diff --git a/src/pipeline_manager.cpp b/src/pipeline_manager.cpp
index 9a204f0..0f35368 100644
--- a/src/pipeline_manager.cpp
+++ b/src/pipeline_manager.cpp
@@ -120,6 +120,23 @@ bool PipelineManager::setup_pipeline() {
     return true;
 }
 
+gboolean PipelineManager::event_thread_func(gpointer arg) {
+    DataPointer* data = static_cast<DataPointer*>(arg);
+    // show which source camera. called every 4o ms.
+    // if (value==true){
+    // gst_element_set_state (pipeline, GST_STATE_PAUSED);
+    // gst_element_set_state (pipeline, GST_STATE_PLAYING);
+    // IMPORTANT:
+
+    guint show_source = -1;  // which source to show: should be an integer
+                             // between the range (0, num_sources-1)
+    // to show the selected source number only.
+    //  choose show_source=-1 to show the results for all the videos at once
+    g_object_set(G_OBJECT(data->tiler_manager->tiler), "show-source",
+                 show_source, NULL);
+    return true;
+}
+
 bool PipelineManager::create_pipeline_elements(int num_sources,
                                                char** url_camera) {
     streammux_manager->create_streammux(num_sources);
@@ -168,5 +185,12 @@ bool PipelineManager::create_pipeline_elements(int num_sources,
     playing_pipeline(num_sources, url_camera);
     rtsp_streaming_manager->start_rtsp_streaming();
 
+    /* Wait till pipeline encounters an error or EOS */
+    g_print("Running... \n");
+    // event executed every 40 ms for selecting show_source
+
+    DataPointer* pointer_data = new DataPointer{tiler_manager};
+    g_timeout_add(40, event_thread_func, pointer_data);  // NULL
+
     return true;
 }
\ No newline at end of file
diff --git a/src/pipeline_manager.hpp b/src/pipeline_manager.hpp
index 0151141..5f8ccf3 100644
--- a/src/pipeline_manager.hpp
+++ b/src/pipeline_manager.hpp
@@ -31,9 +31,14 @@ class PipelineManager {
     MessageHandling *message_handling = new MessageHandling();
     RtspStreamingManager *rtsp_streaming_manager = new RtspStreamingManager();
 
+    typedef struct {
+        TilerManager *tiler_manager;
+    } DataPointer;
+
    public:
     int current_device = -1;
     struct cudaDeviceProp prop;
+
     QueueManager queue_array[5];
     PipelineManager();
     PipelineManager(int, char **);
@@ -42,5 +47,6 @@ class PipelineManager {
     bool setup_pipeline();
     void playing_pipeline(int, char **);
     void set_cuda_device();
+    static gboolean event_thread_func(gpointer);
     ~PipelineManager();
 };
\ No newline at end of file