From 5b35713111c38108f3560595a0a428836ec6e749 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sun, 9 Jun 2024 12:06:48 +0200
Subject: Make MNSC compatible with Easydabv2 again

---
 src/DabMultiplexer.cpp | 21 ++++++++++++++-------
 src/DabMultiplexer.h   | 14 +++++++++++++-
 2 files changed, 27 insertions(+), 8 deletions(-)

(limited to 'src')

diff --git a/src/DabMultiplexer.cpp b/src/DabMultiplexer.cpp
index b1f2c75..c402d84 100644
--- a/src/DabMultiplexer.cpp
+++ b/src/DabMultiplexer.cpp
@@ -142,6 +142,9 @@ void DabMultiplexer::prepare(bool require_tai_clock)
         offset_ms -= 24;
     }
 
+    mnsc_increment_time = false;
+    mnsc_time = m_edi_time;
+
     etiLog.log(info, "Startup CIF Count %i with timestamp: %d + %f",
             m_currentFrame, m_edi_time,
             (m_timestamp & 0xFFFFFF) / 16384000.0);
@@ -393,6 +396,9 @@ void DabMultiplexer::increment_timestamp()
     if (m_timestamp > 0xf9FFff) {
         m_timestamp -= 0xfa0000; // Substract 16384000, corresponding to one second
         m_edi_time += 1;
+
+        // Also update MNSC time for next time FP==0
+        mnsc_increment_time = true;
     }
 }
 
@@ -554,14 +560,9 @@ void DabMultiplexer::mux_frame(std::vector<std::shared_ptr<DabOutput> >& outputs
 
     eoh->MNSC = 0;
 
-    if (fc->FP == 0) {
-        // update the latched time only when FP==0 to ensure MNSC encodes
-        // a consistent time
-        m_edi_time_latched_for_mnsc = edi_time;
-    }
-
     struct tm time_tm;
-    gmtime_r(&m_edi_time_latched_for_mnsc, &time_tm);
+    gmtime_r(&mnsc_time, &time_tm);
+
     switch (fc->FP & 0x3) {
         case 0:
             {
@@ -571,6 +572,12 @@ void DabMultiplexer::mux_frame(std::vector<std::shared_ptr<DabOutput> >& outputs
                 mnsc->identifier = 0;
                 mnsc->rfa = 0;
             }
+
+            if (mnsc_increment_time)
+            {
+                mnsc_increment_time = false;
+                mnsc_time += 1;
+            }
             break;
         case 1:
             {
diff --git a/src/DabMultiplexer.h b/src/DabMultiplexer.h
index 44155dc..89d547e 100644
--- a/src/DabMultiplexer.h
+++ b/src/DabMultiplexer.h
@@ -88,7 +88,19 @@ class DabMultiplexer : public RemoteControllable {
 
         uint32_t m_timestamp = 0;
         std::time_t m_edi_time = 0;
-        std::time_t m_edi_time_latched_for_mnsc = 0;
+
+        /* Pre v3 odr-dabmux did the MNSC calculation differently,
+         * which works with the easydabv2. The rework in odr-dabmux,
+         * deriving MNSC time from EDI time broke this.
+         *
+         * That's why we're now tracking MNSC time in separate variables,
+         * to get the same behaviour back.
+         *
+         * I'm not aware of any devices using MNSC time besides the
+         * easydab. ODR-DabMod now considers EDI seconds or ZMQ metadata.
+         */
+        bool mnsc_increment_time = false;
+        std::time_t mnsc_time = 0;
 
         edi::configuration_t edi_conf;
         std::shared_ptr<edi::Sender> edi_sender;
-- 
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