Add stereo separation filter.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/StereoSeparationFilter.java b/src/main/java/net/pterodactylus/sonitus/data/filter/StereoSeparationFilter.java
new file mode 100644 (file)
index 0000000..d3ec652
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/StereoSeparationFilter.java
@@ -0,0 +1,68 @@
+/*
+ * Sonitus - StereoSeparationFilter.java - Copyright © 2013 David Roden
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sonitus.data.filter;
+
+import java.util.Arrays;
+import java.util.List;
+
+import net.pterodactylus.sonitus.data.Controller;
+import net.pterodactylus.sonitus.data.Filter;
+import net.pterodactylus.sonitus.data.controller.Knob;
+
+/**
+ * {@link Filter} implementation that can reduce the stereo width of a signal,
+ * or even reverse the channels.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class StereoSeparationFilter extends AudioProcessingFilter {
+
+       /** The separation knob. */
+       private final Knob separationKnob;
+
+       /** Creates a new stereo separation filter. */
+       public StereoSeparationFilter() {
+               separationKnob = new Knob("Separation", 1.0);
+       }
+
+       //
+       // CONTROLLED METHODS
+       //
+
+       @Override
+       public List<Controller<?>> controllers() {
+               return Arrays.<Controller<?>>asList(separationKnob);
+       }
+
+       //
+       // AUDIOPROCESSINGFILTER METHODS
+       //
+
+       @Override
+       protected int[] processSamples(int[] samples) {
+               if (samples.length == 1) {
+                       return samples;
+               }
+               int[] processedSamples = new int[samples.length];
+               double a = (separationKnob.value() + 1) / 2.0;
+               processedSamples[0] = (int) (samples[0] * a + samples[1] * (1 - a));
+               processedSamples[1] = (int) (samples[1] * a + samples[0] * (1 - a));
+               return processedSamples;
+       }
+
+}