@@ -223,6 +223,11 @@ int ffurl_alloc(URLContext **puc, const char *filename, int flags)

     char proto_str[128], proto_nested[128], *ptr;

     size_t proto_len = strspn(filename, URL_SCHEME_CHARS);

+    if (!first_protocol) {

+        av_log(NULL, AV_LOG_WARNING, "No URL Protocols are registered. "

+                                     "Missing call to av_register_all()?\n");

+    }

+

     if (filename[proto_len] != ':' || is_dos_path(filename))

         strcpy(proto_str, "file");

     else