add song buffer to prevent duplication

mpd_ws.c

@@ -250,7 +250,12 @@ void mpd_ws_update_song(struct mpd_ws_server *server) {
   }
 
   syslog(LOG_DEBUG, "Broadcasting: %s", server->current_song);
-  client_broadcast(server, server->current_song);
+
+  /* Only broadcast if song actually changed */
+  if (strcmp(server->current_song, server->previous_song) != 0) {
+    client_broadcast(server, server->current_song);
+    strcpy(server->previous_song, server->current_song);
+  }
 
   if (song) {
     mpd_song_free(song);

mpd_ws.h

@@ -24,6 +24,7 @@ struct mpd_ws_server {
   struct mpd_connection *mpd_conn;
   struct client_session *clients;
   char current_song[MAX_MESSAGE_SIZE];
+  char previous_song[MAX_MESSAGE_SIZE];
   volatile int running;
   int mpd_idle_active;
 };