Added AGC filter

src/uk/co/majenko/audiobookrecorder/AGC.java

@@ -0,0 +1,57 @@
+package uk.co.majenko.audiobookrecorder;
+
+import java.util.ArrayList;
+
+public class AGC implements Effect {
+    double limit;
+    double gain;
+    double ceiling;
+    double decay;
+    double attack;
+
+    public AGC(double c, double a, double d, double l) {
+        ceiling = c;
+        attack = a;
+        decay = d;
+        limit = l;
+    }
+
+    public String getName() {
+        return "AGC (Ceiling = " + ceiling + " attack = " + attack + " decay = " + decay + " limit = " + limit;
+    }
+
+    public String toString() {
+        return getName();
+    }
+
+    public double process(double sample) {
+        double absSample = Math.abs(sample) * gain;
+
+        if (absSample > ceiling) {
+            gain -= attack;
+            if (gain < 0) gain = 0;
+        }
+        
+        if (absSample < ceiling) {
+            gain += decay;
+            if (gain > limit) {
+                gain = limit;
+            }
+        }
+
+        sample *= gain;
+
+        return sample;
+    }
+
+    public void init(double sr) {
+    }
+
+    public void dump() {
+        System.out.println(toString());
+    }
+
+    public ArrayList<Effect> getChildEffects() {
+        return null;
+    }
+}

src/uk/co/majenko/audiobookrecorder/AudiobookRecorder.java

@@ -2587,6 +2587,11 @@ System.err.println(format);
                     if (eff != null) {
                         group.addEffect(eff);
                     }
+                } else if (e.getTagName().equals("agc")) {
+                    Effect eff = (Effect)loadAGC(e);
+                    if (eff != null) {
+                        group.addEffect(eff);
+                    }
                 }
             }
         }
@@ -2667,6 +2672,11 @@ System.err.println(format);
                                 if (eff != null) {
                                     store.addEffect(eff);
                                 }
+                            } else if (ie.getTagName().equals("agc")) {
+                                Effect eff = (Effect)loadAGC(ie);
+                                if (eff != null) {
+                                    store.addEffect(eff);
+                                }
                             }
                         }
                     }
@@ -2689,6 +2699,21 @@ System.err.println(format);
         return new LFO(f, d, p);
     }
 
+    public AGC loadAGC(Element root) {
+        double ceiling = Utils.s2d(root.getAttribute("ceiling"));
+        double limit = Utils.s2d(root.getAttribute("limit"));
+        double attack = Utils.s2d(root.getAttribute("attack"));
+        double decay = Utils.s2d(root.getAttribute("decay"));
+        if (ceiling < 0.0001d) {
+            ceiling = 0.708d; // -3dB
+        }
+        if (limit < 0.0001d) {
+            limit = 1d; // No gain
+        }
+        AGC agc = new AGC(ceiling, attack, decay, limit);
+        return agc;
+    }
+
     public void updateEffectChains() {
         int sel = effectChain.getSelectedIndex();
         KVPair<String, String> ent = effectChain.getItemAt(sel);

src/uk/co/majenko/audiobookrecorder/Waveform.java

@@ -62,9 +62,12 @@ public class Waveform extends JPanel implements MouseListener, MouseMotionListen
             g.drawLine(x, 0, x, h);
         }
 
+        int h2 = h/2;
+        int db3 = (int) (h2 * 0.708);
+
         for (int x = 0; x < w; x += 4) {
-            g.drawLine(x, h/4, x, h/4);
-            g.drawLine(x, h/4*3, x, h/4*3);
+            g.drawLine(x, h2 + db3, x, h2 + db3);
+            g.drawLine(x, h2 - db3, x, h2 - db3);
         }
 
         double scale = (h/2);