--- a
+++ b/sc2src/watcher.h
@@ -0,0 +1,34 @@
+/* Copyright (C) 2017 J.F.Dockes
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _WATCHER_H_INCLUDED_
+#define _WATCHER_H_INCLUDED_
+
+#include <string>
+
+#include "conftree.h"
+
+/**
+ Start the watcher thread. If configured, it polls at regular
+ intervals for audio activity (indicated by the queue packet counter,
+ and, depending on configuration parameters, executes the external
+ command with an argument of 'off' if the queue was idle for more
+ than idlesecs seconds, and again with an argument of 'on' as soon as
+ it detects new activity and/or closes/opens the alsa device */
+extern void startWatcher(ConfSimple& config);
+
+#endif /* _WATCHER_H_INCLUDED_ */