Fix 0 BPM when starting carla as transport master, and not rolling

source/backend/engine/CarlaEngine.cpp

@@ -1536,6 +1536,8 @@ void CarlaEngine::transportPause() noexcept
 
 void CarlaEngine::transportBPM(const double bpm) noexcept
 {
+    CARLA_SAFE_ASSERT_RETURN(bpm >= 20.0,)
+
     try {
         pData->time.setBPM(bpm);
     } CARLA_SAFE_EXCEPTION("CarlaEngine::transportBPM");

source/backend/engine/CarlaEngineJack.cpp

@@ -1221,6 +1221,20 @@ public:
     }
 #endif
 
+    void callback(const bool sendHost, const bool sendOsc,
+                  const EngineCallbackOpcode action, const uint pluginId,
+                  const int value1, const int value2, const int value3,
+                  const float valuef, const char* const valueStr) noexcept override
+    {
+        if (action == ENGINE_CALLBACK_PROJECT_LOAD_FINISHED && fTimebaseMaster)
+        {
+            // project finished loading, need to set bpm here, so we force an update of timebase master
+            transportRelocate(pData->timeInfo.frame);
+        }
+
+        CarlaEngine::callback(sendHost, sendOsc, action, pluginId, value1, value2, value3, valuef, valueStr);
+    }
+
     bool setBufferSizeAndSampleRate(const uint bufferSize, const double sampleRate) override
     {
         CARLA_SAFE_ASSERT_RETURN(carla_isEqual(pData->sampleRate, sampleRate), false);

source/frontend/carla_host.py

@@ -838,7 +838,8 @@ class HostWindow(QMainWindow):
                 settings = QSettings()
                 lastBpm  = settings.value("LastBPM", 120.0, type=float)
                 del settings
-                self.host.transport_bpm(lastBpm)
+                if lastBpm >= 20.0:
+                    self.host.transport_bpm(lastBpm)
             return
 
         elif firstInit: