FS-7513 FS-7509: add control for png and fix bug with null args

html5/verto/video_demo/verto.js

@@ -619,10 +619,16 @@ function pop(id, cname, dft) {
     });
 }
 
+var devinit = false;
+
 function refresh_devices()
 {
-    $("#usecamera").empty();
-    $("#usemic").empty();
+    if (devinit) {
+	$("#usecamera").empty();
+	$("#usemic").empty();
+    }
+
+    devinit = true;
 
     $.verto.findDevices(function() {
 	var x = 0;

src/mod/applications/mod_conference/mod_conference.c

@@ -2877,7 +2877,7 @@ static void conference_mod_event_channel_handler(const char *event_channel, cJSO
 		exec = switch_mprintf("%s %s %d %s", conf_name, action, cid, argv[0]);
 	} else if (!strcasecmp(action, "play") || !strcasecmp(action, "stop")) {
 		exec = switch_mprintf("%s %s %s", conf_name, action, argv[0]);
-	} else if (!strcasecmp(action, "recording") || !strcasecmp(action, "vid-layout")) {
+	} else if (!strcasecmp(action, "recording") || !strcasecmp(action, "vid-layout") || !strcasecmp(action, "vid-write-png")) {
 		if (!argv[1]) {
 			argv[1] = "all";
 		}