1288,7 +1294,24 @@ int dvb_tune(int aid, transponder *tp) {
 
         ADD_PROP(DTV_SYMBOL_RATE, tp->sr, 0)
         ADD_PROP(DTV_INNER_FEC, tp->fec, FEC_AUTO)
+#if FORCE_PILOT_AUTO
+        // SAT>IP 1.2.2 makes plts mandatory for DVB-S/S2 and allows only
+        // "on" and "off": there is no way for a client to say "let the demod
+        // decide". A client that guesses wrong prevents the frontend from
+        // locking, which forces the user to enable pilots for every
+        // transponder, including those that do not carry them.
+        //
+        // Pilot presence is signalled in the DVB-S2 PLHEADER, so a demod that
+        // supports PILOT_AUTO detects it on its own. Ignore what the client
+        // asked for and let the demod decide.
+        if (tp->plts.has_value() && tp->plts.value() != PILOT_AUTO)
+            LOGM("dvb_tune: overriding client pilots=%d with PILOT_AUTO",
+                 tp->plts.value());
+        p_cmd[iProp].cmd = DTV_PILOT;
+        p_cmd[iProp++].u.data = PILOT_AUTO;
+#else
         ADD_PROP(DTV_PILOT, tp->plts, PILOT_AUTO)
+#endif
         ADD_PROP(DTV_ROLLOFF, tp->ro, ROLLOFF_AUTO)
 #if DVBAPIVERSION >= 0x0502
 #if DVBAPIVERSION >= 0x050b /* 5.11 */