My first phase of changes to:

1) Solved CMakeList.txt problem with SDL library
2) Commented out the line of the code that was nagging about unknown tagdata
3) Added the service for turning navdata_demo on/off
4) Sending critical configuration some time after init.

ARDroneLib/Soft/Lib/ardrone_tool/Navdata/navdata.c

@@ -130,7 +130,7 @@ C_RESULT ardrone_navdata_unpack_all(navdata_unpacked_t* navdata_unpacked, navdat
 
 
         default:
-          PRINT("Tag %d is an unknown navdata option tag\n", (int) navdata_option_ptr->tag);
+          //PRINT("Tag %d is an unknown navdata option tag\n", (int) navdata_option_ptr->tag);
           navdata_option_ptr = (navdata_option_t *)(((uint32_t)navdata_option_ptr) + navdata_option_ptr->size);
           break;
       }

CMakeLists.txt

@@ -32,4 +32,4 @@ set(SDK ARDroneLib/)
 link_directories(${PROJECT_SOURCE_DIR}/lib/)
 include_directories(${SDK} ${SDK}/Soft/Common ${SDK}/Soft/Lib ${SDK}/VP_SDK ${SDK}/VP_SDK/VP_Os/linux)
 rosbuild_add_executable(ardrone_driver src/ardrone_driver.cpp src/video.cpp src/ardrone_sdk.cpp src/teleop_twist.cpp)
-target_link_libraries(ardrone_driver vlib pc_ardrone SDL sdk)
+target_link_libraries(ardrone_driver vlib pc_ardrone sdk SDL)

README.md

@@ -1,4 +1,7 @@
 ardrone_brown_mod
 =================
 
-The fork of ardrone_brown ROS driver
+The fork of ardrone_brown ROS driver from 
+
+http://brown-ros-pkg.googlecode.com/svn/trunk/experimental/ardrone_brown --revision 2775
+

src/ardrone_driver.cpp

@@ -20,7 +20,7 @@ ARDroneDriver::ARDroneDriver()
 #ifdef _USING_SDK_1_7_
 	//Ensure that the horizontal camera is running
 	int cam_state = 0; // horizontal
-	int set_navdata_demo_value = 0;
+	int set_navdata_demo_value = 1;
 	ARDRONE_TOOL_CONFIGURATION_ADDEVENT (video_channel, &cam_state, NULL);
 	ARDRONE_TOOL_CONFIGURATION_ADDEVENT (navdata_demo, &set_navdata_demo_value, NULL);
 #else
@@ -29,8 +29,7 @@ ARDroneDriver::ARDroneDriver()
 #endif
 
 	toggleCam_service = node_handle.advertiseService("/ardrone/togglecam", toggleCamCallback);
-
-
+        toggleNavdataDemo_service = node_handle.advertiseService("/ardrone/togglenavdatademo", toggleNavdataDemoCallback);
 }
 
 ARDroneDriver::~ARDroneDriver()
@@ -41,8 +40,41 @@ void ARDroneDriver::run()
 {
 	ros::Rate loop_rate(40);
 
+	int configWate = 250;
+	int cam_state = 0; // horizontal
+	int set_navdata_demo_value = 1; // Low bandwidth usage
+	bool configDone = false;
+        
+        //These are some extra params (experimental)
+        int mCodec = P264_CODEC;
+        int vbcMode = VBC_MODE_DYNAMIC;
+        
 	while (node_handle.ok())
 	{
+		// For some unknown reason, sometimes the ardrone critical configurations are not applied
+		// when the commands are being sent during SDK initialization. This is a trick to send critical 
+		// configurations sometime after SDK boots up. The navdata_demo saves around 300 KBytes/Sec bw!
+		if (configDone == false) 
+		{
+			configWate--;
+			if (configWate == 0) 
+			{
+				configDone = true;
+				fprintf(stderr, "\nSending some critical initial configuration after some delay...\n");
+				#ifdef _USING_SDK_1_7_
+					//Ensure that the horizontal camera is running
+					ARDRONE_TOOL_CONFIGURATION_ADDEVENT (video_channel, &cam_state, NULL);
+					ARDRONE_TOOL_CONFIGURATION_ADDEVENT (navdata_demo, &set_navdata_demo_value, NULL);
+                                        //ARDRONE_TOOL_CONFIGURATION_ADDEVENT (video_codec, &mCodec, NULL);
+                                        //ARDRONE_TOOL_CONFIGURATION_ADDEVENT (bitrate_ctrl_mode, &vbcMode, NULL);
+
+				#else
+					//Ensure that the horizontal camera is running
+					ardrone_at_set_toy_configuration("video:video_channel","0");
+				#endif
+				
+			}
+		}
 		if (current_frame_id != last_frame_id)
 		{
 			publish_video();

src/ardrone_driver.h

@@ -30,6 +30,7 @@ private:
 
 	//ros::Subscriber toggleCam_sub;
 	ros::ServiceServer toggleCam_service;
+        ros::ServiceServer toggleNavdataDemo_service;
 
 	int last_frame_id;
 	int flying_state;

src/teleop_twist.cpp

@@ -7,7 +7,17 @@ bool is_flying = false;
 bool needs_reset = false;
 geometry_msgs::Twist cmd_vel;
 
-int cam_state=0; // 0 for forward and 1 for vertical, change to enum later
+int cam_state = 0; // 0 for forward and 1 for vertical, change to enum later
+int set_navdata_demo_value = TRUE;
+
+
+bool toggleNavdataDemoCallback(std_srvs::Empty::Request& request, std_srvs::Empty::Response& response)
+{
+    set_navdata_demo_value ^= 1;
+    ARDRONE_TOOL_CONFIGURATION_ADDEVENT (navdata_demo, &set_navdata_demo_value, NULL);
+    fprintf(stderr, "\nToggling navdata_demo, set to %d.\n", set_navdata_demo_value);
+    return true;
+}
 
 // ros service callback function for toggling Cam
 bool toggleCamCallback(std_srvs::Empty::Request& request, std_srvs::Empty::Response& response)

src/teleop_twist.h

@@ -17,5 +17,7 @@ void takeoffCallback(const std_msgs::Empty &msg);
 
 //void toggleCamCallback(const std_msgs::Empty &msg);
 bool toggleCamCallback(std_srvs::Empty::Request& request, std_srvs::Empty::Response& response);
+bool toggleNavdataDemoCallback(std_srvs::Empty::Request& request, std_srvs::Empty::Response& response);
+
 #endif