for format_id, format_dict in formats_dict.items():
                 if not isinstance(format_dict, dict):
                     continue
             for format_id, format_dict in formats_dict.items():
                 if not isinstance(format_dict, dict):
                     continue
-                src = format_dict.get('src')
-                if not isinstance(src, compat_str) or not src.startswith('http'):
+                src = url_or_none(format_dict.get('src'))
+                if not src or not src.startswith('http'):