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diff --git a/src/main/java/com/jsyn/unitgen/VariableRateMonoReader.java b/src/main/java/com/jsyn/unitgen/VariableRateMonoReader.java
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+/*
+ * Copyright 2009 Phil Burk, Mobileer Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.jsyn.unitgen;
+
+import com.jsyn.data.FloatSample;
+import com.jsyn.data.SegmentedEnvelope;
+import com.jsyn.data.ShortSample;
+import com.jsyn.ports.UnitOutputPort;
+
+/**
+ * This reader can play any SequentialData and will interpolate between adjacent values. It can play
+ * both {@link SegmentedEnvelope envelopes} and {@link FloatSample samples}.
+ *
+ * <pre><code>
+	// Queue an envelope to the dataQueue port.
+	ampEnv.dataQueue.queue(ampEnvelope);
+</code></pre>
+ *
+ * @author Phil Burk (C) 2009 Mobileer Inc
+ * @see FloatSample
+ * @see ShortSample
+ * @see SegmentedEnvelope
+ */
+public class VariableRateMonoReader extends VariableRateDataReader {
+    private double phase; // ranges from 0.0 to 1.0
+    private double baseIncrement;
+    private double source;
+    private double current;
+    private double target;
+    private boolean starved;
+    private boolean ranout;
+
+    public VariableRateMonoReader() {
+        super();
+        addPort(output = new UnitOutputPort("Output"));
+        starved = true;
+        baseIncrement = 1.0;
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] amplitudes = amplitude.getValues();
+        double[] rates = rate.getValues();
+        double[] outputs = output.getValues();
+
+        for (int i = start; i < limit; i++) {
+            // Decrement phase and advance through queued data until phase back
+            // in range.
+            if (phase >= 1.0) {
+                while (phase >= 1.0) {
+                    source = target;
+                    phase -= 1.0;
+                    baseIncrement = advanceToNextFrame();
+                }
+            } else if ((i == 0) && (starved || !dataQueue.isTargetValid())) {
+                // A starved condition can only be cured at the beginning of a
+                // block.
+                source = target = current;
+                phase = 0.0;
+                baseIncrement = advanceToNextFrame();
+            }
+
+            // Interpolate along line segment.
+            current = ((target - source) * phase) + source;
+            outputs[i] = current * amplitudes[i];
+
+            double phaseIncrement = baseIncrement * rates[i];
+            phase += limitPhaseIncrement(phaseIncrement);
+        }
+
+        if (ranout) {
+            ranout = false;
+            if (dataQueue.testAndClearAutoStop()) {
+                autoStop();
+            }
+        }
+    }
+
+    public double limitPhaseIncrement(double phaseIncrement) {
+        return phaseIncrement;
+    }
+
+    private double advanceToNextFrame() {
+        // Fire callbacks before getting next value because we already got the
+        // target value previously.
+        dataQueue.firePendingCallbacks();
+        if (dataQueue.hasMore()) {
+            starved = false;
+            target = dataQueue.readNextMonoDouble(getFramePeriod());
+
+            // calculate phase increment;
+            return getFramePeriod() * dataQueue.getNormalizedRate();
+        } else {
+            starved = true;
+            ranout = true;
+            phase = 0.0;
+            return 0.0;
+        }
+    }
+
+}