Move stddev to own filter.

1 files changed, 50 insertions, 0 deletions

diff --git a/src/velocityfilter.cc b/src/velocityfilter.cc
new file mode 100644
index 0000000..e774843
--- /dev/null
+++ b/src/velocityfilter.cc
@@ -0,0 +1,50 @@
+/* -*- Mode: c++ -*- */
+/***************************************************************************
+ *            velocityfilter.cc
+ *
+ *  Sun May 12 16:01:41 CEST 2019
+ *  Copyright 2019 André Nusser
+ *  andre.nusser@googlemail.com
+ ****************************************************************************/
+
+/*
+ *  This file is part of DrumGizmo.
+ *
+ *  DrumGizmo is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  DrumGizmo 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 Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with DrumGizmo; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "velocityfilter.h"
+
+#include "random.h"
+#include "settings.h"
+
+VelocityFilter::VelocityFilter(Settings& settings, Random& random, Instruments const& instruments)
+	: settings(settings), random(random), instruments(instruments)
+{
+}
+
+bool VelocityFilter::filter(event_t& event, size_t pos)
+{
+	auto power_max = instruments[event.instrument]->getMaxPower();
+	auto power_min = instruments[event.instrument]->getMinPower();
+	float power_span = power_max - power_min;
+
+	float mean = event.velocity - .5f/127.f; // XXX: this should actually be done when reading the events
+	float stddev = settings.velocity_stddev.load();
+	// the 20.0f we determined empirically
+	float lvl = power_min + random.normalDistribution(mean, stddev / 20.0f) * power_span;
+
+	event.velocity = lvl;
+	return true;
+}