Found a way to unify the hdr_output_folder so that it's set across both

the publisher and the camera_simulator with just the flag

event_camera_simulator/esim_common/src/hdr.cpp

@@ -0,0 +1,9 @@
+#include "esim/common/hdr.hpp"
+
+DEFINE_string(
+    hdr_output_folder,
+    "/home/arno/sim_ws/out",
+    "Folder in which to output the events."
+);
+
+std::string hdr_output_folder = FLAGS_hdr_output_folder;