support user-defined interval between syncing visualizer and audio outputs

src/settings.cpp

@@ -386,6 +386,7 @@ void NcmpcppConfig::SetDefaults()
 	regex_type = 0;
 	lines_scrolled = 2;
 	search_engine_default_search_mode = 0;
+	visualizer_sync_interval = 30;
 	selected_item_suffix_length = 0;
 	now_playing_suffix_length = 0;
 #	ifdef HAVE_LANGINFO_H
@@ -1002,6 +1003,12 @@ void NcmpcppConfig::Read()
 						search_engine_default_search_mode = mode;
 				}
 			}
+			else if (cl.find("visualizer_sync_interval") != std::string::npos)
+			{
+				unsigned interval = StrToInt(v);
+				if (interval)
+					visualizer_sync_interval = interval;
+			}
 			else if (cl.find("song_window_title_format") != std::string::npos)
 			{
 				if (!v.empty())

src/settings.h

@@ -240,6 +240,7 @@ struct NcmpcppConfig
 	
 	unsigned lines_scrolled;
 	unsigned search_engine_default_search_mode;
+	unsigned visualizer_sync_interval;
 	
 	size_t selected_item_suffix_length;
 	size_t now_playing_suffix_length;

src/visualizer.cpp

@@ -111,9 +111,10 @@ void Visualizer::Update()
 		return;
 	}
 	
-	if (itsOutputID != -1 && Global::Timer.tv_sec > itsTimer.tv_sec+120)
+	if (itsOutputID != -1 && Global::Timer.tv_sec > itsTimer.tv_sec+Config.visualizer_sync_interval)
 	{
 		Mpd.DisableOutput(itsOutputID);
+		usleep(50000);
 		Mpd.EnableOutput(itsOutputID);
 		gettimeofday(&itsTimer, 0);
 	}