initially pass at libardour VCA implementation

libs/ardour/ardour/gain_control.h

@@ -40,6 +40,7 @@ class LIBARDOUR_API GainControl : public AutomationControl {
 
 	void set_value (double val, PBD::Controllable::GroupControlDisposition group_override);
 	void set_value_unchecked (double);
+	double get_value () const;
 
 	double internal_to_interface (double) const;
 	double interface_to_internal (double) const;
@@ -49,8 +50,13 @@ class LIBARDOUR_API GainControl : public AutomationControl {
 
 	double lower_db;
 	double range_db;
+
+	boost::shared_ptr<GainControl> master() const { return _master; }
+	void set_master (boost::shared_ptr<GainControl>);
+
   private:
 	void _set_value (double val, PBD::Controllable::GroupControlDisposition group_override);
+	boost::shared_ptr<GainControl> _master;
 };
 
 } /* namespace */

libs/ardour/ardour/vca.h

@@ -0,0 +1,53 @@
+/*
+    Copyright (C) 2016 Paul Davis
+
+    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.,
+    675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#ifndef __ardour_vca_h__
+#define __ardour_vca_h__
+
+#include <string>
+#include <boost/shared_ptr.hpp>
+
+#include "pbd/controllable.h"
+
+#include "ardour/session_handle.h"
+
+namespace ARDOUR {
+
+class GainControl;
+class Route;
+
+class LIBARDOUR_API VCA : public SessionHandleRef {
+  public:
+	VCA (Session& session, const std::string& name);
+
+	void set_value (double val, PBD::Controllable::GroupControlDisposition group_override);
+	double get_value () const;
+
+	boost::shared_ptr<AutomationControl> control() const { return _control; }
+
+	void add (boost::shared_ptr<Route>);
+	void remove (boost::shared_ptr<Route>);
+
+  private:
+	std::string name;
+	boost::shared_ptr<GainControl> _control;
+};
+
+} /* namespace */
+
+#endif /* __ardour_vca_h__ */

libs/ardour/gain_control.cc

@@ -36,6 +36,15 @@ GainControl::GainControl (Session& session, const Evoral::Parameter &param, boos
 	range_db = accurate_coefficient_to_dB (_desc.upper) - lower_db;
 }
 
+double
+GainControl::get_value() const
+{
+	if (!_master) {
+		return AutomationControl::get_value();
+	}
+	return AutomationControl::get_value() * _master->get_value();
+}
+
 void
 GainControl::set_value (double val, PBD::Controllable::GroupControlDisposition group_override)
 {
@@ -97,3 +106,29 @@ GainControl::get_user_string () const
 	return std::string(theBuf);
 }
 
+void
+GainControl::set_master (boost::shared_ptr<GainControl> m)
+{
+	double old_master_val;
+
+	if (_master) {
+		old_master_val = _master->get_value();
+	} else {
+		old_master_val = 1.0;
+	}
+
+	_master = m;
+
+	double new_master_val;
+
+	if (_master) {
+		new_master_val = _master->get_value();
+	} else {
+		new_master_val = 1.0;
+	}
+
+	if (old_master_val != new_master_val) {
+		Changed(); /* EMIT SIGNAL */
+	}
+}
+

libs/ardour/vca.cc

@@ -0,0 +1,62 @@
+/*
+    Copyright (C) 2016 Paul Davis
+
+    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.,
+    675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "ardour/automation_control.h"
+#include "ardour/gain_control.h"
+#include "ardour/route.h"
+#include "ardour/vca.h"
+
+using namespace ARDOUR;
+using namespace PBD;
+using std::string;
+
+VCA::VCA (Session& s, const string& n)
+	: SessionHandleRef (s)
+	, name (n)
+	, _control (new GainControl (s, Evoral::Parameter (GainAutomation), boost::shared_ptr<AutomationList> ()))
+{
+}
+
+void
+VCA::set_value (double val, Controllable::GroupControlDisposition gcd)
+{
+	_control->set_value (val, gcd);
+}
+
+double
+VCA::get_value() const
+{
+	return _control->get_value();
+}
+
+void
+VCA::add (boost::shared_ptr<Route> r)
+{
+	boost::dynamic_pointer_cast<GainControl>(r->gain_control())->set_master (_control);
+}
+
+void
+VCA::remove (boost::shared_ptr<Route> r)
+{
+	boost::shared_ptr<GainControl> route_gain = boost::dynamic_pointer_cast<GainControl>(r->gain_control());
+	boost::shared_ptr<GainControl> current_master = route_gain->master();
+
+	if (current_master == _control) {
+		route_gain->set_master (boost::shared_ptr<GainControl>());
+	}
+}

libs/ardour/wscript

@@ -231,6 +231,7 @@ libardour_sources = [
         'unknown_processor.cc',
         'user_bundle.cc',
         'utils.cc',
+        'vca.cc',
         'vumeterdsp.cc',
         'worker.cc'
 ]