use system utilities

@@ -410,7 +410,7 @@ string SrsFlvSegment::generate_path()
     std::string path_config = _srs_config->get_dvr_path(req->vhost);
     
     // add [stream].[timestamp].flv as filename for dir
-    if (path_config.find(".flv") != path_config.length() - 4) {
+    if (!srs_string_ends_with(path_config, ".flv")) {
         path_config += "/[stream].[timestamp].flv";
     }
     

@@ -219,7 +219,7 @@ int SrsFFMPEG::initialize_transcode(SrsConfDirective* engine)
     // for not rtmp input, donot append the iformat,
     // for example, "-f flv" before "-i udp://192.168.1.252:2222"
     // @see https://github.com/simple-rtmp-server/srs/issues/290
-    if (input.find("rtmp://") != 0) {
+    if (!srs_string_starts_with(input, "rtmp://")) {
         iformat = "";
     }